bims-cagime Biomed News
on Cancer, aging and metabolism
Issue of 2020–12–13
fifty-nine papers selected by
Kıvanç Görgülü, Technical University of Munich
  1. Obesity Shapes Metabolism in the Tumor Microenvironment to Suppress Anti-Tumor Immunity.
  2. Intercellular Mitochondria Transfer to Macrophages Regulates White Adipose Tissue Homeostasis and Is Impaired in Obesity.
  3. Tumor-Derived Myeloid Cell Chemoattractants and T Cell Exclusion in Pancreatic Cancer.
  4. Lipid Droplet Nucleation.
  5. SIRT1 - a new mammalian substrate of nuclear autophagy.
  6. Targeting Mitochondrial Complex I Overcomes Chemoresistance in High OXPHOS Pancreatic Cancer.
  7. Overcoming Adaptive Resistance to KRAS and MEK Inhibitors by Co-targeting mTORC1/2 Complexes in Pancreatic Cancer.
  8. Direct lysosome-based autophagy of lipid droplets in hepatocytes.
  9. Neutrophils Fuel Effective Immune Responses through Gluconeogenesis and Glycogenesis.
  10. TRPV4 integrates matrix mechanosensing with Ca2+ signaling to regulate extracellular matrix remodeling.
  11. CiBER-seq dissects genetic networks by quantitative CRISPRi profiling of expression phenotypes.
  12. P53 induces senescence in the unstable progeny of aneuploid cells.
  13. Cytology-based Detection of Circulating Tumour Cells in Human Pancreatic Cancer Xenograft Models With KRAS Mutation.
  14. Selective Labeling and Identification of the Tumor Cell Proteome of Pancreatic Cancer In Vivo.
  15. Hypoxia Dictates Metabolic Rewiring of Tumors: Implications for Chemoresistance.
  16. EMTome: a resource for pan-cancer analysis of epithelial-mesenchymal transition genes and signatures.
  17. The Nuclear Receptor ESRRA Protects from Kidney Disease by Coupling Metabolism and Differentiation.
  18. Stem-like CD8 T cells mediate response of adoptive cell immunotherapy against human cancer.
  19. Neutrophil infiltration regulates clock-gene expression to organize daily hepatic metabolism.
  20. A Novel Four-Gene Score to Predict Pathologically Complete (R0) Resection and Survival in Pancreatic Cancer.
  21. Autophagy in the cancer-immunity dialogue.
  22. Hypoxic induction of exosome uptake through proteoglycan dependent endocytosis fuels the lipid droplet phenotype in glioma.
  23. Nerve fibers in the tumor microenvironment in neurotropic cancer-pancreatic cancer and cholangiocarcinoma.
  24. The present and future of systemic and microenvironment-targeted therapy for pancreatic adenocarcinoma.
  25. A simple indirect colorimetric assay for measuring mitochondrial energy metabolism based on uncoupling sensitivity.
  26. Arterialization requires the timely suppression of cell growth.
  27. Fat and Furious: Lipid Metabolism in Antitumoral Therapy Response and Resistance.
  28. EMT-induced gemcitabine resistance in pancreatic cancer involves the functional loss of equilibrative nucleoside transporter 1.
  29. Mechanisms by which adiponectin reverses high fat diet-induced insulin resistance in mice.
  30. Protein condensates as aging Maxwell fluids.
  31. SUMMER, a shiny utility for metabolomics and multiomics exploratory research.
  32. Lymphoangiocrine signals promote cardiac growth and repair.
  33. Mitochondria as a Novel Target for Cancer Chemoprevention: Emergence of Mitochondrial Targeting Agents.
  34. Deciphering Organoids: High-Dimensional Analysis of Biomimetic Cultures.
  35. A metastasis map of human cancer cell lines.
  36. The role of lysosomes in cancer development and progression.
  37. Cell Migration Guided by Cell-Cell Contacts in Innate Immunity.
  38. mTOR inhibition acts as an unexpected checkpoint in p53-mediated tumor suppression.
  39. Cell non-autonomous regulation of health and longevity.
  40. Histone H1 loss drives lymphoma by disrupting 3D chromatin architecture.
  41. Extracellular Citrate Is a Trojan Horse for Cancer Cells.
  42. Selective inhibition of stemness through EGFR/FOXA2/SOX9 axis reduces pancreatic cancer metastasis.
  43. Mechanisms of EMRE-Dependent MCU Opening in the Mitochondrial Calcium Uniporter Complex.
  44. HPB cancers in older patients | inclusion of older/senior patients in clinical trials.
  45. Enhancing anti-tumour efficacy with immunotherapy combinations.
  46. Dissecting the immunogenomic biology of cancer for biomarker development.
  47. H1 histones control the epigenetic landscape by local chromatin compaction.
  48. Two-pore and TRP cation channels in endolysosomal osmo-/mechanosensation and volume regulation.
  49. Stressful development: Integrating endoderm development, stress, and longevity.
  50. When lipid homeostasis runs havoc: lipotoxicity links lysosomal dysfunction to autophagy.
  51. Autophagy-mediated metabolic effects of aspirin.
  52. Pancreatic, but not myeloid-cell, expression of interleukin-1alpha is required for maintenance of insulin secretion and whole body glucose homeostasis.
  53. The Two-Way Relationship Between Calcium and Metabolism in Cancer.
  54. Pontin arginine methylation by CARM1 is crucial for epigenetic regulation of autophagy.
  55. Molecular links between endocrine, nervous and immune system during chronic stress.
  56. The conformational and mutational landscape of the ubiquitin-like marker for autophagosome formation in cancer.
  57. Loss of Fas-signaling in fibroblasts impairs homeostatic fibrosis resolution and promotes persistent pulmonary fibrosis.
  58. Phase I Study of Afatinib and Selumetinib in Patients with KRAS-Mutated Colorectal, Non-Small Cell Lung, and Pancreatic Cancer.
  59. Alternative paths to telomere elongation.
  1. Cell. 2020 Dec 07. pii: S0092-8674(20)31526-9. [Epub ahead of print]
    Obesity Shapes Metabolism in the Tumor Microenvironment to Suppress Anti-Tumor Immunity.
    Alison E Ringel, Jefte M Drijvers, Gregory J Baker, Alessia Catozzi, Juan C García-Cañaveras, Brandon M Gassaway, Brian C Miller, Vikram R Juneja, Thao H Nguyen, Shakchhi Joshi, Cong-Hui Yao, Haejin Yoon, Peter T Sage, Martin W LaFleur, Justin D Trombley, Connor A Jacobson, Zoltan Maliga, Steven P Gygi, Peter K Sorger, Joshua D Rabinowitz, Arlene H Sharpe, Marcia C Haigis.
      Obesity is a major cancer risk factor, but how differences in systemic metabolism change the tumor microenvironment (TME) and impact anti-tumor immunity is not understood. Here, we demonstrate that high-fat diet (HFD)-induced obesity impairs CD8+ T cell function in the murine TME, accelerating tumor growth. We generate a single-cell resolution atlas of cellular metabolism in the TME, detailing how it changes with diet-induced obesity. We find that tumor and CD8+ T cells display distinct metabolic adaptations to obesity. Tumor cells increase fat uptake with HFD, whereas tumor-infiltrating CD8+ T cells do not. These differential adaptations lead to altered fatty acid partitioning in HFD tumors, impairing CD8+ T cell infiltration and function. Blocking metabolic reprogramming by tumor cells in obese mice improves anti-tumor immunity. Analysis of human cancers reveals similar transcriptional changes in CD8+ T cell markers, suggesting interventions that exploit metabolism to improve cancer immunotherapy.
    Keywords:  CD8+ T cells; anti-tumor immunity; colorectal cancer; fat oxidation; metabolism; obesity; tumor microenvironment
    DOI:  https://doi.org/10.1016/j.cell.2020.11.009
  2. Cell Metab. 2020 Nov 26. pii: S1550-4131(20)30603-3. [Epub ahead of print]
    Intercellular Mitochondria Transfer to Macrophages Regulates White Adipose Tissue Homeostasis and Is Impaired in Obesity.
    Jonathan R Brestoff, Craig B Wilen, John R Moley, Yongjia Li, Wei Zou, Nicole P Malvin, Marina N Rowen, Brian T Saunders, Hongming Ma, Madison R Mack, Barry L Hykes, Dale R Balce, Anthony Orvedahl, Jesse W Williams, Nidhi Rohatgi, Xiaoyan Wang, Michael R McAllaster, Scott A Handley, Brian S Kim, John G Doench, Bernd H Zinselmeyer, Michael S Diamond, Herbert W Virgin, Andrew E Gelman, Steven L Teitelbaum.
      Recent studies suggest that mitochondria can be transferred between cells to support the survival of metabolically compromised cells. However, whether intercellular mitochondria transfer occurs in white adipose tissue (WAT) or regulates metabolic homeostasis in vivo remains unknown. We found that macrophages acquire mitochondria from neighboring adipocytes in vivo and that this process defines a transcriptionally distinct macrophage subpopulation. A genome-wide CRISPR-Cas9 knockout screen revealed that mitochondria uptake depends on heparan sulfates (HS). High-fat diet (HFD)-induced obese mice exhibit lower HS levels on WAT macrophages and decreased intercellular mitochondria transfer from adipocytes to macrophages. Deletion of the HS biosynthetic gene Ext1 in myeloid cells decreases mitochondria uptake by WAT macrophages, increases WAT mass, lowers energy expenditure, and exacerbates HFD-induced obesity in vivo. Collectively, this study suggests that adipocytes and macrophages employ intercellular mitochondria transfer as a mechanism of immunometabolic crosstalk that regulates metabolic homeostasis and is impaired in obesity.
    Keywords:  beige adipose tissue; brown adipose tissue; horizontal mitochondria transfer; immunometabolism; intercellular mitochondria transfer; macrophage; metabolism; mitochondria; obesity; white adipose tissue
    DOI:  https://doi.org/10.1016/j.cmet.2020.11.008
  3. Front Immunol. 2020 ;11 605619
    Tumor-Derived Myeloid Cell Chemoattractants and T Cell Exclusion in Pancreatic Cancer.
    Robert H Vonderheide, Adham S Bear.
      Like many tumor types, pancreatic ductal adenocarcinoma (PDAC) exhibits a rich network of tumor-derived cytokines and chemokines that drive recruitment of myeloid cells to the tumor microenvironment (TME). These cells, which include tumor-associated macrophages and myeloid derived suppressor cells, block the recruitment and priming of T cells, resulting in T cell exclusion within the TME. Genetic or pharmacologic disruption of this chemokine/cytokine network reliably converts the PDAC TME to a T cell-high phenotype and sensitizes tumors to immunotherapy across multiple preclinical models. Thus, neutralization of tumor-derived chemokines/cytokines or blockade of their respective receptors represents a potentially potent strategy to reverse myeloid immunosuppression in PDAC, enabling benefit from checkpoint inhibition not otherwise achievable in this disease. Inhibition of oncogenic pathways that drive tumor-intrinsic expression of chemoattractants may be similarly effective.
    Keywords:  T cells; chemoattractant molecules; macrophages; myeloid; pancreatic
    DOI:  https://doi.org/10.3389/fimmu.2020.605619
  4. Trends Cell Biol. 2020 Dec 05. pii: S0962-8924(20)30231-2. [Epub ahead of print]
    Lipid Droplet Nucleation.
    Abdou Rachid Thiam, Elina Ikonen.
      All living organisms can make lipid droplets (LDs), intracellular oil-in-water droplets, surrounded by a phospholipid and protein monolayer. LDs are at the nexus of cellular lipid metabolism and function in diverse biological processes. During the past decade, multidisciplinary approaches have shed light on LD assembly steps from the endoplasmic reticulum (ER): nucleation, growth, budding, and formation of a separate organelle. However, the molecular mechanisms underpinning these steps remain elusive. In this review, we focus on the nucleation step, defining where and how LD assembly is initiated. We present how membrane biophysical and physicochemical properties control this step and how proteins act on it to orchestrate LD biogenesis.
    Keywords:  lipid droplet biogenesis; membrane chemistry; membrane curvature; neutral lipids; phase transitions; seipin
    DOI:  https://doi.org/10.1016/j.tcb.2020.11.006
  5. Autophagy. 2020 Dec 08.
    SIRT1 - a new mammalian substrate of nuclear autophagy.
    Lu Wang, Caiyue Xu, Terje Johansen, Shelley L Berger, Zhixun Dou.
      Macroautophagic/autophagic degradation of nuclear components (or nuclear autophagy) is a poorly understood area in autophagy research. We previously reported the nuclear lamina protein LMNB1 (lamin B1) as a nuclear autophagy substrate in primary human cells, stimulating the investigation of nuclear autophagy in the mammalian system. We recently reported the sirtuin protein SIRT1 as a new selective substrate of nuclear autophagy in senescence and aging. Upon senescence of primary human cells, SIRT1 degradation is mediated by a direct nuclear SIRT1-LC3 interaction, followed by nucleus-to-cytoplasm shuttling of SIRT1 and autophagosome-lysosome degradation. In vivo, SIRT1 is downregulated by lysosomes in hematopoietic and immune organs upon natural aging in mice and in aged human T cells. Our study identified another substrate of nuclear autophagy and suggests a new strategy to promote SIRT1-mediated health benefits by suppressing its autophagic degradation.
    Keywords:  Aging; SIRT1; nuclear autophagy; senescence; sirtuin
    DOI:  https://doi.org/10.1080/15548627.2020.1860541
  6. Cell Rep Med. 2020 Nov 17. 1(8): 100143
    Targeting Mitochondrial Complex I Overcomes Chemoresistance in High OXPHOS Pancreatic Cancer.
    Rawand Masoud, Gabriela Reyes-Castellanos, Sophie Lac, Julie Garcia, Samir Dou, Laetitia Shintu, Nadine Abdel Hadi, Tristan Gicquel, Abdessamad El Kaoutari, Binta Diémé, Fabrice Tranchida, Laurie Cormareche, Laurence Borge, Odile Gayet, Eddy Pasquier, Nelson Dusetti, Juan Iovanna, Alice Carrier.
      Mitochondrial respiration (oxidative phosphorylation, OXPHOS) is an emerging target in currently refractory cancers such as pancreatic ductal adenocarcinoma (PDAC). However, the variability of energetic metabolic adaptations between PDAC patients has not been assessed in functional investigations. In this work, we demonstrate that OXPHOS rates are highly heterogeneous between patient tumors, and that high OXPHOS tumors are enriched in mitochondrial respiratory complex I at protein and mRNA levels. Therefore, we treated PDAC cells with phenformin (complex I inhibitor) in combination with standard chemotherapy (gemcitabine), showing that this treatment is synergistic specifically in high OXPHOS cells. Furthermore, phenformin cooperates with gemcitabine in high OXPHOS tumors in two orthotopic mouse models (xenografts and syngeneic allografts). In conclusion, this work proposes a strategy to identify PDAC patients likely to respond to the targeting of mitochondrial energetic metabolism in combination with chemotherapy, and that phenformin should be clinically tested in appropriate PDAC patient subpopulations.
    Keywords:  OXPHOS; cancer metabolism; energetic metabolism; metabolic heterogeneity; mitochondria; mitochondrial Complex I; pancreatic cancer; personalized medicine; phenformin; therapeutic strategy
    DOI:  https://doi.org/10.1016/j.xcrm.2020.100143
  7. Cell Rep Med. 2020 Nov 17. 1(8): 100131
    Overcoming Adaptive Resistance to KRAS and MEK Inhibitors by Co-targeting mTORC1/2 Complexes in Pancreatic Cancer.
    Wells S Brown, Paul C McDonald, Oksana Nemirovsky, Shannon Awrey, Shawn C Chafe, David F Schaeffer, Jinyang Li, Daniel J Renouf, Ben Z Stanger, Shoukat Dedhar.
      Activating KRAS mutations are found in over 90% of pancreatic ductal adenocarcinomas (PDACs), yet KRAS has remained a difficult target to inhibit pharmacologically. Here, we demonstrate, using several human and mouse models of PDACs, rapid acquisition of tumor resistance in response to targeting KRAS or MEK, associated with integrin-linked kinase (ILK)-mediated increased phosphorylation of the mTORC2 component Rictor, and AKT. Although inhibition of mTORC1/2 results in a compensatory increase in ERK phosphorylation, combinatorial treatment of PDAC cells with either KRAS (G12C) or MEK inhibitors, together with mTORC1/2 inhibitors, results in synergistic cytotoxicity and cell death reflected by inhibition of pERK and pRictor/pAKT and of downstream regulators of protein synthesis and cell survival. Relative to single agents alone, this combination leads to durable inhibition of tumor growth and metastatic progression in vivo and increased survival. We have identified an effective combinatorial treatment strategy using clinically viable inhibitors, which can be applied to PDAC tumors with different KRAS mutations.
    Keywords:  AMG 510; KRAS; PDAC; acquired resistance; cellular toxicity; protein translation; signal transduction; tumor regression
    DOI:  https://doi.org/10.1016/j.xcrm.2020.100131
  8. Proc Natl Acad Sci U S A. 2020 Dec 07. pii: 202011442. [Epub ahead of print]
    Direct lysosome-based autophagy of lipid droplets in hepatocytes.
    Ryan J Schulze, Eugene W Krueger, Shaun G Weller, Katherine M Johnson, Carol A Casey, Micah B Schott, Mark A McNiven.
      Hepatocytes metabolize energy-rich cytoplasmic lipid droplets (LDs) in the lysosome-directed process of autophagy. An organelle-selective form of this process (macrolipophagy) results in the engulfment of LDs within double-membrane delimited structures (autophagosomes) before lysosomal fusion. Whether this is an exclusive autophagic mechanism used by hepatocytes to catabolize LDs is unclear. It is also unknown whether lysosomes alone might be sufficient to mediate LD turnover in the absence of an autophagosomal intermediate. We performed live-cell microscopy of hepatocytes to monitor the dynamic interactions between lysosomes and LDs in real-time. We additionally used a fluorescent variant of the LD-specific protein (PLIN2) that exhibits altered fluorescence in response to LD interactions with the lysosome. We find that mammalian lysosomes and LDs undergo interactions during which proteins and lipids can be transferred from LDs directly into lysosomes. Electron microscopy (EM) of primary hepatocytes or hepatocyte-derived cell lines supports the existence of these interactions. It reveals a dramatic process whereby the lipid contents of the LD can be "extruded" directly into the lysosomal lumen under nutrient-limited conditions. Significantly, these interactions are not affected by perturbations to crucial components of the canonical macroautophagy machinery and can occur in the absence of double-membrane lipoautophagosomes. These findings implicate the existence of an autophagic mechanism used by mammalian cells for the direct transfer of LD components into the lysosome for breakdown. This process further emphasizes the critical role of lysosomes in hepatic LD catabolism and provides insights into the mechanisms underlying lipid homeostasis in the liver.
    Keywords:  hepatocyte; lipid droplet; lipolysis; lysosome; microautophagy
    DOI:  https://doi.org/10.1073/pnas.2011442117
  9. Cell Metab. 2020 Dec 01. pii: S1550-4131(20)30651-3. [Epub ahead of print]
    Neutrophils Fuel Effective Immune Responses through Gluconeogenesis and Glycogenesis.
    Pranvera Sadiku, Joseph A Willson, Eilise M Ryan, David Sammut, Patricia Coelho, Emily R Watts, Robert Grecian, Jason M Young, Martin Bewley, Simone Arienti, Ananda S Mirchandani, Manuel A Sanchez Garcia, Tyler Morrison, Ailing Zhang, Leila Reyes, Tobias Griessler, Privjyot Jheeta, Gordon G Paterson, Christopher J Graham, John P Thomson, Kenneth Baillie, A A Roger Thompson, Jessie-May Morgan, Abel Acosta-Sanchez, Veronica M Dardé, Jordi Duran, Joan J Guinovart, Gio Rodriguez-Blanco, Alex Von Kriegsheim, Richard R Meehan, Massimiliano Mazzone, David H Dockrell, Bart Ghesquiere, Peter Carmeliet, Moira K B Whyte, Sarah R Walmsley.
      Neutrophils can function and survive in injured and infected tissues, where oxygen and metabolic substrates are limited. Using radioactive flux assays and LC-MS tracing with U-13C glucose, glutamine, and pyruvate, we observe that neutrophils require the generation of intracellular glycogen stores by gluconeogenesis and glycogenesis for effective survival and bacterial killing. These metabolic adaptations are dynamic, with net increases in glycogen stores observed following LPS challenge or altitude-induced hypoxia. Neutrophils from patients with chronic obstructive pulmonary disease have reduced glycogen cycling, resulting in impaired function. Metabolic specialization of neutrophils may therefore underpin disease pathology and allow selective therapeutic targeting.
    Keywords:  COPD; GYS1; gluconeogenesis; glycogen; glycogenesis; glycogenolysis; glycolysis; inflammation; neutrophil
    DOI:  https://doi.org/10.1016/j.cmet.2020.11.016
  10. FEBS J. 2020 Dec 09.
    TRPV4 integrates matrix mechanosensing with Ca2+ signaling to regulate extracellular matrix remodeling.
    Chenfan Ji, C A McCulloch.
      In healthy connective tissues, mechanosensors trigger the generation of Ca2+ signals, which enable cells to maintain the structure of the fibrillar collagen matrix through actomyosin contractile forces. TRPV4 is a mechanosensitive Ca2+ -permeable channel that, when expressed in cell-matrix adhesions of the plasma membrane, regulates extracellular matrix (ECM) remodeling. In high prevalence disorders such as fibrosis and tumour metastasis, dysregulated matrix remodeling is associated with disruptions of Ca2+ homeostasis and TRPV4 function. Here we consider that ECM polymers transmit cell-activating mechanical signals to TRPV4 in cell adhesions. When activated, TRPV4 regulates fibrillar collagen remodeling, thereby altering the mechanical properties of the ECM. In this review we integrate functionally connected processes of matrix remodeling to highlight how TRPV4 in cell adhesions and matrix mechanics are reciprocally regulated through Ca2+ signaling.
    Keywords:  TRPV4; cell contractility; collagen; fibrosis; matrix signaling; remodeling
    DOI:  https://doi.org/10.1111/febs.15665
  11. Science. 2020 Dec 11. pii: eabb9662. [Epub ahead of print]370(6522):
    CiBER-seq dissects genetic networks by quantitative CRISPRi profiling of expression phenotypes.
    Ryan Muller, Zuriah A Meacham, Lucas Ferguson, Nicholas T Ingolia.
      To realize the promise of CRISPR-Cas9-based genetics, approaches are needed to quantify a specific, molecular phenotype across genome-wide libraries of genetic perturbations. We addressed this challenge by profiling transcriptional, translational, and posttranslational reporters using CRISPR interference (CRISPRi) with barcoded expression reporter sequencing (CiBER-seq). Our barcoding approach allowed us to connect an entire library of guides to their individual phenotypic consequences using pooled sequencing. CiBER-seq profiling fully recapitulated the integrated stress response (ISR) pathway in yeast. Genetic perturbations causing uncharged transfer RNA (tRNA) accumulation activated ISR reporter transcription. Notably, tRNA insufficiency also activated the reporter, independent of the uncharged tRNA sensor. By uncovering alternate triggers for ISR activation, we illustrate how precise, comprehensive CiBER-seq profiling provides a powerful and broadly applicable tool for dissecting genetic networks.
    DOI:  https://doi.org/10.1126/science.abb9662
  12. Cell Cycle. 2020 Dec 11. 1-13
    P53 induces senescence in the unstable progeny of aneuploid cells.
    Maybelline Giam, Cheng Kit Wong, Jun Siong Low, Matteo Sinelli, Oliver Dreesen, Giulia Rancati.
      Aneuploidy is the condition of having an imbalanced karyotype, which is associated with tumor initiation, evolution, and acquisition of drug-resistant features, possibly by generating heterogeneous populations of cells with distinct genotypes and phenotypes. Multicellular eukaryotes have therefore evolved a range of extrinsic and cell-autonomous mechanisms for restraining proliferation of aneuploid cells, including activation of the tumor suppressor protein p53. However, accumulating evidence indicates that a subset of aneuploid cells can escape p53-mediated growth restriction and continue proliferating in vitro. Here we show that such aneuploid cell lines display a robust modal karyotype and low frequency of chromosomal aberrations despite ongoing chromosome instability. Indeed, while these aneuploid cells are able to survive for extended periods in vitro, their chromosomally unstable progeny remain subject to p53-induced senescence and growth restriction, leading to subsequent elimination from the aneuploid pool. This mechanism helps maintain low levels of heterogeneity in aneuploid populations and may prevent detrimental evolutionary processes such as cancer progression and development of drug resistance.
    Keywords:  P53; aneuploidy; genome instability; senescence
    DOI:  https://doi.org/10.1080/15384101.2020.1850968
  13. Anticancer Res. 2020 Dec;40(12): 6781-6789
    Cytology-based Detection of Circulating Tumour Cells in Human Pancreatic Cancer Xenograft Models With KRAS Mutation.
    Yukako Ito, Eriko Inoue, Yuki Matsui, Shinji Kobuchi, Chiami Moyama, Kikuko Amagase, Mayumi Yoshimura, Yuzuru Ikehara, Susumu Nakata, Hayao Nakanishi.
       BACKGROUND/AIM: To examine the dynamics of circulating tumour cells (CTCs) in pancreatic cancer (PC), new mouse CTC models from human PC xenografts were developed.
    MATERIALS AND METHODS: Orthotopic (pancreas) and heterotopic (subcutaneous) transplantation models using GFP-tagged SUIT-2 PC cells were prepared. Using a cytology-based CTC detection platform, CTCs and metastasis were compared.
    RESULTS: The two types of orthotopic models, including the surgical transplantation model and the intraperitoneal injection model, showed a similar pattern of initial pancreatic tumour formation and subsequent development of peritoneal and hematogenous lung metastases. In the heterotopic model, only hematogenous lung metastasis was observed, and the number of CTCs and lung metastases was higher than that of the orthotopic model. Furthermore, KRAS mutation (G12D) was detected in CTCs.
    CONCLUSION: These orthotopic and heterotopic models clearly differ in terms of the pattern of metastasis and CTCs and therefore, would be useful PC models to investigate the effect of drug-therapy on CTCs and the role of KRAS mutation.
    Keywords:  CTC; CTC detection platform; KRAS mutation; cytology; mouse model; pancreatic cancer
    DOI:  https://doi.org/10.21873/anticanres.14701
  14. J Proteome Res. 2020 Dec 08.
    Selective Labeling and Identification of the Tumor Cell Proteome of Pancreatic Cancer In Vivo.
    Nancy G Azizian, Delaney K Sullivan, Litong Nie, Sammy Pardo, Dana Molleur, Junjie Chen, Susan T Weintraub, Yulin Li.
      Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest cancers. Dissecting the tumor cell proteome from that of the non-tumor cells in the PDAC tumor bulk is critical for tumorigenesis studies, biomarker discovery, and development of therapeutics. However, investigating the tumor cell proteome has proven evasive due to the tumor's extremely complex cellular composition. To circumvent this technical barrier, we have combined bioorthogonal noncanonical amino acid tagging (BONCAT) and data-independent acquisition mass spectrometry (DIA-MS) in an orthotopic PDAC model to specifically identify the tumor cell proteome in vivo. Utilizing the tumor cell-specific expression of a mutant tRNA synthetase transgene, this approach provides tumor cells with the exclusive ability to incorporate an azide-bearing methionine analogue into newly synthesized proteins. The azide-tagged tumor cell proteome is subsequently enriched and purified via a bioorthogonal reaction and then identified and quantified using DIA-MS. Applying this workflow to the orthotopic PDAC model, we have identified thousands of proteins expressed by the tumor cells. Furthermore, by comparing the tumor cell and tumor bulk proteomes, we showed that the approach can distinctly differentiate proteins produced by tumor cells from those of non-tumor cells within the tumor microenvironment. Our study, for the first time, reveals the tumor cell proteome of PDAC under physiological conditions, providing broad applications for tumorigenesis, therapeutics, and biomarker studies in various human cancers.
    Keywords:  azidonorleucine (ANL); bioorthogonal noncanonical amino acid tagging (BONCAT); data-independent acquisition mass spectrometry (DIA-MS); methionyl-tRNA synthetase (MetRS); pancreatic ductal adenocarcinoma (PDAC); patient-derived xenografts (PDX)
    DOI:  https://doi.org/10.1021/acs.jproteome.0c00666
  15. Cells. 2020 Dec 04. pii: E2598. [Epub ahead of print]9(12):
    Hypoxia Dictates Metabolic Rewiring of Tumors: Implications for Chemoresistance.
    Dimas Carolina Belisario, Joanna Kopecka, Martina Pasino, Muhlis Akman, Enrico De Smaele, Massimo Donadelli, Chiara Riganti.
      Hypoxia is a condition commonly observed in the core of solid tumors. The hypoxia-inducible factors (HIF) act as hypoxia sensors that orchestrate a coordinated response increasing the pro-survival and pro-invasive phenotype of cancer cells, and determine a broad metabolic rewiring. These events favor tumor progression and chemoresistance. The increase in glucose and amino acid uptake, glycolytic flux, and lactate production; the alterations in glutamine metabolism, tricarboxylic acid cycle, and oxidative phosphorylation; the high levels of mitochondrial reactive oxygen species; the modulation of both fatty acid synthesis and oxidation are hallmarks of the metabolic rewiring induced by hypoxia. This review discusses how metabolic-dependent factors (e.g., increased acidification of tumor microenvironment coupled with intracellular alkalinization, and reduced mitochondrial metabolism), and metabolic-independent factors (e.g., increased expression of drug efflux transporters, stemness maintenance, and epithelial-mesenchymal transition) cooperate in determining chemoresistance in hypoxia. Specific metabolic modifiers, however, can reverse the metabolic phenotype of hypoxic tumor areas that are more chemoresistant into the phenotype typical of chemosensitive cells. We propose these metabolic modifiers, able to reverse the hypoxia-induced metabolic rewiring, as potential chemosensitizer agents against hypoxic and refractory tumor cells.
    Keywords:  cancer; chemoresistance; hypoxia; metabolic reprogramming
    DOI:  https://doi.org/10.3390/cells9122598
  16. Br J Cancer. 2020 Dec 10.
    EMTome: a resource for pan-cancer analysis of epithelial-mesenchymal transition genes and signatures.
    Suhas V Vasaikar, Abhijeet P Deshmukh, Petra den Hollander, Sridevi Addanki, Nick Allen Kuburich, Sriya Kudaravalli, Robiya Joseph, Jeffrey T Chang, Rama Soundararajan, Sendurai A Mani.
       BACKGROUND: The epithelial-mesenchymal transition (EMT) enables dissociation of tumour cells from the primary tumour mass, invasion through the extracellular matrix, intravasation into blood vessels and colonisation of distant organs. Cells that revert to the epithelial state via the mesenchymal-epithelial transition cause metastases, the primary cause of death in cancer patients. EMT also empowers cancer cells with stem-cell properties and induces resistance to chemotherapeutic drugs. Understanding the driving factors of EMT is critical for the development of effective therapeutic interventions.
    METHODS: This manuscript describes the generation of a database containing EMT gene signatures derived from cell lines, patient-derived xenografts and patient studies across cancer types and multiomics data and the creation of a web-based portal to provide a comprehensive analysis resource.
    RESULTS: EMTome incorporates (i) EMT gene signatures; (ii) EMT-related genes with multiomics features across different cancer types; (iii) interactomes of EMT-related genes (miRNAs, transcription factors, and proteins); (iv) immune profiles identified from The Cancer Genome Atlas (TCGA) cohorts by exploring transcriptomics, epigenomics, and proteomics, and drug sensitivity and (iv) clinical outcomes of cancer cohorts linked to EMT gene signatures.
    CONCLUSION: The web-based EMTome portal is a resource for primary and metastatic tumour research publicly available at www.emtome.org .
    DOI:  https://doi.org/10.1038/s41416-020-01178-9
  17. Cell Metab. 2020 Dec 01. pii: S1550-4131(20)30606-9. [Epub ahead of print]
    The Nuclear Receptor ESRRA Protects from Kidney Disease by Coupling Metabolism and Differentiation.
    Poonam Dhillon, Jihwan Park, Carmen Hurtado Del Pozo, Lingzhi Li, Tomohito Doke, Shizheng Huang, Juanjuan Zhao, Hyun Mi Kang, Rojesh Shrestra, Michael S Balzer, Shatakshee Chatterjee, Patricia Prado, Seung Yub Han, Hongbo Liu, Xin Sheng, Pieterjan Dierickx, Kirill Batmanov, Juan P Romero, Felipe Prósper, Mingyao Li, Liming Pei, Junhyong Kim, Nuria Montserrat, Katalin Susztak.
      Kidney disease is poorly understood because of the organ's cellular diversity. We used single-cell RNA sequencing not only in resolving differences in injured kidney tissue cellular composition but also in cell-type-specific gene expression in mouse models of kidney disease. This analysis highlighted major changes in cellular diversity in kidney disease, which markedly impacted whole-kidney transcriptomics outputs. Cell-type-specific differential expression analysis identified proximal tubule (PT) cells as the key vulnerable cell type. Through unbiased cell trajectory analyses, we show that PT cell differentiation is altered in kidney disease. Metabolism (fatty acid oxidation and oxidative phosphorylation) in PT cells showed the strongest and most reproducible association with PT cell differentiation and disease. Coupling of cell differentiation and the metabolism was established by nuclear receptors (estrogen-related receptor alpha [ESRRA] and peroxisomal proliferation-activated receptor alpha [PPARA]) that directly control metabolic and PT-cell-specific gene expression in mice and patient samples while protecting from kidney disease in the mouse model.
    Keywords:  ESRRA; PPARA; chronic kidney disease; fatty-acid oxidation; fibrosis; kidney; organoids; proximal tubule cells; single-cell ATAC sequencing; single-cell RNA sequencing
    DOI:  https://doi.org/10.1016/j.cmet.2020.11.011
  18. Science. 2020 Dec 11. 370(6522): 1328-1334
    Stem-like CD8 T cells mediate response of adoptive cell immunotherapy against human cancer.
    Sri Krishna, Frank J Lowery, Amy R Copeland, Erol Bahadiroglu, Ratnadeep Mukherjee, Li Jia, James T Anibal, Abraham Sachs, Serifat O Adebola, Devikala Gurusamy, Zhiya Yu, Victoria Hill, Jared J Gartner, Yong F Li, Maria Parkhurst, Biman Paria, Pia Kvistborg, Michael C Kelly, Stephanie L Goff, Grégoire Altan-Bonnet, Paul F Robbins, Steven A Rosenberg.
      Adoptive T cell therapy (ACT) using ex vivo-expanded autologous tumor-infiltrating lymphocytes (TILs) can mediate complete regression of certain human cancers. The impact of TIL phenotypes on clinical success of TIL-ACT is currently unclear. Using high-dimensional analysis of human ACT products, we identified a memory-progenitor CD39-negative stem-like phenotype (CD39-CD69-) associated with complete cancer regression and TIL persistence and a terminally differentiated CD39-positive state (CD39+CD69+) associated with poor TIL persistence. Most antitumor neoantigen-reactive TILs were found in the differentiated CD39+ state. However, ACT responders retained a pool of CD39- stem-like neoantigen-specific TILs that was lacking in ACT nonresponders. Tumor-reactive stem-like TILs were capable of self-renewal, expansion, persistence, and superior antitumor response in vivo. These data suggest that TIL subsets mediating ACT response are distinct from TIL subsets enriched for antitumor reactivity.
    DOI:  https://doi.org/10.1126/science.abb9847
  19. Elife. 2020 12 08. pii: e59258. [Epub ahead of print]9
    Neutrophil infiltration regulates clock-gene expression to organize daily hepatic metabolism.
    María Crespo, Barbara Gonzalez-Teran, Ivana Nikolic, Alfonso Mora, Cintia Folgueira, Elena Rodríguez, Luis Leiva-Vega, Aránzazu Pintor-Chocano, Macarena Fernández-Chacón, Irene Ruiz-Garrido, Beatriz Cicuéndez, Antonia Tomás-Loba, Noelia A-Gonzalez, Ainoa Caballero-Molano, Daniel Beiroa, Lourdes Hernández-Cosido, Jorge L Torres, Norman J Kennedy, Roger J Davis, Rui Benedito, Miguel Marcos, Ruben Nogueiras, Andrés Hidalgo, Nuria Matesanz, Magdalena Leiva, Guadalupe Sabio.
      Liver metabolism follows diurnal fluctuations through the modulation of molecular clock genes. Disruption of this molecular clock can result in metabolic disease but its potential regulation by immune cells remains unexplored. Here, we demonstrated that in steady state, neutrophils infiltrated the mouse liver following a circadian pattern and regulated hepatocyte clock-genes by neutrophil elastase (NE) secretion. NE signals through c-Jun NH2-terminal kinase (JNK) inhibiting fibroblast growth factor 21 (FGF21) and activating Bmal1 expression in the hepatocyte. Interestingly, mice with neutropenia, defective neutrophil infiltration or lacking elastase were protected against steatosis correlating with lower JNK activation, reduced Bmal1 and increased FGF21 expression, together with decreased lipogenesis in the liver. Lastly, using a cohort of human samples we found a direct correlation between JNK activation, NE levels and Bmal1 expression in the liver. This study demonstrates that neutrophils contribute to the maintenance of daily hepatic homeostasis through the regulation of the NE/JNK/Bmal1 axis.
    Keywords:  JNK; cell biology; circadian rhythm; immunology; inflammation; mouse; neutrophil elastase; steatosis
    DOI:  https://doi.org/10.7554/eLife.59258
  20. Cancers (Basel). 2020 Dec 04. pii: E3635. [Epub ahead of print]12(12):
    A Novel Four-Gene Score to Predict Pathologically Complete (R0) Resection and Survival in Pancreatic Cancer.
    Masanori Oshi, Yoshihisa Tokumaru, Ankit Patel, Li Yan, Ryusei Matsuyama, Itaru Endo, Matthew H G Katz, Kazuaki Takabe.
      Pathologically complete (R0) resection is essential for prolonged survival in pancreatic cancer. Survival depends not only on surgical technique, but also on cancer biology. A biomarker to predict survival is a critical need in pancreatic treatment. We hypothesized that this 4-gene score, which was reported to reflect cell proliferation, is a translatable predictive biomarker for pancreatic cancer. A total of 954 pancreatic cancer patients from multiple cohorts were analyzed and validated. Pancreatic cancer had the 10th highest median score of 32 cancers in The Cancer Genome Atlas (TCGA) cohort. The four-gene score significantly correlated with pathological grade and MKI67 expression. The high four-gene score enriched cell proliferation-related and cancer aggressiveness-related gene sets. The high score was associated with activation of KRAS, p53, transforming growth factor (TGF)-β, and E2F pathways, and with high alteration rate of KRAS and CDKN2A genes. The high score was also significantly associated with reduced CD8+ T cell infiltration of tumors, but with high levels of interferon-γ and cytolytic activity in tumors. The four-gene score correlated with the area under the curve of irinotecan and sorafenib in primary pancreatic cancer, and with paclitaxel and doxorubicin in metastatic pancreatic cancer. The high four-gene score was associated with significantly fewer R0 resections and worse survival. The novelty of the study is in the application of the four-gene score to pancreatic cancer, rather than the bioinformatics technique itself. Future analyses of inoperable lesions are expected to clarify the utility of our score as a predictive biomarker of systemic treatments.
    Keywords:  alteration; biomarker; four-gene score; gene set; immune cell; pancreatic cancer; pathway analysis; proliferation; resection; treatment response; tumor gene expression
    DOI:  https://doi.org/10.3390/cancers12123635
  21. Adv Drug Deliv Rev. 2020 Dec 07. pii: S0169-409X(20)30274-X. [Epub ahead of print]
    Autophagy in the cancer-immunity dialogue.
    Takahiro Yamazaki, José Manuel Bravo-San Pedro, Lorenzo Galluzzi, Guido Kroemer, Federico Pietrocola.
      Autophagy is quintessential for the maintenance of cellular homeostasis in all eukaryotic cells, explaining why both normal and malignant cells benefit from proficient autophagic responses. Moreover, autophagy is intimately involved in the immunological control of malignant transformation, tumor progression and response to therapy. However, the net effect of autophagy activation or inhibition on the natural growth or therapeutic response of tumors evolving in immunocompetent hosts exhibits a considerable degree of context dependency. Here, we discuss the complex cross-talk between autophagy and immuno-oncology as delineated by genetic and pharmacological approaches in mouse models of cancer.
    Keywords:  ATG5; Antigen presentation; Beclin 1; CGAS/STING signaling; Cytotoxic T lymphocytes; Dendritic cells; Mitophagy; T(REG) cells
    DOI:  https://doi.org/10.1016/j.addr.2020.12.003
  22. Mol Cancer Res. 2020 Dec 07. pii: molcanres.0560.2020. [Epub ahead of print]
    Hypoxic induction of exosome uptake through proteoglycan dependent endocytosis fuels the lipid droplet phenotype in glioma.
    Myriam Cerezo-Magana, Helena C Christianson, Toin H van Kuppevelt, Karin Forsberg-Nilsson, Mattias Belting.
      As an adaptive response to hypoxic stress, aggressive tumors rewire their metabolic phenotype into increased malignant behavior through extracellular lipid scavenging and storage in lipid droplets (LDs). However, the underlying mechanisms and potential lipid source retrieved in the hypoxic tumor microenvironment remain poorly understood. Here, we show that exosome-like extracellular vesicles (EVs), known as influential messengers in the tumor microenvironment, may also serve anabolic functions by transforming hypoxic, patient-derived human glioblastoma cell lines into the LD+ phenotype. EVs were internalized via a hypoxia-sensitive, endocytic mechanism that fueled LD formation through direct lipid transfer, and independently of fatty acid synthase activity. EVs can enter cells through multiple and yet ill-defined pathways. On a mechanistic level, we found that hypoxia-mediated EV uptake depends on increased heparan sulfate proteoglycan (HSPG) endocytosis that preferentially followed the lipid raft pathway. The functional relevance of HSPG was evidenced by the reversal of EV-mediated LD loading by targeting of HSPG receptor function. Implications: Together, our data extend the multifaceted role of EVs in cancer biology by showing their LD-inducing capacity in hypoxic glioma cells. Moreover, the present findings highlight a potential function for HSPG-mediated endocytosis as a salvage pathway for EV retrieval during tumor stress conditions.
    DOI:  https://doi.org/10.1158/1541-7786.MCR-20-0560
  23. Oncogene. 2020 Dec 07.
    Nerve fibers in the tumor microenvironment in neurotropic cancer-pancreatic cancer and cholangiocarcinoma.
    Xiuxiang Tan, Shivan Sivakumar, Jan Bednarsch, Georg Wiltberger, Jakob Nikolas Kather, Jan Niehues, Judith de Vos-Geelen, Liselot Valkenburg-van Iersel, Svetlana Kintsler, Anjali Roeth, Guangshan Hao, Sven Lang, Mariëlle E Coolsen, Marcel den Dulk, Merel R Aberle, Jarne Koolen, Nadine T Gaisa, Steven W M Olde Damink, Ulf P Neumann, Lara R Heij.
      Pancreatic ductal adenocarcinoma (PDAC) and cholangiocarcinoma (CCA) are both deadly cancers and they share many biological features besides their close anatomical location. One of the main histological features is neurotropism, which results in frequent perineural invasion. The underlying mechanism of cancer cells favoring growth by and through the nerve fibers is not fully understood. In this review, we provide knowledge of these cancers with frequent perineural invasion. We discuss nerve fiber crosstalk with the main different components of the tumor microenvironment (TME), the immune cells, and the fibroblasts. Also, we discuss the crosstalk between the nerve fibers and the cancer. We highlight the shared signaling pathways of the mechanisms behind perineural invasion in PDAC and CCA. Hereby we have focussed on signaling neurotransmitters and neuropeptides which may be a target for future therapies. Furthermore, we have summarized retrospective results of the previous literature about nerve fibers in PDAC and CCA patients. We provide our point of view in the potential for nerve fibers to be used as powerful biomarker for prognosis, as a tool to stratify patients for therapy or as a target in a (combination) therapy. Taking the presence of nerves into account can potentially change the field of personalized care in these neurotropic cancers.
    DOI:  https://doi.org/10.1038/s41388-020-01578-4
  24. Ann Pancreat Cancer. 2020 May;pii: 3. [Epub ahead of print]3
    The present and future of systemic and microenvironment-targeted therapy for pancreatic adenocarcinoma.
    Arnav Mehta, William L Hwang, Colin Weekes.
      Metastatic pancreatic adenocarcinoma remains one of the deadliest cancer diagnoses with 5-year survival rates as low as 3%. For decades, gemcitabine remained the mainstay of systemic therapy before the approvals of FOLFIRINOX and gemcitabine with nab-paclitaxel. Despite these advances in the early 2010s, almost all patients progress on systemic chemotherapy and significant effort is needed to identify novel therapeutic targets. A promising array of approaches is currently under investigation, enabled by deeper understanding of the immune system within the tumor microenvironment (TME) and of the key vulnerabilities in pathways essential for tumor survival. In this review, we will explore the different approaches to boost tumor immunity and to target tumor metabolic pathways that are currently under clinical investigation for systemic treatment, and highlight the promising therapeutic areas that may give rise to the next generation of therapies for pancreatic cancer.
    Keywords:  Pancreatic cancer; immunotherapy; metabolic reprogramming; systemic therapy; tumor microenvironment
    DOI:  https://doi.org/10.21037/apc-2020-pda-05
  25. Biochem Biophys Rep. 2020 Dec;24 100858
    A simple indirect colorimetric assay for measuring mitochondrial energy metabolism based on uncoupling sensitivity.
    Patries M Herst, Carole Grasso, Marie-Sophie Fabre, Stepana Boukalova, Zuzana Ezrova, Jiri Neuzil, Michael V Berridge.
       Purpose: Cancer cells rapidly adjust their balance between glycolytic and mitochondrial ATP production in response to changes in their microenvironment and to treatments like radiation and chemotherapy. Reliable, simple, high throughput assays that measure the levels of mitochondrial energy metabolism in cells are useful determinants of treatment effects. Mitochondrial metabolism is routinely determined by measuring the rate of oxygen consumption (OCR). We have previously shown that indirect inhibition of plasma membrane electron transport (PMET) by the mitochondrial uncoupler, FCCP, may also be a reliable measure of mitochondrial energy metabolism. Here, we aimed to validate these earlier findings by exploring the relationship between stimulation of oxygen consumption by FCCP and inhibition of PMET.
    Methods: We measured PMET by reduction of the cell impermeable tetrazolium salt WST-1/PMS. We characterised the effect of different growth conditions on the extent of PMET inhibition by FCCP. Next, we compared FCCP-mediated PMET inhibition with FCCP-mediated stimulation of OCR using the Seahorse XF96e flux analyser, in a panel of cancer cell lines.
    Results: We found a strong inverse correlation between stimulation of OCR and PMET inhibition by FCCP. PMET and OCR were much more severely affected by FCCP in cells that rely on mitochondrial energy production than in cells with a more glycolytic phenotype.
    Conclusion: Indirect inhibition of PMET by FCCP is a reliable, simple and inexpensive high throughput assay to determine the level of mitochondrial energy metabolism in cancer cells.
    Keywords:  Oxygen consumption rates; Plasma membrane electron transport; Seahorse XF96 flux analyser; Tetrazolium salts; WST-1/PMS
    DOI:  https://doi.org/10.1016/j.bbrep.2020.100858
  26. Nature. 2020 Dec 09.
    Arterialization requires the timely suppression of cell growth.
    Wen Luo, Irene Garcia-Gonzalez, Macarena Fernández-Chacón, Verónica Casquero-Garcia, Maria S Sanchez-Muñoz, Severin Mühleder, Lourdes Garcia-Ortega, Jorge Andrade, Michael Potente, Rui Benedito.
      The formation of arteries is thought to occur by the induction of a highly conserved arterial genetic programme in a subset of vessels that will later experience an increase in oxygenated blood flow1,2. The initial steps of arterial specification require both the VEGF and Notch signalling pathways3-5. Here, we combine inducible genetic mosaics and transcriptomics to modulate and define the function of these signalling pathways in cell proliferation, arteriovenous differentiation and mobilization. We show that endothelial cells with high levels of VEGF or Notch signalling are intrinsically biased to mobilize and form arteries; however, they are not genetically pre-determined, and can also form veins. Mechanistically, we found that increased levels of VEGF and Notch signalling in pre-arterial capillaries suppresses MYC-dependent metabolic and cell-cycle activities, and promotes the incorporation of endothelial cells into arteries. Mosaic lineage-tracing studies showed that endothelial cells that lack the Notch-RBPJ transcriptional activator complex rarely form arteries; however, these cells regained the ability to form arteries when the function of MYC was suppressed. Thus, the development of arteries does not require the direct induction of a Notch-dependent arterial differentiation programme, but instead depends on the timely suppression of endothelial cell-cycle progression and metabolism, a process that precedes arterial mobilization and complete differentiation.
    DOI:  https://doi.org/10.1038/s41586-020-3018-x
  27. Trends Cancer. 2020 Dec 03. pii: S2405-8033(20)30278-8. [Epub ahead of print]
    Fat and Furious: Lipid Metabolism in Antitumoral Therapy Response and Resistance.
    Marina Bacci, Nicla Lorito, Alfredo Smiriglia, Andrea Morandi.
      Lipid metabolic reprogramming is an established trait of cancer metabolism that guides response and resistance to antitumoral therapies. Enhanced lipogenesis, increased lipid content (either free or stored into lipid droplets), and lipid-dependent catabolism sustain therapy desensitization and the emergence of a resistant phenotype of tumor cells exposed to chemotherapy or targeted therapies. Aberrant lipid metabolism, therefore, has emerged as a potential metabolic vulnerability of therapy-resistant cancers that could be exploited for therapeutic interventions or for identifying tumors more likely to respond to further lines of therapies. This review gathers recent findings on the role of aberrant lipid metabolism in influencing antitumoral therapy response and in sustaining the emergence of resistance.
    Keywords:  lipid droplets; lipid metabolism; metabolic reprogramming; metabolic targeting; therapy resistance
    DOI:  https://doi.org/10.1016/j.trecan.2020.10.004
  28. Mol Cancer Ther. 2020 Dec 09. pii: molcanther.0316.2020. [Epub ahead of print]
    EMT-induced gemcitabine resistance in pancreatic cancer involves the functional loss of equilibrative nucleoside transporter 1.
    Brenna Weadick, Debasis Nayak, Avinash K Persaud, Sau Wai Hung, Radhika Raj, Moray J Campbell, Wei Chen, Junan Li, Terence M Williams, Rajgopal Govindarajan.
      Epithelial-mesenchymal transition (EMT) in cancer cells drives cancer chemoresistance, yet the molecular events of EMT that underpin the acquisition of chemoresistance are poorly understood. Here, we demonstrate a loss of gemcitabine chemosensitivity facilitated by human equilibrative nucleoside transporter 1 (ENT1) during EMT in pancreatic cancer and identify that cadherin switching from the epithelial (E) to neuronal (N) type, a hallmark of EMT, contributes to this loss. Our findings demonstrate that N-cadherin decreases ENT1 expression, membrane localization and gemcitabine transport, while E-cadherin augments each of these. Besides E- and N-cadherin, another epithelial cell adhesion molecule, EpCAM, played a more prominent role in determining ENT1 membrane localization. Forced expression of EpCAM opposed cadherin switching with restored ENT1 expression, membrane localization and gemcitabine transport in EMT-committed pancreatic cancer cells. In gemcitabine-treated mice, EpCAM positive tumors had high ENT1 expression and reduced metastasis, whereas tumors with N-cadherin expression resisted gemcitabine treatment and formed extensive secondary metastatic nodules. Tissue microarray profiling and multiplexed immunohistochemical analysis of pancreatic cancer patient-derived primary tumors revealed EpCAM and ENT1 cell surface co-expression is favored, and ENT1 plasma membrane expression positively predicted median overall survival times in patients treated with adjuvant gemcitabine. Together, our findings identify ENT1 as an inadvertent target of EMT signaling mediated by cadherin switching and provide a mechanism by which mesenchymal pancreatic cancer cells evade gemcitabine therapy during EMT.
    DOI:  https://doi.org/10.1158/1535-7163.MCT-20-0316
  29. Proc Natl Acad Sci U S A. 2020 Dec 08. pii: 201922169. [Epub ahead of print]
    Mechanisms by which adiponectin reverses high fat diet-induced insulin resistance in mice.
    Xiruo Li, Dongyan Zhang, Daniel F Vatner, Leigh Goedeke, Sandro M Hirabara, Ye Zhang, Rachel J Perry, Gerald I Shulman.
      Adiponectin has emerged as a potential therapy for type 2 diabetes mellitus, but the molecular mechanism by which adiponectin reverses insulin resistance remains unclear. Two weeks of globular adiponectin (gAcrp30) treatment reduced fasting plasma glucose, triglyceride (TAG), and insulin concentrations and reversed whole-body insulin resistance, which could be attributed to both improved insulin-mediated suppression of endogenous glucose production and increased insulin-stimulated glucose uptake in muscle and adipose tissues. These improvements in liver and muscle sensitivity were associated with ∼50% reductions in liver and muscle TAG and plasma membrane (PM)-associated diacylglycerol (DAG) content and occurred independent of reductions in total ceramide content. Reductions of PM DAG content in liver and skeletal muscle were associated with reduced PKCε translocation in liver and reduced PKCθ and PKCε translocation in skeletal muscle resulting in increased insulin-stimulated insulin receptor tyrosine1162 phosphorylation, IRS-1/IRS-2-associated PI3-kinase activity, and Akt-serine phosphorylation. Both gAcrp30 and full-length adiponectin (Acrp30) treatment increased eNOS/AMPK activation in muscle and muscle fatty acid oxidation. gAcrp30 and Acrp30 infusions also increased TAG uptake in epididymal white adipose tissue (eWAT), which could be attributed to increased lipoprotein lipase (LPL) activity. These data suggest that adiponectin and adiponectin-related molecules reverse lipid-induced liver and muscle insulin resistance by reducing ectopic lipid storage in these organs, resulting in decreased plasma membrane sn-1,2-DAG-induced nPKC activity and increased insulin signaling. Adiponectin mediates these effects by both promoting the storage of TAG in eWAT likely through stimulation of LPL as well as by stimulation of AMPK in muscle resulting in increased muscle fat oxidation.
    Keywords:  adiponectin; ceramides; diacylglycerol; lipoprotein lipase; protein kinase C
    DOI:  https://doi.org/10.1073/pnas.1922169117
  30. Science. 2020 Dec 11. 370(6522): 1317-1323
    Protein condensates as aging Maxwell fluids.
    Louise Jawerth, Elisabeth Fischer-Friedrich, Suropriya Saha, Jie Wang, Titus Franzmann, Xiaojie Zhang, Jenny Sachweh, Martine Ruer, Mahdiye Ijavi, Shambaditya Saha, Julia Mahamid, Anthony A Hyman, Frank Jülicher.
      Protein condensates are complex fluids that can change their material properties with time. However, an appropriate rheological description of these fluids remains missing. We characterize the time-dependent material properties of in vitro protein condensates using laser tweezer-based active and microbead-based passive rheology. For different proteins, the condensates behave at all ages as viscoelastic Maxwell fluids. Their viscosity strongly increases with age while their elastic modulus varies weakly. No significant differences in structure were seen by electron microscopy at early and late ages. We conclude that protein condensates can be soft glassy materials that we call Maxwell glasses with age-dependent material properties. We discuss possible advantages of glassy behavior for modulation of cellular biochemistry.
    DOI:  https://doi.org/10.1126/science.aaw4951
  31. Metabolomics. 2020 Dec 09. 16(12): 126
    SUMMER, a shiny utility for metabolomics and multiomics exploratory research.
    Ling Huang, Antonio Currais, Maxim N Shokhirev.
       INTRODUCTION: Cellular metabolites are generated by a complex network of biochemical reactions. This makes interpreting changes in metabolites exceptionally challenging.
    OBJECTIVES: To develop a computational tool that integrates multiomics data at the level of reactions.
    METHODS: Changes in metabolic reactions are modeled with input from transcriptomics/proteomics measurements of enzymes and metabolomic measurements of metabolites.
    RESULTS: We developed SUMMER, which identified more relevant signals, key metabolic reactions, and relevant underlying biological pathways in a real-world case study.
    CONCLUSION: SUMMER performs integrative analysis for data interpretation and exploration. SUMMER is freely accessible at http://summer.salk.edu and the code is available at https://bitbucket.org/salkigc/summer .
    Keywords:  Bioinformatics software; Integrative analysis; Interactive user interface; Metabolomics; Multiomics; Web server
    DOI:  https://doi.org/10.1007/s11306-020-01750-7
  32. Nature. 2020 Dec 09.
    Lymphoangiocrine signals promote cardiac growth and repair.
    Xiaolei Liu, Ester De la Cruz, Xiaowu Gu, Laszlo Balint, Michael Oxendine-Burns, Tamara Terrones, Wanshu Ma, Hui-Hsuan Kuo, Connor Lantz, Trisha Bansal, Edward Thorp, Paul Burridge, Zoltán Jakus, Joachim Herz, Ondine Cleaver, Miguel Torres, Guillermo Oliver.
      Recent studies have suggested that lymphatics help to restore heart function after cardiac injury1-6. Here we report that lymphatics promote cardiac growth, repair and cardioprotection in mice. We show that a lymphoangiocrine signal produced by lymphatic endothelial cells (LECs) controls the proliferation and survival of cardiomyocytes during heart development, improves neonatal cardiac regeneration and is cardioprotective after myocardial infarction. Embryos that lack LECs develop smaller hearts as a consequence of reduced cardiomyocyte proliferation and increased cardiomyocyte apoptosis. Culturing primary mouse cardiomyocytes in LEC-conditioned medium increases cardiomyocyte proliferation and survival, which indicates that LECs produce lymphoangiocrine signals that control cardiomyocyte homeostasis. Characterization of the LEC secretome identified the extracellular protein reelin (RELN) as a key component of this process. Moreover, we report that LEC-specific Reln-null mouse embryos develop smaller hearts, that RELN is required for efficient heart repair and function after neonatal myocardial infarction, and that cardiac delivery of RELN using collagen patches improves heart function in adult mice after myocardial infarction by a cardioprotective effect. These results highlight a lymphoangiocrine role of LECs during cardiac development and injury response, and identify RELN as an important mediator of this function.
    DOI:  https://doi.org/10.1038/s41586-020-2998-x
  33. Cancer Prev Res (Phila). 2020 Dec 10. pii: canprevres.0425.2020. [Epub ahead of print]
    Mitochondria as a Novel Target for Cancer Chemoprevention: Emergence of Mitochondrial Targeting Agents.
    Mofei Huang, Charles R Myers, Yian Wang, Ming You.
      Cancer chemoprevention is the most effective approach to control cancer in the population. Despite significant progress, chemoprevention has not been widely adopted because agents that are safe tend to be less effective and those that are highly effective tend to be toxic. Thus, there is an urgent need to develop novel and effective chemopreventive agents, such as mitochondria-targeted agents, that can prevent cancer and prolong survival. Mitochondria, the central site for cellular energy production, have important functions in cell survival and death. Several studies have revealed a significant role for mitochondrial metabolism in promoting cancer development and progression, making mitochondria a promising new target for cancer prevention. Conjugating delocalized lipophilic cations such triphenylphosphonium cation (TPP+) to compounds of interest is an effective approach for mitochondrial targeting. The hyperpolarized tumor cell membrane and mitochondrial membrane potential allow for selective accumulation of TPP+ conjugates in tumor cell mitochondria versus those in normal cells. This could enhance direct killing of pre-cancerous, dysplastic, and tumor cells while minimizing potential toxicities to normal cells.
    DOI:  https://doi.org/10.1158/1940-6207.CAPR-20-0425
  34. Trends Biotechnol. 2020 Dec 02. pii: S0167-7799(20)30290-0. [Epub ahead of print]
    Deciphering Organoids: High-Dimensional Analysis of Biomimetic Cultures.
    Xiao Qin, Christopher J Tape.
      Organoids are self-organising stem cell-derived ex vivo cultures widely adopted as biomimetic models of healthy and diseased tissues. Traditional low-dimensional experimental methods such as microscopy and bulk molecular analysis have generated remarkable biological insights from organoids. However, as complex heterocellular systems, organoids are especially well-positioned to take advantage of emerging high-dimensional technologies. In particular, single-cell methods offer considerable opportunities to analyse organoids at unprecedented scale and depth, enabling comprehensive characterisation of cellular processes and spatial organisation underpinning organoid heterogeneity. This review evaluates state-of-the-art analytical methods applied to organoids, discusses the latest advances in single-cell technologies, and speculates on the integration of these two rapidly developing fields.
    Keywords:  omics technology; organoid; single-cell analysis; systems biology
    DOI:  https://doi.org/10.1016/j.tibtech.2020.10.013
  35. Nature. 2020 Dec;588(7837): 331-336
    A metastasis map of human cancer cell lines.
    Xin Jin, Zelalem Demere, Karthik Nair, Ahmed Ali, Gino B Ferraro, Ted Natoli, Amy Deik, Lia Petronio, Andrew A Tang, Cong Zhu, Li Wang, Danny Rosenberg, Vamsi Mangena, Jennifer Roth, Kwanghun Chung, Rakesh K Jain, Clary B Clish, Matthew G Vander Heiden, Todd R Golub.
      Most deaths from cancer are explained by metastasis, and yet large-scale metastasis research has been impractical owing to the complexity of in vivo models. Here we introduce an in vivo barcoding strategy that is capable of determining the metastatic potential of human cancer cell lines in mouse xenografts at scale. We validated the robustness, scalability and reproducibility of the method and applied it to 500 cell lines1,2 spanning 21 types of solid tumour. We created a first-generation metastasis map (MetMap) that reveals organ-specific patterns of metastasis, enabling these patterns to be associated with clinical and genomic features. We demonstrate the utility of MetMap by investigating the molecular basis of breast cancers capable of metastasizing to the brain-a principal cause of death in patients with this type of cancer. Breast cancers capable of metastasizing to the brain showed evidence of altered lipid metabolism. Perturbation of lipid metabolism in these cells curbed brain metastasis development, suggesting a therapeutic strategy to combat the disease and demonstrating the utility of MetMap as a resource to support metastasis research.
    DOI:  https://doi.org/10.1038/s41586-020-2969-2
  36. Cell Biosci. 2020 Nov 18. 10(1): 131
    The role of lysosomes in cancer development and progression.
    Tao Tang, Ze-Yu Yang, Di Wang, Xian-Yan Yang, Jun Wang, Lin Li, Qian Wen, Lei Gao, Xiu-Wu Bian, Shi-Cang Yu.
      Lysosomes are an important component of the inner membrane system and participate in numerous cell biological processes, such as macromolecular degradation, antigen presentation, intracellular pathogen destruction, plasma membrane repair, exosome release, cell adhesion/migration and apoptosis. Thus, lysosomes play important roles in cellular activity. In addition, previous studies have shown that lysosomes may play important roles in cancer development and progression through the abovementioned biological processes and that the functional status and spatial distribution of lysosomes are closely related to cancer cell proliferation, energy metabolism, invasion and metastasis, immune escape and tumor-associated angiogenesis. Therefore, identifying the factors and mechanisms that regulate the functional status and spatial distribution of lysosomes and elucidating the relationship between lysosomes and the development and progression of cancer can provide important information for cancer diagnosis and prognosis prediction and may yield new therapeutic targets. This study briefly reviews the above information and explores the potential value of lysosomes in cancer therapy.
    Keywords:  Cancer; Energy metabolism; Lysosomes; Metastasis; Spatial distribution
    DOI:  https://doi.org/10.1186/s13578-020-00489-x
  37. Trends Cell Biol. 2020 Dec 03. pii: S0962-8924(20)30227-0. [Epub ahead of print]
    Cell Migration Guided by Cell-Cell Contacts in Innate Immunity.
    Veronika Miskolci, Lucas C Klemm, Anna Huttenlocher.
      The directed migration of leukocytes to sites of damage or infection is necessary for a productive immune response. There is substantial evidence supporting a key role for chemoattractants in directed migration, however, less is known about how cell-cell contacts affect the migratory behavior of leukocytes in innate immunity. Here, we explore how cell-cell contacts can affect the directed migration of innate immune cells, including their role in attracting, repelling, or stopping cell motility. Further investigation of cell contact dynamics as guidance cues may yield new insights into the regulation of innate immunity.
    Keywords:  cell–cell contact; macrophages; migration; neutrophils
    DOI:  https://doi.org/10.1016/j.tcb.2020.11.002
  38. Genes Dev. 2020 Dec 10.
    mTOR inhibition acts as an unexpected checkpoint in p53-mediated tumor suppression.
    Ning Kon, Yang Ou, Shang-Jui Wang, Huan Li, Anil K Rustgi, Wei Gu.
      Here, we showed that the acetylation-defective p53-4KR mice, lacking the ability of cell cycle arrest, senescence, apoptosis, and ferroptosis, were tumor prone but failed to develop early-onset tumors. By identifying a novel p53 acetylation site at lysine K136, we found that simultaneous mutations at all five acetylation sites (p53-5KR) diminished its remaining tumor suppression function. Moreover, the embryonic lethality caused by the deficiency of mdm2 was fully rescued in the background of p535KR/5KR , but not p534KR/4KR background. p53-4KR retained the ability to suppress mTOR function but this activity was abolished in p53-5KR cells. Notably, the early-onset tumor formation observed in p535KR/5KR and p53-null mice was suppressed upon the treatment of the mTOR inhibitor. These results suggest that p53-mediated mTOR regulation plays an important role in both embryonic development and tumor suppression, independent of cell cycle arrest, senescence, apoptosis, and ferroptosis.
    Keywords:  DDIT4/REDD1; Mdm2; SESN2; acetylation; mTOR; p53; transcriptional regulation; tumor suppression
    DOI:  https://doi.org/10.1101/gad.340919.120
  39. Elife. 2020 Dec 10. pii: e62659. [Epub ahead of print]9
    Cell non-autonomous regulation of health and longevity.
    Hillary A Miller, Elizabeth S Dean, Scott D Pletcher, Scott F Leiser.
      As the demographics of the modern world skew older, understanding and mitigating the effects of aging is increasingly important within biomedical research. Recent studies in model organisms demonstrate that the aging process is frequently modified by an organism's ability to perceive and respond to changes in its environment. Many well-studied pathways that influence aging involve sensory cells, frequently neurons, that signal to peripheral tissues and promote survival during the presence of stress. Importantly, this activation of stress response pathways is often sufficient to improve health and longevity even in the absence of stress. Here, we review the current landscape of research highlighting the importance of cell non-autonomous signaling in modulating aging from C. elegans to mammals. We also discuss emerging concepts including retrograde signaling, approaches to mapping these networks, and development of potential therapeutics.
    Keywords:  C. elegans; D. melanogaster; aging; genetics; genomics; healthspan; insulin signaling; neuroscience; sensory perception
    DOI:  https://doi.org/10.7554/eLife.62659
  40. Nature. 2020 Dec 09.
    Histone H1 loss drives lymphoma by disrupting 3D chromatin architecture.
    Nevin Yusufova, Andreas Kloetgen, Matt Teater, Adewola Osunsade, Jeannie M Camarillo, Christopher R Chin, Ashley S Doane, Bryan J Venters, Stephanie Portillo-Ledesma, Joseph Conway, Jude M Phillip, Olivier Elemento, David W Scott, Wendy Béguelin, Jonathan D Licht, Neil L Kelleher, Louis M Staudt, Arthur I Skoultchi, Michael-Christopher Keogh, Effie Apostolou, Christopher E Mason, Marcin Imielinski, Tamar Schlick, Yael David, Aristotelis Tsirigos, C David Allis, Alexey A Soshnev, Ethel Cesarman, Ari M Melnick.
      Linker histone H1 proteins bind to nucleosomes and facilitate chromatin compaction1, although their biological functions are poorly understood. Mutations in the genes that encode H1 isoforms B-E (H1B, H1C, H1D and H1E; also known as H1-5, H1-2, H1-3 and H1-4, respectively) are highly recurrent in B cell lymphomas, but the pathogenic relevance of these mutations to cancer and the mechanisms that are involved are unknown. Here we show that lymphoma-associated H1 alleles are genetic driver mutations in lymphomas. Disruption of H1 function results in a profound architectural remodelling of the genome, which is characterized by large-scale yet focal shifts of chromatin from a compacted to a relaxed state. This decompaction drives distinct changes in epigenetic states, primarily owing to a gain of histone H3 dimethylation at lysine 36 (H3K36me2) and/or loss of repressive H3 trimethylation at lysine 27 (H3K27me3). These changes unlock the expression of stem cell genes that are normally silenced during early development. In mice, loss of H1c and H1e (also known as H1f2 and H1f4, respectively) conferred germinal centre B cells with enhanced fitness and self-renewal properties, ultimately leading to aggressive lymphomas with an increased repopulating potential. Collectively, our data indicate that H1 proteins are normally required to sequester early developmental genes into architecturally inaccessible genomic compartments. We also establish H1 as a bona fide tumour suppressor and show that mutations in H1 drive malignant transformation primarily through three-dimensional genome reorganization, which leads to epigenetic reprogramming and derepression of developmentally silenced genes.
    DOI:  https://doi.org/10.1038/s41586-020-3017-y
  41. Front Mol Biosci. 2020 ;7 593866
    Extracellular Citrate Is a Trojan Horse for Cancer Cells.
    Agata Petillo, Vittorio Abruzzese, Prashant Koshal, Angela Ostuni, Faustino Bisaccia.
      The first intermediate in the mitochondrial tricarboxylic acid (TCA) cycle is citrate, which is essential and acts as a metabolic regulator for glycolysis, TCA cycle, gluconeogenesis, and fatty acid synthesis. Within the cytosol, citrate is cleaved by ATP citrate lyase (ACLY) into oxaloacetate (OAA) and acetyl-CoA; OAA can be used for neoglucogenesis or in the TCA cycle, while acetyl-CoA is the precursor of some biosynthetic processes, including the synthesis of fatty acids. Accumulating evidence suggests that citrate is involved in numerous physiological and pathophysiological processes such as inflammation, insulin secretion, neurological disorders, and cancer. Considering the crucial role of citrate to supply the acetyl-CoA pool for fatty acid synthesis and histone acetylation in tumors, in this study we evaluated the effect of citrate added to the growth medium on lipid deposition and histone H4 acetylation in hepatoma cells (HepG2). At low concentration, citrate increased both histone H4 acetylation and lipid deposition; at high concentration, citrate inhibited both, thus suggesting a crucial role of acetyl-CoA availability, which prompted us to investigate the effect of citrate on ACLY. In HepG2 cells, the expression of ACLY is correlated with histone acetylation, which, in turn, depends on citrate concentration. A decrease in H4 acetylation was also observed when citrate was added at a high concentration to immortalized human hepatic cells, whereas ACLY expression was unaffected, indicating a lack of control by histone acetylation. Considering the strong demand for acetyl-CoA but not for OAA in tumor cells, the exogenous citrate would behave like a trojan horse that carries OAA inside the cells and reduces ACLY expression and cellular metabolism. In addition, this study confirmed the already reported dual role of citrate both as a promoter of cell proliferation (at lower concentrations) and as an anticancer agent (at higher concentrations), providing useful tips on the use of citrate for the treatment of tumors.
    Keywords:  ATP citrate lyase; HepG2; IHH; cancer; citrate; epigenetics; histone acetylation
    DOI:  https://doi.org/10.3389/fmolb.2020.593866
  42. Oncogene. 2020 Dec 07.
    Selective inhibition of stemness through EGFR/FOXA2/SOX9 axis reduces pancreatic cancer metastasis.
    Garima Kaushik, Parthasarathy Seshacharyulu, Sanchita Rauth, Palanisamy Nallasamy, Satyanarayana Rachagani, Rama Krishna Nimmakayala, Raghupathy Vengoji, Kavita Mallya, Ramakanth Chirravuri-Venkata, Amar B Singh, Jason M Foster, Quan P Ly, Lynette M Smith, Subodh M Lele, Mokenge P Malafa, Maneesh Jain, Moorthy P Ponnusamy, Surinder K Batra.
      Pancreatic cancer (PC) is difficult to defeat due to mechanism (s) driving metastasis and drug resistance. Cancer stemness is a major challenging phenomenon associated with PC metastasis and limiting therapy efficacy. In this study, we evaluated the pre-clinical and clinical significance of eradicating pancreatic cancer stem cells (PCSC) and its components using a pan-EGFR inhibitor afatinib in combination with gemcitabine. Afatinib in combination with gemcitabine significantly reduced KrasG12D/+; Pdx-1 Cre (KC) (P < 0.01) and KrasG12D/+; p53R172H/+; Pdx-1 Cre (KPC) (P < 0.05) derived mouse tumoroids and KPC-derived murine syngeneic cell line growth compared to gemcitabine/afatinib alone treatment. The drug combination also reduced PC xenograft tumor burden (P < 0.05) and the incidence of metastasis by affecting key stemness markers, as confirmed by co-localization studies. Moreover, the drug combination significantly decreases the growth of various PC patient-derived organoids (P < 0.001). We found that SOX9 is significantly overexpressed in high-grade PC tumors (P < 0.05) and in chemotherapy-treated patients compared to chemo-naïve patients (P < 0.05). These results were further validated using publicly available datasets. Moreover, afatinib alone or in combination with gemcitabine decreased stemness and tumorspheres by reducing phosphorylation of EGFR family proteins, ERK, FAK, and CSC markers. Mechanistically, afatinib treatment decreased CSC markers by downregulating SOX9 via FOXA2. Indeed, EGFR and FOXA2 depletion reduced SOX9 expression in PCSCs. Taken together, pan-EGFR inhibition by afatinib impedes PCSCs growth and metastasis via the EGFR/ERK/FOXA2/SOX9 axis. This novel mechanism of pan-EGFR inhibitor and its ability to eradicate CSC may serve as a tailor-made approach to enhance chemotherapeutic benefits in other cancer types.
    DOI:  https://doi.org/10.1038/s41388-020-01564-w
  43. Cell Rep. 2020 Dec 08. pii: S2211-1247(20)31475-3. [Epub ahead of print]33(10): 108486
    Mechanisms of EMRE-Dependent MCU Opening in the Mitochondrial Calcium Uniporter Complex.
    Anna M Van Keuren, Chen-Wei Tsai, Enrique Balderas, Madison X Rodriguez, Dipayan Chaudhuri, Ming-Feng Tsai.
      The mitochondrial calcium uniporter is a multi-subunit Ca2+-activated Ca2+ channel, made up of the pore-forming MCU protein, a metazoan-specific EMRE subunit, and MICU1/MICU2, which mediate Ca2+ activation. It has been established that metazoan MCU requires EMRE binding to conduct Ca2+, but how EMRE promotes MCU opening remains unclear. Here, we demonstrate that EMRE controls MCU activity via its transmembrane helix, while using an N-terminal PKP motif to strengthen binding with MCU. Opening of MCU requires hydrophobic interactions mediated by MCU residues near the pore's luminal end. Enhancing these interactions by single mutation allows human MCU to transport Ca2+ without EMRE. We further show that EMRE may facilitate MCU opening by stabilizing the open state in a conserved MCU gating mechanism, present also in non-metazoan MCU homologs. These results provide insights into the evolution of the uniporter machinery and elucidate the mechanism underlying the physiologically crucial EMRE-dependent MCU activation process.
    Keywords:  calcium channels; calcium signaling; membrane transport; mitochondrial calcium
    DOI:  https://doi.org/10.1016/j.celrep.2020.108486
  44. Eur J Surg Oncol. 2020 Dec 03. pii: S0748-7983(20)30879-9. [Epub ahead of print]
    HPB cancers in older patients | inclusion of older/senior patients in clinical trials.
    Alison Backen, Angela Lamarca, Richard A Hubner, Mairéad G McNamara, Juan W Valle.
      Liver, biliary tract and pancreatic cancers are increasingly diseases of older people and the global population is aging. 'Older/senior' patients are a heterogeneous group who vary widely in their general health, physical reserve and degree of dependence on others. Cancer is not the only disease that becomes more prevalent in old age, which means older/senior patients may also have comorbidities and lower resilience. The use of chemotherapy decreases as age increases. Chemotherapy treatment regimens may require modification to reduce toxicity, which is more common in older/senior patients. The effect this has on treatment efficacy is not fully understood. Older/senior patients are not represented well in clinical trials which makes estimating benefit for these patients challenging. Medicine demands that new drugs are rigorously tested and evaluated before use, yet clinicians are treating older/senior patients on the basis of extrapolating from randomised controlled trials which actively exclude comorbidities and older patients. This review considers the current situation and the value of retrospective analyses and real-world evidence to plug the older/senior patient 'data gaps'. Moving forwards it is essential to broaden clinical trial inclusion criteria to include more older/senior people. The use of appropriate geriatric assessments may help selection of older patients who are fit enough for more rigorous treatment regimens, alongside effective methods of predicting and managing treatment toxicities. The ability to see past the numerical age of a person and offer appropriate therapeutic choices to individual patients in clinic, is an important skill for younger (and not so young) Medical Oncologists to learn.
    Keywords:  Chemotherapy; Clinical trial; Liver; Older/senior; Pancreatic and biliary tract cancers
    DOI:  https://doi.org/10.1016/j.ejso.2020.11.002
  45. Lancet. 2020 Dec 04. pii: S0140-6736(20)32598-8. [Epub ahead of print]
    Enhancing anti-tumour efficacy with immunotherapy combinations.
    Funda Meric-Bernstam, James Larkin, Josep Tabernero, Chiara Bonini.
      Several tumour types are responsive to immunotherapy, as shown by regulatory approvals for immune checkpoint inhibitors. However, many patients either do not respond or do not have durable clinical benefit. Thus, there is great interest in developing predictors of response to immunotherapy and rational combination therapies that can enhance efficacy by overcoming primary and acquired resistance. In this Review, we provide an assessment of immunotherapy response biomarkers that can identify patients who will benefit from monotherapy rather than from combinations. We review the rationale for combination therapy and different strategies, including combinations with chemotherapy, targeted therapy, radiation therapy, intratumoural therapies, other immunomodulators, and adaptive cell therapy, including chimeric antigen T-cell receptors and other novel T-cell receptor-based therapies. There are many combination partners in development; therefore, a programmatic approach is needed to develop a framework for biomarker-driven combination therapy selection.
    DOI:  https://doi.org/10.1016/S0140-6736(20)32598-8
  46. Nat Rev Clin Oncol. 2020 Dec 09.
    Dissecting the immunogenomic biology of cancer for biomarker development.
    Eliezer M Van Allen, Toni K Choueiri.
      
    DOI:  https://doi.org/10.1038/s41571-020-00461-1
  47. Nature. 2020 Dec 09.
    H1 histones control the epigenetic landscape by local chromatin compaction.
    Michael A Willcockson, Sean E Healton, Cary N Weiss, Boris A Bartholdy, Yair Botbol, Laxmi N Mishra, Dhruv S Sidhwani, Tommy J Wilson, Hugo B Pinto, Maxim I Maron, Karin A Skalina, Laura Norwood Toro, Jie Zhao, Chul-Hwan Lee, Harry Hou, Nevin Yusufova, Cem Meydan, Adewola Osunsade, Yael David, Ethel Cesarman, Ari M Melnick, Simone Sidoli, Benjamin A Garcia, Winfried Edelmann, Fernando Macian, Arthur I Skoultchi.
      H1 linker histones are the most abundant chromatin-binding proteins1. In vitro studies indicate that their association with chromatin determines nucleosome spacing and enables arrays of nucleosomes to fold into more compact chromatin structures. However, the in vivo roles of H1 are poorly understood2. Here we show that the local density of H1 controls the balance of repressive and active chromatin domains by promoting genomic compaction. We generated a conditional triple-H1-knockout mouse strain and depleted H1 in haematopoietic cells. H1 depletion in T cells leads to de-repression of T cell activation genes, a process that mimics normal T cell activation. Comparison of chromatin structure in normal and H1-depleted CD8+ T cells reveals that H1-mediated chromatin compaction occurs primarily in regions of the genome containing higher than average levels of H1: the chromosome conformation capture (Hi-C) B compartment and regions of the Hi-C A compartment marked by PRC2. Reduction of H1 stoichiometry leads to decreased H3K27 methylation, increased H3K36 methylation, B-to-A-compartment shifting and an increase in interaction frequency between compartments. In vitro, H1 promotes PRC2-mediated H3K27 methylation and inhibits NSD2-mediated H3K36 methylation. Mechanistically, H1 mediates these opposite effects by promoting physical compaction of the chromatin substrate. Our results establish H1 as a critical regulator of gene silencing through localized control of chromatin compaction, 3D genome organization and the epigenetic landscape.
    DOI:  https://doi.org/10.1038/s41586-020-3032-z
  48. Biochim Biophys Acta Mol Cell Res. 2020 Dec 03. pii: S0167-4889(20)30279-2. [Epub ahead of print] 118921
    Two-pore and TRP cation channels in endolysosomal osmo-/mechanosensation and volume regulation.
    Cheng-Chang Chen, Einar Krogsaeter, Christian Grimm.
      Two pore channels (TPCs) and mucolipins (TRPML) are the most prominent cation channels expressed in endolysosomes. Recently, roles of TPCs and TRPML2 have been revealed in regulating and detecting osmotically-driven changes in the surface-to-volume ratio of endolysosomes to promote endocytic and recycling traffic. TPCs and TRPML2 are highly expressed in macrophages and contribute to immune cell function. Here, we provide an overview of the emerging roles of these channels in innate immune cells, in particular macrophages, and highlight two models for osmo-mechanical regulation of intracellular organelle volume, trafficking, and cell homeostasis involving either TPCs or TRPML2.
    Keywords:  Endolysosomal ion channel; TPC; TRPML; intracellular organelle trafficking; surface-to-volume ratio; tubulation; vesiculation
    DOI:  https://doi.org/10.1016/j.bbamcr.2020.118921
  49. Dev Biol. 2020 Dec 08. pii: S0012-1606(20)30312-2. [Epub ahead of print]
    Stressful development: Integrating endoderm development, stress, and longevity.
    Chee Kiang Ewe, Geneva Alok, Joel H Rothman.
      In addition to performing digestion and nutrient absorption, the intestine serves as one of the first barriers to the external environment, crucial for protecting the host from environmental toxins, pathogenic invaders, and other stress inducers. The gene regulatory network (GRN) governing embryonic development of the endoderm and subsequent differentiation and maintenance of the intestine has been well-documented in C. elegans. A key regulatory input that initiates activation of the embryonic GRN for endoderm and mesoderm in this animal is the maternally provided SKN-1 transcription factor, an ortholog of the vertebrate Nrf-1 and -2, which, like C. elegans SKN-1, perform conserved regulatory roles in mediating a variety of stress responses across metazoan phylogeny. Other key regulatory factors in early gut development also participate in stress response as well as in innate immunity and aging and longevity. In this review, we discuss the intersection between genetic nodes that mediate endoderm/intestine differentiation and regulation of stress and homeostasis. We also consider how direct signaling from the intestine to the germline, in some cases involving SKN-1, facilitates heritable epigenetic changes, allowing transmission of adaptive stress responses across multiple generations. These connections between regulation of endoderm/intestine development and stress response mechanisms suggest that varying selective pressure exerted on the stress response pathways may influence the architecture of the endoderm GRN, thereby leading to genetic and epigenetic variation in early embryonic GRN regulatory events.
    Keywords:  Caenorhabditis elegans; Embryonic development; Epigenetics inheritance; Innate immunity; Longevity; Pleiotropy; Stress
    DOI:  https://doi.org/10.1016/j.ydbio.2020.12.002
  50. Matrix Biol. 2020 Dec 05. pii: S0945-053X(20)30115-3. [Epub ahead of print]
    When lipid homeostasis runs havoc: lipotoxicity links lysosomal dysfunction to autophagy.
    Irmgard Tegeder, Donat Kögel.
      Autophagy is one of the major cellular degradation pathways, which prevents accumulation of cellular wastes including "hazardous" material such as oxidized proteins and lipids and allows removal of aggregates and dysfunctional organelles. Hence, autophagy is meant to preserve cell survival, and is mostly protective. However, autophagy may trigger a feedforward, exaggerated cycle in which cells continue to degrade proteins and organelles, finally leading to autophagy-dependent cell death (ADCD), a process that can be initiated with lysosomotropic detergents, which are protonated within the lysosome and cause a permeabilization of the membrane. Such drugs may be useful to combat cancer. In some paradigms of ADCD, there is evidence that the cellular fate is determined by the integrity of lysosomal membranes, transporters, enzymes and ion gradients. Detergent-like effects of lysosomotropic drugs can over-activate autophagy. A disruption of the lysosomal membrane barrier with leakage of lysosomal enzymes or lipids may trigger a vicious cycle via proteases and accumulation of lipids, which impair the functions of the plasma - and organelle membranes. This review summarizes the current evidence for a crosstalk between lysosomal dysfunction and autophagy and the lysosomal events, which progress toward ADCD with a focus on the role of sphingolipids and cholesterol as cargo and as regulators of ADCD.
    Keywords:  Lysosomal leak; cell death; ceramides; cholesterol; sphingolipids
    DOI:  https://doi.org/10.1016/j.matbio.2020.11.005
  51. Cell Death Discov. 2020 Nov 24. 6(1): 129
    Autophagy-mediated metabolic effects of aspirin.
    Francesca Castoldi, Juliette Humeau, Isabelle Martins, Sylvie Lachkar, Damarys Loew, Florent Dingli, Sylvère Durand, David Enot, Noëlie Bossut, Alexis Chery, Fanny Aprahamian, Yohann Demont, Paule Opolon, Nicolas Signolle, Allan Sauvat, Michaela Semeraro, Lucillia Bezu, Elisa Elena Baracco, Erika Vacchelli, Jonathan G Pol, Sarah Lévesque, Norma Bloy, Valentina Sica, Maria Chiara Maiuri, Guido Kroemer, Federico Pietrocola.
      Salicylate, the active derivative of aspirin (acetylsalicylate), recapitulates the mode of action of caloric restriction inasmuch as it stimulates autophagy through the inhibition of the acetyltransferase activity of EP300. Here, we directly compared the metabolic effects of aspirin medication with those elicited by 48 h fasting in mice, revealing convergent alterations in the plasma and the heart metabolome. Aspirin caused a transient reduction of general protein acetylation in blood leukocytes, accompanied by the induction of autophagy. However, these effects on global protein acetylation could not be attributed to the mere inhibition of EP300, as determined by epistatic experiments and exploration of the acetyl-proteome from salicylate-treated EP300-deficient cells. Aspirin reduced high-fat diet-induced obesity, diabetes, and hepatosteatosis. These aspirin effects were observed in autophagy-competent mice but not in two different models of genetic (Atg4b-/- or Bcln1+/-) autophagy-deficiency. Aspirin also improved tumor control by immunogenic chemotherapeutics, and this effect was lost in T cell-deficient mice, as well as upon knockdown of an essential autophagy gene (Atg5) in cancer cells. Hence, the health-improving effects of aspirin depend on autophagy.
    DOI:  https://doi.org/10.1038/s41420-020-00365-0
  52. Mol Metab. 2020 Dec 04. pii: S2212-8778(20)30214-3. [Epub ahead of print] 101140
    Pancreatic, but not myeloid-cell, expression of interleukin-1alpha is required for maintenance of insulin secretion and whole body glucose homeostasis.
    J Jason Collier, Heidi M Batdorf, Thomas M Martin, Kristen E Rohli, David H Burk, Danhong Lu, Chris R Cooley, Michael D Karlstad, Joseph W Jackson, Tim E Sparer, Jingying Zhang, Randall L Mynatt, Susan J Burke.
       OBJECTIVE: The expression of the interleukin-1 receptor type I (IL-1R) is enriched in pancreatic islet β-cells, signifying that ligands activating this pathway are important for the health and function of the insulin-secreting cell. Using isolated mouse, rat, and human islets, we identified the cytokine IL-1α as a highly inducible gene in response to IL-1R activation. In addition, IL-1α is elevated in mouse and rat models of obesity and Type 2 diabetes. Since less is known about the biology of IL-1α relative to IL-1β in pancreatic tissue, our objective was to investigate the contribution of IL-1α to pancreatic β-cell function and overall glucose homeostasis in vivo.
    METHODS AND RESULTS: We generated a novel mouse line with conditional IL-1α alleles and subsequently produced mice with either pancreatic- or myeloid lineage-specific deletion of IL-1α. Using this approach, we discovered that pancreatic (IL-1αPdx1-/-), but not myeloid-cell expression of IL-1α (IL-1αLysM-/-), was required for maintenance of whole body glucose homeostasis in both male and female mice. Moreover, pancreatic deletion of IL-1α led to impaired glucose tolerance with no change in insulin sensitivity. This observation was consistent with our finding that glucose-stimulated insulin secretion was reduced in islets isolated from IL-1αPdx1-/- mice. Alternatively, IL-1αLysM-/- mice (male and female) did not have any detectable changes in glucose tolerance, respiratory quotient, physical activity, or food intake when compared with littermate controls.
    CONCLUSIONS: Taken together, we conclude that there is an important physiological role for pancreatic IL-1α to promote glucose homeostasis by supporting glucose-stimulated insulin secretion and islet β-cell mass in vivo.
    Keywords:  cytokine receptors; cytokines; inflammation; pancreatic islet; rodent
    DOI:  https://doi.org/10.1016/j.molmet.2020.101140
  53. Front Cell Dev Biol. 2020 ;8 573747
    The Two-Way Relationship Between Calcium and Metabolism in Cancer.
    Camille Dejos, Dimitra Gkika, Anna Rita Cantelmo.
      Calcium ion (Ca2+) signaling is critical to many physiological processes, and its kinetics and subcellular localization are tightly regulated in all cell types. All Ca2+ flux perturbations impact cell function and may contribute to various diseases, including cancer. Several modulators of Ca2+ signaling are attractive pharmacological targets due to their accessibility at the plasma membrane. Despite this, the number of specific inhibitors is still limited, and to date there are no anticancer drugs in the clinic that target Ca2+ signaling. Ca2+ dynamics are impacted, in part, by modifications of cellular metabolic pathways. Conversely, it is well established that Ca2+ regulates cellular bioenergetics by allosterically activating key metabolic enzymes and metabolite shuttles or indirectly by modulating signaling cascades. A coordinated interplay between Ca2+ and metabolism is essential in maintaining cellular homeostasis. In this review, we provide a snapshot of the reciprocal interaction between Ca2+ and metabolism and discuss the potential consequences of this interplay in cancer cells. We highlight the contribution of Ca2+ to the metabolic reprogramming observed in cancer. We also describe how the metabolic adaptation of cancer cells influences this crosstalk to regulate protumorigenic signaling pathways. We suggest that the dual targeting of these processes might provide unprecedented opportunities for anticancer strategies. Interestingly, promising evidence for the synergistic effects of antimetabolites and Ca2+-modulating agents is emerging.
    Keywords:  calcium; cancer; interplay; metabolism; signaling
    DOI:  https://doi.org/10.3389/fcell.2020.573747
  54. Nat Commun. 2020 12 08. 11(1): 6297
    Pontin arginine methylation by CARM1 is crucial for epigenetic regulation of autophagy.
    Young Suk Yu, Hijai R Shin, Dongha Kim, Seon Ah Baek, Seon Ah Choi, Hyejin Ahn, Amen Shamim, Jeonghwan Kim, Ik Soo Kim, Kyeong Kyu Kim, Kyoung-Jae Won, Sung Hee Baek.
      Autophagy is a catabolic process through which cytoplasmic components are degraded and recycled in response to various stresses including starvation. Recently, transcriptional and epigenetic regulations of autophagy have emerged as essential mechanisms for maintaining homeostasis. Here, we identify that coactivator-associated arginine methyltransferase 1 (CARM1) methylates Pontin chromatin-remodeling factor under glucose starvation, and methylated Pontin binds Forkhead Box O 3a (FOXO3a). Genome-wide analyses and biochemical studies reveal that methylated Pontin functions as a platform for recruiting Tip60 histone acetyltransferase with increased H4 acetylation and subsequent activation of autophagy genes regulated by FOXO3a. Surprisingly, CARM1-Pontin-FOXO3a signaling axis can work in the distal regions and activate autophagy genes through enhancer activation. Together, our findings provide a signaling axis of CARM1-Pontin-FOXO3a and further expand the role of CARM1 in nuclear regulation of autophagy.
    DOI:  https://doi.org/10.1038/s41467-020-20080-9
  55. Brain Behav. 2020 Dec 08. e01960
    Molecular links between endocrine, nervous and immune system during chronic stress.
    Roberto Zefferino, Sante Di Gioia, Massimo Conese.
       INTRODUCTION: The stress response is different in various individuals, however, the mechanisms that could explain these distinct effects are not well known and the molecular correlates have been considered one at the time. Particular harmful conditions occur if the subject, instead to cope the stressful events, succumb to them, in this case, a cascade reaction happens that through different signaling causes a specific reaction named "sickness behaviour." The aim of this article is to review the complex relations among important molecules belonging to Central nervous system (CNS), immune system (IS), and endocrine system (ES) during the chronic stress response.
    METHODS: After having verified the state of art concerning the function of cortisol, norepinephrine (NE), interleukin (IL)-1β and melatonin, we describe as they work together.
    RESULTS: We propose a speculative hypothesis concerning the complex interplay of these signaling molecules during chronic stress, highlighting the role of IL-1β as main biomarker of this effects, indeed, during chronic stress its increment transforms this inflammatory signal into a nervous signal (NE), in turn, this uses the ES (melatonin and cortisol) to counterbalance again IL-1β. During cortisol resistance, a vicious loop occurs that increments all mediators, unbalancing IS, ES, and CNS networks. This IL-1β increase would occur above all when the individual succumbs to stressful events, showing the Sickness Behaviour Symptoms. IL-1β might, through melatonin and vice versa, determine sleep disorders too.
    CONCLUSION: The molecular links here outlined could explain how stress plays a role in etiopathogenesis of several diseases through this complex interplay.
    Keywords:  circadian rhythm; cortisol; interleukin-1β; melatonin; sickness behavior
    DOI:  https://doi.org/10.1002/brb3.1960
  56. Autophagy. 2020 Dec 11. 1-24
    The conformational and mutational landscape of the ubiquitin-like marker for autophagosome formation in cancer.
    Burcu Aykac Fas, Emiliano Maiani, Valentina Sora, Mukesh Kumar, Maliha Mashkoor, Matteo Lambrughi, Matteo Tiberti, Elena Papaleo.
      Macroautophagy/autophagy is a cellular process to recycle damaged cellular components, and its modulation can be exploited for disease treatments. A key autophagy player is the ubiquitin-like protein MAP1LC3B/LC3B. Mutations and changes in MAP1LC3B expression occur in cancer samples. However, the investigation of the effects of these mutations on MAP1LC3B protein structure is still missing. Despite many LC3B structures that have been solved, a comprehensive study, including dynamics, has not yet been undertaken. To address this knowledge gap, we assessed nine physical models for biomolecular simulations for their capabilities to describe the structural ensemble of MAP1LC3B. With the resulting MAP1LC3B structural ensembles, we characterized the impact of 26 missense mutations from pan-cancer studies with different approaches, and we experimentally validated our prediction for six variants using cellular assays. Our findings shed light on damaging or neutral mutations in MAP1LC3B, providing an atlas of its modifications in cancer. In particular, P32Q mutation was found detrimental for protein stability with a propensity to aggregation. In a broader context, our framework can be applied to assess the pathogenicity of protein mutations or to prioritize variants for experimental studies, allowing to comprehensively account for different aspects that mutational events alter in terms of protein structure and function. Abbreviations: ATG: autophagy-related; Cα: alpha carbon; CG: coarse-grained; CHARMM: Chemistry at Harvard macromolecular mechanics; CONAN: contact analysis; FUNDC1: FUN14 domain containing 1; FYCO1: FYVE and coiled-coil domain containing 1; GABARAP: GABA type A receptor-associated protein; GROMACS: Groningen machine for chemical simulations; HP: hydrophobic pocket; LIR: LC3 interacting region; MAP1LC3B/LC3B microtubule associated protein 1 light chain 3 B; MD: molecular dynamics; OPTN: optineurin; OSF: open software foundation; PE: phosphatidylethanolamine, PLEKHM1: pleckstrin homology domain-containing family M 1; PSN: protein structure network; PTM: post-translational modification; SA: structural alphabet; SLiM: short linear motif; SQSTM1/p62: sequestosome 1; WT: wild-type.
    Keywords:  Autophagy; MAP1LC3B; cancer mutations; molecular dynamics; protein structure network; structural alphabets
    DOI:  https://doi.org/10.1080/15548627.2020.1847443
  57. JCI Insight. 2020 Dec 08. pii: 141618. [Epub ahead of print]
    Loss of Fas-signaling in fibroblasts impairs homeostatic fibrosis resolution and promotes persistent pulmonary fibrosis.
    Elizabeth F Redente, Sangeeta Chakraborty, Satria P Sajuthi, Bart P Black, Ben L Edelman, Max A Seibold, David Wh Riches.
      Idiopathic pulmonary fibrosis (IPF) is a progressive, irreversible fibrotic disease of the distal lung alveoli that culminates in respiratory failure and reduced lifespan. Unlike normal lung repair in response to injury, IPF is associated with the accumulation and persistence of fibroblasts and myofibroblasts and continued production of collagen and other extracellular matrix (ECM) components. Prior in vitro studies have led to the hypothesis that the development of resistance to Fas-induced apoptosis by lung fibroblasts and myofibroblasts contibributes to their accumulation in the distal lung tissues of IPF patients. Here, we test this hypothesis in vivo in the resolving model of bleomycin-induced pulmonary fibrosis in mice. Using genetic loss-of-function approaches to inhibit Fas signaling in fibroblasts, novel flow cytometry strategies to quantify lung fibroblast subsets and transcriptional profiling of lung fibroblasts by bulk and single cell RNA-sequencing, we show that Fas is necessary for lung fibroblast apoptosis during homeostatic resolution of bleomycin-induced pulmonary fibrosis in vivo. Furthermore, we show that loss of Fas signaling leads to the persistence and continued pro-fibrotic functions of lung fibroblasts. Our studies provide novel insights into the mechanisms that contribute to fibroblast survival, persistence and continued ECM deposition in the context of IPF and how failure to undergo Fas-induced apoptosis prevents fibrosis resolution.
    Keywords:  Apoptosis; Fas signaling; Fibrosis; Pulmonology
    DOI:  https://doi.org/10.1172/jci.insight.141618
  58. Oncologist. 2020 Dec 09.
    Phase I Study of Afatinib and Selumetinib in Patients with KRAS-Mutated Colorectal, Non-Small Cell Lung, and Pancreatic Cancer.
    Emilie M J van Brummelen, Sanne Huijberts, Carla van Herpen, Ingrid Desar, Frans Opdam, Robin van Geel, Serena Marchetti, Neeltje Steeghs, Kim Monkhorst, Bas Thijssen, Hilde Rosing, Alwin Huitema, Jos Beijnen, Rene Bernards, Jan Schellens.
       LESSONS LEARNED: Afatinib and selumetinib can be combined in continuous and intermittent dosing schedules, albeit at lower doses than approved for monotherapy. Maximum tolerated dose for continuous and intermittent schedules is afatinib 20 mg QD and selumetinib 25 mg BID. Since the anticancer activity was limited, we do not recommend to further develop this combination until better biomarkers for response and resistance are defined.
    BACKGROUND: Anti-tumor effects of MEK inhibitors are limited in KRAS-mutated tumors due to feedback activation of upstream epidermal growth factor receptors which reactivates the MAPK and the phosphoinositide 3-kinase (PI3K)-AKT pathway. Therefore, this phase I trial was initiated with the pan-HER inhibitor afatinib plus the MEK inhibitor selumetinib in patients with KRASmt, PIK3CA wild type tumors.
    METHODS: Afatinib and selumetinib were administered according to a 3+3 design in continuous and intermittent schedules. The primary objective was safety, and the secondary objective was clinical efficacy.
    RESULTS: Twenty-six patients were enrolled with colorectal cancer (n = 19), non-small cell lung cancer (NSCLC) (n = 6), and pancreatic cancer (n = 1). Dose-limiting toxicities occurred in six patients, including grade 3 diarrhea, dehydration, decreased appetite, nausea, vomiting, and mucositis. The RP2D was 20 mg afatinib QD and 25 mg selumetinib BID (21 days on/7 days off) for continuous afatinib dosing and for intermittent dosing with both drugs 5 days on/2 days off. Efficacy was limited with disease stabilization for 221 days in a patient with NSCLC as best response.
    CONCLUSION: Afatinib and selumetinib can be combined in continuous and intermittent schedules in patients with KRASmt tumors. Although target engagement was observed, the clinical efficacy was limited.
    Keywords:  Afatinib; Colorectal cancer; KRAS; Non-small cell lung cancer; Pancreatic cancer; Selumetinib
    DOI:  https://doi.org/10.1002/onco.13631
  59. Semin Cell Dev Biol. 2020 Dec 05. pii: S1084-9521(19)30120-X. [Epub ahead of print]
    Alternative paths to telomere elongation.
    Jennifer J Lee, Junyeop Lee, Hyunsook Lee.
      Overcoming cellular senescence that is induced by telomere shortening is critical in tumorigenesis. A majority of cancers achieve telomere maintenance through telomerase expression. However, a subset of cancers takes an alternate route for elongating telomeres: recombination-based alternative lengthening of telomeres (ALT). Current evidence suggests that break-induced replication (BIR), independent of RAD51, underlies ALT telomere synthesis. However, RAD51-dependent homologous recombination is required for homology search and inter-chromosomal telomere recombination in human ALT cancer cell maintenance. Accumulating evidence suggests that the breakdown of stalled replication forks, the replication stress, induces BIR at telomeres. Nevertheless, ALT research is still in its early stage and a comprehensive view is still unclear. Here, we review the current findings regarding the genesis of ALT, how this recombinant pathway is chosen, the epigenetic regulation of telomeres in ALT, and perspectives for clinical applications with the hope that this overview will generate new questions.
    Keywords:  Alternative lengthening of telomeres (ALT); Break-induced replication (BIR); Replication stress; Telomere maintenance mechanism (TMM); Telomeric recombination
    DOI:  https://doi.org/10.1016/j.semcdb.2020.11.003
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