bims-cagime Biomed News
on Cancer, aging and metabolism
Issue of 2020‒08‒16
seventy-six papers selected by
Kıvanç Görgülü
Technical University of Munich

  1. Nat Commun. 2020 Aug 13. 11(1): 4055
    Bechard ME, Smalling R, Hayashi A, Zhong Y, Word AE, Campbell SL, Tran AV, Weiss VL, Iacobuzio-Donahue C, Wellen KE, McDonald OG.
      Although metastasis is the most common cause of cancer deaths, metastasis-intrinsic dependencies remain largely uncharacterized. We previously reported that metastatic pancreatic cancers were dependent on the glucose-metabolizing enzyme phosphogluconate dehydrogenase (PGD). Surprisingly, PGD catalysis was constitutively elevated without activating mutations, suggesting a non-genetic basis for enhanced activity. Here we report a metabolic adaptation that stably activates PGD to reprogram metastatic chromatin. High PGD catalysis prevents transcriptional up-regulation of thioredoxin-interacting protein (TXNIP), a gene that negatively regulates glucose import. This allows glucose consumption rates to rise in support of PGD, while simultaneously facilitating epigenetic reprogramming through a glucose-fueled histone hyperacetylation pathway. Restoring TXNIP normalizes glucose consumption, lowers PGD catalysis, reverses hyperacetylation, represses malignant transcripts, and impairs metastatic tumorigenesis. We propose that PGD-driven suppression of TXNIP allows pancreatic cancers to avidly consume glucose. This renders PGD constitutively activated and enables metaboloepigenetic selection of additional traits that increase fitness along glucose-replete metastatic routes.
  2. Cancer Discov. 2020 Aug 12. pii: CD-20-0442. [Epub ahead of print]
    Zafra MP, Parsons MJ, Kim J, Alonso-Curbelo D, Goswami S, Schatoff EM, Han T, Katti A, Calvo Fernandez MT, Wilkinson JE, Piskounova E, Dow LE.
      KRAS is the most frequently mutated oncogene in cancer, yet there is little understanding of how specific KRAS amino acid changes impact tumor initiation, progression, or therapy response. Using high-fidelity CRISPR-based engineering, we created an allelic series of new LSL-Kras mutant mice, reflecting codon 12 and 13 mutations that are highly prevalent in lung (KRASG12C), pancreas (KRASG12R) and colon (KRASG13D) cancers. Induction of each allele in either the murine colon or pancreas revealed striking quantitative and qualitative differences between KRAS mutants in driving the early stages of transformation. Further, using pancreatic organoid models we show that KRASG13D mutants are sensitive to EGFR inhibition, while KRASG12C mutant organoids are selectively responsive to covalent G12C inhibitors only when EGFR is suppressed. Together, these new mouse strains provide an ideal platform for investigating KRAS biology in vivo and for developing pre-clinical precision oncology models of KRAS-mutant pancreas, colon, and lung cancers.
  3. EMBO Rep. 2020 Aug 11. e48260
    Xu R, Jones W, Wilcz-Villega E, Costa AS, Rajeeve V, Bentham RB, Bryson K, Nagano A, Yaman B, Olendo Barasa S, Wang Y, Chelala C, Cutillas P, Szabadkai G, Frezza C, Bianchi K.
      IκB kinase ε (IKKε) is a key molecule at the crossroads of inflammation and cancer. Known to regulate cytokine secretion via NFκB and IRF3, the kinase is also a breast cancer oncogene, overexpressed in a variety of tumours. However, to what extent IKKε remodels cellular metabolism is currently unknown. Here, we used metabolic tracer analysis to show that IKKε orchestrates a complex metabolic reprogramming that affects mitochondrial metabolism and consequently serine biosynthesis independently of its canonical signalling role. We found that IKKε upregulates the serine biosynthesis pathway (SBP) indirectly, by limiting glucose-derived pyruvate utilisation in the TCA cycle, inhibiting oxidative phosphorylation. Inhibition of mitochondrial function induces activating transcription factor 4 (ATF4), which in turn drives upregulation of the expression of SBP genes. Importantly, pharmacological reversal of the IKKε-induced metabolic phenotype reduces proliferation of breast cancer cells. Finally, we show that in a highly proliferative set of ER negative, basal breast tumours, IKKε and PSAT1 are both overexpressed, corroborating the link between IKKε and the SBP in the clinical context.
    Keywords:  ATF4; IKKε; breast cancer; mitochondrial metabolism; serine biosynthesis
  4. Elife. 2020 Aug 10. pii: e55795. [Epub ahead of print]9
    Zipper L, Jassmann D, Burgmer S, Görlich B, Reiff T.
      Developmental studies revealed fundamental principles on how organ size and function is achieved, but less is known about organ adaptation to new physiological demands. In fruit flies, juvenile hormone (JH) induces intestinal stem cell (ISC) driven absorptive epithelial expansion balancing energy uptake with increased energy demands of pregnancy. Here, we show 20-Hydroxy-Ecdysone (20HE)-signaling controlling organ homeostasis with physiological and pathological implications. Upon mating, 20HE titer in ovaries and hemolymph are increased and act on nearby midgut progenitors inducing Ecdysone-induced-protein-75B (Eip75B). Strikingly, the PPARγ-homologue Eip75B drives ISC daughter cells towards absorptive enterocyte lineage ensuring epithelial growth. To our knowledge, this is the first time a systemic hormone is shown to direct local stem cell fate decisions. Given the protective, but mechanistically unclear role of steroid hormones in female colorectal cancer patients, our findings suggest a tumor-suppressive role for steroidal signaling by promoting postmitotic fate when local signaling is deteriorated.
    Keywords:  D. melanogaster; regenerative medicine; stem cells
  5. Mol Cell. 2020 Jul 29. pii: S1097-2765(20)30470-6. [Epub ahead of print]
    Zhu J, Zhou Q, Xia Y, Lin L, Li J, Peng M, Zhang R, Zhang M.
      Enzymes or enzyme complexes can be concentrated in different cellular loci to modulate distinct functional processes in response to specific signals. How cells condense and compartmentalize enzyme complexes for spatiotemporally distinct cellular events is not well understood. Here we discover that specific and tight association of GIT1 and β-Pix, a pair of GTPase regulatory enzymes, leads to phase separation of the complex without additional scaffolding molecules. GIT1/β-Pix condensates are modular in nature and can be positioned at distinct cellular compartments, such as neuronal synapses, focal adhesions, and cell-cell junctions, by upstream adaptors. Guided by the structure of the GIT/PIX complex, we specifically probed the role of phase separation of the enzyme complex in cell migration and synapse formation. Our study suggests that formation of modular enzyme complex condensates via phase separation can dynamically concentrate limited quantities of enzymes to distinct cellular compartments for specific and optimal signaling.
    Keywords:  GIT/PIX complex; GTPase-activating protein; biological condensates; focal adhesion; guanine nucleotide exchange factor; membrane-less organelles; phase separation; synapse formation
  6. Nat Chem Biol. 2020 Aug 10.
    Soula M, Weber RA, Zilka O, Alwaseem H, La K, Yen F, Molina H, Garcia-Bermudez J, Pratt DA, Birsoy K.
      Cancer cells rewire their metabolism and rely on endogenous antioxidants to mitigate lethal oxidative damage to lipids. However, the metabolic processes that modulate the response to lipid peroxidation are poorly defined. Using genetic screens, we compared metabolic genes essential for proliferation upon inhibition of cystine uptake or glutathione peroxidase-4 (GPX4). Interestingly, very few genes were commonly required under both conditions, suggesting that cystine limitation and GPX4 inhibition may impair proliferation via distinct mechanisms. Our screens also identify tetrahydrobiopterin (BH4) biosynthesis as an essential metabolic pathway upon GPX4 inhibition. Mechanistically, BH4 is a potent radical-trapping antioxidant that protects lipid membranes from autoxidation, alone and in synergy with vitamin E. Dihydrofolate reductase catalyzes the regeneration of BH4, and its inhibition by methotrexate synergizes with GPX4 inhibition. Altogether, our work identifies the mechanism by which BH4 acts as an endogenous antioxidant and provides a compendium of metabolic modifiers of lipid peroxidation.
  7. Nature. 2020 Aug 12.
    Muthusamy T, Cordes T, Handzlik MK, You L, Lim EW, Gengatharan J, Pinto AFM, Badur MG, Kolar MJ, Wallace M, Saghatelian A, Metallo CM.
      Serine, glycine and other nonessential amino acids are critical for tumour progression, and strategies to limit their availability are emerging as potential therapies for cancer1-3. However, the molecular mechanisms driving this response remain unclear and the effects on lipid metabolism are relatively unexplored. Serine palmitoyltransferase (SPT) catalyses the de novo biosynthesis of sphingolipids but also produces noncanonical 1-deoxysphingolipids when using alanine as a substrate4,5. Deoxysphingolipids accumulate in the context of mutations in SPTLC1 or SPTLC26,7-or in conditions of low serine availability8,9-to drive neuropathy, and deoxysphinganine has previously been investigated as an anti-cancer agent10. Here we exploit amino acid metabolism and the promiscuity of SPT to modulate the endogenous synthesis of toxic deoxysphingolipids and slow tumour progression. Anchorage-independent growth reprogrammes a metabolic network involving serine, alanine and pyruvate that drives the endogenous synthesis and accumulation of deoxysphingolipids. Targeting the mitochondrial pyruvate carrier promotes alanine oxidation to mitigate deoxysphingolipid synthesis and improve spheroid growth, similar to phenotypes observed with the direct inhibition of SPT or ceramide synthesis. Restriction of dietary serine and glycine potently induces the accumulation of deoxysphingolipids while decreasing tumour growth in xenograft models in mice. Pharmacological inhibition of SPT rescues xenograft growth in mice fed diets restricted in serine and glycine, and the reduction of circulating serine by inhibition of phosphoglycerate dehydrogenase (PHGDH) leads to the accumulation of deoxysphingolipids and mitigates tumour growth. The promiscuity of SPT therefore links serine and mitochondrial alanine metabolism to membrane lipid diversity, which further sensitizes tumours to metabolic stress.
  8. Nat Commun. 2020 Aug 13. 11(1): 4056
    Bosc C, Broin N, Fanjul M, Saland E, Farge T, Courdy C, Batut A, Masoud R, Larrue C, Skuli S, Espagnolle N, Pagès JC, Carrier A, Bost F, Bertrand-Michel J, Tamburini J, Récher C, Bertoli S, Mansat-De Mas V, Manenti S, Sarry JE, Joffre C.
      Autophagy has been associated with oncogenesis with one of its emerging key functions being its contribution to the metabolism of tumors. Therefore, deciphering the mechanisms of how autophagy supports tumor cell metabolism is essential. Here, we demonstrate that the inhibition of autophagy induces an accumulation of lipid droplets (LD) due to a decrease in fatty acid β-oxidation, that leads to a reduction of oxidative phosphorylation (OxPHOS) in acute myeloid leukemia (AML), but not in normal cells. Thus, the autophagic process participates in lipid catabolism that supports OxPHOS in AML cells. Interestingly, the inhibition of OxPHOS leads to LD accumulation with the concomitant inhibition of autophagy. Mechanistically, we show that the disruption of mitochondria-endoplasmic reticulum (ER) contact sites (MERCs) phenocopies OxPHOS inhibition. Altogether, our data establish that mitochondria, through the regulation of MERCs, controls autophagy that, in turn finely tunes lipid degradation to fuel OxPHOS supporting proliferation and growth in leukemia.
  9. J Biol Chem. 2020 Aug 11. pii: jbc.RA120.014173. [Epub ahead of print]
    Sharma RB, Darko C, Alonso LC.
      Success or failure of pancreatic beta cell adaptation to ER stress is a determinant of diabetes susceptibility. The ATF6 and IRE1/XBP1 pathways are separate ER stress response effectors important to beta cell health and function. ATF6 and XBP1 direct overlapping transcriptional responses in some cell types. However, the signaling dynamics and interdependence of ATF6α and XBP1 in pancreatic beta cells have not been explored. To assess pathway-specific signal onset, we performed timed exposures of primary mouse islet cells to ER stressors and measured the early transcriptional response. Comparing the time course of induction of ATF6 and XBP1 targets suggested the two pathways have similar response dynamics. The role of ATF6α in target induction was assessed by acute knockdown using islet cells from Atf6αflox/flox mice transduced with adenovirus expressing Cre recombinase. Surprisingly given the mild impact of chronic deletion in mice, acute ATF6α knockdown markedly reduced ATF6-pathway target gene expression under both basal and stressed conditions. Intriguingly, while ATF6α knockdown did not alter Xbp1 splicing dynamics or intensity, it did reduce induction of XBP1 targets. Inhibition of Xbp1 splicing did not decrease induction of ATF6α targets. Taken together, these data suggest that the XBP1 and ATF6 pathways are simultaneously activated in islet cells in response to acute stress, and that ATF6α is required for full activation of XBP1 targets, but XBP1 is not required for activation of ATF6α targets. These observations improve understanding of the ER stress transcriptional response in pancreatic islets.
    Keywords:  diabetes; endoplasmic reticulum stress (ER stress); insulin synthesis; pancreatic beta cell; pancreatic islet; unfolded protein response (UPR)
  10. EMBO Rep. 2020 Aug 12. e50718
    Malaquin N, Olivier MA, Martinez A, Nadeau S, Sawchyn C, Coppé JP, Cardin G, Mallette FA, Campisi J, Rodier F.
      Senescent cells display senescence-associated (SA) phenotypic programs such as stable proliferation arrest (SAPA) and a secretory phenotype (SASP). Senescence-inducing persistent DNA double-strand breaks (pDSBs) cause an immediate DNA damage response (DDR) and SAPA, but the SASP requires days to develop. Here, we show that following the immediate canonical DDR, a delayed chromatin accumulation of the ATM and MRN complexes coincides with the expression of SASP factors. Importantly, histone deacetylase inhibitors (HDACi) trigger SAPA and SASP in the absence of DNA damage. However, HDACi-induced SASP also requires ATM/MRN activities and causes their accumulation on chromatin, revealing a DNA damage-independent, non-canonical DDR activity that underlies SASP maturation. This non-canonical DDR is required for the recruitment of the transcription factor NF-κB on chromatin but not for its nuclear translocation. Non-canonical DDR further does not require ATM kinase activity, suggesting structural ATM functions. We propose that delayed chromatin recruitment of SASP modulators is the result of non-canonical DDR signaling that ensures SASP activation only in the context of senescence and not in response to transient DNA damage-induced proliferation arrest.
    Keywords:  DNA damage response; MRN complex; NF-κB; chromatin; senescence secretome
  11. Elife. 2020 Aug 14. pii: e52558. [Epub ahead of print]9
    Panic V, Pearson S, Banks J, Tippetts TS, Velasco-Silva JN, Lee S, Simcox J, Geoghegan G, Bensard CL, van Ry T, Holland WL, Summers SA, Cox J, Ducker GS, Rutter J, Villanueva CJ.
      Brown adipose tissue (BAT) is composed of thermogenic cells that convert chemical energy into heat to help maintain a constant body temperature and counteract metabolic disease in mammals. The metabolic adaptations required for thermogenesis are not fully understood. Here we explore how steady state levels of metabolic intermediates are altered in brown adipose tissue in response to cold exposure. Transcriptome and metabolome analysis revealed changes in pathways involved in amino acid, glucose, and TCA cycle metabolism. Using isotopic labeling experiments, we found that activated brown adipocytes increased labeling of pyruvate and TCA cycle intermediates from U13C-glucose. Although glucose oxidation has been implicated as being essential for thermogenesis, its requirement for efficient thermogenesis has not been directly tested. Here we show that mitochondrial pyruvate uptake is essential for optimal thermogenesis, as conditional deletion of Mpc1 in brown adipocytes leads to impaired cold adaptation. Isotopic labeling experiments using U13C-glucose showed that loss of MPC1 led to impaired labeling of TCA cycle intermediates, while labeling of glycolytic intermediates was unchanged. Loss of MPC1 in BAT increased 3-hydroxybutyrate levels in blood and BAT in response to the cold, suggesting that ketogenesis provides an alternative fuel source to compensate for impaired mitochondrial oxidation of cytosolic pyruvate. Collectively, these studies highlight that complete glucose oxidation is essential for optimal brown fat thermogenesis.
    Keywords:  biochemistry; chemical biology; mouse
  12. Nat Commun. 2020 Aug 11. 11(1): 4012
    Kim HK, Bhattarai KR, Junjappa RP, Ahn JH, Pagire SH, Yoo HJ, Han J, Lee D, Kim KW, Kim HR, Chae HJ.
      Transmembrane B cell lymphoma 2-associated X protein inhibitor motif-containing (TMBIM) 6, a Ca2+ channel-like protein, is highly up-regulated in several cancer types. Here, we show that TMBIM6 is closely associated with survival in patients with cervical, breast, lung, and prostate cancer. TMBIM6 deletion or knockdown suppresses primary tumor growth. Further, mTORC2 activation is up-regulated by TMBIM6 and stimulates glycolysis, protein synthesis, and the expression of lipid synthesis genes and glycosylated proteins. Moreover, ER-leaky Ca2+ from TMBIM6, a unique characteristic, is shown to affect mTORC2 assembly and its association with ribosomes. In addition, we identify that the BIA compound, a potentialTMBIM6 antagonist, prevents TMBIM6 binding to mTORC2, decreases mTORC2 activity, and also regulates TMBIM6-leaky Ca2+, further suppressing tumor formation and progression in cancer xenograft models. This previously unknown signaling cascade in which mTORC2 activity is enhanced via the interaction with TMBIM6 provides potential therapeutic targets for various malignancies.
  13. Nat Commun. 2020 Aug 07. 11(1): 3978
    Xu Q, Li Y, Gao X, Kang K, Williams JG, Tong L, Liu J, Ji M, Deterding LJ, Tong X, Locasale JW, Li L, Shats I, Li X.
      Methionine restriction, a dietary regimen that protects against metabolic diseases and aging, represses cancer growth and improves cancer therapy. However, the response of different cancer cells to this nutritional manipulation is highly variable, and the molecular determinants of this heterogeneity remain poorly understood. Here we report that hepatocyte nuclear factor 4α (HNF4α) dictates the sensitivity of liver cancer to methionine restriction. We show that hepatic sulfur amino acid (SAA) metabolism is under transcriptional control of HNF4α. Knocking down HNF4α or SAA enzymes in HNF4α-positive epithelial liver cancer lines impairs SAA metabolism, increases resistance to methionine restriction or sorafenib, promotes epithelial-mesenchymal transition, and induces cell migration. Conversely, genetic or metabolic restoration of the transsulfuration pathway in SAA metabolism significantly alleviates the outcomes induced by HNF4α deficiency in liver cancer cells. Our study identifies HNF4α as a regulator of hepatic SAA metabolism that regulates the sensitivity of liver cancer to methionine restriction.
  14. J Cell Biol. 2020 Oct 05. pii: e202002120. [Epub ahead of print]219(10):
    Piñeiro-Hermida S, Autilio C, Martínez P, Bosch F, Pérez-Gil J, Blasco MA.
      Short/dysfunctional telomeres are at the origin of idiopathic pulmonary fibrosis (IPF) in patients mutant for telomere maintenance genes. However, it remains unknown whether physiological aging leads to short telomeres in the lung, thus leading to IPF with aging. Here, we find that physiological aging in wild-type mice leads to telomere shortening and a reduced proliferative potential of alveolar type II cells and club cells, increased cellular senescence and DNA damage, increased fibroblast activation and collagen deposits, and impaired lung biophysics, suggestive of a fibrosis-like pathology. Treatment of both wild-type and telomerase-deficient mice with telomerase gene therapy prevented the onset of lung profibrotic pathologies. These findings suggest that short telomeres associated with physiological aging are at the origin of IPF and that a potential treatment for IPF based on telomerase activation would be of interest not only for patients with telomerase mutations but also for sporadic cases of IPF associated with physiological aging.
  15. Semin Immunopathol. 2020 Aug 12.
    Frasca D, Blomberg BB.
      Obesity represents a serious health problem as it is rapidly increasing worldwide. Obesity is associated with reduced healthspan and lifespan, decreased responses to infections and vaccination, and increased frequency of inflammatory conditions typical of old age. Obesity is characterized by increased fat mass and remodeling of the adipose tissue (AT). In this review, we summarize published data on the different types of AT present in mice and humans, and their roles as fat storage as well as endocrine and immune tissues. We review the age-induced changes, including those in the distribution of fat in the body, in abundance and function of adipocytes and their precursors, and in the infiltration of immune cells from the peripheral blood. We also show that cells with a senescent-associated secretory phenotype accumulate in the AT of mice and humans with age, where they secrete several factors involved in the establishment and maintenance of local inflammation, oxidative stress, cell death, tissue remodeling, and infiltration of pro-inflammatory immune cells. Not only adipocytes and pre-adipocytes but also immune cells show a senescent phenotype in the AT. With the increase in human lifespan, it is crucial to identify strategies of intervention and target senescent cells in the AT to reduce local and systemic inflammation and the development of age-associated diseases. Several studies have indeed shown that senescent cells can be effectively targeted in the AT by selectively removing them or by inhibiting the pathways that lead to the secretion of pro-inflammatory factors.
    Keywords:  Adipocytes; Adipose tissue; Aging; Cell senescence; Immune cells
  16. Rev Physiol Biochem Pharmacol. 2020 Aug 14.
    Danese A, Marchi S, Vitto VAM, Modesti L, Leo S, Wieckowski MR, Giorgi C, Pinton P.
      Endoplasmic reticulum (ER)-mitochondria regions are specialized subdomains called also mitochondria-associated membranes (MAMs). MAMs allow regulation of lipid synthesis and represent hubs for ion and metabolite signaling. As these two organelles can module both the amplitude and the spatiotemporal patterns of calcium (Ca2+) signals, this particular interaction controls several Ca2+-dependent pathways well known for their contribution to tumorigenesis, such as metabolism, survival, sensitivity to cell death, and metastasis. Mitochondria-mediated apoptosis arises from mitochondrial Ca2+ overload, permeabilization of the mitochondrial outer membrane, and the release of mitochondrial apoptotic factors into the cytosol. Decreases in Ca2+ signaling at the ER-mitochondria interface are being studied in depth as failure of apoptotic-dependent cell death is one of the predominant characteristics of cancer cells. However, some recent papers that linked MAMs Ca2+ crosstalk-related upregulation to tumor onset and progression have aroused the interest of the scientific community.In this review, we will describe how different MAMs-localized proteins modulate the effectiveness of Ca2+-dependent apoptotic stimuli by causing both increases and decreases in the ER-mitochondria interplay and, specifically, by modulating Ca2+ signaling.
    Keywords:  Calcium; Calcium signaling; Cancer; Downregulation; MAMs; Upregulation
  17. Free Radic Biol Med. 2020 Aug 05. pii: S0891-5849(20)31183-7. [Epub ahead of print]
    Utyro O, Perła-Kaján J, Kubalska J, Graban A, Jakubowski H.
      Telomere shortening and mitochondrial DNA (mtDNA) copy number are associated with human disease and a reduced life span. Cystathionine β-synthase (CBS) is a housekeeping enzyme that catalyzes the first step in metabolic conversion of homocysteine (Hcy) to cysteine. Mutations in the CBS gene cause CBS deficiency, a rare recessive metabolic disease, manifested by severe hyperhomocysteinemia (HHcy) and thromboembolism, which ultimately reduces the life span. However, it was not known whether telomere shortening or mtDNA is involved in the pathology of human CBS deficiency. We quantified leukocyte telomere length (TL), mtDNA copy number, and plasma Hcy levels in CBS-/- patients (n=23) and in sex- and age-matched unaffected CBS+/+ control individuals (n=28) 0.1 to 57 years old. We found that TL was significantly increased in severely HHcy CBS-/- female patients but unaffected in severely HHcy CBS-/- male patients, relative to the corresponding CBS+/+ controls who had normal plasma Hcy levels. In multiple regression analysis TL was associated with CBS genotype in women but not in men. MtDNA copy number was not significantly affected by the CBS-/- genotype. Taken together, these findings identify the CBS gene as a new locus in human DNA that affects TL in women and illustrate a concept that a housekeeping metabolic gene can be involved in telomere biology. Our findings suggest that neither telomere shortening nor reduced mtDNA copy number contribute to the reduced life span in CBS-/- patients.
    Keywords:  cystathionine β-synthase deficiency; homocysteine; life span; mtDNA; telomere dynamics; thromboembolism
  18. EMBO J. 2020 Aug 13. e104063
    Wu SZ, Roden DL, Wang C, Holliday H, Harvey K, Cazet AS, Murphy KJ, Pereira B, Al-Eryani G, Bartonicek N, Hou R, Torpy JR, Junankar S, Chan CL, Lam CE, Hui MN, Gluch L, Beith J, Parker A, Robbins E, Segara D, Mak C, Cooper C, Warrier S, Forrest A, Powell J, O'Toole S, Cox TR, Timpson P, Lim E, Liu XS, Swarbrick A.
      The tumour stroma regulates nearly all stages of carcinogenesis. Stromal heterogeneity in human triple-negative breast cancers (TNBCs) remains poorly understood, limiting the development of stromal-targeted therapies. Single-cell RNA sequencing of five TNBCs revealed two cancer-associated fibroblast (CAF) and two perivascular-like (PVL) subpopulations. CAFs clustered into two states: the first with features of myofibroblasts and the second characterised by high expression of growth factors and immunomodulatory molecules. PVL cells clustered into two states consistent with a differentiated and immature phenotype. We showed that these stromal states have distinct morphologies, spatial relationships and functional properties in regulating the extracellular matrix. Using cell signalling predictions, we provide evidence that stromal-immune crosstalk acts via a diverse array of immunoregulatory molecules. Importantly, the investigation of gene signatures from inflammatory-CAFs and differentiated-PVL cells in independent TNBC patient cohorts revealed strong associations with cytotoxic T-cell dysfunction and exclusion, respectively. Such insights present promising candidates to further investigate for new therapeutic strategies in the treatment of TNBCs.
    Keywords:  cancer-associated fibroblasts; single-cell RNA sequencing; stromal heterogeneity; triple-negative breast cancer; tumour microenvironment
  19. Nat Commun. 2020 Aug 07. 11(1): 3944
    Caillon L, Nieto V, Gehan P, Omrane M, Rodriguez N, Monticelli L, Thiam AR.
      Triacylglycerols (TG) are synthesized at the endoplasmic reticulum (ER) bilayer and packaged into organelles called lipid droplets (LDs). LDs are covered by a single phospholipid monolayer contiguous with the ER bilayer. This connection is used by several monotopic integral membrane proteins, with hydrophobic membrane association domains (HDs), to diffuse between the organelles. However, how proteins partition between ER and LDs is not understood. Here, we employed synthetic model systems and found that HD-containing proteins strongly prefer monolayers and returning to the bilayer is unfavorable. This preference for monolayers is due to a higher affinity of HDs for TG over membrane phospholipids. Protein distribution is regulated by PC/PE ratio via alterations in monolayer packing and HD-TG interaction. Thus, HD-containing proteins appear to non-specifically accumulate to the LD surface. In cells, protein editing mechanisms at the ER membrane would be necessary to prevent unspecific relocation of HD-containing proteins to LDs.
  20. JCI Insight. 2020 Aug 11. pii: 141115. [Epub ahead of print]
    Xia H, Li S, Li X, Wang W, Bian Y, Wei S, Grove S, Wang W, Vatan L, Liu JR, McLean K, Rattan R, Munkarah AR, Guan JL, Kryczek I, Zou W.
      Tumor-associated macrophages (TAMs) affect cancer progression and therapy. Ovarian carcinoma often metastasizes to the peritoneal cavity. Here, we found two peritoneal macrophage subsets in mice bearing ID8 ovarian cancer based on the Tim-4 (T-cell immunoglobulin and mucin domain containing 4) expression. Tim-4+ TAMs were embryonically originated and locally sustained while Tim-4- TAMs were replenished from circulating monocytes. Tim-4+ TAMs, but not Tim-4- TAMs, promoted tumor growth in vivo. Relative to Tim-4- TAMs, Tim-4+ TAMs manifested high oxidative phosphorylation and adapted mitophagy to alleviate oxidative stress. High levels of arginase-1 in Tim-4+ TAMs contributed to potent mitophagy activities via weakened mTORC1 activation due to low arginine resultant from arginase-1-mediated metabolism. Furthermore, genetic deficiency of autophagy element FIP200 resulted in Tim-4+ TAM loss via ROS-mediated apoptosis, and elevated T cell-immunity and ID8 tumor inhibition in vivo. Moreover, human ovarian cancer-associated CRIg (complement receptor of the Immunoglobulin superfamily) positive macrophages were transcriptionally, metabolically, and functionally similar to murine Tim-4+ TAMs. Thus, targeting CRIg+ (Tim-4+) TAMs may potentially treat ovarian cancer patients with peritoneal metastasis.
    Keywords:  Cancer; Immunology
  21. Nat Methods. 2020 Aug 10.
    Schiavon CR, Zhang T, Zhao B, Moore AS, Wales P, Andrade LR, Wu M, Sung TC, Dayn Y, Feng JW, Quintero OA, Shadel GS, Grosse R, Manor U.
      The actin cytoskeleton plays multiple critical roles in cells, from cell migration to organelle dynamics. The small and transient actin structures regulating organelle dynamics are challenging to detect with fluorescence microscopy, making it difficult to determine whether actin filaments are directly associated with specific membranes. To address these limitations, we developed fluorescent-protein-tagged actin nanobodies, termed 'actin chromobodies' (ACs), targeted to organelle membranes to enable high-resolution imaging of sub-organellar actin dynamics.
  22. Nat Commun. 2020 Aug 14. 11(1): 4085
    Noë M, Niknafs N, Fischer CG, Hackeng WM, Beleva Guthrie V, Hosoda W, Debeljak M, Papp E, Adleff V, White JR, Luchini C, Pea A, Scarpa A, Butturini G, Zamboni G, Castelli P, Hong SM, Yachida S, Hiraoka N, Gill AJ, Samra JS, Offerhaus GJA, Hoorens A, Verheij J, Jansen C, Adsay NV, Jiang W, Winter J, Albores-Saavedra J, Terris B, Thompson ED, Roberts NJ, Hruban RH, Karchin R, Scharpf RB, Brosens LAA, Velculescu VE, Wood LD.
      Intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs) are non-invasive neoplasms that are often observed in association with invasive pancreatic cancers, but their origins and evolutionary relationships are poorly understood. In this study, we analyze 148 samples from IPMNs, MCNs, and small associated invasive carcinomas from 18 patients using whole exome or targeted sequencing. Using evolutionary analyses, we establish that both IPMNs and MCNs are direct precursors to pancreatic cancer. Mutations in SMAD4 and TGFBR2 are frequently restricted to invasive carcinoma, while RNF43 alterations are largely in non-invasive lesions. Genomic analyses suggest an average window of over three years between the development of high-grade dysplasia and pancreatic cancer. Taken together, these data establish non-invasive IPMNs and MCNs as origins of invasive pancreatic cancer, identifying potential drivers of invasion, highlighting the complex clonal dynamics prior to malignant transformation, and providing opportunities for early detection and intervention.
  23. J Am Chem Soc. 2020 Aug 13.
    Yoo DY, Barros SA, Brown GC, Rabot C, Bar-Sagi D, Arora PS.
      Peptides and peptidomimetics represent the middle space between small molecules and large proteins-they retain the relatively small size and synthetic accessibility of small molecules while providing high binding specificity for biomolecular partners typically observed with proteins. During the course of our efforts to target intracellular protein-protein interactions in cancer, we observed that the cellular uptake of peptides is critically determined by the cell line-specifically, we noted that peptides show better uptake in cancer cells with enhanced macropinocytic indices. Here, we describe the results of our analysis of cellular penetration by different classes of conformationally stabilized peptides. We tested the uptake of linear peptides, peptide macrocycles, stabilized helices, β-hairpin peptides, and cross-linked helix dimers in 11 different cell lines. Efficient uptake of these conformationally defined constructs directly correlated with the macropinocytic activity of each cell line: high uptake of compounds was observed in cells with mutations in certain signaling pathways. Significantly, the study shows that constrained peptides follow the same uptake mechanism as proteins in macropinocytic cells, but unlike proteins, peptide mimics can be readily designed to resist denaturation and proteolytic degradation. Our findings expand the current understanding of cellular uptake in cancer cells by designed peptidomimetics and suggest that cancer cells with certain mutations are suitable mediums for the study of biological pathways with peptide leads.
  24. Science. 2020 Aug 13. pii: eabc3421. [Epub ahead of print]
    Mager LF, Burkhard R, Pett N, Cooke NCA, Brown K, Ramay H, Paik S, Stagg J, Groves RA, Gallo M, Lewis IA, Geuking MB, McCoy KD.
      Several species of intestinal bacteria have been associated with enhanced efficacy of checkpoint blockade immunotherapy, but the underlying mechanisms by which the microbiome enhances anti-tumor immunity is unclear. Here, we isolated three bacterial species, including Bifidobacterium pseudolongum, Lactobacillus johnsonii and Olsenella species, that significantly enhanced efficacy of immune checkpoint inhibitors in four mouse models of cancer. We found that intestinal B. pseudolongum modulated enhanced immunotherapy response through production of the metabolite inosine. Decreased gut barrier function induced by immunotherapy increased systemic translocation of inosine and activated anti-tumor T cells. The effect of inosine was dependent on T cell expression of the adenosine A2A receptor and required co-stimulation. Collectively, our study identifies a novel microbial metabolite-immune pathway that is activated by immunotherapy that may be exploited to develop microbial-based adjuvant therapies.
  25. Cancer Metastasis Rev. 2020 Aug 11.
    Avula LR, Hagerty B, Alewine C.
      Pancreatic cancer is the third leading cause of cancer death in the USA, and pancreatic ductal adenocarcinoma (PDA) constitutes 85% of pancreatic cancer diagnoses. PDA frequently metastasizes to the peritoneum, but effective treatment of peritoneal metastasis remains a clinical challenge. Despite this unmet need, understanding of the biological mechanisms that contribute to development and progression of PDA peritoneal metastasis is sparse. By contrast, a vast number of studies have investigated mechanisms of peritoneal metastasis in ovarian and gastric cancers. Here, we contrast similarities and differences between peritoneal metastasis in PDA as compared with those in gastric and ovarian cancer by outlining molecular mediators involved in each step of the peritoneal metastasis cascade. This review aims to provide mechanistic insights that could be translated into effective targeted therapies for patients with peritoneal metastasis from PDA.
    Keywords:  Gastric cancer; Ovarian cancer; Pancreatic adenocarcinoma; Peritoneal metastasis
  26. Am J Cancer Res. 2020 ;10(7): 1937-1953
    Wang S, Li Y, Xing C, Ding C, Zhang H, Chen L, You L, Dai M, Zhao Y.
      Pancreatic cancer (PC) is a fatal disease with high malignancy and difficult for early diagnosis. PC causes more than 400,000 patient deaths world widely and becomes the severe health problems. The tumor microenvironment (TME) is comprised of acellular stroma, pancreatic stellate cells, immune cells, and soluble factors. TME is maintained by continuous cell-matrix and cell-cell interactions. TME induced by the interaction among pancreatic cancer cells, epithelial cells and stromal cells is essential for the progression of PC and leads to resistance to chemotherapy. Components in the microenvironment can also promote the formation of connective tissue in the primary or metastatic site, or promote the metastatic ability of PC by enhancing angiogenesis, epithelial-mesenchymal transformation, and lymph angiogenesis. In addition, the TME also leaves pancreatic cancer unsusceptible to different immunotherapeutic strategies. In this review, we summarized the current knowledge about TME in PC. And the focus was placed on the role of TME in chemotherapeutic resistance and metastasis in the field of PC. And we also paid attention to the immunological therapy targeting the TME, aiming to provide the novel therapy for pancreatic cancer.
    Keywords:  Pancreatic cancer; chemoresistance; immunotherapy; metastasis; tumor microenvironment
  27. Cell Metab. 2020 Aug 10. pii: S1550-4131(20)30371-5. [Epub ahead of print]
    Hui S, Cowan AJ, Zeng X, Yang L, TeSlaa T, Li X, Bartman C, Zhang Z, Jang C, Wang L, Lu W, Rojas J, Baur J, Rabinowitz JD.
      Mammalian organs are nourished by nutrients carried by the blood circulation. These nutrients originate from diet and internal stores, and can undergo various interconversions before their eventual use as tissue fuel. Here we develop isotope tracing, mass spectrometry, and mathematical analysis methods to determine the direct sources of circulating nutrients, their interconversion rates, and eventual tissue-specific contributions to TCA cycle metabolism. Experiments with fifteen nutrient tracers enabled extensive accounting for both circulatory metabolic cycles and tissue TCA inputs, across fed and fasted mice on either high-carbohydrate or ketogenic diet. We find that a majority of circulating carbon flux is carried by two major cycles: glucose-lactate and triglyceride-glycerol-fatty acid. Futile cycling through these pathways is prominent when dietary content of the associated nutrients is low, rendering internal metabolic activity robust to food choice. The presented in vivo flux quantification methods are broadly applicable to different physiological and disease states.
    Keywords:  TCA cycle; circulating metabolites; energy metabolism; in vivo flux quantification; isotope tracing; ketogenic diet; metabolic cycling
  28. Sci Adv. 2020 Jul;6(31): eabb2529
    Zhu D, Wu X, Zhou J, Li X, Huang X, Li J, Wu J, Bian Q, Wang Y, Tian Y.
      Mild mitochondrial stress experienced early in life can have beneficial effects on the life span of organisms through epigenetic regulations. Here, we report that acetyl-coenzyme A (CoA) represents a critical mitochondrial signal to regulate aging through the chromatin remodeling and histone deacetylase complex (NuRD) in Caenorhabditis elegans. Upon mitochondrial stress, the impaired tricarboxylic acid cycle results in a decreased level of citrate, which accounts for reduced production of acetyl-CoA and consequently induces nuclear accumulation of the NuRD and a homeodomain-containing transcription factor DVE-1, thereby enabling decreased histone acetylation and chromatin reorganization. The metabolic stress response is thus established during early life and propagated into adulthood to allow transcriptional regulation for life-span extension. Furthermore, adding nutrients to restore acetyl-CoA production is sufficient to counteract the chromatin changes and diminish the longevity upon mitochondrial stress. Our findings uncover the molecular mechanism of the metabolite-mediated epigenome for the regulation of organismal aging.
  29. Aging Cell. 2020 Aug 11. e13211
    Gao F, Zhang Y, Hou X, Tao Z, Ren H, Wang G.
      Accumulation of PINK1 on the outer mitochondrial membrane (OMM) is necessary for PINK-mediated mitophagy. The proton ionophores, like carbonyl cyanide m-chlorophenylhydrazone (CCCP) and carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP), inhibit PINK1 import into mitochondrial matrix and induce PINK1 OMM accumulation. Here, we show that the CHCHD4/GFER disulfide relay system in the mitochondrial intermembrane space (IMS) is required for PINK1 stabilization when mitochondrial membrane potential is lost. Activation of CHCHD4/GFER system by mitochondrial oxidative stress or inhibition of CHCHD4/GFER system with antioxidants can promote or suppress PINK1 accumulation, respectively. Thus data suggest a pivotal role of CHCHD4/GFER system in PINK1 accumulation. The amyotrophic lateral sclerosis-related superoxide dismutase 1 mutants dysregulated redox state and CHCHD4/GFER system in the IMS, leading to inhibitions of PINK1 accumulation and mitophagy. Thus, the redox system in the IMS is involved in PINK1 accumulation and damaged mitochondrial clearance, which may play roles in mitochondrial dysfunction-related neurodegenerative diseases.
    Keywords:  PINK1; autophagy; mitochondrion; mitophagy; neurodegenerative diseases
  30. Elife. 2020 Aug 10. pii: e58463. [Epub ahead of print]9
    Fernandes RA, Li C, Wang G, Yang X, Savvides CS, Glassman CR, Dong S, Luxenberg E, Sibener LV, Birnbaum ME, Benoist C, Mathis D, Garcia KC.
      T regulatory (Treg) cells play vital roles in modulating immunity and tissue homeostasis. Their actions depend on TCR recognition of peptide-MHC molecules; yet the degree of peptide specificity of Treg-cell function, and whether Treg ligands can be used to manipulate Treg cell biology are unknown. Here, we developed an Ab-peptide library that enabled unbiased screening of peptides recognized by a bona fide murine Treg cell clone isolated from the visceral adipose tissue (VAT), and identified surrogate agonist peptides, with differing affinities and signaling potencies. The VAT-Treg cells expanded in vivo by one of the surrogate agonists preserved the typical VAT-Treg transcriptional programs. Immunization with this surrogate, especially when coupled with blockade of TNFa signaling, expanded VAT-Treg cells, resulting in protection from inflammation and improved metabolic indices, including promotion of insulin sensitivity. These studies suggest that antigen-specific targeting of VAT-localized Treg cells could eventually be a strategy for improving metabolic disease.
    Keywords:  immunology; inflammation; mouse
  31. Cell. 2020 Aug 04. pii: S0092-8674(20)30873-4. [Epub ahead of print]
    Licznerski P, Park HA, Rolyan H, Chen R, Mnatsakanyan N, Miranda P, Graham M, Wu J, Cruz-Reyes N, Mehta N, Sohail S, Salcedo J, Song E, Effman C, Effman S, Brandao L, Xu GN, Braker A, Gribkoff VK, Levy RJ, Jonas EA.
      Loss of the gene (Fmr1) encoding Fragile X mental retardation protein (FMRP) causes increased mRNA translation and aberrant synaptic development. We find neurons of the Fmr1-/y mouse have a mitochondrial inner membrane leak contributing to a "leak metabolism." In human Fragile X syndrome (FXS) fibroblasts and in Fmr1-/y mouse neurons, closure of the ATP synthase leak channel by mild depletion of its c-subunit or pharmacological inhibition normalizes stimulus-induced and constitutive mRNA translation rate, decreases lactate and key glycolytic and tricarboxylic acid (TCA) cycle enzyme levels, and triggers synapse maturation. FMRP regulates leak closure in wild-type (WT), but not FX synapses, by stimulus-dependent ATP synthase β subunit translation; this increases the ratio of ATP synthase enzyme to its c-subunit, enhancing ATP production efficiency and synaptic growth. In contrast, in FXS, inability to close developmental c-subunit leak prevents stimulus-dependent synaptic maturation. Therefore, ATP synthase c-subunit leak closure encourages development and attenuates autistic behaviors.
    Keywords:  Fragile X syndrome; autism; autism syndrome; glycolysis; mitochondria; oxidative phosphorylation; permeability transition pore; protein synthesis; repetitive mouse behavior; synaptic development; synaptic plasticity
  32. Cell. 2020 Aug 04. pii: S0092-8674(20)30875-8. [Epub ahead of print]
    Chen FY, Jung HW, Tsuei CY, Liao JC.
      Methanol, being electron rich and derivable from methane or CO2, is a potentially renewable one-carbon (C1) feedstock for microorganisms. Although the ribulose monophosphate (RuMP) cycle used by methylotrophs to assimilate methanol differs from the typical sugar metabolism by only three enzymes, turning a non-methylotrophic organism to a synthetic methylotroph that grows to a high cell density has been challenging. Here we reprogrammed E. coli using metabolic robustness criteria followed by laboratory evolution to establish a strain that can efficiently utilize methanol as the sole carbon source. This synthetic methylotroph alleviated a so far uncharacterized hurdle, DNA-protein crosslinking (DPC), by insertion sequence (IS)-mediated copy number variations (CNVs) and balanced the metabolic flux by mutations. Being capable of growing at a rate comparable with natural methylotrophs in a wide range of methanol concentrations, this synthetic methylotrophic strain illustrates genome editing and evolution for microbial tropism changes and expands the scope of biological C1 conversion.
    Keywords:  C1 metabolism; DNA-protein crosslinking; copy number variation; formaldehyde; greenhouse gas; metabolic engineering; methanol; methylotroph; ribulose monophosphate cycle; synthetic biology
  33. Nat Chem Biol. 2020 Aug 10.
    Bazhin AA, Sinisi R, De Marchi U, Hermant A, Sambiagio N, Maric T, Budin G, Goun EA.
      Mitochondrial membrane potential (ΔΨm) is a universal selective indicator of mitochondrial function and is known to play a central role in many human pathologies, such as diabetes mellitus, cancer and Alzheimer's and Parkinson's diseases. Here, we report the design, synthesis and several applications of mitochondria-activatable luciferin (MAL), a bioluminescent probe sensitive to ΔΨm, and partially to plasma membrane potential (ΔΨp), for non-invasive, longitudinal monitoring of ΔΨm in vitro and in vivo. We applied this new technology to evaluate the aging-related change of ΔΨm in mice and showed that nicotinamide riboside (NR) reverts aging-related mitochondrial depolarization, revealing another important aspect of the mechanism of action of this potent biomolecule. In addition, we demonstrated application of the MAL probe for studies of brown adipose tissue (BAT) activation and non-invasive in vivo assessment of ΔΨm in animal cancer models, opening exciting opportunities for understanding the underlying mechanisms and for discovery of effective treatments for many human pathologies.
  34. J Cell Sci. 2020 Aug 11. pii: jcs.239681. [Epub ahead of print]
    Baschieri F, Le Devedec D, Tettarasar S, Elkhatib N, Montagnac G.
      Cells experience mechanical stresses in different physiological and pathological settings. Clathrin-coated structures (CCSs) are sensitive to such perturbations in a way that often results in a mechanical impairment of endocytic budding. Compressive stress is a mechanical perturbation that leads to increased membrane tension and promotes proliferative signals. Here, we report that compression leads to CCSs frustration and that CCSs are required to potentiate receptor-mediated signaling in these conditions. We show that cell compression stalled CCSs dynamics and slowed down the dynamic exchange of CCSs building blocks. As previously reported, compression-induced paracrine activation of the epidermal growth factor receptor (EGFR) was the primary cause of ERK activation in these conditions. We observed that the EGFR was efficiently recruited at CCSs upon compression and that CCSs were required for full ERK activation. In addition, we demonstrated that compression-induced frustrated CCSs could also increase ligand-dependent signaling of other receptors. We thus propose that CCS frustration resulting from mechanical perturbations can potentiate signaling through different receptors with potential important consequences on cell adaptation to its environment.
    Keywords:  clathrin; endocytosis; signaling
  35. Cells. 2020 Aug 11. pii: E1880. [Epub ahead of print]9(8):
    Bhatia R, Thompson C, Ganguly K, Singh S, Batra SK, Kumar S.
      Pancreatitis is a condition of pancreatic inflammation driven by injury to the pancreatic parenchyma. The extent of acinar insult, intensity, and type of immune response determines the severity of the disease. Smoking, alcohol and autoimmune pancreatitis are some of the predominant risk factors that increase the risk of pancreatitis by differentially influencing the adaptive immune system. The overall decrease in peripheral lymphocyte (T-, B- and (natural killer T-) NKT-cell) count and increased infiltration into the damaged pancreatic tissue highlight the contribution of adaptive immunity in the disease pathology. Smoking and alcohol modulate the responsiveness and apoptosis of T- and B-cells during pancreatic insult. Acute pancreatitis worsens with smoking and alcohol, leading to the development of systemic inflammatory response syndrome and compensatory anti-inflammatory response syndrome, suggesting the critical role of adaptive immunity in fatal outcomes such as multiple organ dysfunction. The presence of CD4+ and CD8+ T-lymphocytes and perforin-expressing cells in the fibrotic tissue in chronic pancreatitis modulate the severity of the disease. Due to their important role in altering the severity of the disease, attempts to target adaptive immune mediators will be critical for the development of novel therapeutic interventions.
    Keywords:  acute pancreatitis; adaptive immunity; alcohol; chronic pancreatitis; collagen; lymphocytes; pancreatic stellate cells; pancreatitis; smoking
  36. Ann Transl Med. 2020 Jul;8(14): 904
    Yu D, Liu C, Guo L.
      Metastasis is regarded as the most important cause of cancer-related deaths around the world. During the complicated metastatic cascade, altered mitochondrial metabolism adapts to serve distinct conditions and microenvironments. In this review, we discuss how cells regulate their mitochondria metabolism to adapt to environmental cues during the metastasis, as well as how cancer cells and their tumor micro-environment (TME) are metabolically coupled during the metastatic cascade. We place a strong emphasis on how mitochondrial proline metabolism and extracellular matrix (ECM) are coupled.
    Keywords:  Metastasis; extracellular matrix (ECM); mitochondrial metabolism; proline metabolism; tumor micro-environment (TME)
  37. Cell Metab. 2020 Jul 31. pii: S1550-4131(20)30366-1. [Epub ahead of print]
    Hamaidi I, Zhang L, Kim N, Wang MH, Iclozan C, Fang B, Liu M, Koomen JM, Berglund AE, Yoder SJ, Yao J, Engelman RW, Creelan BC, Conejo-Garcia JR, Antonia SJ, Mulé JJ, Kim S.
      Dysregulated metabolism is a key driver of maladaptive tumor-reactive T lymphocytes within the tumor microenvironment. Actionable targets that rescue the effector activity of antitumor T cells remain elusive. Here, we report that the Sirtuin-2 (Sirt2) NAD+-dependent deacetylase inhibits T cell metabolism and impairs T cell effector functions. Remarkably, upregulation of Sirt2 in human tumor-infiltrating lymphocytes (TILs) negatively correlates with response to TIL therapy in advanced non-small-cell lung cancer. Mechanistically, Sirt2 suppresses T cell metabolism by targeting key enzymes involved in glycolysis, tricarboxylic acid-cycle, fatty acid oxidation, and glutaminolysis. Accordingly, Sirt2-deficient murine T cells exhibit increased glycolysis and oxidative phosphorylation, resulting in enhanced proliferation and effector functions and subsequently exhibiting superior antitumor activity. Importantly, pharmacologic inhibition of Sirt2 endows human TILs with these superior metabolic fitness and effector functions. Our findings unveil Sirt2 as an unexpected actionable target for reprogramming T cell metabolism to augment a broad spectrum of cancer immunotherapies.
    Keywords:  FAO; OxPhos; Sirt2; T cells; antitumor immunity; deacetylase; dysregulated metabolism; glutaminolysis; glycolysis; metabolic checkpoint
  38. J Clin Invest. 2020 Aug 11. pii: 136363. [Epub ahead of print]
    Schriever SC, Kabra DG, Pfuhlmann K, Baumann P, Baumgart EV, Nagler J, Seebacher F, Harrison L, Irmler M, Kullmann S, Corrêa-da-Silva F, Giesert F, Jain R, Schug H, Castel J, Martinez S, Wu M, Häring HU, Hrabe de Angelis M, Beckers J, Müller TD, Stemmer K, Wurst W, Rozman J, Nogueiras R, De Angelis M, Molkentin JD, Krahmer N, Yi CX, Schmidt MV, Luquet S, Heni M, Tschoep MH, Pfluger PT.
      Recent genome-wide association studies (GWAS) identified DUSP8, a dual-specificity phosphatase targeting MAP kinases, as type 2 diabetes (T2D) risk gene. Here, we unravel Dusp8 as gatekeeper in the hypothalamic control of glucose homeostasis in mice and humans. Male but not female Dusp8 loss-of-function mice, either with global or CRH neuron-specific deletion, had impaired systemic glucose tolerance and insulin sensitivity when exposed to high-fat diet (HFD). Mechanistically, we found impaired hypothalamic-pituitary-adrenal (HPA) axis feedback, blunted sympathetic responsiveness, and chronically elevated corticosterone levels driven by hypothalamic hyperactivation of Jnk signaling. Accordingly, global Jnk1 ablation, AAV-mediated Dusp8 overexpression in the mediobasal hypothalamus, or metyrapone-induced chemical adrenalectomy rescued the impaired glucose homeostasis of obese male Dusp8 KO mice, respectively. The sex-specific role of murine Dusp8 in governing hypothalamic Jnk signaling, insulin sensitivity and systemic glucose tolerance was consistent with fMRI data in human volunteers that revealed an association of the DUSP8 rs2334499 risk variant with hypothalamic insulin resistance in men. Further, expression of DUSP8 was increased in the infundibular nucleus of T2D humans. In summary, our findings suggest the GWAS-identified gene Dusp8 as novel hypothalamic factor that plays a functional role in the etiology of T2D.
    Keywords:  Diabetes; Metabolism; Obesity
  39. J Biol Chem. 2020 Aug 11. pii: jbc.RA120.014687. [Epub ahead of print]
    Rangarajan N, Kapoor I, Li S, Drossopoulos P, White KK, Madden VJ, Dohlman HG.
      Autophagy is a conserved process that recycles cellular contents to promote survival. Although nitrogen limitation is the canonical inducer of autophagy, recent studies have revealed several other nutrients important to this process. In this study, we used a quantitative, high-throughput assay to identify potassium starvation as a new and potent inducer of autophagy in the yeast Saccharomyces cerevisiae We found that potassium-dependent autophagy requires the core pathway kinases Atg1, Atg5, Vps34, as well as other components of the phosphatidylinositol 3-kinase complex. Transmission electron microscopy revealed abundant autophagosome formation in response to both stimuli. RNA sequencing indicated distinct transcriptional responses - nitrogen affects transport of ions such as copper while potassium targets the organization of other cellular components. Thus, nitrogen and potassium share the ability to influence molecular supply and demand but do so in different ways. Both inputs promote catabolism through bulk autophagy, but result in distinct mechanisms of cellular remodeling and synthesis.
    Keywords:  RNA sequencing; autophagy; electron microscopy (EM); phosphatidylinositide 3-kinase (PI 3-kinase); potassium; starvation; transcriptomics; yeast
  40. J Cell Sci. 2020 Aug 11. pii: jcs.248880. [Epub ahead of print]
    Zhou W, Hsu AY, Wang Y, Syahirah R, Wang T, Jeffries J, Wang X, Mohammad H, Seleem MN, Umulis D, Deng Q.
      Neutrophils rely on glycolysis for energy production. How mitochondria regulate neutrophil function is not fully understood. Here, we report that mitochondrial outer membrane protein Mitofusin 2 (Mfn2) regulates neutrophil homeostasis and chemotaxis in vivo. Mfn2-deficient neutrophils are released from the hematopoietic tissue, trapped in the vasculature in zebrafish embryos, and not capable of chemotaxis. Consistently, human neutrophil-like cells deficient with MFN2 fail to arrest on activated endothelium under sheer stress or perform chemotaxis on 2D surfaces. Deletion of Mfn2 results in a significant reduction of neutrophil infiltration to the inflamed peritoneal cavity in mice. Mechanistically, MFN2-deficient neutrophil-like cells display disrupted mitochondria-ER interaction, heightened intracellular calcium levels, and elevated Rac activation after chemokine stimulation. Restoring mitochondria-ER tether rescues the abnormal calcium levels, Rac hyperactivation, and chemotaxis defect resulted from MFN2 depletion. Finally, inhibition of Rac activation restores chemotaxis in MFN2-deficient neutrophils. Altogether, we identified that MFN2 regulates neutrophil migration via maintaining mitochondria-ER interaction to suppress Rac activation and uncovered a previously unrecognized role of MFN2 in regulating cell migration and the actin cytoskeleton.
    Keywords:  Actin; Chemotaxis; Leukocyte; Mitochondria; Rac; Zebrafish
  41. Biochem J. 2020 Aug 14. 477(15): 2893-2919
    Kattan WE, Hancock JF.
      The three human RAS proteins are mutated and constitutively activated in ∼20% of cancers leading to cell growth and proliferation. For the past three decades, many attempts have been made to inhibit these proteins with little success. Recently; however, multiple methods have emerged to inhibit KRAS, the most prevalently mutated isoform. These methods and the underlying biology will be discussed in this review with a special focus on KRAS-plasma membrane interactions.
    Keywords:  RAS; cancer; phospholipids; plasma membrane; small molecule inhibitors; therapeutics
  42. J Cell Biol. 2020 Oct 05. pii: e201911120. [Epub ahead of print]219(10):
    Khalil AA, Ilina O, Vasaturo A, Venhuizen JH, Vullings M, Venhuizen V, Bilos A, Figdor CG, Span PN, Friedl P.
      Progression of epithelial cancers predominantly proceeds by collective invasion of cell groups with coordinated cell-cell junctions and multicellular cytoskeletal activity. Collectively invading breast cancer cells express the gap junction protein connexin-43 (Cx43), yet whether Cx43 regulates collective invasion remains unclear. We here show that Cx43 mediates gap-junctional coupling between collectively invading breast cancer cells and, via hemichannels, adenosine nucleotide/nucleoside release into the extracellular space. Using molecular interference and rescue strategies, we identify that Cx43 hemichannel function, but not intercellular communication, induces leader cell activity and collective migration through the engagement of the adenosine receptor 1 (ADORA1) and AKT signaling. Accordingly, pharmacological inhibition of ADORA1 or AKT signaling caused leader cell collapse and halted collective invasion. ADORA1 inhibition further reduced local invasion of orthotopic mammary tumors in vivo, and joint up-regulation of Cx43 and ADORA1 in breast cancer patients correlated with decreased relapse-free survival. This identifies autocrine purinergic signaling, through Cx43 hemichannels, as a critical pathway in leader cell function and collective invasion.
  43. J Natl Cancer Inst. 2020 Aug 08. pii: djaa113. [Epub ahead of print]
    Magbanua MJM, Hendrix LH, Hyslop T, Barry WT, Winer EP, Hudis C, Toppmeyer D, Carey LA, Partridge AH, Pierga JY, Fehm T, Vidal-Martínez J, Mavroudis D, Garcia-Saenz JA, Stebbing J, Gazzaniga P, Manso L, Zamarchi R, Antelo ML, De Mattos-Arruda L, Generali D, Caldas C, Munzone E, Dirix L, Delson AL, Burstein H, Qadir M, Ma C, Scott JH, Bidard FC, Park JW, Rugo HS.
      BACKGROUND: We examined the prognostic significance of circulating tumor cell (CTC) dynamics during treatment in metastatic breast cancer (MBC) patients receiving first-line chemotherapy.METHODS: Serial CTC data from 469 patients (2,202 samples) were used to build a novel latent mixture model to identify groups with similar CTC trajectory (tCTC) patterns during the course of treatment. Cox regression was used to estimate hazard ratios for progression-free survival (PFS) and overall survival (OS) in groups based on baseline CTCs (bCTC), combined CTC status at baseline to the end of cycle 1 (cCTC), and tCTC. Akaike Information Criterion (AIC) was used to select the model that best predicted PFS and OS.
    RESULTS: Latent mixture modeling revealed 4 distinct tCTC patterns: undetectable CTCs (tCTCneg, 56.9% ), low (tCTClo, 23.7%), intermediate (tCTCmid, 14.5%), or high (tCTChi, 4.9%). Patients with tCTClo, tCTCmid and tCTChi patterns had statistically significant inferior PFS and OS compared to those with tCTCneg (P<.001). AIC indicated that the tCTC model best predicted PFS and OS when compared to bCTC and cCTC models. Validation studies in an independent cohort of 1,856 MBC patients confirmed these findings. Further validation using only a single pretreatment CTC measurement confirmed prognostic performance of the tCTC model.
    CONCLUSIONS: We identified four novel prognostic groups in MBC based on similarities in CTC trajectory patterns during chemotherapy. Prognostic groups included patients with very poor outcome (tCTCmid+tCTChi, 19.4%) who could benefit from more effective treatment. Our novel prognostic classification approach may be utilized for fine-tuning of CTC-based risk-stratification strategies to guide future prospective clinical trials in MBC.
  44. Proc Natl Acad Sci U S A. 2020 Aug 11. pii: 202003771. [Epub ahead of print]
    Paterson C, Clevers H, Bozic I.
      Quantifying evolutionary dynamics of cancer initiation and progression can provide insights into more effective strategies of early detection and treatment. Here we develop a mathematical model of colorectal cancer initiation through inactivation of two tumor suppressor genes and activation of one oncogene, accounting for the well-known path to colorectal cancer through loss of tumor suppressors APC and TP53 and gain of the KRAS oncogene. In the model, we allow mutations to occur in any order, leading to a complex network of premalignant mutational genotypes on the way to colorectal cancer. We parameterize the model using experimentally measured parameter values, many of them only recently available, and compare its predictions to epidemiological data on colorectal cancer incidence. We find that the reported lifetime risk of colorectal cancer can be recovered using a mathematical model of colorectal cancer initiation together with experimentally measured mutation rates in colorectal tissues and proliferation rates of premalignant lesions. We demonstrate that the order of driver events in colorectal cancer is determined primarily by the fitness effects that they provide, rather than their mutation rates. Our results imply that there may not be significant immune suppression of untreated benign and malignant colorectal lesions.
    Keywords:  cancer evolution; driver mutations; stochastic model
  45. Nat Rev Genet. 2020 Aug 10.
    Baker NE.
      The growth and survival of cells within tissues can be affected by 'cell competition' between different cell clones. This phenomenon was initially recognized between wild-type cells and cells with mutations in ribosomal protein (Rp) genes in Drosophila melanogaster. However, competition also affects D. melanogaster cells with mutations in epithelial polarity genes, and wild-type cells exposed to 'super-competitor' cells with mutation in the Salvador-Warts-Hippo tumour suppressor pathway or expressing elevated levels of Myc. More recently, cell competition and super-competition were recognized in mammalian development, organ homeostasis and cancer. Genetic and cell biological studies have revealed that mechanisms underlying cell competition include the molecular recognition of 'different' cells, signalling imbalances between distinct cell populations and the mechanical consequences of differential growth rates; these mechanisms may also involve innate immune proteins, p53 and changes in translation.
  46. Rev Physiol Biochem Pharmacol. 2020 Aug 14.
    Song MS, Grabocka E.
      The capacity of cells to organize complex biochemical reactions in intracellular space is a fundamental organizational principle of life. Key to this organization is the compartmentalization of the cytoplasm into distinct organelles, which is frequently achieved through intracellular membranes. Recent evidence, however, has added a new layer of flexibility to cellular compartmentalization. As such, in response to specific stimuli, liquid-liquid phase separations can lead to the rapid rearrangements of the cytoplasm to form membraneless organelles. Stress granules (SGs) are one such type of organelle that form specifically when cells are faced with stress stimuli, to aid cells in coping with stress. Inherently, altered SG formation has been linked to the pathogenesis of diseases associated with stress and inflammatory conditions, including cancer. Exciting discoveries have indicated an intimate link between SGs and tumorigenesis. Several pro-tumorigenic signaling molecules including the RAS oncogene, mTOR, and histone deacetylase 6 (HDAC6) have been shown to upregulate SG formation. Based on these studies, SGs have emerged as structures that can integrate oncogenic signaling and tumor-associated stress stimuli to enhance cancer cell fitness. In addition, growing evidence over the past decade suggests that SGs function not only to regulate the switch between survival and cell death, but also contribute to cancer cell proliferation, invasion, metastasis, and drug resistance. Although much remains to be learned about the role of SGs in tumorigenesis, these studies highlight SGs as a key regulatory hub in cancer and a promising therapeutic target.
    Keywords:  Cancer; Membraneless organelles; Stress adaptation; Stress granules
  47. Nat Commun. 2020 Aug 13. 11(1): 4053
    Montaudon E, Nikitorowicz-Buniak J, Sourd L, Morisset L, El Botty R, Huguet L, Dahmani A, Painsec P, Nemati F, Vacher S, Chemlali W, Masliah-Planchon J, Château-Joubert S, Rega C, Leal MF, Simigdala N, Pancholi S, Ribas R, Nicolas A, Meseure D, Vincent-Salomon A, Reyes C, Rapinat A, Gentien D, Larcher T, Bohec M, Baulande S, Bernard V, Decaudin D, Coussy F, Le Romancer M, Dutertre G, Tariq Z, Cottu P, Driouch K, Bièche I, Martin LA, Marangoni E.
      A significant proportion of patients with oestrogen receptor (ER) positive breast cancers (BC) develop resistance to endocrine treatments (ET) and relapse with metastatic disease. Here we perform whole exome sequencing and gene expression analysis of matched primary breast tumours and bone metastasis-derived patient-derived xenografts (PDX). Transcriptomic analyses reveal enrichment of the G2/M checkpoint and up-regulation of Polo-like kinase 1 (PLK1) in PDX. PLK1 inhibition results in tumour shrinkage in highly proliferating CCND1-driven PDX, including different RB-positive PDX with acquired palbociclib resistance. Mechanistic studies in endocrine resistant cell lines, suggest an ER-independent function of PLK1 in regulating cell proliferation. Finally, in two independent clinical cohorts of ER positive BC, we find a strong association between high expression of PLK1 and a shorter metastases-free survival and poor response to anastrozole. In conclusion, our findings support clinical development of PLK1 inhibitors in patients with advanced CCND1-driven BC, including patients progressing on palbociclib treatment.
  48. Life Sci Alliance. 2020 Oct;pii: e202000718. [Epub ahead of print]3(10):
    MacEwen MJ, Markhard AL, Bozbeyoglu M, Bradford F, Goldberger O, Mootha VK, Sancak Y.
      The mitochondrial calcium uniporter (MCU) is a calcium-activated calcium channel critical for signaling and bioenergetics. MCU, the pore-forming subunit of the uniporter, contains two transmembrane domains and is found in all major eukaryotic taxa. In amoeba and fungi, MCU homologs are sufficient to form a functional calcium channel, whereas human MCU exhibits a strict requirement for the metazoan protein essential MCU regulator (EMRE) for conductance. Here, we exploit this evolutionary divergence to decipher the molecular basis of human MCU's dependence on EMRE. By systematically generating chimeric proteins that consist of EMRE-independent Dictyostelium discoideum MCU and Homo sapiens MCU (HsMCU), we converged on a stretch of 10 amino acids in D. discoideum MCU that can be transplanted to HsMCU to render it EMRE independent. We call this region in human MCU the EMRE dependence domain (EDD). Crosslinking experiments show that EMRE directly interacts with HsMCU at its transmembrane domains as well as the EDD. Our results suggest that EMRE stabilizes the EDD of MCU, permitting both channel opening and calcium conductance, consistent with recently published structures of MCU-EMRE.
  49. EMBO J. 2020 Aug 13. e104285
    Wu W, Shen Q, Zhang R, Qiu Z, Wang Y, Zheng J, Jia Z.
      The MICU1-MICU2 heterodimer regulates the mitochondrial calcium uniporter (MCU) and mitochondrial calcium uptake. Herein, we present two crystal structures of the MICU1-MICU2 heterodimer, in which Ca2+ -free and Ca2+ -bound EF-hands are observed in both proteins, revealing both electrostatic and hydrophobic interfaces. Furthermore, we show that MICU1 interacts with EMRE, another regulator of MCU, through a Ca2+ -dependent alkaline groove. Ca2+ binding strengthens the MICU1-EMRE interaction, which in turn facilitates Ca2+ uptake. Conversely, the MICU1-MCU interaction is favored in the absence of Ca2+ , thus inhibiting the channel activity. This Ca2+ -dependent switch illuminates how calcium signals are transmitted from regulatory subunits to the calcium channel and the transition between gatekeeping and activation channel functions. Furthermore, competition with an EMRE peptide alters the uniporter threshold in resting conditions and elevates Ca2+ accumulation in stimulated mitochondria, confirming the gatekeeper role of the MICU1-MICU2 heterodimer. Taken together, these structural and functional data provide new insights into the regulation of mitochondrial calcium uptake.
    Keywords:   EMRE ; MICU1-MICU2; mitochondria; uniporter
  50. Rev Physiol Biochem Pharmacol. 2020 Aug 09.
    Ling Q, Kalthoff H.
      Ion channels and transporters (ICT) play important roles in almost all basic cellular processes. During last decades, abundant evidences have been provided that ICT (e.g., Ca2+ and K+ channels) are notable for regulating physiological pancreatic duct cellular function and deregulation of ICT is closely associated with the widely accepted hallmarks of pancreatic ductal adenocarcinoma (PDAC) such as proliferation, apoptosis resistance, invasion, and metastasis. Hence this review focuses on the role of ICT malfunctions in context with the hallmarks of PDAC. After briefly introducing epidemiology and history of molecular oncology of PDAC and summarizing the recent studies on molecular classification systems, we focus then on the exocrine pancreas as a very active secretory gland which considerably impacts the changes in the ion transport system (the transportome) upon malignant transformation. We highlight multiplicity of ICT members (H+ transporters, Ca2+, K+, Na+ and Cl- channels) and their functional impact in PDAC. We also present some selective therapeutic options to interfere with transportome functions and thereby with key mechanisms of malignant progression. This will hopefully contribute to a better clinical outcome based on improved therapeutic strategies for this still extremely deadly disease.
    Keywords:  Invasion; Ion channels and transporters; Metastasis; Pancreatic ductal adenocarcinoma; Proliferation
  51. Front Cell Dev Biol. 2020 ;8 663
    Lipp NF, Ikhlef S, Milanini J, Drin G.
      Lipids are amphiphilic molecules that self-assemble to form biological membranes. Thousands of lipid species coexist in the cell and, once combined, define organelle identity. Due to recent progress in lipidomic analysis, we now know how lipid composition is finely tuned in different subcellular regions. Along with lipid synthesis, remodeling and flip-flop, lipid transfer is one of the active processes that regulates this intracellular lipid distribution. It is mediated by Lipid Transfer Proteins (LTPs) that precisely move certain lipid species across the cytosol and between the organelles. A particular subset of LTPs from three families (Sec14, PITP, OSBP/ORP/Osh) act as lipid exchangers. A striking feature of these exchangers is that they use phosphatidylinositol or phosphoinositides (PIPs) as a lipid ligand and thereby have specific links with PIP metabolism and are thus able to both control the lipid composition of cellular membranes and their signaling capacity. As a result, they play pivotal roles in cellular processes such as vesicular trafficking and signal transduction at the plasma membrane. Recent data have shown that some PIPs are used as energy by lipid exchangers to generate lipid gradients between organelles. Here we describe the importance of lipid counter-exchange in the cell, its structural basis, and presumed links with pathologies.
    Keywords:  lipid exchange; lipid transfer proteins; membrane contact sites; phosphatidylserine; phosphoinositides; signaling; sterol; vesicular trafficking
  52. Science. 2020 Aug 14. 369(6505): 823-828
    Guey B, Wischnewski M, Decout A, Makasheva K, Kaynak M, Sakar MS, Fierz B, Ablasser A.
      The appearance of DNA in the cytosol is perceived as a danger signal that stimulates potent immune responses through cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS). How cells regulate the activity of cGAS toward self-DNA and guard against potentially damaging autoinflammatory responses is a fundamental biological question. Here, we identify barrier-to-autointegration factor 1 (BAF) as a natural opponent of cGAS activity on genomic self-DNA. We show that BAF dynamically outcompetes cGAS for DNA binding, hence prohibiting the formation of DNA-cGAS complexes that are essential for enzymatic activity. Upon acute loss of nuclear membrane integrity, BAF is necessary to restrict cGAS activity on exposed DNA. Our observations reveal a safeguard mechanism, distinct from physical separation, by which cells protect themselves against aberrant immune responses toward genomic DNA.
  53. Elife. 2020 Aug 12. pii: e58654. [Epub ahead of print]9
    Hatch A, Curry S.
      The San Francisco Declaration on Research Assessment (DORA) was published in 2013 and described how funding agencies, institutions, publishers, organizations that supply metrics, and individual researchers could better evaluate the outputs of scientific research. Since then DORA has evolved into an active initiative that gives practical advice to institutions on new ways to assess and evaluate research. This article outlines a framework for driving institutional change that was developed at a meeting convened by DORA and the Howard Hughes Medical Institute. The framework has four broad goals: understanding the obstacles to changes in the way research is assessed; experimenting with different approaches; creating a shared vision when revising existing policies and practices; and communicating that vision on campus and beyond.
    Keywords:  careers in science; culture change; institutional change; none; research assessment; research culture
  54. Biol Chem. 2020 Aug 01. pii: /j/bchm.just-accepted/hsz-2020-0157/hsz-2020-0157.xml. [Epub ahead of print]
    Galber C, Acosta MJ, Minervini G, Giorgio V.
      The mitochondrial ATP synthase is a multi-subunit enzyme complex located in the inner mitochondrial membrane which is essential for oxidative phosphorylation under physiological conditions. In this review, we analyse the enzyme functions involved in cancer progression by dissecting specific conditions in which ATP synthase contributes to cancer development or metastasis. Moreover, we propose the role of ATP synthase in the formation of the permeability transition pore (PTP) as an additional mechanism which controls tumour cell death. We further describe transcriptional and translational modifications of the enzyme subunits and of the inhibitor protein IF1that may promote adaptations leading to cancer metabolism. Finally, we outline ATP synthase gene mutations and epigenetic modifications associated with cancer development or drug resistance, with the aim of highlighting this enzyme complex as a potential novel target for future anti-cancer therapy.
    Keywords:  ATP synthase; cancer; mitochondria; permeability transition
  55. J Hepatobiliary Pancreat Sci. 2020 Aug 12.
    Yoon SJ, Shin SH, Yoon SK, Jung JH, You Y, Han IW, Choi DW, Heo JS.
      BACKGROUND/PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) is regarded as incurable, with a limited survival rate after curative resection. The aim of this study was to explore long-term survival and late recurrence of PDAC after surgery.METHODS: Medical data of 859 patients who underwent resection between 1995 and 2014 were retrospectively examined. The clinicopathological features of the 5-year recurrence-free survivors and the patients with recurrent disease after 5 years were investigated separately.
    RESULTS: Among the 768 patients who were finally included in this study, elevated CA 19-9, tumor size, poor differentiation, and positive lymph node metastasis were associated with recurrence. In 89 patients with 5-year RFS, age, tumor size, differentiation, and lymph node metastasis were statistically significant predictive factors. Among these patients, disease relapse occurred in 11 patients; age was the only difference compared to those who remained free of recurrence.
    CONCLUSIONS: Most prognosticators failed to predict the risk of recurrence in the 5 years following surgery for PDAC, and recurrence can occur even at time points up to 100 months. Therefore, cure of PDAC cannot be guaranteed by a 5-year recurrence-free interval, and further studies into the inherent nature of PDAC are needed to develop adequate surveillance systems which may lead to improvements in survival.
  56. JAMA Oncol. 2020 Aug 13.
    Yuan C, Babic A, Khalaf N, Nowak JA, Brais LK, Rubinson DA, Ng K, Aguirre AJ, Pandharipande PV, Fuchs CS, Giovannucci EL, Stampfer MJ, Rosenthal MH, Sander C, Kraft P, Wolpin BM.
      Importance: Pancreatic cancer is the third-leading cause of cancer death in the United States; however, few high-risk groups have been identified to facilitate early diagnosis strategies.Objective: To evaluate the association of diabetes duration and recent weight change with subsequent risk of pancreatic cancer in the general population.
    Design, Setting, and Participants: This cohort study obtained data from female participants in the Nurses' Health Study and male participants in the Health Professionals Follow-Up Study, with repeated exposure assessments over 30 years. Incident cases of pancreatic cancer were identified from self-report or during follow-up of participant deaths. Deaths were ascertained through reports from the next of kin, the US Postal Service, or the National Death Index. Data collection was conducted from October 1, 2018, to December 31, 2018. Data analysis was performed from January 1, 2019, to June 30, 2019.
    Exposures: Duration of physician-diagnosed diabetes and recent weight change.
    Main Outcome and Measures: Hazard ratios (HRs) for subsequent development of pancreatic cancer.
    Results: Of the 112 818 women (with a mean [SD] age of 59.4 [11.7] years) and 46 207 men (with a mean [SD] age of 64.7 [10.8] years) included in the analysis, 1116 incident cases of pancreatic cancers were identified. Compared with participants with no diabetes, those with recent-onset diabetes had an age-adjusted HR for pancreatic cancer of 2.97 (95% CI, 2.31-3.82) and those with long-standing diabetes had an age-adjusted HR of 2.16 (95% CI, 1.78-2.60). Compared with those with no weight loss, participants who reported a 1- to 4-lb weight loss had an age-adjusted HR for pancreatic cancer of 1.25 (95% CI, 1.03-1.52), those with a 5- to 8-lb weight loss had an age-adjusted HR of 1.33 (95% CI, 1.06-1.66), and those with more than an 8-lb weight loss had an age-adjusted HR of 1.92 (95% CI, 1.58-2.32). Participants with recent-onset diabetes accompanied by weight loss of 1 to 8 lb (91 incident cases per 100 000 person-years [95% CI, 55-151]; HR, 3.61 [95% CI, 2.14-6.10]) or more than 8 lb (164 incident cases per 100 000 person-years [95% CI, 114-238]; HR, 6.75 [95% CI, 4.55-10.00]) had a substantially increased risk for pancreatic cancer compared with those with neither exposure (16 incident cases per 100 000 person-years; 95% CI, 14-17). Incidence rates were even higher among participants with recent-onset diabetes and weight loss with a body mass index of less than 25 before weight loss (400 incident cases per 100 000 person-years) or whose weight loss was not intentional judging from increased physical activity or healthier dietary choices (334 incident cases per 100 000 person-years).
    Conclusions and Relevance: This study demonstrates that recent-onset diabetes accompanied by weight loss is associated with a substantially increased risk for developing pancreatic cancer. Older age, previous healthy weight, and no intentional weight loss further elevate this risk.
  57. Science. 2020 Aug 14. 369(6505): 842-846
    Marvaldi L, Panayotis N, Alber S, Dagan SY, Okladnikov N, Koppel I, Di Pizio A, Song DA, Tzur Y, Terenzio M, Rishal I, Gordon D, Rother F, Hartmann E, Bader M, Fainzilber M.
      How is neuropathic pain regulated in peripheral sensory neurons? Importins are key regulators of nucleocytoplasmic transport. In this study, we found that importin α3 (also known as karyopherin subunit alpha 4) can control pain responsiveness in peripheral sensory neurons in mice. Importin α3 knockout or sensory neuron-specific knockdown in mice reduced responsiveness to diverse noxious stimuli and increased tolerance to neuropathic pain. Importin α3-bound c-Fos and importin α3-deficient neurons were impaired in c-Fos nuclear import. Knockdown or dominant-negative inhibition of c-Fos or c-Jun in sensory neurons reduced neuropathic pain. In silico screens identified drugs that mimic importin α3 deficiency. These drugs attenuated neuropathic pain and reduced c-Fos nuclear localization. Thus, perturbing c-Fos nuclear import by importin α3 in peripheral neurons can promote analgesia.
  58. Development. 2020 Aug 12. pii: dev146621. [Epub ahead of print]147(15):
    Jakab M, Augustin HG.
      Blood vessels have long been considered as passive conduits for delivering blood. However, in recent years, cells of the vessel wall (endothelial cells, smooth muscle cells and pericytes) have emerged as active, highly dynamic components that orchestrate crosstalk between the circulation and organs. Encompassing the whole body and being specialized to the needs of distinct organs, it is not surprising that vessel lining cells come in different flavours. There is calibre-specific specialization (arteries, arterioles, capillaries, venules, veins), but also organ-specific heterogeneity in different microvascular beds (continuous, discontinuous, sinusoidal). Recent technical advances in the field of single cell biology have enabled the profiling of thousands of single cells and, hence, have allowed for the molecular dissection of such angiodiversity, yielding a hitherto unparalleled level of spatial and functional resolution. Here, we review how these approaches have contributed to our understanding of angiodiversity.
    Keywords:  Angiodiversity; Endothelial cell; Single cell biology; Smooth muscle cell
  59. Dev Cell. 2020 Aug 06. pii: S1534-5807(20)30579-7. [Epub ahead of print]
    Miao ZF, Lewis MA, Cho CJ, Adkins-Threats M, Park D, Brown JW, Sun JX, Burclaff JR, Kennedy S, Lu J, Mahar M, Vietor I, Huber LA, Davidson NO, Cavalli V, Rubin DC, Wang ZN, Mills JC.
      Differentiated cells can re-enter the cell cycle to repair tissue damage via a series of discrete morphological and molecular stages coordinated by the cellular energetics regulator mTORC1. We previously proposed the term "paligenosis" to describe this conserved cellular regeneration program. Here, we detail a molecular network regulating mTORC1 during paligenosis in both mouse pancreatic acinar and gastric chief cells. DDIT4 initially suppresses mTORC1 to induce autodegradation of differentiated cell components and damaged organelles. Later in paligenosis, IFRD1 suppresses p53 accumulation. Ifrd1-/- cells do not complete paligenosis because persistent p53 prevents mTORC1 reactivation and cell proliferation. Ddit4-/- cells never suppress mTORC1 and bypass the IFRD1 checkpoint on proliferation. Previous reports and our current data implicate DDIT4/IFRD1 in governing paligenosis in multiple organs and species. Thus, we propose that an evolutionarily conserved, dedicated molecular network has evolved to allow differentiated cells to re-enter the cell cycle (i.e., undergo paligenosis) after tissue injury. VIDEO ABSTRACT.
    Keywords:  ADM; Drosophila; SPEM; Schizosaccharomyces pombe; acinar-ductal metaplasia; regeneration; spasmolytic polypeptide-expressing metaplasia
  60. Cancer Metastasis Rev. 2020 Aug 07.
    Orgován Z, Keserű GM.
      RAS proteins control a number of essential cellular processes as molecular switches in the human body. Presumably due to their important signalling role, RAS proteins are among the most frequently mutated oncogenes in human cancers. Hence, numerous efforts were done to develop appropriate therapies for RAS-mutant cancers in the last three decades. This review aimed to collect all of the reported small molecules that affect RAS signalling. These molecules can be divided in four main branches. First, we address approaches blocking RAS membrane association. Second, we focus on the stabilization efforts of non-productive RAS complexes. Third, we examine the approach to block RAS downstream signalling through disturbance of RAS-effector complex formation. Finally, we discuss direct inhibition; particularly the most recently reported covalent inhibitors, which are already advanced to human clinical trials.
    Keywords:  GTPases; Oncogenic mutations; RAS proteins; Small molecular inhibitors
  61. N Engl J Med. 2020 Aug 12.
    Walker MA, Lareau CA, Ludwig LS, Karaa A, Sankaran VG, Regev A, Mootha VK.
      Many mitochondrial diseases are caused by mutations in mitochondrial DNA (mtDNA). Patients' cells contain a mixture of mutant and nonmutant mtDNA (a phenomenon called heteroplasmy). The proportion of mutant mtDNA varies across patients and among tissues within a patient. We simultaneously assayed single-cell heteroplasmy and cell state in thousands of blood cells obtained from three unrelated patients who had A3243G-associated mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes. We observed a broad range of heteroplasmy across all cell types but also found markedly reduced heteroplasmy in T cells, a finding consistent with purifying selection within this lineage. We observed this pattern in six additional patients who had heteroplasmic A3243G without strokelike episodes. (Funded by the Marriott Foundation and others.).
  62. Sci Signal. 2020 Aug 11. pii: eabb4749. [Epub ahead of print]13(644):
    Hughes DT, Halliday M, Smith HL, Verity NC, Molloy C, Radford H, Butcher AJ, Mallucci GR.
      Chronic activation of the unfolded protein response (UPR), notably the branch comprising the kinase PERK and the translation initiation factor eIF2α, is a pathological feature of many neurodegenerative diseases caused by protein misfolding. Partial reduction of UPR signaling at the level of phosphorylated eIF2α is neuroprotective and avoids the pancreatic toxicity caused by full inhibition of PERK kinase activity. However, other stress pathways besides the UPR converge on phosphorylated eIF2α in the integrated stress response (ISR), which is critical to normal cellular function. We explored whether partial inhibition of PERK signaling may be a better therapeutic option. PERK-mediated phosphorylation of eIF2α requires its binding to the insert loop within PERK's kinase domain, which is, itself, phosphorylated at multiple sites. We found that, as expected, Akt mediates the phosphorylation of Thr799 in PERK. This phosphorylation event reduced eIF2α binding to PERK and selectively attenuated downstream signaling independently of PERK activity and the broader ISR. Induction of Thr799 phosphorylation with a small-molecule activator of Akt similarly reduced PERK signaling and increased both neuronal and animal survival without measurable pancreatic toxicity in a mouse model of prion disease. Thus, promoting PERK phosphorylation at Thr799 to partially down-regulate PERK-eIF2α signaling while avoiding widespread ISR inhibition may be a safe therapeutic approach in neurodegenerative disease.
  63. Nat Cancer. 2020 Mar;1(3): 315-328
    Amgalan D, Garner TP, Pekson R, Jia XF, Yanamandala M, Paulino V, Liang FG, Corbalan JJ, Lee J, Chen Y, Karagiannis GS, Sanchez LR, Liang H, Narayanagari SR, Mitchell K, Lopez A, Margulets V, Scarlata M, Santulli G, Asnani A, Peterson RT, Hazan RB, Condeelis JS, Oktay MH, Steidl U, Kirshenbaum LA, Gavathiotis E, Kitsis RN.
      Doxorubicin remains an essential component of many cancer regimens, but its use is limited by lethal cardiomyopathy, which has been difficult to target, owing to pleiotropic mechanisms leading to apoptotic and necrotic cardiac cell death. Here we show that BAX is rate-limiting in doxorubicin-induced cardiomyopathy and identify a small-molecule BAX inhibitor that blocks both apoptosis and necrosis to prevent this syndrome. By allosterically inhibiting BAX conformational activation, this compound blocks BAX translocation to mitochondria, thereby abrogating both forms of cell death. When co-administered with doxorubicin, this BAX inhibitor prevents cardiomyopathy in zebrafish and mice. Notably, cardioprotection does not compromise the efficacy of doxorubicin in reducing leukemia or breast cancer burden in vivo, primarily due to increased priming of mitochondrial death mechanisms and higher BAX levels in cancer cells. This study identifies BAX as an actionable target for doxorubicin-induced cardiomyopathy and provides a prototype small-molecule therapeutic.
  64. Science. 2020 Aug 13. pii: eaaz8432. [Epub ahead of print]
    Davis CW, Jackson KJL, McCausland MM, Darce J, Chang C, Linderman SL, Chennareddy C, Gerkin R, Brown SJ, Wrammert J, Mehta AK, Cheung WC, Boyd SD, Waller EK, Ahmed R.
      A universal vaccine against influenza would ideally generate protective immune responses that are not only broadly reactive against multiple influenza strains, but also long-lasting. Because long-term serum antibody levels are maintained by bone marrow plasma cells (BMPC), we investigated the production and maintenance of these cells after influenza vaccination. We found increased numbers of influenza-specific BMPC four weeks after immunization with the seasonal inactivated influenza vaccine, but numbers returned to near their pre-vaccination levels after one year. This decline was driven by the loss of BMPC induced by the vaccine, while pre-existing BMPC were maintained. Our results suggest that most BMPC generated by influenza vaccination in adults are short-lived. Designing strategies to enhance their persistence will be a key challenge for the next generation of influenza vaccines.
  65. Cell Death Dis. 2020 Aug 13. 11(8): 616
    Roca-Portoles A, Rodriguez-Blanco G, Sumpton D, Cloix C, Mullin M, Mackay GM, O'Neill K, Lemgruber L, Luo X, Tait SWG.
      BH3-mimetics are a new class of anti-cancer drugs that inhibit anti-apoptotic Bcl-2 proteins. In doing so, BH3-mimetics sensitise to cell death. Venetoclax is a potent, BCL-2 selective BH3-mimetic that is clinically approved for use in chronic lymphocytic leukaemia. Venetoclax has also been shown to inhibit mitochondrial metabolism, this is consistent with a proposed role for BCL-2 in metabolic regulation. We used venetoclax to understand BCL-2 metabolic function. Similar to others, we found that venetoclax inhibited mitochondrial respiration. In addition, we also found that venetoclax impairs TCA cycle activity leading to activation of reductive carboxylation. Importantly, the metabolic effects of venetoclax were independent of cell death because they were also observed in apoptosis-resistant BAX/BAK-deficient cells. However, unlike venetoclax treatment, inhibiting BCL-2 expression had no effect on mitochondrial respiration. Unexpectedly, we found that venetoclax also inhibited mitochondrial respiration and the TCA cycle in BCL-2 deficient cells and in cells lacking all anti-apoptotic BCL-2 family members. Investigating the basis of this off-target effect, we found that venetoclax-induced metabolic reprogramming was dependent upon the integrated stress response and ATF4 transcription factor. These data demonstrate that venetoclax affects cellular metabolism independent of BCL-2 inhibition. This off-target metabolic effect has potential to modulate venetoclax cytotoxicity.
  66. Cells. 2020 Aug 08. pii: E1862. [Epub ahead of print]9(8):
    Barth E, Sieber P, Stark H, Schuster S.
      Understanding the process of aging is still an important challenge to enable healthy aging and to prevent age-related diseases. Most studies in age research investigate the decline in organ functionality and gene activity with age. The focus on decline can even be considered a paradigm in that field. However, there are certain aspects that remain surprisingly stable and keep the organism robust. Here, we present and discuss various properties of robust behavior during human and animal aging, including physiological and molecular biological features, such as the hematocrit, body temperature, immunity against infectious diseases and others. We examine, in the context of robustness, the different theories of how aging occurs. We regard the role of aging in the light of evolution.
    Keywords:  age-related diseases; failure accumulation; healthy aging; immunosenescence; robustness; theories of aging
  67. Cell. 2020 Aug 04. pii: S0092-8674(20)30809-6. [Epub ahead of print]
    Katzenelenbogen Y, Sheban F, Yalin A, Yofe I, Svetlichnyy D, Jaitin DA, Bornstein C, Moshe A, Keren-Shaul H, Cohen M, Wang SY, Li B, David E, Salame TM, Weiner A, Amit I.
      Cell function and activity are regulated through integration of signaling, epigenetic, transcriptional, and metabolic pathways. Here, we introduce INs-seq, an integrated technology for massively parallel recording of single-cell RNA sequencing (scRNA-seq) and intracellular protein activity. We demonstrate the broad utility of INs-seq for discovering new immune subsets by profiling different intracellular signatures of immune signaling, transcription factor combinations, and metabolic activity. Comprehensive mapping of Arginase 1-expressing cells within tumor models, a metabolic immune signature of suppressive activity, discovers novel Arg1+ Trem2+ regulatory myeloid (Mreg) cells and identifies markers, metabolic activity, and pathways associated with these cells. Genetic ablation of Trem2 in mice inhibits accumulation of intra-tumoral Mreg cells, leading to a marked decrease in dysfunctional CD8+ T cells and reduced tumor growth. This study establishes INs-seq as a broadly applicable technology for elucidating integrated transcriptional and intra-cellular maps and identifies the molecular signature of myeloid suppressive cells in tumors.
    Keywords:  MDSC; Trem2; cancer immunology; fixation; immunotherapy; intracellular staining; myeloid suppressive cells; scRNA-seq; single cell genomics; tumor microenvironment
  68. Science. 2020 Aug 14. 369(6505): 793-799
    Kumar A, Planchais C, Fronzes R, Mouquet H, Reyes N.
      Monoclonal antibodies (mAbs) targeting human antigen CD20 (cluster of differentiation 20) constitute important immunotherapies for the treatment of B cell malignancies and autoimmune diseases. Type I and II therapeutic mAbs differ in B cell binding properties and cytotoxic effects, reflecting differential interaction mechanisms with CD20. Here we present 3.7- to 4.7-angstrom cryo-electron microscopy structures of full-length CD20 in complexes with prototypical type I rituximab and ofatumumab and type II obinutuzumab. The structures and binding thermodynamics demonstrate that upon binding to CD20, type II mAbs form terminal complexes that preclude recruitment of additional mAbs and complement components, whereas type I complexes act as molecular seeds to increase mAb local concentration for efficient complement activation. Among type I mAbs, ofatumumab complexes display optimal geometry for complement recruitment. The uncovered mechanisms should aid rational design of next-generation immunotherapies targeting CD20.
  69. Protein Cell. 2020 Aug 11.
    Zheng Y, Liu X, Le W, Xie L, Li H, Wen W, Wang S, Ma S, Huang Z, Ye J, Shi W, Ye Y, Liu Z, Song M, Zhang W, Han JJ, Belmonte JCI, Xiao C, Qu J, Wang H, Liu GH, Su W.
      Age-associated changes in immune cells have been linked to an increased risk for infection. However, a global and detailed characterization of the changes that human circulating immune cells undergo with age is lacking. Here, we combined scRNA-seq, mass cytometry and scATAC-seq to compare immune cell types in peripheral blood collected from young and old subjects and patients with COVID-19. We found that the immune cell landscape was reprogrammed with age and was characterized by T cell polarization from naive and memory cells to effector, cytotoxic, exhausted and regulatory cells, along with increased late natural killer cells, age-associated B cells, inflammatory monocytes and age-associated dendritic cells. In addition, the expression of genes, which were implicated in coronavirus susceptibility, was upregulated in a cell subtype-specific manner with age. Notably, COVID-19 promoted age-induced immune cell polarization and gene expression related to inflammation and cellular senescence. Therefore, these findings suggest that a dysregulated immune system and increased gene expression associated with SARS-CoV-2 susceptibility may at least partially account for COVID-19 vulnerability in the elderly.
    Keywords:  COVID-19; aging; blood; immune cells; single-cell sequencing
  70. Sci Adv. 2020 Jul;6(31): eabb8725
    Xu F, Li X, Huang X, Pan J, Wang Y, Zhou S.
      Autophagy is involved in the occurrence and development of tumors. Here, a pH-responsive polymersome codelivering hydroxychloroquine (HCQ) and tunicamycin (Tuni) drugs is developed to simultaneously induce endoplasmic reticulum (ER) stress and autophagic flux blockade for achieving an antitumor effect and inhibiting tumor metastasis. The pH response of poly(β-amino ester) and HCQ synergistically deacidifies the lysosomes, thereby blocking the fusion of autophagosomes and lysosomes and lastly blocking autophagic flux. The function mechanism of regulating autophagy was systematically investigated on orthotopic luciferase gene-transfected, 4T1 tumor-bearing BALB/c mice through Western blot and immunohistochemistry analyses. The Tuni triggers ER stress to regulate the PERK/Akt signaling pathway to increase the autophagic level. The "autophagic stress" generated by triggering ER stress-induced autophagy and blocking autophagic flux is effective against tumors. The reduced expression of matrix metalloproteinase-2 due to ER stress and reduced focal adhesions turnover due to the blockade of autophagic flux synergistically inhibit tumor metastasis.
  71. Visc Med. 2020 Jun;36(3): 220-226
    Desai V, Patel K, Sheth R, Barlass U, Chan YM, Sclamberg J, Bishehsari F.
      Background: Pancreatic ductal adenocarcinoma (PDAC) has a poor survival rate, partly due to delayed diagnosis. Identifying high-risk individuals could lead to early detection and improve survival. A number of risk factors such as alcohol consumption and metabolic syndrome are associated with fatty infiltration of the pancreas. Experimental models show that a fatty pancreas promotes tissue inflammation and fibrosis, which could promote PDAC.Methods: We conducted a case-control study in a single-university tertiary hospital. Sixty-eight PDAC cases with recent non-contrast computed tomography (CT) and 235 controls were studied. The controls had no history of malignancy and underwent CT colonography for cancer screening in the same period. Pancreatic fat was estimated by calculating pancreatic (P) attenuation, corrected to splenic (S) attenuation, measured in three 1.0-cm2 regions of the pancreas. The P.S100 value calculated was used to estimate fatty infiltration of the pancreas (FIP), with a lower P.S100 representing a higher FIP.
    Results: The PDAC patients had a lower BMI and a higher rate of type 2 diabetes mellitus. The P.S100 was lower in cases than in controls (86.452 vs. 92.414, p = 4.016e-06), suggesting that FIP is higher with PDAC. The risk of developing PDAC steadily increased significantly for the quartiles with a higher FIP compared to the low FIP quartile. No correlation between BMI and FIP (r = -0.1031179; 95% confidence interval [CI] -0.22267106 to 0.01949092) was found. Adjusting for confounders (age, sex, BMI, and DM), the risk of developing PDAC according to the FIP was estimated to be 3.75 (95% CI 1.9234408-7.993337; p = 0.000171). FIP was stable before and after the diagnosis of PDAC in 9 cases with prior CT scans when no pancreatic tumor was identifiable.
    Conclusion: Fatty pancreas is associated with an increased risk of pancreatic cancer. Once confirmed in larger-scale studies, these findings could help to identify at-risk individuals, particularly in high-risk groups such as chronic alcohol consumers.
    Keywords:  Alcohol; Fatty pancreas; Metabolic syndrome; Pancreatic cancer
  72. Cell. 2020 Aug 06. pii: S0092-8674(20)30878-3. [Epub ahead of print]
    Molgora M, Esaulova E, Vermi W, Hou J, Chen Y, Luo J, Brioschi S, Bugatti M, Omodei AS, Ricci B, Fronick C, Panda SK, Takeuchi Y, Gubin MM, Faccio R, Cella M, Gilfillan S, Unanue ER, Artyomov MN, Schreiber RD, Colonna M.
      Checkpoint immunotherapy unleashes T cell control of tumors, but is undermined by immunosuppressive myeloid cells. TREM2 is a myeloid receptor that transmits intracellular signals that sustain microglial responses during Alzheimer's disease. TREM2 is also expressed by tumor-infiltrating macrophages. Here, we found that Trem2-/- mice are more resistant to growth of various cancers than wild-type mice and are more responsive to anti-PD-1 immunotherapy. Furthermore, treatment with anti-TREM2 mAb curbed tumor growth and fostered regression when combined with anti-PD-1. scRNA-seq revealed that both TREM2 deletion and anti-TREM2 are associated with scant MRC1+ and CX3CR1+ macrophages in the tumor infiltrate, paralleled by expansion of myeloid subsets expressing immunostimulatory molecules that promote improved T cell responses. TREM2 was expressed in tumor macrophages in over 200 human cancer cases and inversely correlated with prolonged survival for two types of cancer. Thus, TREM2 might be targeted to modify tumor myeloid infiltrates and augment checkpoint immunotherapy.
    Keywords:  TREM2; breast cancer; checkpoint blockade; colorectal cancer; human; macrophages; sarcoma; tumor
  73. Gastroenterology. 2020 Aug 03. pii: S0016-5085(20)35009-5. [Epub ahead of print]
    Tiwari A, Tashiro K, Dixit A, Soni A, Vogel K, Hall B, Shafqat I, Slaughter J, Param N, Le A, Saunders E, Paithane U, Garcia G, Campos AR, Zettervall J, Carlson M, Starr TK, Marahrens Y, Deshpande AJ, Commisso C, Provenzano PP, Bagchi A.
      BACKGROUND & AIMS: Pancreatic ductal adenocarcinomas (PDACs) are hypovascular, resulting in the upregulation of hypoxia inducible factor 1 alpha (HIF1A), which promotes survival of cells under low-oxygen conditions. We studied the roles of HIF1A in development of pancreatic tumors in mice.METHODS: We performed studies with KrasLSL-G12D/+;Trp53LSL-R172H/+; Pdx1-Cre (KPC) mice, KPC mice with labeled pancreatic epithelial cells (EKPC), and EKPC mice with pancreas-specific depletion of HIF1A. Pancreatic and other tissues were collected and analyzed by histology, and immunohistochemistry. Cancer cells were cultured from PDACs from mice and analyzed in cell migration and invasion assays and by immunoblots, real-time PCR, and liquid chromatography-mass spectrometry. We performed studies with the human pancreatic cancer cell lines PATU-8988T, BxPC-3, PANC-1 and MiaPACA-2, which have no or low metastatic activity, and PATU-8988S, AsPC-1, SUIT-2 and Capan-1, which have high-metastatic activity. Expression of genes was knocked down in primary cancer cells and pancreatic cancer cell lines using small hairpin RNAs; cells were injected intravenously into immune-competent and NOD/SCID mice and lung metastases were quantified. We compared levels of mRNAs in pancreatic tumors and normal pancreas in the Cancer Genome Atlas.
    RESULTS: EKPC mice with pancreas-specific deletion of HIF1A developed more advanced pancreatic neoplasias and PDACs with more invasion and metastasis, and had significantly shorter survival times, than EKPC mice. Pancreatic cancer cells from these tumors had higher invasive and metastatic activity in culture than cells from tumors of EKPC mice. HIF1A-knockout pancreatic cancer cells had increased expression of protein phosphatase 1 regulatory inhibitor subunit 1B (PPP1R1B). There was an inverse correlation between levels of HIF1A and PPP1R1B in human PDAC tumors; higher expression of PPP1R1B correlated with shorter survival times of patients. Metastatic human pancreatic cancer cell lines had increased levels of PPP1R1B and lower levels of HIF1A compared with non-metastatic cancer cell lines; knockdown of PPP1R1B significantly reduced the ability of pancreatic cancer cells to form lung metastases in mice. PPP1R1B promoted degradation of p53 by stabilizing phosphorylation of MDM2 at Ser166.
    CONCLUSIONS: HIF1A can act a tumor suppressor by preventing expression of PPP1R1B and subsequent degradation of the p53 protein in pancreatic cancer cells. Loss of HIF1A from pancreatic cancer cells increases their invasive and metastatic activity.
    Keywords:  Carcinogenesis; Cell Motility; Signal Transduction; Tumor Progression
  74. Cancer Metab. 2020 ;8 9
    Oizel K, Yang C, Renoult O, Gautier F, Do QN, Joalland N, Gao X, Ko B, Vallette F, Ge WP, Paris F, DeBerardinis RJ, Pecqueur C.
      Background: Glioblastoma (GBM) are highly heterogeneous on the cellular and molecular basis. It has been proposed that glutamine metabolism of primary cells established from human tumors discriminates aggressive mesenchymal GBM subtype to other subtypes.Methods: To study glutamine metabolism in vivo, we used a human orthotopic mouse model for GBM. Tumors evolving from the implanted primary GBM cells expressing different molecular signatures were analyzed using mass spectrometry for their metabolite pools and enrichment in carbon 13 (13C) after 13C-glutamine infusion.
    Results: Our results showed that mesenchymal GBM tumors displayed increased glutamine uptake and utilization compared to both control brain tissue and other GBM subtypes. Furthermore, both glutamine synthetase and transglutaminase-2 were expressed accordingly to GBM metabolic phenotypes.
    Conclusion: Thus, our results outline the specific enhanced glutamine flux in vivo of the aggressive mesenchymal GBM subtype.
    Keywords:  Glioblastoma; Glutamine; Human primary cells; Mesenchymal; Metabolism; Molecular subtype; Orthotopic model
  75. Elife. 2020 Aug 10. pii: e59099. [Epub ahead of print]9
    Shi X, Chang C, Yokom AL, Jensen LE, Hurley JH.
      The selective autophagy pathways of xenophagy and mitophagy are initiated when the adaptor NDP52 recruits the ULK1 complex to autophagic cargo. Hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) was used to map the membrane and NDP52 binding sites of the ULK1 complex to unique regions of the coiled coil of the FIP200 subunit. Electron microscopy of the full-length ULK1 complex shows that the FIP200 coiled coil projects away from the crescent-shaped FIP200 N-terminal domain dimer. NDP52 allosterically stimulates membrane-binding by FIP200 and the ULK1 complex by promoting a more dynamic conformation of the membrane-binding portion of the FIP200 coiled coil. Giant unilamellar vesicle (GUV) reconstitution confirmed that membrane recruitment by the ULK1 complex is triggered by NDP52 engagement. These data reveal how the allosteric linkage between NDP52 and the ULK1 complex could drive the first membrane recruitment event of phagophore biogenesis in xenophagy and mitophagy.
    Keywords:  biochemistry; cell biology; chemical biology; human