bims-cagime Biomed News
on Cancer, aging and metabolism
Issue of 2021‒06‒20
forty papers selected by
Kıvanç Görgülü
Technical University of Munich

  1. Nat Cancer. 2020 Jun;1(6): 603-619
      Primary tumor-derived factors (TDFs) act upon normal cells to generate a pre-metastatic niche, which promotes colonization of target organs by disseminated malignant cells. Here we report that TDFs-induced activation of the p38α kinase in lung fibroblasts plays a critical role in the formation of a pre-metastatic niche in the lungs and subsequent pulmonary metastases. Activation of p38α led to inactivation of type I interferon signaling and stimulation of expression of fibroblast activation protein (FAP). FAP played a key role in remodeling of the extracellular matrix as well as inducing the expression of chemokines that enable lung infiltration by neutrophils. Increased activity of p38 in normal cells was associated with metastatic disease and poor prognosis in human melanoma patients whereas inactivation of p38 suppressed lung metastases. We discuss the p38α-driven mechanisms stimulating the metastatic processes and potential use of p38 inhibitors in adjuvant therapy of metastatic cancers.
    Keywords:  IFNAR1; adjuvant therapy; fibroblast activation protein; interferon; lung metastasis; melanoma; metastatic cancer; p38 inhibitor; p38 kinase; pancreatic ductal adenocarcinoma; pre-metastatic niche; tumor-derived factors
  2. Cell Biochem Funct. 2021 Jun 15.
      Energetically inefficient inter-organ substrate shuttles are proposed contributors to cachexia-related weight loss. Here, we examined glycolytic pathway metabolites, enzyme activity and transport proteins in skeletal muscle, liver and tumours of mice with cachexia-related weight loss induced by colon-26 cancer cells. Skeletal muscle of cachexic mice had increased [L-lactate]/[pyruvate], LDH activity and lactate transporter MCT1. Cachexic livers also showed increased MCT1. This is consistent with the proposal that the rate of muscle-derived lactate shuttling to liver for use in gluconeogenesis is increased, that is, an increased Cori cycle flux in weight-losing cachexic mice. A second shuttle between liver and tumour may also contribute to disrupted energy balance and weight loss. We found increased high-affinity glucose transporter GLUT1 in tumours, suggesting active glucose uptake, tumour MCT1 detection and decreased intratumour [L-lactate]/[pyruvate], implying increased lactate efflux and/or intratumour lactate oxidation. Last, high [L-lactate]/[pyruvate] and MCT1 in cachexic muscle provides a potential muscle-derived lactate supply for the tumour (a 'reverse Warburg effect'), supporting tumour growth and consequent cachexia. Our findings suggest several substrate shuttles among liver, skeletal muscle and tumour contribute to metabolic disruption and weight loss. Therapies that aim to normalize dysregulated substrate shuttling among energy-regulating tissues may alleviate unintended weight loss in cancer cachexia. SIGNIFICANCE OF THE STUDY: Cachexia is a serious complication of cancer characterized by severe weight loss, muscle atrophy and frailty. Cachexia occurs in roughly half of all cancer patients, and in up to 80% of patients with advanced disease. Cachexia independently worsens patient prognosis, lowers treatment efficacy, increases hospitalization cost and length of stay, and accounts for 20-30% of cancer-related deaths. There are no effective treatments. Our findings suggest several substrate shuttles among liver, skeletal muscle and tumour contribute to metabolic disruption and weight loss in cancer cachexia. Identifying therapies that normalize dysregulated substrate shuttling among energy-regulating tissues may protect against cachexia-related weight loss.
    Keywords:  Colon-26; Cori cycle; Warburg effect; energy metabolism; glucose transporter; lactate; monocarboxylate transporter
  3. Trends Cancer. 2021 Jun 07. pii: S2405-8033(21)00104-7. [Epub ahead of print]
      Autophagy is a catabolic intracellular nutrient-scavenging pathway triggered by nutrient deprivation and stress that captures and degrades intracellular proteins and organelles in lysosomes. The breakdown products are then recycled into metabolic pathways to sustain survival. Organelle turnover by autophagy contributes to quality control and suppresses inflammation. Autophagy is upregulated in many cancers and supports their growth, survival, and malignancy in a tumor cell-autonomous fashion. Host autophagy also promotes tumor growth by maintaining a supply of essential nutrients and suppressing innate and adaptive antitumor immune responses. Autophagy is also upregulated in response to cancer therapy and confers treatment resistance. Thus, autophagy is a cancer vulnerability and its inhibition is under investigation as a novel therapeutic approach.
    Keywords:  T cells; autophagy; cancer; immune response; interferon; metabolism
  4. Nat Commun. 2021 06 16. 12(1): 3660
      The mechanistic target of rapamycin complex 1 (mTORC1) integrates cellular nutrient signaling and hormonal cues to control metabolism. We have previously shown that constitutive nutrient signaling to mTORC1 by means of genetic activation of RagA (expression of GTP-locked RagA, or RagAGTP) in mice resulted in a fatal energetic crisis at birth. Herein, we rescue neonatal lethality in RagAGTP mice and find morphometric and metabolic alterations that span glucose, lipid, ketone, bile acid and amino acid homeostasis in adults, and a median lifespan of nine months. Proteomic and metabolomic analyses of livers from RagAGTP mice reveal a failed metabolic adaptation to fasting due to a global impairment in PPARα transcriptional program. These metabolic defects are partially recapitulated by restricting activation of RagA to hepatocytes, and revert by pharmacological inhibition of mTORC1. Constitutive hepatic nutrient signaling does not cause hepatocellular damage and carcinomas, unlike genetic activation of growth factor signaling upstream of mTORC1. In summary, RagA signaling dictates dynamic responses to feeding-fasting cycles to tune metabolism so as to match the nutritional state.
  5. J Clin Invest. 2021 Jun 15. pii: 146870. [Epub ahead of print]
      Disordered lysosomal/autophagy pathways initiate and drive pancreatitis, but the underlying mechanisms and links to disease pathology are poorly understood. Here, we show that mannose-6-phosphate (M6P) pathway of hydrolase delivery to lysosomes critically regulates pancreatic acinar cell cholesterol metabolism. Ablation of the Gnptab gene coding for a key enzyme in M6P pathway disrupted acinar cell cholesterol turnover, causing accumulation of non-esterified cholesterol in lysosomes/autolysosomes, its' depletion in the plasma membrane, and upregulation of cholesterol synthesis and uptake. We found similar dysregulation of acinar cell cholesterol, and a decrease in GNPTAB levels, in both WT experimental pancreatitis and human disease. The mechanisms mediating pancreatic cholesterol dyshomeostasis in Gnptab-/- and experimental models involve disordered endolysosomal system, resulting in impaired cholesterol transport through lysosomes and blockage of autophagic flux. By contrast, in Gnptab-/- liver the endolysosomal system and cholesterol homeostasis were largely unaffected. Gnptab-/- mice developed spontaneous pancreatitis. Normalization of cholesterol metabolism by pharmacologic means alleviated responses of experimental pancreatitis, particularly trypsinogen activation, the disease hallmark. The results reveal the essential role of M6P pathway in maintaining exocrine pancreas homeostasis and function, and implicate cholesterol disordering in the pathogenesis of pancreatitis.
    Keywords:  Autophagy; Cell Biology; Gastroenterology; Lysosomes; Mitochondria
  6. Cancer Lett. 2021 Jun 08. pii: S0304-3835(21)00255-X. [Epub ahead of print]517 66-77
      Mutations in KRAS frequently occur in human cancer and are especially prevalent in pancreatic ductal adenocarcinoma (PDAC), where they have been shown to promote aggressive phenotypes. However, targeting this onco-protein has proven to be challenging, highlighting the need to further identify the various mechanisms used by KRAS to drive cancer progression. Here, we considered the role played by exosomes, a specific class of extracellular vesicles (EVs) derived from the endocytic cellular trafficking machinery, in mediating the ability of KRAS to promote cell survival. We found that exosomes isolated from the serum of PDAC patients, as well as from KRAS-transformed fibroblasts and pancreatic cancer cells, were all highly enriched in the cell survival protein Survivin. Exosomes containing Survivin, upon engaging serum-starved cells, strongly enhanced their survival. Moreover, they significantly compromised the effectiveness of the conventional chemotherapy drug paclitaxel, as well as a novel therapy that combines an ERK inhibitor with chloroquine, which is currently in clinical trials for PDAC. The survival benefits provided by oncogenic KRAS-derived exosomes were markedly reduced when depleted of Survivin using siRNA or upon treatment with the Survivin inhibitor YM155. Taken together, these findings demonstrate how KRAS mutations give rise to exosomes that provide a unique form of intercellular communication to promote cancer cell survival and therapy resistance, as well as raise interesting possibilities regarding their potential for serving as therapeutic targets and diagnostic markers for KRAS-dependent cancers.
    Keywords:  Exosome; Extracellular vesicle; KRAS; Pancreatic cancer; Survivin
  7. Sci Adv. 2021 Jun;pii: eabf4885. [Epub ahead of print]7(25):
      Cancer cells exhibit hyperactive secretory states that maintain cancer cell viability and remodel the tumor microenvironment. However, the oncogenic signals that heighten secretion remain unclear. Here, we show that p53 loss activates prometastatic secretory vesicle biogenesis in the Golgi. p53 loss up-regulates the expression of a Golgi scaffolding protein, progestin and adipoQ receptor 11 (PAQR11), which recruits an adenosine diphosphate ribosylation factor 1-containing protein complex that loads cargos into secretory vesicles. PAQR11-dependent secretion of a protease, PLAU, prevents anoikis and initiates autocrine activation of a PLAU receptor/signal transducer and activator of transcription-3-dependent pathway that up-regulates PAQR11 expression, thereby completing a feedforward loop that amplifies prometastatic effector protein secretion. Pharmacologic inhibition of PLAU receptor impairs the growth and metastasis of p53-deficient cancers. Blockade of PAQR11-dependent secretion inhibits immunosuppressive processes in the tumor microenvironment. Thus, Golgi reprogramming by p53 loss is a key driver of hypersecretion in cancer.
  8. EMBO J. 2021 06 14. e105985
      Autophagy is a process through which intracellular cargoes are catabolised inside lysosomes. It involves the formation of autophagosomes initiated by the serine/threonine kinase ULK and class III PI3 kinase VPS34 complexes. Here, unbiased phosphoproteomics screens in mouse embryonic fibroblasts deleted for Ulk1/2 reveal that ULK loss significantly alters the phosphoproteome, with novel high confidence substrates identified including VPS34 complex member VPS15 and AMPK complex subunit PRKAG2. We identify six ULK-dependent phosphorylation sites on VPS15, mutation of which reduces autophagosome formation in cells and VPS34 activity in vitro. Mutation of serine 861, the major VPS15 phosphosite, decreases both autophagy initiation and autophagic flux. Analysis of VPS15 knockout cells reveals two novel ULK-dependent phenotypes downstream of VPS15 removal that can be partially recapitulated by chronic VPS34 inhibition, starvation-independent accumulation of ULK substrates and kinase activity-regulated recruitment of autophagy proteins to ubiquitin-positive structures.
    Keywords:  PIK3R4; PRKAG2; ULK1; VPS15; p62
  9. JCI Insight. 2021 Jun 17. pii: 138835. [Epub ahead of print]
      Cancer cells re-program cellular metabolism to maintain adequate nutrient pools to sustain proliferation. Moreover, autophagy is a regulated mechanism to breakdown dysfunctional cellular components and recycle cellular nutrients. However, the requirement for autophagy and the integration in cancer cell metabolism is not clear in colon cancer. Here we show a cell-autonomous dependency of autophagy for cell growth in colorectal cancer. Loss of epithelial autophagy inhibits tumor growth in both sporadic and colitis associated cancer models. Genetic and pharmacological inhibition of autophagy inhibits cell growth in colon cancer-derived cell lines and patient-derived enteroid models. Importantly, normal colon epithelium and patient-derived normal enteroid growth was not decreased following autophagy inhibition. To couple the role of autophagy to cellular metabolism, a cell culture screen in conjunction with metabolomic analysis was performed. We identified a critical role of autophagy to maintain mitochondrial metabolites for growth. Loss of mitochondrial recycling through inhibition of mitophagy hinders colon cancer cell growth. These findings have revealed a cell-autonomous role of autophagy that plays a critical role in regulating nutrient pools in vivo and in cell models and provides therapeutic targets for colon cancer.
    Keywords:  Colorectal cancer; Gastroenterology; Oncology
  10. Cell Rep. 2021 Jun 15. pii: S2211-1247(21)00597-0. [Epub ahead of print]35(11): 109238
      Metabolic adaptations and the signaling events that control them promote the survival of pancreatic ductal adenocarcinoma (PDAC) at the fibrotic tumor site, overcoming stresses associated with nutrient and oxygen deprivation. Recently, rewiring of NADPH production has been shown to play a key role in this process. NADPH is recycled through reduction of NADP+ by several enzymatic systems in cells. However, de novo NADP+ is synthesized only through one known enzymatic reaction, catalyzed by NAD+ kinase (NADK). In this study, we show that oncogenic KRAS promotes protein kinase C (PKC)-mediated NADK phosphorylation, leading to its hyperactivation, thus sustaining both NADP+ and NADPH levels in PDAC cells. Together, our data show that increased NADK activity is an important adaptation driven by oncogenic signaling. Our findings indicate that NADK could serve as a much-needed therapeutic target for PDAC.
    Keywords:  KRAS; NADK; NADP+; NADPH; PDAC; PKC
  11. Nat Metab. 2021 Jun 14.
      Pre-operative exercise therapy improves outcomes for many patients who undergo surgery. Despite the well-known effects on tolerance to systemic perturbation, the mechanisms by which pre-operative exercise protects the organ that is operated on from inflammatory injury are unclear. Here, we show that four-week aerobic pre-operative exercise significantly attenuates liver injury and inflammation from ischaemia and reperfusion in mice. Remarkably, these beneficial effects last for seven more days after completing pre-operative exercising. We find that exercise specifically drives Kupffer cells toward an anti-inflammatory phenotype with trained immunity via metabolic reprogramming. Mechanistically, exercise-induced HMGB1 release enhances itaconate metabolism in the tricarboxylic acid cycle that impacts Kupffer cells in an NRF2-dependent manner. Therefore, these metabolites and cellular/molecular targets can be investigated as potential exercise-mimicking pharmaceutical candidates to protect against liver injury during surgery.
  12. J Cancer Res Ther. 2021 Apr-Jun;17(2):17(2): 510-515
      Aim: We aimed to evaluate whether tumor markers and inflammation parameters effect on survival in patients with metastatic pancreatic cancer (MPC).Patients and Methods: This retrospective analysis included 170 patients with pancreatic cancer who were admitted to the oncology clinic at the metastatic stage. Basic patient demographic characteristics, chemotherapy (CT) that patients received in the first line, complete blood count, neutrophil/lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), albumin/globulin ratio (AGR), prognostic nutritional index (PNI), tumor markers (carcinoembryonic antigen [CEA], carbohydrate antigen 19-9 [CA19-9]), and survival were analyzed. Receiver operating characteristic analysis was used to determine the optimum cutoff value of NLR, PLR, AGR, PNI, CEA, and CA 19-9, which could predict survival.
    Results: The median age of the patients was 63 years (range, 33-87). About 63.5% of the patients were male and 44.5% were female. 161 (94.7%) patients died, and the median overall survival (OS) was 8.0 months (95% confidence interval = 6.6-9.4) for all patients. In univariate analysis, age (P < 0.001), CT regime (P < 0.002), AGR (P < 0.006), PNI (P < 0.017), NLR (P < 0.001), PLR (P < 0.062), and CA19-9 (P < 0.002) were statistically significant. In multivariate analysis, age (hazard ratio [HR] 1.534 95% 1.079-2.182 P < 0.017) CA19-9 (HR1.410 95% 1.001-1.989, P ≤0.005) and, NLR (HR 1.569 95% 1.001-2.463, P < 0.049) were significant.
    Conclusion: We determined, age, CA19-9, and basal high NLR as independent adverse prognostic factors for OS in APC. Fluorouracil, leucovorin, irinotecan, and oxaliplatin CT resulted in a significant increase in OS.
    Keywords:  Inflammation-based parameters; metastatic pancreatic cancer; tumor markers
  13. Cancer Invest. 2021 Jun 18. 1-20
      Data on Mesothelin expression in human normal and cancerous tissues is controversial. We employed immunohistochemistry on a tissue microarray from 599 pancreatic cancers and 12 large tissue sections of pancreatitis. Mesothelin expression was highest in pancreatic adenocarcinomas (89%) and adenocarcinomas of the ampulla Vateri (79%), infrequent in pancreatitis and absent in 6 acinus cell carcinomas and normal pancreas. Mesothelin expression was unrelated to pathological tumor stage, grade, metastasis, and tumor infiltrating CD8+ lymphocytes. In conclusion, pancreatic cancer may be ideally suited for putative anti-mesothelin therapies, and mesothelin may represent a suitable biomarker for pancreatic cancer diagnosis, especially on small biopsies.
  14. Mol Oncol. 2021 Jun 16.
      Senescence is a cellular state in which cells undergo persistent cell cycle arrest in response to non-lethal stress. In the treatment of cancer, senescence induction is a potent method of suppressing tumour cell proliferation. In spite of this, senescent cancer cells and adjacent non-transformed cells of the tumour microenvironment can remain metabolically active, resulting in paradoxical secretion of pro-inflammatory factors, collectively termed the senescence-associated secretory phenotype (SASP). The SASP plays a critical role in tumourigenesis, affecting numerous processes including invasion, metastasis, epithelial-to-mesenchymal transition (EMT) induction, therapy resistance and immunosuppression, among others. With increasing evidence, it is becoming clear that cell type, tissue of origin and the primary cellular stressor are key determinants in how the SASP will influence tumour development and progression, including whether it will be pro- or anti-tumourigenic. In this review, we will focus on recent evidence regarding therapy-induced senescence (TIS) from anti-cancer agents, including chemotherapy, radiation, immunotherapy, and targeted therapies, and how each therapy can trigger the SASP, which in turn influences treatment efficacy. We will also discuss novel pharmacological manipulation of senescent cancer cells and the SASP, which offers an exciting and contemporary approach to cancer therapeutics. With future research, these adjuvant options may help to mitigate many of the negative side effects and pro-tumorigenic roles that are currently associated with TIS in cancer.
    Keywords:  cancer; cellular senescence; senescence-associated secretory phenotype; therapy-induced senescence
  15. Proc Natl Acad Sci U S A. 2021 Jun 29. pii: e2026786118. [Epub ahead of print]118(26):
      Cells are the basic units of all living matter which harness the flow of energy to drive the processes of life. While the biochemical networks involved in energy transduction are well-characterized, the energetic costs and constraints for specific cellular processes remain largely unknown. In particular, what are the energy budgets of cells? What are the constraints and limits energy flows impose on cellular processes? Do cells operate near these limits, and if so how do energetic constraints impact cellular functions? Physics has provided many tools to study nonequilibrium systems and to define physical limits, but applying these tools to cell biology remains a challenge. Physical bioenergetics, which resides at the interface of nonequilibrium physics, energy metabolism, and cell biology, seeks to understand how much energy cells are using, how they partition this energy between different cellular processes, and the associated energetic constraints. Here we review recent advances and discuss open questions and challenges in physical bioenergetics.
    Keywords:  energetic constraints; energetic costs; energy fluxes; physical bioenergetics
  16. Cancer Immunol Res. 2021 Jun 18. pii: canimm.0785.2020. [Epub ahead of print]
      T cell recognition of tumor neoantigens is critical for cancer immune surveillance and the efficacy of immunotherapy. Tumors can evade host immunity by altering their antigenicity or orchestrating an immunosuppressive microenvironment, leading to outgrowth of poorly immunogenic tumors through the well-established process of cancer immunoediting. Whether cancer immune surveillance and immunoediting depends on the tissue site of origin, however, is poorly understood. Herein, we study T cell-mediated surveillance of highly antigenic, clonal murine pancreatic adenocarcinoma cells expressing neoantigen. Whereas such tumors are robustly eliminated after subcutaneous or intravenous challenge, we observed selective immune escape within the pancreas and peritoneum. Tumor outgrowth occurred in the absence of immunoediting, and antitumor immunity could not be rescued by PD-1 or CTLA-4 checkpoint blockade. Instead, tumor escape was associated with diminished CD8+ T cell priming by type I conventional dendritic cells (cDC1s). Enhancing cDC1 cross-presentation by CD40 agonist treatment restored immunologic control by promoting T cell priming and broadening T cell responses through epitope spread. These findings demonstrate that immune escape of highly antigenic tumors can occur without immunoediting in a tissue-restricted manner, and highlight barriers to cDC1-mediated T cell priming imposed by certain microenvironments that must be addressed for successful combination immunotherapies.
  17. Ageing Res Rev. 2021 Jun 14. pii: S1568-1637(21)00140-9. [Epub ahead of print] 101393
      Ageing is a multifactorial biological process leading to a progressive decline of physiological functions. The process of ageing includes numerous changes in the cells and the interactions between cell-cell and cell-microenvironment remaining as a critical risk factor for the development of chronic degenerative diseases. Systemic inflammation, known as inflammageing, increases as a consequence of ageing contributing to age-related morbidities. But also, persistent and uncontrolled activation of fibrotic pathways, with excessive accumulation of extracellular matrix (ECM) and organ dysfunction is markedly more frequent in the elderly. In this context, we introduce here the concept of Fibroageing, that is, the propensity to develop tissue fibrosis associated with ageing, and propose that ECM is a key player underlying this process. During ageing, molecules of the ECM become damaged through many modifications including glycation, crosslinking, and accumulation, leading to matrix stiffness which intensifies ageing-associated alterations. We provide a framework with some mechanistic hypotheses proposing that stiff ECM, in addition to the well-known activation of fibrotic positive feedback loops, affect several of the hallmarks of ageing, such as cell senescence and mitochondrial dysfunction, and in this context, is a key mechanism and a driver thread of Fibroageing.
    Keywords:  Ageing; extracellular matrix; fibrosis; senescence
  18. Elife. 2021 Jun 11. pii: e64744. [Epub ahead of print]10
      Lipid droplets are lipid storage organelles found in nearly all cell types from adipocytes to cancer cells. Although increasingly implicated in disease, current methods to study lipid droplets in vertebrate models rely on static imaging or the use of fluorescent dyes, limiting investigation of their rapid in vivo dynamics. To address this, we created a lipid droplet transgenic reporter in whole animals and cell culture by fusing tdTOMATO to Perilipin-2 (PLIN2), a lipid droplet structural protein. Expression of this transgene in transparent casper zebrafish enabled in vivo imaging of adipose depots responsive to nutrient deprivation and high-fat diet. Simultaneously, we performed a large-scale in vitro chemical screen of 1280 compounds and identified several novel regulators of lipolysis in adipocytes. Using our Tg(-3.5ubb:plin2-tdTomato) zebrafish line, we validated several of these novel regulators and revealed an unexpected role for nitric oxide in modulating adipocyte lipid droplets. Similarly, we expressed the PLIN2-tdTOMATO transgene in melanoma cells and found that the nitric oxide pathway also regulated lipid droplets in cancer. This model offers a tractable imaging platform to study lipid droplets across cell types and disease contexts using chemical, dietary, or genetic perturbations.
    Keywords:  adipocyte; cancer metabolism; cell biology; lipid droplet; obesity; zebrafish
  19. Proc Natl Acad Sci U S A. 2021 Jun 22. pii: e2100099118. [Epub ahead of print]118(25):
      Maintaining homeostasis is a fundamental characteristic of living systems. In cells, this is contributed to by the assembly of biochemically distinct organelles, many of which are not membrane bound but form by the physical process of liquid-liquid phase separation (LLPS). By analogy with LLPS in binary solutions, cellular LLPS was hypothesized to contribute to homeostasis by facilitating "concentration buffering," which renders the local protein concentration within the organelle robust to global variations in the average cellular concentration (e.g., due to expression noise). Interestingly, concentration buffering was experimentally measured in vivo in a simple organelle with a single solute, while it was observed not to be obeyed in one with several solutes. Here, we formulate theoretically and solve analytically a physical model of LLPS in a ternary solution of two solutes (ϕ and ψ) that interact both homotypically (ϕ-ϕ attractions) and heterotypically (ϕ-ψ attractions). Our physical theory predicts how the coexisting concentrations in LLPS are related to expression noise and thus, generalizes the concept of concentration buffering to multicomponent systems. This allows us to reconcile the seemingly contradictory experimental observations. Furthermore, we predict that incremental changes of the homotypic and heterotypic interactions among the molecules that undergo LLPS, such as those that are caused by mutations in the genes encoding the proteins, may increase the efficiency of concentration buffering of a given system. Thus, we hypothesize that evolution may optimize concentration buffering as an efficient mechanism to maintain LLPS homeostasis and suggest experimental approaches to test this in different systems.
    Keywords:  biological noise; biological physics; out-of-equilibrium thermodynamics; phase separation; soft matter
  20. Cancer Sci. 2021 Jun 19.
      Tissue-clearing technology is an emerging imaging technique currently utilized not only in neuroscience research but also in cancer research. In our previous reports, tissue-clearing methods were used for the detection of metastatic tumors. Here, we showed that the cell cycles of primary and metastatic tumors were visualized by tissue-clearing methods using a reporter system. First, we established cancer cell lines stably expressing fluorescent ubiquitination-based cell cycle indicator (Fucci) reporter with widely used cancer cell lines A549 and 4T1. Fluorescence patterns of the Fucci reporter were investigated in various tumor inoculation models in mice. Interestingly, fluorescence patterns of the Fucci reporter of tumor colonies were different between various organs, and even among colonies in the same organs. The effects of anti-tumor drugs were also evaluated using these Fucci reporter cells. Of the three anti-tumor drugs studied, 5-fluorouracil (5-FU) treatment on 4T1-Fucci cells resulted in characteristic fluorescent patterns by the induction of G2/M arrest both in vitro and in vivo. Thus, the combination of a tissue-clearing method with the Fucci reporter is useful for analyzing the mechanisms of cancer metastasis and drug resistance.
    Keywords:  Fucci system; anti-tumor drugs; cell cycle; metastasis; tissue-clearing technology
  21. JGH Open. 2021 Jun;5(6): 679-685
      Background and Aim: The optimal standard second-line chemotherapy for metastatic pancreatic cancer (MPC) remains unclear. Here, we evaluated the efficacy and safety of modified fluorouracil/leucovorin plus irinotecan and oxaliplatin (mFOLFIRINOX) compared with oral fluoropyrimidine S-1 as a second-line chemotherapy in patients with MPC.Methods: We retrospectively reviewed 76 consecutive patients with metastatic pancreatic adenocarcinoma who underwent mFOLFIRINOX or S-1 treatment as a second-line chemotherapy after gemcitabine plus nab-paclitaxel (GnP) failure at our department between December 2014 and February 2019.
    Results: Patients who underwent mFOLFIRINOX treatment exhibited significantly better objective response rates (ORRs) and progression-free survival (PFS) than S-1 (ORR, 20.0% vs 0%, P = 0.003; PFS, 3.7 vs 2.1 months, P = 0.010). Although baseline patient characteristics of age, performance status, and serum albumin levels differed significantly between the two groups, mFOLFIRINOX was identified as an independent factor of favorable PFS on multivariate analyses. Grade 3-4 neutropenia and peripheral sensory neuropathy occurred more frequently in the mFOLFIRINOX group. The median overall survival from the initiation of second-line chemotherapy was not significantly longer in the mFOLFIRINOX group than in the S1 group (8.5 vs 5.8 months, respectively; P = 0.213); however, the 8-month survival rate was significantly higher in the mFOLFIRINOX group (56.0% vs 27.5%, respectively; P = 0.030).
    Conclusions: mFOLFIRINOX as a second-line regimen contributed to favorable treatment outcomes, but induced more frequent adverse events than S-1. On multivariate analyses, mFOLFIRINOX was identified as an independent factor with favorable PFS, suggesting that mFOLFIRINOX could be a promising treatment option for patients with GnP failure.
    Keywords:  adverse event; overall survival; pancreatic adenocarcinoma; peripheral sensory neuropathy; progression‐free survival
  22. Nat Commun. 2021 Jun 18. 12(1): 3742
      Claudin-low breast cancer represents an aggressive molecular subtype that is comprised of mostly triple-negative mammary tumor cells that possess stem cell-like and mesenchymal features. Little is known about the cellular origin and oncogenic drivers that promote claudin-low breast cancer. In this study, we show that persistent oncogenic RAS signaling causes highly metastatic triple-negative mammary tumors in mice. More importantly, the activation of endogenous mutant KRAS and expression of exogenous KRAS specifically in luminal epithelial cells in a continuous and differentiation stage-independent manner induces preneoplastic lesions that evolve into basal-like and claudin-low mammary cancers. Further investigations demonstrate that the continuous signaling of oncogenic RAS, as well as regulators of EMT, play a crucial role in the cellular plasticity and maintenance of the mesenchymal and stem cell characteristics of claudin-low mammary cancer cells.
  23. Clin Cancer Res. 2021 Jun 10. pii: clincanres.CCR-21-1047-E.2021. [Epub ahead of print]
      PURPOSE: CD40 activation is a novel clinical opportunity for cancer immunotherapy. Despite numerous active clinical trials with agonistic CD40 monoclonal antibodies (mAb), biological effects and treatment-related modulation of the tumor microenvironment (TME) remain poorly understood.EXPERIMENTAL DESIGN: Here, we performed a neoadjuvant clinical trial of agonistic CD40 mAb (selicrelumab) administered intravenously with or without chemotherapy to 16 patients with resectable pancreatic ductal adenocarcinoma (PDAC) prior to surgery followed by adjuvant chemotherapy and CD40 mAb.
    RESULTS: The toxicity profile was acceptable and overall survival was 23.4 months (95% CI 18.0 - 28.8). Based on a novel multiplexed immunohistochemistry platform, we report evidence that neoadjuvant selicrelumab leads to major differences in the TME compared to resection specimens from treatment-naive PDAC patients or patients given neoadjuvant chemotherapy/chemoradiotherapy only. For selicrelumab-treated tumors, 82% were T cell-enriched, compared to 37% of untreated tumors (p=0.004) and 23% of chemotherapy/chemoradiation-treated tumors (p=0.012). T cells in both the TME and circulation were more active and proliferative after selicrelumab. Tumor fibrosis was reduced, M2-like tumor-associated macrophages were fewer, and intratumoral dendritic cells were more mature. Inflammatory cytokines CXCL10 and CCL22 increased systemically after selicrelumab.
    CONCLUSIONS: This unparalleled examination of CD40 therapeutic mechanisms in patients provides insights for design of subsequent clinical trials targeting this pathway.
  24. Elife. 2021 Jun 17. pii: e70298. [Epub ahead of print]10
      Two proteins called Sec17 and Sec18 may have a larger role in membrane fusion than is commonly assumed in textbook models.
    Keywords:  HOPS; S. cerevisiae; SNAREs; Sec17; Sec18; biochemistry; chemical biology; membrane fusion; yeast vacuoles
  25. EMBO J. 2021 Jun 15. 40(12): e107346
      Mutations in the shelterin protein POT1 are associated with chronic lymphocytic leukemia (CLL), Hodgkin lymphoma, angiosarcoma, melanoma, and other cancers. These cancer-associated POT1 (caPOT1) mutations are generally heterozygous, missense, or nonsense mutations occurring throughout the POT1 reading frame. Cancers with caPOT1 mutations have elongated telomeres and show increased genomic instability, but which of the two phenotypes promotes tumorigenesis is unclear. We tested the effects of CAS9-engineered caPOT1 mutations in human embryonic and hematopoietic stem cells (hESCs and HSCs, respectively). HSCs with caPOT1 mutations did not show overt telomere damage. In vitro and in vivo competition experiments showed the caPOT1 mutations did not confer a selective disadvantage. Since DNA damage signaling is known to affect the fitness of HSCs, the data argue that caPOT1 mutations do not cause significant telomere damage. Furthermore, hESC lines with caPOT1 mutations showed no detectable telomere damage response while showing consistent telomere elongation. Thus, caPOT1 mutations are likely selected for during cancer progression because of their ability to elongate telomeres and extend the proliferative capacity of the incipient cancer cells.
    Keywords:  POT1; cancer; genome editing; human stem cells; humanized mouse models; telomeres
  26. J Clin Invest. 2021 Jun 15. pii: 145800. [Epub ahead of print]131(12):
      Although tissue uptake of fatty acids from chylomicrons is primarily via lipoprotein lipase (LpL) hydrolysis of triglycerides (TGs), studies of patients with genetic LpL deficiency suggest additional pathways deliver dietary lipids to tissues. Despite an intact endothelial cell (EC) barrier, hyperchylomicronemic patients accumulate chylomicron-derived lipids within skin macrophages, leading to the clinical finding eruptive xanthomas. We explored whether an LpL-independent pathway exists for transfer of circulating lipids across the EC barrier. We found that LpL-deficient mice had a marked increase in aortic EC lipid droplets before and after a fat gavage. Cultured ECs internalized chylomicrons, which were hydrolyzed within lysosomes. The products of this hydrolysis fueled lipid droplet biogenesis in ECs and triggered lipid accumulation in cocultured macrophages. EC chylomicron uptake was inhibited by competition with HDL and knockdown of the scavenger receptor-BI (SR-BI). In vivo, SR-BI knockdown reduced TG accumulation in aortic ECs and skin macrophages of LpL-deficient mice. Thus, ECs internalize chylomicrons, metabolize them in lysosomes, and either store or release their lipids. This latter process may allow accumulation of TGs within skin macrophages and illustrates a pathway that might be responsible for creation of eruptive xanthomas.
    Keywords:  Endocrinology; Lipoproteins; Metabolism
  27. Cancer Res. 2021 Jun 18. pii: canres.CAN-21-1677-E.2021. [Epub ahead of print]
      Deregulated expression of the MYC oncoprotein enables tumor cells to evade immune surveillance, but the mechanisms underlying this surveillance are poorly understood. We show here that endogenous MYC protects pancreatic ductal adenocarcinoma driven by KRASG12D and TP53R172H from eradication by the immune system. Deletion of TANK-Binding Kinase 1 (TBK1) bypassed the requirement for high MYC expression. TBK1 was active due to the accumulation of double-stranded RNA (dsRNA), which was derived from inverted repetitive elements localized in introns of nuclear genes. Nuclear-derived dsRNA is packaged into extracellular vesicles and subsequently recognized by toll-like receptor 3 (TLR3) to activate TBK1 and downstream MHC class I expression in an autocrine or paracrine manner before being degraded in lysosomes. MYC suppressed loading of dsRNA onto TLR3 and its subsequent degradation via association with MIZ1. Collectively, these findings suggest that MYC and MIZ1 suppress a surveillance pathway that signals perturbances in mRNA processing to the immune system, which facilitates immune evasion in pancreatic ductal adenocarcinoma.
  28. FEBS J. 2021 Jun 18.
      The cell cycle is the essential biological process where one cell replicates its genome and segregates the resulting two copies into the daughter cells during mitosis. Several aspects of this process have fascinated humans since the nineteenth century. Today the cell cycle is exhaustively investigated because of its profound connections with human diseases and cancer. At the heart of the molecular network controlling the cell cycle we find the cyclin-dependent kinases (CDKs) acting as an oscillator to impose an orderly and highly regulated progression through the different cell cycle phases. This oscillator integrates both internal and external signals via a multitude of signalling pathways involving post-translational modifications including phosphorylation, protein ubiquitination and mechanisms of transcriptional regulation. These tasks are specifically performed by multi-subunit complexes, which are intensively studied both biochemically and structurally with the aim to unveil mechanistic insights into their molecular function. The scope of this review is to summarise the structural biology of the cell cycle machinery, with specific focus on the core cell cycle machinery involving the CDK-cyclin oscillator. We highlight the contribution of cryo-electron microscopy (cryo-EM), which has started to revolutionise our understanding of the molecular function and dynamics of the key players of the cell cycle.
    Keywords:  Cell cycle; cryo-electron microscopy; structural biology; transcriptional regulation; ubiquitin
  29. Aging Cell. 2021 Jun 12. e13407
      The mechanism of kidney injury in aging are not well understood. In order to identify hitherto unknown pathways of aging-related kidney injury, we performed RNA-Seq on kidney extracts of young and aged mice. Expression of chloride (Cl) channel accessory 1 (CLCA1) mRNA and protein was increased in the kidneys of aged mice. Immunostaining showed a marked increase in CLCLA1 expression in the proximal tubules of the kidney from aged mice. Increased kidney CLCA1 gene expression also correlated with aging in marmosets and in a human cohort. In aging mice, increased renal cortical CLCA1 content was associated with hydrogen sulfide (H2 S) deficiency, which was ameliorated by administering sodium hydrosulfide (NaHS), a source of H2 S. In order to study whether increased CLCA1 expression leads to injury phenotype and the mechanisms involved, stable transfection of proximal tubule epithelial cells overexpressing human CLCA1 (hCLCA1) was performed. Overexpression of hCLCA1 augmented Cl- current via the Ca++ -dependent Cl- channel TMEM16A (anoctamin-1) by patch-clamp studies. hCLCA1 overexpression also increased the expression of fibronectin, a matrix protein, and induced the senescence-associated secretory phenotype (SASP). Mechanistic studies underlying these changes showed that hCLCA1 overexpression leads to inhibition of AMPK activity and stimulation of mTORC1 as cellular signaling determinants of injury. Both TMEM16A inhibitor and NaHS reversed these signaling events and prevented changes in fibronectin and SASP. We conclude that CLCA1-TMEM16A-Cl- current pathway is a novel mediator of kidney injury in aging that is regulated by endogenous H2 S.
    Keywords:  fibrosis; ion transport; senescence-associated secretory phenotype
  30. ESMO Open. 2021 Jun;pii: S2059-7029(21)00049-1. [Epub ahead of print]6(3): 100092
    Keywords:  Clinical Practice Guidelines; assessment; cachexia; cancer; nutrition; treatment
  31. Science. 2021 Jun 18. 372(6548): 1349-1353
      The epigenome of macrophages can be reprogrammed by extracellular cues, but the extent to which different stimuli achieve this is unclear. Nuclear factor κB (NF-κB) is a transcription factor that is activated by all pathogen-associated stimuli and can reprogram the epigenome by activating latent enhancers. However, we show that NF-κB does so only in response to a subset of stimuli. This stimulus specificity depends on the temporal dynamics of NF-κB activity, in particular whether it is oscillatory or non-oscillatory. Non-oscillatory NF-κB opens chromatin by sustained disruption of nucleosomal histone-DNA interactions, enabling activation of latent enhancers that modulate expression of immune response genes. Thus, temporal dynamics can determine a transcription factor's capacity to reprogram the epigenome in a stimulus-specific manner.
  32. Ann Surg Oncol. 2021 Jun 15.
      BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a common fatal disease with unfavorable prognosis, even after oncological resection. To improve survival, adding hyperthermic intraperitoneal chemotherapy (HIPEC) has been suggested. Whether HIPEC entails disproportional short-term mortality is unknown and a prospectively determined adverse events profile is lacking. Since both pancreatic resection and HIPEC may relevantly influence morbidity and mortality, this uncontrolled single-arm, open-label, phase I/II pilot trial was designed to assess the 30-day mortality rate, treatment feasibility, and adverse events connected with HIPEC after oncological pancreatic surgery.METHODS: This trial recruited patients scheduled for PDAC resection. A sample size of 16 patients receiving study interventions was estimated to establish a predefined margin of treatment-associated short-term mortality with a power of > 80%. Patients achieving complete macroscopic resection received HIPEC with gemcitabine administered at 1000 mg/m2 body surface area heated to 42 °C for 1 hour.
    RESULTS: Within 30 days after intervention, no patient died or experienced any adverse events higher than grade 3 that were related to HIPEC. Furthermore, treatment-related adverse events were prospectively documented and categorized as expected or unexpected. This trial supports that the actual mortality rate after PDAC resection and HIPEC is below 10%. HIPEC treatment proved feasible in 89% of patients allocated to intervention. Pancreatic fistulas, as key complications after pancreas surgery, occurred in 3/13 patients under risk.
    CONCLUSION: Combined pancreas resection and gemcitabine HIPEC proved feasible and safe, with acceptable morbidity and mortality. Based on these results, further clinical evaluation can be justified.
  33. J Biomed Sci. 2021 Jun 19. 28(1): 48
      Accurate and complete replication of the genome is essential not only for genome stability but also for cell viability. However, cells face constant threats to the replication process, such as spontaneous DNA modifications and DNA lesions from endogenous and external sources. Any obstacle that slows down replication forks or perturbs replication dynamics is generally considered to be a form of replication stress, and the past decade has seen numerous advances in our understanding of how cells respond to and resolve such challenges. Furthermore, recent studies have also uncovered links between defects in replication stress responses and genome instability or various diseases, such as cancer. Because replication stress takes place in the context of chromatin, histone dynamics play key roles in modulating fork progression and replication stress responses. Here, we summarize the current understanding of histone dynamics in replication stress, highlighting recent advances in the characterization of fork-protective mechanisms.
    Keywords:  Genome instability; Histone dynamics; Histone modifications; Histone variants; Replication stress
  34. JCI Insight. 2021 Jun 15. pii: 149381. [Epub ahead of print]
      Neurogenic muscle atrophy is the loss of skeletal muscle mass and function that occurs with nerve injury and in denervating diseases such as amyotrophic lateral sclerosis. Aside from prompt restoration of innervation and exercise where feasible, there are currently no effective strategies for maintaining skeletal muscle mass in the setting of denervation. We conducted a longitudinal analysis of gene expression changes occurring in atrophying skeletal muscle, and identified Gadd45a as a gene that shows one of the earliest and most sustained increases in expression in skeletal muscle after denervation. We evaluated the role of this induction using genetic mouse models and found that mice lacking GADD45A show accelerated and exacerbated neurogenic muscle atrophy, as well as loss of fiber type identity. Our genetic analyses demonstrate that, rather than directly contributing to muscle atrophy as proposed in earlier studies, GADD45A induction likely represents a protective negative feedback response to denervation. Establishing the downstream effectors that mediate this protective effect and the pathways they participate in may yield new opportunities to modify the course of muscle atrophy.
    Keywords:  Muscle Biology; Neuromuscular disease; Neuroscience; Skeletal muscle
  35. Trends Cancer. 2021 Jun 16. pii: S2405-8033(21)00107-2. [Epub ahead of print]
      Stress granules (SGs) and processing bodies (P-bodies) are membraneless cytoplasmic condensates of ribonucleoproteins (RNPs). They both regulate RNA fate under physiological and pathological conditions, and are thereby involved in the regulation and maintenance of cellular integrity. During tumorigenesis, cancer cells use these granules to thrive, to adapt to the harsh conditions of the tumor microenvironment (TME), and to protect themselves from anticancer treatments. This ability to provide multiple outcomes not only makes RNP granules promising targets for cancer therapy but also emphasizes the need for more knowledge about the biology of these granules to achieve clinical use. In this review we focus on the role of RNP granules in cancer, and on how their composition and regulation might be used to elaborate therapeutic strategies.
    Keywords:  cancer; post-transcriptional regulation; processing bodies; stress granules; therapeutic target; translation
  36. J Biol Chem. 2021 Jun 15. pii: S0021-9258(21)00680-3. [Epub ahead of print] 100880
      More than half a century ago, reversible protein phosphorylation was first linked to mitochondrial metabolism through the regulation of pyruvate dehydrogenase. Since this discovery, the number of identified mitochondrial protein phosphorylation sites has increased by orders of magnitude, driven largely by technological advances in mass spectrometry-based phosphoproteomics. However, the majority of these modifications remain uncharacterized, rendering their function and relevance unclear. Nonetheless, recent studies have shown that disruption of resident mitochondrial protein phosphatases causes substantial metabolic dysfunction across organisms, suggesting that proper management of mitochondrial phosphorylation is vital for organellar and organismal homeostasis. While these data suggest that phosphorylation within mitochondria is of critical importance, significant gaps remain in our knowledge of how these modifications influence organellar function. Here, we curate publicly available datasets to map the extent of protein phosphorylation within mammalian mitochondria and to highlight the known functions of mitochondrial-resident phosphatases. We further propose models by which phosphorylation may affect mitochondrial enzyme activities, protein import and processing, and overall organellar homeostasis.
    Keywords:  mitochondria; phosphoproteomics; protein kinase; protein phosphatase; protein phosphorylation
  37. Trends Genet. 2021 Jun 10. pii: S0168-9525(21)00130-X. [Epub ahead of print]
      DNA methylation is a chemical modification that defines cell type and lineage through the control of gene expression and genome stability. Disruption of DNA methylation control mechanisms causes a variety of diseases, including cancer. Cancer cells are characterized by aberrant DNA methylation (i.e., genome-wide hypomethylation and site-specific hypermethylation), mainly targeting CpG islands in gene expression regulatory elements. In particular, the early findings that a variety of tumor suppressor genes (TSGs) are targets of DNA hypermethylation in cancer led to the proposal of a model in which aberrant DNA methylation promotes cellular oncogenesis through TSGs silencing. However, recent genome-wide analyses have revealed that this classical model needs to be reconsidered. In this review, we will discuss the molecular mechanisms of DNA methylation abnormalities in cancer as well as their therapeutic potential.
    Keywords:  DNA methylation; DNA methyltransferase; cancer; histone modification
  38. Elife. 2021 Jun 14. pii: e62927. [Epub ahead of print]10
      Collagens are a primary component of the extracellular matrix and are functional ligands for the inhibitory immune receptor leukocyte associated immunoglobulin-like receptor (LAIR)-1. LAIR-2 is a secreted protein that can act as a decoy receptor by binding collagen with higher affinity than LAIR-1. We propose that collagens promote immune evasion by interacting with LAIR-1 expressed on immune cells, and that LAIR-2 releases LAIR-1 mediated immune suppression. Analysis of public human datasets show that collagens, LAIR-1 and LAIR-2 have unique and overlapping associations with survival in certain tumors. We designed a dimeric LAIR-2 with a functional IgG1 Fc tail, NC410, and showed that NC410 increases human T cell expansion and effector function in vivo in a mouse xenogeneic-graft versus-host disease model. In humanized mouse tumor models NC410 reduces tumor growth that is dependent on T cells. Immunohistochemical analysis of human tumors shows that NC410 binds to collagen-rich areas where LAIR-1+ immune cells are localized. Our findings show that NC410 might be a novel strategy for cancer immunotherapy for immune-excluded tumors.
    Keywords:  cancer biology; mouse
  39. Commun Biol. 2021 Jun 16. 4(1): 747
      Tumour recurrence is a serious impediment to cancer treatment, but the mechanisms involved are poorly understood. The most frequently used anti-tumour therapies-chemotherapy and radiotherapy-target highly proliferative cancer cells. However non- or slow-proliferative dormant cancer cells can persist after treatment, eventually causing tumour relapse. Whereas the reversible growth arrest mechanism allows quiescent cells to re-enter the cell cycle, senescent cells are largely thought to be irreversibly arrested, and may instead contribute to tumour growth and relapse through paracrine signalling mechanisms. Thus, due to the differences in their growth arrest mechanism, metabolic features, plasticity and adaptation to their respective tumour microenvironment, dormant-senescent and -quiescent cancer cells could have different but complementary roles in fuelling tumour growth. In this review article, we discuss the implication of dormant cancer cells in tumour relapse and the need to understand how quiescent and senescent cells, respectively, may play a part in this process.