bims-cagime Biomed News
on Cancer, aging and metabolism
Issue of 2020–07–19
forty-nine papers selected by
Kıvanç Görgülü, Technical University of Munich
  1. L1CAM defines the regenerative origin of metastasis-initiating cells in colorectal cancer.
  2. Glucose-6-phosphate dehydrogenase is not essential for K-Ras-driven tumor growth or metastasis.
  3. Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis.
  4. Aging shifts mitochondrial dynamics toward fission to promote germline stem cell loss.
  5. PHD3 Loss Promotes Exercise Capacity and Fat Oxidation in Skeletal Muscle.
  6. Cancer cells with defective oxidative phosphorylation require endoplasmic reticulum-to-mitochondria Ca2+ transfer for survival.
  7. Tumors induce de novo steroid biosynthesis in T cells to evade immunity.
  8. A programmable fate decision landscape underlies single-cell aging in yeast.
  9. The regulation of glucose and lipid homeostasis via PLTP as a mediator of BAT-liver communication.
  10. Structures reveal gatekeeping of the mitochondrial Ca2+ uniporter by MICU1-MICU2.
  11. Skp2 dictates cell cycle-dependent metabolic oscillation between glycolysis and TCA cycle.
  12. Fructose contributes to the Warburg effect for cancer growth.
  13. Nucleolar RNA polymerase II drives ribosome biogenesis.
  14. Pex24 and Pex32 are required to tether peroxisomes to the ER for organelle biogenesis, positioning and segregation.
  15. Tissue-Biased Expansion of DNMT3A-Mutant Clones in a Mosaic Individual Is Associated with Conserved Epigenetic Erosion.
  16. Cancer cells deploy lipocalin-2 to collect limiting iron in leptomeningeal metastasis.
  17. Antibody-mediated inhibition of GDF15-GFRAL activity reverses cancer cachexia in mice.
  18. Bacterial immunotherapy for cancer induces CD4-dependent tumor-specific immunity through tumor-intrinsic interferon-γ signaling.
  19. Impaired mitochondrial oxidative phosphorylation limits the self-renewal of T cells exposed to persistent antigen.
  20. Mitochondrial Metabolism as a Target for Cancer Therapy.
  21. Structures and Mechanisms in the cGAS-STING Innate Immunity Pathway.
  22. Getting around the cell: physical transport in the intracellular world.
  23. Tumor Microenvironment-Derived NRG1 Promotes Antiandrogen Resistance in Prostate Cancer.
  24. Evolutionary stalling and a limit on the power of natural selection to improve a cellular module.
  25. PRMT5 inhibition modulates E2F1 methylation and gene regulatory networks leading to therapeutic efficacy in JAK2V617F mutant MPN.
  26. The choline transporter Slc44a2 controls platelet activation and thrombosis by regulating mitochondrial function.
  27. Dynamic changes in glioma macrophage populations after radiotherapy reveal CSF-1R inhibition as a strategy to overcome resistance.
  28. Tumor-initiating cells establish an IL-33-TGF-β niche signaling loop to promote cancer progression.
  29. CDK4/6 regulate lysosome biogenesis through TFEB/TFE3.
  30. Mitophagy, Mitochondrial Homeostasis, and Cell Fate.
  31. Fasting-mimicking diet and hormone therapy induce breast cancer regression.
  32. ATP-Driven Separation of Liquid Phase Condensates in Bacteria.
  33. IL6/STAT3 Signaling Hijacks Estrogen Receptor α Enhancers to Drive Breast Cancer Metastasis.
  34. Dissemination of RasV12-transformed cells requires the mechanosensitive channel Piezo.
  35. Ageing hallmarks exhibit organ-specific temporal signatures.
  36. Mitochondrial genome editing: another win for curiosity-driven research.
  37. ΔNp63 regulated epithelial-to-mesenchymal transition state heterogeneity confers a leader-follower relationship that drives collective invasion.
  38. Model membrane systems to reconstitute immune cell signaling.
  39. Targeting EMT in Cancer with Repurposed Metabolic Inhibitors.
  40. Functional anatomy of the full-length CXCR4-CXCL12 complex systematically dissected by quantitative model-guided mutagenesis.
  41. Role of Energy Excretion in Human Body Weight Regulation.
  42. A single-cell transcriptomic atlas characterizes ageing tissues in the mouse.
  43. Vitamin D Prevents Pancreatic Cancer-Induced Apoptosis Signaling of Inflammatory Cells.
  44. Hypothalamic CDK4 regulates thermogenesis by modulating sympathetic innervation of adipose tissues.
  45. Characterization of circulating breast cancer cells with tumorigenic and metastatic capacity.
  46. Persistence of a regeneration-associated, transitional alveolar epithelial cell state in pulmonary fibrosis.
  47. A Mitochondria-Immobilized Unimolecular Fluorescent Probe for Multiplexing Imaging of Living Cancer Cells.
  48. Clinical Trials in the Evolving Landscape of Precision Medicine.
  49. Telomere-to-telomere assembly of a complete human X chromosome.
  1. Nat Cancer. 2020 Jan;1(1): 28-45
    L1CAM defines the regenerative origin of metastasis-initiating cells in colorectal cancer.
    Karuna Ganesh, Harihar Basnet, Yasemin Kaygusuz, Ashley M Laughney, Lan He, Roshan Sharma, Kevin P O'Rourke, Vincent P Reuter, Yun-Han Huang, Mesruh Turkekul, Ekrem Emrah, Ignas Masilionis, Katia Manova-Todorova, Martin R Weiser, Leonard B Saltz, Julio Garcia-Aguilar, Richard Koche, Scott W Lowe, Dana Pe'er, Jinru Shia, Joan Massagué.
      Metastasis-initiating cells with stem-like properties drive cancer lethality, yet their origins and relationship to primary-tumor-initiating stem cells are not known. We show that L1CAM+ cells in human colorectal cancer (CRC) have metastasis-initiating capacity, and we define their relationship to tissue regeneration. L1CAM is not expressed in the homeostatic intestinal epithelium, but is induced and required for epithelial regeneration following colitis and in CRC organoid growth. By using human tissues and mouse models, we show that L1CAM is dispensable for adenoma initiation but required for orthotopic carcinoma propagation, liver metastatic colonization and chemoresistance. L1CAMhigh cells partially overlap with LGR5high stem-like cells in human CRC organoids. Disruption of intercellular epithelial contacts causes E-cadherin-REST transcriptional derepression of L1CAM, switching chemoresistant CRC progenitors from an L1CAMlow to an L1CAMhigh state. Thus, L1CAM dependency emerges in regenerative intestinal cells when epithelial integrity is lost, a phenotype of wound healing deployed in metastasis-initiating cells.
    DOI:  https://doi.org/10.1038/s43018-019-0006-x
  2. Cancer Res. 2020 Jul 13. pii: canres.2486.2019. [Epub ahead of print]
    Glucose-6-phosphate dehydrogenase is not essential for K-Ras-driven tumor growth or metastasis.
    Jonathan M Ghergurovich, Mark Esposito, Zihong Chen, Joshua Z Wang, Vrushank Bhatt, Taijin Lan, Eileen White, Yibin Kang, Jessie Yanxiang Guo, Joshua D Rabinowitz.
      The enzyme glucose-6-phosphate dehydrogenase (G6PD) is a major contributor to NADPH production and redox homeostasis and its expression is upregulated and correlated with negative patient outcomes in multiple human cancer types. Despite these associations, whether G6PD is essential for tumor initiation, growth, or metastasis remains unclear. Here we employ modern genetic tools to evaluate the role of G6PD in lung, breast, and colon cancer driven by oncogenic K-Ras. Human HCT116 colorectal cancer cells lacking G6PD exhibited metabolic indicators of oxidative stress but developed into subcutaneous xenografts with growth comparable to that of wild-type controls. In a genetically engineered mouse model of non-small-cell lung cancer driven by K-Ras G12D and p53-deficiency, G6PD knockout did not block formation or proliferation of primary lung tumors. In MDA-MB 231-derived human triple-negative breast cancer cells implanted as orthotopic xenografts, loss of G6PD modestly decreased primary site growth without ablating spontaneous metastasis to the lung and moderately impaired the ability of breast cancer cells to colonize the lung when delivered via tail vein injection. Thus, in the studied K-Ras tumor models, G6PD is not strictly essential for tumorigenesis and at most modestly promotes disease progression.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-19-2486
  3. Nat Commun. 2020 Jul 16. 11(1): 3559
    Alveolar regeneration through a Krt8+ transitional stem cell state that persists in human lung fibrosis.
    Maximilian Strunz, Lukas M Simon, Meshal Ansari, Jaymin J Kathiriya, Ilias Angelidis, Christoph H Mayr, George Tsidiridis, Marius Lange, Laura F Mattner, Min Yee, Paulina Ogar, Arunima Sengupta, Igor Kukhtevich, Robert Schneider, Zhongming Zhao, Carola Voss, Tobias Stoeger, Jens H L Neumann, Anne Hilgendorff, Jürgen Behr, Michael O'Reilly, Mareike Lehmann, Gerald Burgstaller, Melanie Königshoff, Harold A Chapman, Fabian J Theis, Herbert B Schiller.
      The cell type specific sequences of transcriptional programs during lung regeneration have remained elusive. Using time-series single cell RNA-seq of the bleomycin lung injury model, we resolved transcriptional dynamics for 28 cell types. Trajectory modeling together with lineage tracing revealed that airway and alveolar stem cells converge on a unique Krt8 + transitional stem cell state during alveolar regeneration. These cells have squamous morphology, feature p53 and NFkB activation and display transcriptional features of cellular senescence. The Krt8+ state appears in several independent models of lung injury and persists in human lung fibrosis, creating a distinct cell-cell communication network with mesenchyme and macrophages during repair. We generated a model of gene regulatory programs leading to Krt8+ transitional cells and their terminal differentiation to alveolar type-1 cells. We propose that in lung fibrosis, perturbed molecular checkpoints on the way to terminal differentiation can cause aberrant persistence of regenerative intermediate stem cell states.
    DOI:  https://doi.org/10.1038/s41467-020-17358-3
  4. Aging Cell. 2020 Jul 14. e13191
    Aging shifts mitochondrial dynamics toward fission to promote germline stem cell loss.
    Oyundari Amartuvshin, Chi-Hung Lin, Shao-Chun Hsu, Shih-Han Kao, Alvin Chen, Wei-Chun Tang, Han-Lin Chou, Dong-Lin Chang, Yen-Yang Hsu, Bai-Shiou Hsiao, Elham Rastegari, Kun-Yang Lin, Yu-Ting Wang, Chi-Kuang Yao, Guang-Chao Chen, Bi-Chang Chen, Hwei-Jan Hsu.
      Changes in mitochondrial dynamics (fusion and fission) are known to occur during stem cell differentiation; however, the role of this phenomenon in tissue aging remains unclear. Here, we report that mitochondrial dynamics are shifted toward fission during aging of Drosophila ovarian germline stem cells (GSCs), and this shift contributes to aging-related GSC loss. We found that as GSCs age, mitochondrial fragmentation and expression of the mitochondrial fission regulator, Dynamin-related protein (Drp1), are both increased, while mitochondrial membrane potential is reduced. Moreover, preventing mitochondrial fusion in GSCs results in highly fragmented depolarized mitochondria, decreased BMP stemness signaling, impaired fatty acid metabolism, and GSC loss. Conversely, forcing mitochondrial elongation promotes GSC attachment to the niche. Importantly, maintenance of aging GSCs can be enhanced by suppressing Drp1 expression to prevent mitochondrial fission or treating with rapamycin, which is known to promote autophagy via TOR inhibition. Overall, our results show that mitochondrial dynamics are altered during physiological aging, affecting stem cell homeostasis via coordinated changes in stemness signaling, niche contact, and cellular metabolism. Such effects may also be highly relevant to other stem cell types and aging-induced tissue degeneration.
    Keywords:  BMP; Drp1; GSC; Marf; mitochondrial fission; mitochondrial fusion
    DOI:  https://doi.org/10.1111/acel.13191
  5. Cell Metab. 2020 Jul 09. pii: S1550-4131(20)30318-1. [Epub ahead of print]
    PHD3 Loss Promotes Exercise Capacity and Fat Oxidation in Skeletal Muscle.
    Haejin Yoon, Jessica B Spinelli, Elma Zaganjor, Samantha J Wong, Natalie J German, Elizabeth C Randall, Afsah Dean, Allen Clermont, Joao A Paulo, Daniel Garcia, Hao Li, Olivia Rombold, Nathalie Y R Agar, Laurie J Goodyear, Reuben J Shaw, Steven P Gygi, Johan Auwerx, Marcia C Haigis.
      Rapid alterations in cellular metabolism allow tissues to maintain homeostasis during changes in energy availability. The central metabolic regulator acetyl-CoA carboxylase 2 (ACC2) is robustly phosphorylated during cellular energy stress by AMP-activated protein kinase (AMPK) to relieve its suppression of fat oxidation. While ACC2 can also be hydroxylated by prolyl hydroxylase 3 (PHD3), the physiological consequence thereof is poorly understood. We find that ACC2 phosphorylation and hydroxylation occur in an inverse fashion. ACC2 hydroxylation occurs in conditions of high energy and represses fatty acid oxidation. PHD3-null mice demonstrate loss of ACC2 hydroxylation in heart and skeletal muscle and display elevated fatty acid oxidation. Whole body or skeletal muscle-specific PHD3 loss enhances exercise capacity during an endurance exercise challenge. In sum, these data identify an unexpected link between AMPK and PHD3, and a role for PHD3 in acute exercise endurance capacity and skeletal muscle metabolism.
    Keywords:  Prolyl hydroxylase 3; acetyl-CoA carboxylase 2 modification; exercise capacity; fat catabolism
    DOI:  https://doi.org/10.1016/j.cmet.2020.06.017
  6. Sci Signal. 2020 Jul 14. pii: eaay1212. [Epub ahead of print]13(640):
    Cancer cells with defective oxidative phosphorylation require endoplasmic reticulum-to-mitochondria Ca2+ transfer for survival.
    Cesar Cardenas, Alenka Lovy, Eduardo Silva-Pavez, Felix Urra, Craig Mizzoni, Ulises Ahumada-Castro, Galdo Bustos, Fabian Jaňa, Pablo Cruz, Paula Farias, Elizabeth Mendoza, Hernan Huerta, Paola Murgas, Martin Hunter, Melany Rios, Oscar Cerda, Irene Georgakoudi, Armen Zakarian, Jordi Molgó, J Kevin Foskett.
      Spontaneous Ca2+ signaling from the InsP3R intracellular Ca2+ release channel to mitochondria is essential for optimal oxidative phosphorylation (OXPHOS) and ATP production. In cells with defective OXPHOS, reductive carboxylation replaces oxidative metabolism to maintain amounts of reducing equivalents and metabolic precursors. To investigate the role of mitochondrial Ca2+ uptake in regulating bioenergetics in these cells, we used OXPHOS-competent and OXPHOS-defective cells. Inhibition of InsP3R activity or mitochondrial Ca2+ uptake increased α-ketoglutarate (αKG) abundance and the NAD+/NADH ratio, indicating that constitutive endoplasmic reticulum (ER)-to-mitochondria Ca2+ transfer promoted optimal αKG dehydrogenase (αKGDH) activity. Reducing mitochondrial Ca2+ inhibited αKGDH activity and increased NAD+, which induced SIRT1-dependent autophagy in both OXPHOS-competent and OXPHOS-defective cells. Whereas autophagic flux in OXPHOS-competent cells promoted cell survival, it was impaired in OXPHOS-defective cells because of inhibition of autophagosome-lysosome fusion. Inhibition of αKGDH and impaired autophagic flux in OXPHOS-defective cells resulted in pronounced cell death in response to interruption of constitutive flux of Ca2+ from ER to mitochondria. These results demonstrate that mitochondria play a fundamental role in maintaining bioenergetic homeostasis of both OXPHOS-competent and OXPHOS-defective cells, with Ca2+ regulation of αKGDH activity playing a pivotal role. Inhibition of ER-to-mitochondria Ca2+ transfer may represent a general therapeutic strategy against cancer cells regardless of their OXPHOS status.
    DOI:  https://doi.org/10.1126/scisignal.aay1212
  7. Nat Commun. 2020 Jul 17. 11(1): 3588
    Tumors induce de novo steroid biosynthesis in T cells to evade immunity.
    Bidesh Mahata, Jhuma Pramanik, Louise van der Weyden, Krzysztof Polanski, Gozde Kar, Angela Riedel, Xi Chen, Nuno A Fonseca, Kousik Kundu, Lia S Campos, Edward Ryder, Graham Duddy, Izabela Walczak, Klaus Okkenhaug, David J Adams, Jacqueline D Shields, Sarah A Teichmann.
      Tumors subvert immune cell function to evade immune responses, yet the complex mechanisms driving immune evasion remain poorly understood. Here we show that tumors induce de novo steroidogenesis in T lymphocytes to evade anti-tumor immunity. Using a transgenic steroidogenesis-reporter mouse line we identify and characterize de novo steroidogenic immune cells, defining the global gene expression identity of these steroid-producing immune cells and gene regulatory networks by using single-cell transcriptomics. Genetic ablation of T cell steroidogenesis restricts primary tumor growth and metastatic dissemination in mouse models. Steroidogenic T cells dysregulate anti-tumor immunity, and inhibition of the steroidogenesis pathway is sufficient to restore anti-tumor immunity. This study demonstrates T cell de novo steroidogenesis as a mechanism of anti-tumor immunosuppression and a potential druggable target.
    DOI:  https://doi.org/10.1038/s41467-020-17339-6
  8. Science. 2020 Jul 17. 369(6501): 325-329
    A programmable fate decision landscape underlies single-cell aging in yeast.
    Yang Li, Yanfei Jiang, Julie Paxman, Richard O'Laughlin, Stephen Klepin, Yuelian Zhu, Lorraine Pillus, Lev S Tsimring, Jeff Hasty, Nan Hao.
      Chromatin instability and mitochondrial decline are conserved processes that contribute to cellular aging. Although both processes have been explored individually in the context of their distinct signaling pathways, the mechanism that determines which process dominates during aging of individual cells is unknown. We show that interactions between the chromatin silencing and mitochondrial pathways lead to an epigenetic landscape of yeast replicative aging with multiple equilibrium states that represent different types of terminal states of aging. The structure of the landscape drives single-cell differentiation toward one of these states during aging, whereby the fate is determined quite early and is insensitive to intracellular noise. Guided by a quantitative model of the aging landscape, we genetically engineered a long-lived equilibrium state characterized by an extended life span.
    DOI:  https://doi.org/10.1126/science.aax9552
  9. EMBO Rep. 2020 Jul 16. e49828
    The regulation of glucose and lipid homeostasis via PLTP as a mediator of BAT-liver communication.
    Carlos H Sponton, Takashi Hosono, Junki Taura, Mark P Jedrychowski, Takeshi Yoneshiro, Qiang Wang, Makoto Takahashi, Yumi Matsui, Kenji Ikeda, Yasuo Oguri, Kazuki Tajima, Kosaku Shinoda, Rachana N Pradhan, Yong Chen, Zachary Brown, Lindsay S Roberts, Carl C Ward, Hiroki Taoka, Yoko Yokoyama, Mitsuhiro Watanabe, Hiroshi Karasawa, Daniel K Nomura, Shingo Kajimura.
      While brown adipose tissue (BAT) is well-recognized for its ability to dissipate energy in the form of heat, recent studies suggest multifaced roles of BAT in the regulation of glucose and lipid homeostasis beyond stimulating thermogenesis. One of the functions involves interorgan communication with metabolic organs, such as the liver, through BAT-derived secretory factors, a.k.a., batokine. However, the identity and the roles of such mediators remain insufficiently understood. Here, we employed proteomics and transcriptomics in human thermogenic adipocytes and identified previously unappreciated batokines, including phospholipid transfer protein (PLTP). We found that increased circulating levels of PLTP, via systemic or BAT-specific overexpression, significantly improve glucose tolerance and insulin sensitivity, increased energy expenditure, and decrease the circulating levels of cholesterol, phospholipids, and sphingolipids. Such changes were accompanied by increased bile acids in the circulation, which in turn enhances glucose uptake and thermogenesis in BAT. Our data suggest that PLTP is a batokine that contributes to the regulation of systemic glucose and lipid homeostasis as a mediator of BAT-liver interorgan communication.
    Keywords:  brown adipose tissue; interorgan communication; lipid homeostasis
    DOI:  https://doi.org/10.15252/embr.201949828
  10. Elife. 2020 Jul 15. pii: e59991. [Epub ahead of print]9
    Structures reveal gatekeeping of the mitochondrial Ca2+ uniporter by MICU1-MICU2.
    Chongyuan Wang, Agata Jacewicz, Bryce D Delgado, Rozbeh Baradaran, Stephen Barstow Long.
      The mitochondrial calcium uniporter is a Ca2+-gated ion channel complex that controls mitochondrial Ca2+ entry and regulates cell metabolism. MCU and EMRE form the channel while Ca2+-dependent regulation is conferred by MICU1 and MICU2 through an enigmatic process. We present a cryo-EM structure of an MCU-EMRE-MICU1-MICU2 holocomplex comprising MCU and EMRE subunits from the beetle Tribolium castaneum in complex with a human MICU1-MICU2 heterodimer at 3.3 Å resolution. With analogy to how neuronal channels are blocked by protein toxins, a uniporter interaction domain on MICU1 binds to a channel receptor site comprising MCU and EMRE subunits to inhibit ion flow under resting Ca2+ conditions. A Ca2+-bound structure of MICU1-MICU2 at 3.1 Å resolution indicates how Ca2+-dependent changes enable dynamic response to cytosolic Ca2+ signals.
    Keywords:  biochemistry; chemical biology; human; molecular biophysics; structural biology
    DOI:  https://doi.org/10.7554/eLife.59991
  11. Cell Res. 2020 Jul 15.
    Skp2 dictates cell cycle-dependent metabolic oscillation between glycolysis and TCA cycle.
    Jing Liu, Yunhua Peng, Le Shi, Lixin Wan, Hiroyuki Inuzuka, Jiangang Long, Jianping Guo, Jinfang Zhang, Min Yuan, Shuangxi Zhang, Xun Wang, Jing Gao, Xiangpeng Dai, Shozo Furumoto, Lijun Jia, Pier Paolo Pandolfi, John M Asara, William G Kaelin, Jiankang Liu, Wenyi Wei.
      Whether glucose is predominantly metabolized via oxidative phosphorylation or glycolysis differs between quiescent versus proliferating cells, including tumor cells. However, how glucose metabolism is coordinated with cell cycle in mammalian cells remains elusive. Here, we report that mammalian cells predominantly utilize the tricarboxylic acid (TCA) cycle in G1 phase, but prefer glycolysis in S phase. Mechanistically, coupling cell cycle with metabolism is largely achieved by timely destruction of IDH1/2, key TCA cycle enzymes, in a Skp2-dependent manner. As such, depleting SKP2 abolishes cell cycle-dependent fluctuation of IDH1 protein abundance, leading to reduced glycolysis in S phase. Furthermore, elevated Skp2 abundance in prostate cancer cells destabilizes IDH1 to favor glycolysis and subsequent tumorigenesis. Therefore, our study reveals a mechanistic link between two cancer hallmarks, aberrant cell cycle and addiction to glycolysis, and provides the underlying mechanism for the coupling of metabolic fluctuation with periodic cell cycle in mammalian cells.
    DOI:  https://doi.org/10.1038/s41422-020-0372-z
  12. Cancer Metab. 2020 ;8 16
    Fructose contributes to the Warburg effect for cancer growth.
    Takahiko Nakagawa, Miguel A Lanaspa, Inigo San Millan, Mehdi Fini, Christopher J Rivard, Laura G Sanchez-Lozada, Ana Andres-Hernando, Dean R Tolan, Richard J Johnson.
      Obesity and metabolic syndrome are strongly associated with cancer, and these disorders may share a common mechanism. Recently, fructose has emerged as a driving force to develop obesity and metabolic syndrome. Thus, we assume that fructose may be the mechanism to explain why obesity and metabolic syndrome are linked with cancer. Clinical and experimental evidence showed that fructose intake was associated with cancer growth and that fructose transporters are upregulated in various malignant tumors. Interestingly, fructose metabolism can be driven under low oxygen conditions, accelerates glucose utilization, and exhibits distinct effects as compared to glucose, including production of uric acid and lactate as major byproducts. Fructose promotes the Warburg effect to preferentially downregulate mitochondrial respiration and increases aerobic glycolysis that may aid metastases that initially have low oxygen supply. In the process, uric acid may facilitate carcinogenesis by inhibiting the TCA cycle, stimulating cell proliferation by mitochondrial ROS, and blocking fatty acid oxidation. Lactate may also contribute to cancer growth by suppressing fat oxidation and inducing oncogene expression. The ability of fructose metabolism to directly stimulate the glycolytic pathway may have been protective for animals living with limited access to oxygen, but may be deleterious toward stimulating cancer growth and metastasis for humans in modern society. Blocking fructose metabolism may be a novel approach for the prevention and treatment of cancer.
    Keywords:  Cancer; Fructose; Hypoxia; Lactate; Mitochondria; Polyol pathway; Uric acid
    DOI:  https://doi.org/10.1186/s40170-020-00222-9
  13. Nature. 2020 Jul 15.
    Nucleolar RNA polymerase II drives ribosome biogenesis.
    Karan J Abraham, Negin Khosraviani, Janet N Y Chan, Aparna Gorthi, Anas Samman, Dorothy Y Zhao, Miling Wang, Michael Bokros, Elva Vidya, Lauren A Ostrowski, Roxanne Oshidari, Violena Pietrobon, Parasvi S Patel, Arash Algouneh, Rajat Singhania, Yupeng Liu, V Talya Yerlici, Daniel D De Carvalho, Michael Ohh, Brendan C Dickson, Razq Hakem, Jack F Greenblatt, Stephen Lee, Alexander J R Bishop, Karim Mekhail.
      Proteins are manufactured by ribosomes-macromolecular complexes of protein and RNA molecules that are assembled within major nuclear compartments called nucleoli1,2. Existing models suggest that RNA polymerases I and III (Pol I and Pol III) are the only enzymes that directly mediate the expression of the ribosomal RNA (rRNA) components of ribosomes. Here we show, however, that RNA polymerase II (Pol II) inside human nucleoli operates near genes encoding rRNAs to drive their expression. Pol II, assisted by the neurodegeneration-associated enzyme senataxin, generates a shield comprising triplex nucleic acid structures known as R-loops at intergenic spacers flanking nucleolar rRNA genes. The shield prevents Pol I from producing sense intergenic noncoding RNAs (sincRNAs) that can disrupt nucleolar organization and rRNA expression. These disruptive sincRNAs can be unleashed by Pol II inhibition, senataxin loss, Ewing sarcoma or locus-associated R-loop repression through an experimental system involving the proteins RNaseH1, eGFP and dCas9 (which we refer to as 'red laser'). We reveal a nucleolar Pol-II-dependent mechanism that drives ribosome biogenesis, identify disease-associated disruption of nucleoli by noncoding RNAs, and establish locus-targeted R-loop modulation. Our findings revise theories of labour division between the major RNA polymerases, and identify nucleolar Pol II as a major factor in protein synthesis and nuclear organization, with potential implications for health and disease.
    DOI:  https://doi.org/10.1038/s41586-020-2497-0
  14. J Cell Sci. 2020 Jul 14. pii: jcs.246983. [Epub ahead of print]
    Pex24 and Pex32 are required to tether peroxisomes to the ER for organelle biogenesis, positioning and segregation.
    Fei Wu, Rinse de Boer, Arjen M Krikken, Arman Akşit, Nicola Bordin, Damien P Devos, Ida J van der Klei.
      The yeast Hansenula polymorpha contains four members of the Pex23 family of peroxins, which characteristically contain a DysF domain. Here we show that all four H. polymorpha Pex23 family proteins localize to the ER. Pex24 and Pex32, but not Pex23 and Pex29, predominantly accumulate at peroxisome-ER contacts. Upon deletion of PEX24 or PEX32 - and to a much lesser extent of PEX23 or PEX29 - peroxisome-ER contacts are lost, concomitant with defects in peroxisomal matrix protein import, membrane growth, organelle proliferation, positioning and segregation. These defects are suppressed by the introduction of an artificial peroxisome-ER tether, indicating that Pex24 and Pex32 contribute to tethering peroxisomes to the ER. Accumulation of Pex32 at these contact sites is lost in cells lacking the peroxisomal membrane protein Pex11 in conjunction with disruption of the contacts. This indicates that Pex11 contributes to Pex32-dependent peroxisome-ER contact formation. The absence of Pex32 has no major effect on pre-peroxisomal vesicles that occur in pex3 atg1 cells.
    Keywords:  Endoplasmic reticulum; Membrane contact; Peroxisome; Pex24; Pex32; Yeast
    DOI:  https://doi.org/10.1242/jcs.246983
  15. Cell Stem Cell. 2020 Jul 14. pii: S1934-5909(20)30285-X. [Epub ahead of print]
    Tissue-Biased Expansion of DNMT3A-Mutant Clones in a Mosaic Individual Is Associated with Conserved Epigenetic Erosion.
    Ayala Tovy, Jaime M Reyes, Michael C Gundry, Lorenzo Brunetti, Henry Lee-Six, Mia Petljak, Hyun Jung Park, Anna G Guzman, Carina Rosas, Aaron R Jeffries, Emma Baple, Jonathan Mill, Andrew H Crosby, Valerie Sency, Baozhong Xin, Heather E Machado, Danielle Castillo, Jeffrey N Weitzel, Wei Li, Michael R Stratton, Peter J Campbell, Heng Wang, Mathijs A Sanders, Margaret A Goodell.
      DNA methyltransferase 3A (DNMT3A) is the most commonly mutated gene in clonal hematopoiesis (CH). Somatic DNMT3A mutations arise in hematopoietic stem cells (HSCs) many years before malignancies develop, but difficulties in comparing their impact before malignancy with wild-type cells have limited the understanding of their contributions to transformation. To circumvent this limitation, we derived normal and DNMT3A mutant lymphoblastoid cell lines from a germline mosaic individual in whom these cells co-existed for nearly 6 decades. Mutant cells dominated the blood system, but not other tissues. Deep sequencing revealed similar mutational burdens and signatures in normal and mutant clones, while epigenetic profiling uncovered the focal erosion of DNA methylation at oncogenic regulatory regions in mutant clones. These regions overlapped with those sensitive to DNMT3A loss after DNMT3A ablation in HSCs and in leukemia samples. These results suggest that DNMT3A maintains a conserved DNA methylation pattern, the erosion of which provides a distinct competitive advantage to hematopoietic cells.
    Keywords:  DNMT3A; HSC; cell competition; clonal hematopoiesis; hematopoietic stem cells; mutation burden; mutation signature
    DOI:  https://doi.org/10.1016/j.stem.2020.06.018
  16. Science. 2020 Jul 17. 369(6501): 276-282
    Cancer cells deploy lipocalin-2 to collect limiting iron in leptomeningeal metastasis.
    Yudan Chi, Jan Remsik, Vaidotas Kiseliovas, Camille Derderian, Ugur Sener, Majdi Alghader, Fadi Saadeh, Katie Nikishina, Tejus Bale, Christine Iacobuzio-Donahue, Tiffany Thomas, Dana Pe'er, Linas Mazutis, Adrienne Boire.
      The tumor microenvironment plays a critical regulatory role in cancer progression, especially in central nervous system metastases. Cancer cells within the cerebrospinal fluid (CSF)-filled leptomeninges face substantial microenvironmental challenges, including inflammation and sparse micronutrients. To investigate the mechanism by which cancer cells in these leptomeningeal metastases (LM) overcome these constraints, we subjected CSF from five patients with LM to single-cell RNA sequencing. We found that cancer cells, but not macrophages, within the CSF express the iron-binding protein lipocalin-2 (LCN2) and its receptor SCL22A17. These macrophages generate inflammatory cytokines that induce cancer cell LCN2 expression but do not generate LCN2 themselves. In mouse models of LM, cancer cell growth is supported by the LCN2/SLC22A17 system and is inhibited by iron chelation therapy. Thus, cancer cells appear to survive in the CSF by outcompeting macrophages for iron.
    DOI:  https://doi.org/10.1126/science.aaz2193
  17. Nat Med. 2020 Jul 13.
    Antibody-mediated inhibition of GDF15-GFRAL activity reverses cancer cachexia in mice.
    Rowena Suriben, Michael Chen, Jared Higbee, Julie Oeffinger, Richard Ventura, Betty Li, Kalyani Mondal, Zhengyu Gao, Dina Ayupova, Pranali Taskar, Diana Li, Shelley R Starck, Hung-I Harry Chen, Michele McEntee, Subhash D Katewa, Van Phung, Marilyn Wang, Avantika Kekatpure, Damodharan Lakshminarasimhan, Andre White, Andrea Olland, Raj Haldankar, Mark J Solloway, Jer-Yuan Hsu, Yan Wang, Jie Tang, Darrin A Lindhout, Bernard B Allan.
      Cancer cachexia is a highly prevalent condition associated with poor quality of life and reduced survival1. Tumor-induced perturbations in the endocrine, immune and nervous systems drive anorexia and catabolic changes in adipose tissue and skeletal muscle, hallmarks of cancer cachexia2-4. However, the molecular mechanisms driving cachexia remain poorly defined, and there are currently no approved drugs for the condition. Elevation in circulating growth differentiation factor 15 (GDF15) correlates with cachexia and reduced survival in patients with cancer5-8, and a GDNF family receptor alpha like (GFRAL)-Ret proto-oncogene (RET) signaling complex in brainstem neurons that mediates GDF15-induced weight loss in mice has recently been described9-12. Here we report a therapeutic antagonistic monoclonal antibody, 3P10, that targets GFRAL and inhibits RET signaling by preventing the GDF15-driven interaction of RET with GFRAL on the cell surface. Treatment with 3P10 reverses excessive lipid oxidation in tumor-bearing mice and prevents cancer cachexia, even under calorie-restricted conditions. Mechanistically, activation of the GFRAL-RET pathway induces expression of genes involved in lipid metabolism in adipose tissues, and both peripheral chemical sympathectomy and loss of adipose triglyceride lipase protect mice from GDF15-induced weight loss. These data uncover a peripheral sympathetic axis by which GDF15 elicits a lipolytic response in adipose tissue independently of anorexia, leading to reduced adipose and muscle mass and function in tumor-bearing mice.
    DOI:  https://doi.org/10.1038/s41591-020-0945-x
  18. Proc Natl Acad Sci U S A. 2020 Jul 17. pii: 202004421. [Epub ahead of print]
    Bacterial immunotherapy for cancer induces CD4-dependent tumor-specific immunity through tumor-intrinsic interferon-γ signaling.
    Anthony C Antonelli, Anna Binyamin, Tobias M Hohl, Michael S Glickman, Gil Redelman-Sidi.
      Bacillus Calmette-Guérin (BCG) immunotherapy for bladder cancer is the only bacterial cancer therapy approved for clinical use. Although presumed to induce T cell-mediated immunity, whether tumor elimination depends on bacteria-specific or tumor-specific immunity is unknown. Herein we show that BCG-induced bladder tumor elimination requires CD4 and CD8 T cells, although augmentation or inhibition of bacterial antigen-specific T cell responses does not alter the efficacy of BCG-induced tumor elimination. In contrast, BCG stimulates long-term tumor-specific immunity that primarily depends on CD4 T cells. We demonstrate that BCG therapy results in enhanced effector function of tumor-specific CD4 T cells, mainly through enhanced production of IFN-γ. Accordingly, BCG-induced tumor elimination and tumor-specific immune memory require tumor cell expression of the IFN-γ receptor, but not MHC class II. Our findings establish that a bacterial immunotherapy for cancer is capable of inducing tumor immunity, an antitumor effect that results from enhanced function of tumor-specific CD4 T cells, and ultimately requires tumor-intrinsic IFN-γ signaling, via a mechanism that is distinct from other tumor immunotherapies.
    Keywords:  BCG; T cell; bladder cancer; immunotherapy; tumor immunity
    DOI:  https://doi.org/10.1073/pnas.2004421117
  19. Nat Immunol. 2020 Jul 13.
    Impaired mitochondrial oxidative phosphorylation limits the self-renewal of T cells exposed to persistent antigen.
    Santosha A Vardhana, Madeline A Hwee, Mirela Berisa, Daniel K Wells, Kathryn E Yost, Bryan King, Melody Smith, Pamela S Herrera, Howard Y Chang, Ansuman T Satpathy, Marcel R M van den Brink, Justin R Cross, Craig B Thompson.
      The majority of tumor-infiltrating T cells exhibit a terminally exhausted phenotype, marked by a loss of self-renewal capacity. How repetitive antigenic stimulation impairs T cell self-renewal remains poorly defined. Here, we show that persistent antigenic stimulation impaired ADP-coupled oxidative phosphorylation. The resultant bioenergetic compromise blocked proliferation by limiting nucleotide triphosphate synthesis. Inhibition of mitochondrial oxidative phosphorylation in activated T cells was sufficient to suppress proliferation and upregulate genes linked to T cell exhaustion. Conversely, prevention of mitochondrial oxidative stress during chronic T cell stimulation allowed sustained T cell proliferation and induced genes associated with stem-like progenitor T cells. As a result, antioxidant treatment enhanced the anti-tumor efficacy of chronically stimulated T cells. These data reveal that loss of ATP production through oxidative phosphorylation limits T cell proliferation and effector function during chronic antigenic stimulation. Furthermore, treatments that maintain redox balance promote T cell self-renewal and enhance anti-tumor immunity.
    DOI:  https://doi.org/10.1038/s41590-020-0725-2
  20. Cell Metab. 2020 Jul 08. pii: S1550-4131(20)30320-X. [Epub ahead of print]
    Mitochondrial Metabolism as a Target for Cancer Therapy.
    Karthik Vasan, Marie Werner, Navdeep S Chandel.
      Recent evidence in humans and mice supports the notion that mitochondrial metabolism is active and necessary for tumor growth. Mitochondrial metabolism supports tumor anabolism by providing key metabolites for macromolecule synthesis and generating oncometabolites to maintain the cancer phenotype. Moreover, there are multiple clinical trials testing the efficacy of inhibiting mitochondrial metabolism as a new cancer therapeutic treatment. In this review, we discuss the rationale of using these anti-cancer agents in clinical trials and highlight how to effectively utilize them in different tumor contexts.
    Keywords:  metformin; mitochondria
    DOI:  https://doi.org/10.1016/j.cmet.2020.06.019
  21. Immunity. 2020 Jul 14. pii: S1074-7613(20)30221-1. [Epub ahead of print]53(1): 43-53
    Structures and Mechanisms in the cGAS-STING Innate Immunity Pathway.
    Xuewu Zhang, Xiao-Chen Bai, Zhijian J Chen.
      Besides its role as the blueprint of life, DNA can also alert the cell to the presence of microbial pathogens as well as damaged or malignant cells. A major sensor of DNA that triggers the innate immune response is cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) (cGAMP) synthase (cGAS), which produces the second messenger cGAMP. cGAMP activates stimulator of interferon genes (STING), which activates a signaling cascade leading to the production of type I interferons and other immune mediators. Recent research has demonstrated an expanding role of the cGAS-cGAMP-STING pathway in many physiological and pathological processes, including host defense against microbial infections, anti-tumor immunity, cellular senescence, autophagy, and autoimmune and inflammatory diseases. Biochemical and structural studies have elucidated the mechanism of signal transduction in the cGAS pathway at the atomic resolution. This review focuses on the structural and mechanistic insights into the roles of cGAS and STING in immunity and diseases revealed by these recent studies.
    DOI:  https://doi.org/10.1016/j.immuni.2020.05.013
  22. Phys Biol. 2020 Jul 14.
    Getting around the cell: physical transport in the intracellular world.
    Saurabh Mogre, Aidan Ivar Brown, Elena F Koslover.
      Eukaryotic cells face the challenging task of transporting a variety of particles through the complex intracellular milieu in order to deliver, distribute, and mix the many components that support cell function. In this review, we explore the biological objectives and physical mechanisms of intracellular transport. Our focus is on cytoplasmic and intra-organelle transport at the whole-cell scale. We outline several key biological functions that depend on physically transporting components across the cell, including the delivery of secreted proteins, support of cell growth and repair, propagation of intracellular signals, establishment of organelle contacts, and spatial organization of metabolic gradients. We then review the three primary physical modes of transport in eukaryotic cells: diffusive motion, motor-driven transport, and advection by cytoplasmic flow. For each mechanism, we identify the main factors that determine speed and directionality. We also highlight the efficiency of each transport mode in fulfilling various key objectives of transport, such as particle mixing, directed delivery, and rapid target search. Taken together, the interplay of diffusion, molecular motors, and flows supports the intracellular transport needs that underlie a broad variety of biological phenomena.
    Keywords:  cellular biophysics; cytoplasmic flow; diffusion; intracellular transport; molecular motors; organelle dynamics
    DOI:  https://doi.org/10.1088/1478-3975/aba5e5
  23. Cancer Cell. 2020 Jun 23. pii: S1535-6108(20)30309-3. [Epub ahead of print]
    Tumor Microenvironment-Derived NRG1 Promotes Antiandrogen Resistance in Prostate Cancer.
    Zeda Zhang, Wouter R Karthaus, Young Sun Lee, Vianne R Gao, Chao Wu, Joshua W Russo, Menghan Liu, Jose Mauricio Mota, Wassim Abida, Eliot Linton, Eugine Lee, Spencer D Barnes, Hsuan-An Chen, Ninghui Mao, John Wongvipat, Danielle Choi, Xiaoping Chen, Huiyong Zhao, Katia Manova-Todorova, Elisa de Stanchina, Mary-Ellen Taplin, Steven P Balk, Dana E Rathkopf, Anuradha Gopalan, Brett S Carver, Ping Mu, Xuejun Jiang, Philip A Watson, Charles L Sawyers.
      Despite the development of second-generation antiandrogens, acquired resistance to hormone therapy remains a major challenge in treating advanced prostate cancer. We find that cancer-associated fibroblasts (CAFs) can promote antiandrogen resistance in mouse models and in prostate organoid cultures. We identify neuregulin 1 (NRG1) in CAF supernatant, which promotes resistance in tumor cells through activation of HER3. Pharmacological blockade of the NRG1/HER3 axis using clinical-grade blocking antibodies re-sensitizes tumors to hormone deprivation in vitro and in vivo. Furthermore, patients with castration-resistant prostate cancer with increased tumor NRG1 activity have an inferior response to second-generation antiandrogen therapy. This work reveals a paracrine mechanism of antiandrogen resistance in prostate cancer amenable to clinical testing using available targeted therapies.
    Keywords:  NRG1/neuregulin 1; cancer-associated fibroblast; drug resistance; hormone therapy; tumor microenvironment
    DOI:  https://doi.org/10.1016/j.ccell.2020.06.005
  24. Proc Natl Acad Sci U S A. 2020 Jul 17. pii: 201921881. [Epub ahead of print]
    Evolutionary stalling and a limit on the power of natural selection to improve a cellular module.
    Sandeep Venkataram, Ross Monasky, Shohreh H Sikaroodi, Sergey Kryazhimskiy, Betul Kacar.
      Cells consist of molecular modules which perform vital biological functions. Cellular modules are key units of adaptive evolution because organismal fitness depends on their performance. Theory shows that in rapidly evolving populations, such as those of many microbes, adaptation is driven primarily by common beneficial mutations with large effects, while other mutations behave as if they are effectively neutral. As a consequence, if a module can be improved only by rare and/or weak beneficial mutations, its adaptive evolution would stall. However, such evolutionary stalling has not been empirically demonstrated, and it is unclear to what extent stalling may limit the power of natural selection to improve modules. Here we empirically characterize how natural selection improves the translation machinery (TM), an essential cellular module. We experimentally evolved populations of Escherichia coli with genetically perturbed TMs for 1,000 generations. Populations with severe TM defects initially adapted via mutations in the TM, but TM adaptation stalled within about 300 generations. We estimate that the genetic load in our populations incurred by residual TM defects ranges from 0.5 to 19%. Finally, we found evidence that both epistasis and the depletion of the pool of beneficial mutations contributed to evolutionary stalling. Our results suggest that cellular modules may not be fully optimized by natural selection despite the availability of adaptive mutations.
    Keywords:  adaptation; experimental evolution; translation
    DOI:  https://doi.org/10.1073/pnas.1921881117
  25. Cancer Discov. 2020 Jul 15. pii: CD-20-0026. [Epub ahead of print]
    PRMT5 inhibition modulates E2F1 methylation and gene regulatory networks leading to therapeutic efficacy in JAK2V617F mutant MPN.
    Friederike Pastore, Neha Bhagwat, Alessandro Pastore, Aliaksandra Radzisheuskaya, Abdul Karzai, Aishwarya Krishnan, Bing Li, Robert L Bowman, Wenbin Xiao, Aaron D Viny, Anouar Zouak, Young C Park, Keith B Cordner, Stephanie Braunstein, Jesper L V Maag, Alexander Grego, Jaanvi Mehta, Min Wang, Hong Lin, Benjamin H Durham, Richard P Koche, Raajit K Rampal, Kristian Helin, Peggy Scherle, Kris Vaddi, Ross L Levine.
      We investigated the role of PRMT5 in MPN pathogenesis and aimed to elucidate key PRMT5 targets contributing to MPN maintenance. PRMT5 is overexpressed in primary MPN cells and PRMT5 inhibition potently reduced MPN cell proliferation ex vivo. PRMT5 inhibition was efficacious at reversing elevated hematocrit, leukocytosis and splenomegaly in a model of JAK2V617F+ polycythemia vera (PV) and leukocyte and platelet counts, hepatosplenomegaly and fibrosis in the MPLW515L model of myelofibrosis (MF). Dual targeting of JAK and PRMT5 was superior to JAK or PRMT5 inhibitor monotherapy, further decreasing elevated counts and extramedullary hematopoiesis in vivo. PRMT5 inhibition reduced expression of E2F targets and altered the methylation status of E2F1 leading to attenuated DNA damage repair, cell cycle arrest and increased apoptosis. Our data link PRMT5 to E2F1 regulatory function and MPN cell survival and provide a strong mechanistic rationale for clinical trials of PRMT5 inhibitors in MPN.
    DOI:  https://doi.org/10.1158/2159-8290.CD-20-0026
  26. Nat Commun. 2020 Jul 13. 11(1): 3479
    The choline transporter Slc44a2 controls platelet activation and thrombosis by regulating mitochondrial function.
    J Allen Bennett, Michael A Mastrangelo, Sara K Ture, Charles O Smith, Shannon G Loelius, Rachel A Berg, Xu Shi, Ryan M Burke, Sherry L Spinelli, Scott J Cameron, Thomas E Carey, Paul S Brookes, Robert E Gerszten, Maria Sabater-Lleal, Paul S de Vries, Jennifer E Huffman, Nicholas L Smith, Craig N Morrell, Charles J Lowenstein.
      Genetic factors contribute to the risk of thrombotic diseases. Recent genome wide association studies have identified genetic loci including SLC44A2 which may regulate thrombosis. Here we show that Slc44a2 controls platelet activation and thrombosis by regulating mitochondrial energetics. We find that Slc44a2 null mice (Slc44a2(KO)) have increased bleeding times and delayed thrombosis compared to wild-type (Slc44a2(WT)) controls. Platelets from Slc44a2(KO) mice have impaired activation in response to thrombin. We discover that Slc44a2 mediates choline transport into mitochondria, where choline metabolism leads to an increase in mitochondrial oxygen consumption and ATP production. Platelets lacking Slc44a2 contain less ATP at rest, release less ATP when activated, and have an activation defect that can be rescued by exogenous ADP. Taken together, our data suggest that mitochondria require choline for maximum function, demonstrate the importance of mitochondrial metabolism to platelet activation, and reveal a mechanism by which Slc44a2 influences thrombosis.
    DOI:  https://doi.org/10.1038/s41467-020-17254-w
  27. Sci Transl Med. 2020 Jul 15. pii: eaaw7843. [Epub ahead of print]12(552):
    Dynamic changes in glioma macrophage populations after radiotherapy reveal CSF-1R inhibition as a strategy to overcome resistance.
    Leila Akkari, Robert L Bowman, Jeremy Tessier, Florian Klemm, Shanna M Handgraaf, Marnix de Groot, Daniela F Quail, Lucie Tillard, Jules Gadiot, Jason T Huse, Dieta Brandsma, Johan Westerga, Colin Watts, Johanna A Joyce.
      Tumor-associated macrophages (TAMs) and microglia (MG) are potent regulators of glioma development and progression. However, the dynamic alterations of distinct TAM populations during the course of therapeutic intervention, response, and recurrence have not yet been fully explored. Here, we investigated how radiotherapy changes the relative abundance and phenotypes of brain-resident MG and peripherally recruited monocyte-derived macrophages (MDMs) in glioblastoma. We identified radiation-specific, stage-dependent MG and MDM gene expression signatures in murine gliomas and confirmed altered expression of several genes and proteins in recurrent human glioblastoma. We found that targeting these TAM populations using a colony-stimulating factor-1 receptor (CSF-1R) inhibitor combined with radiotherapy substantially enhanced survival in preclinical models. Our findings reveal the dynamics and plasticity of distinct macrophage populations in the irradiated tumor microenvironment, which has translational relevance for enhancing the efficacy of standard-of-care treatment in gliomas.
    DOI:  https://doi.org/10.1126/scitranslmed.aaw7843
  28. Science. 2020 Jul 17. pii: eaay1813. [Epub ahead of print]369(6501):
    Tumor-initiating cells establish an IL-33-TGF-β niche signaling loop to promote cancer progression.
    Sachiko Taniguchi, Ajit Elhance, Avery Van Duzer, Sushil Kumar, Justin J Leitenberger, Naoki Oshimori.
      Targeting the cross-talk between tumor-initiating cells (TICs) and the niche microenvironment is an attractive avenue for cancer therapy. We show here, using a mouse model of squamous cell carcinoma, that TICs play a crucial role in creating a niche microenvironment that is required for tumor progression and drug resistance. Antioxidant activity in TICs, mediated by the transcription factor NRF2, facilitates the release of a nuclear cytokine, interleukin-33 (IL-33). This cytokine promotes differentiation of macrophages that express the high-affinity immunoglobulin E receptor FcεRIα and are in close proximity to TICs. In turn, these IL-33-responding FcεRIα+ macrophages send paracrine transforming growth factor β (TGF-β) signals to TICs, inducing invasive and drug-resistant properties and further upregulating IL-33 expression. This TIC-driven, IL-33-TGF-β feedforward loop could potentially be exploited for cancer treatment.
    DOI:  https://doi.org/10.1126/science.aay1813
  29. J Cell Biol. 2020 Aug 03. pii: e201911036. [Epub ahead of print]219(8):
    CDK4/6 regulate lysosome biogenesis through TFEB/TFE3.
    Qiuyuan Yin, Youli Jian, Meng Xu, Xiahe Huang, Niya Wang, Zhifang Liu, Qian Li, Jinglin Li, Hejiang Zhou, Lin Xu, Yingchun Wang, Chonglin Yang.
      Lysosomes are degradation and signaling organelles that adapt their biogenesis to meet many different cellular demands; however, it is unknown how lysosomes change their numbers for cell division. Here, we report that the cyclin-dependent kinases CDK4/6 regulate lysosome biogenesis during the cell cycle. Chemical or genetic inactivation of CDK4/6 increases lysosomal numbers by activating the lysosome and autophagy transcription factors TFEB and TFE3. CDK4/6 interact with and phosphorylate TFEB/TFE3 in the nucleus, thereby inactivating them by promoting their shuttling to the cytoplasm. During the cell cycle, lysosome numbers increase in S and G2/M phases when cyclin D turnover diminishes CDK4/6 activity. These findings not only uncover the molecular events that direct the nuclear export of TFEB/TFE3, but also suggest a mechanism that controls lysosome biogenesis in the cell cycle. CDK4/6 inhibitors promote autophagy and lysosome-dependent degradation, which has important implications for the therapy of cancer and lysosome-related disorders.
    DOI:  https://doi.org/10.1083/jcb.201911036
  30. Front Cell Dev Biol. 2020 ;8 467
    Mitophagy, Mitochondrial Homeostasis, and Cell Fate.
    Kaili Ma, Guo Chen, Wenhui Li, Oliver Kepp, Yushan Zhu, Quan Chen.
      Mitochondria are highly plastic and dynamic organelles that have graded responses to the changing cellular, environmental, and developmental cues. Mitochondria undergo constant mitochondrial fission and fusion, mitochondrial biogenesis, and mitophagy, which coordinately control mitochondrial morphology, quantity, quality, turnover, and inheritance. Mitophagy is a cellular process that selectively removes the aged and damaged mitochondria via the specific sequestration and engulfment of mitochondria for subsequent lysosomal degradation. It plays a pivotal role in reinstating cellular homeostasis in normal physiology and conditions of stress. Damaged mitochondria may either instigate innate immunity through the overproduction of ROS or the release of mtDNA, or trigger cell death through the release of cytochrome c and other apoptogenic factors when mitochondria damage is beyond repair. Distinct molecular machineries and signaling pathways are found to regulate these mitochondrial dynamics and behaviors. It is less clear how mitochondrial behaviors are coordinated at molecular levels. BCL2 family proteins interact within family members to regulate mitochondrial outer membrane permeabilization and apoptosis. They were also described as global regulators of mitochondrial homeostasis and mitochondrial fate through their interaction with distinct partners including Drp1, mitofusins, PGAM5, and even LC3 that involved mitochondrial dynamics and behaviors. In this review, we summarize recent findings on molecular pathways governing mitophagy and its coordination with other mitochondrial behaviors, which together determine cellular fate.
    Keywords:  cell fate; mitochondrial apoptosis; mitochondrial dynamics; mitophagy; mitophagy receptors
    DOI:  https://doi.org/10.3389/fcell.2020.00467
  31. Nature. 2020 Jul 15.
    Fasting-mimicking diet and hormone therapy induce breast cancer regression.
    Irene Caffa, Vanessa Spagnolo, Claudio Vernieri, Francesca Valdemarin, Pamela Becherini, Min Wei, Sebastian Brandhorst, Chiara Zucal, Else Driehuis, Lorenzo Ferrando, Francesco Piacente, Alberto Tagliafico, Michele Cilli, Luca Mastracci, Valerio G Vellone, Silvano Piazza, Anna Laura Cremonini, Raffaella Gradaschi, Carolina Mantero, Mario Passalacqua, Alberto Ballestrero, Gabriele Zoppoli, Michele Cea, Annalisa Arrighi, Patrizio Odetti, Fiammetta Monacelli, Giulia Salvadori, Salvatore Cortellino, Hans Clevers, Filippo De Braud, Samir G Sukkar, Alessandro Provenzani, Valter D Longo, Alessio Nencioni.
      Approximately 75% of all breast cancers express the oestrogen and/or progesterone receptors. Endocrine therapy is usually effective in these hormone-receptor-positive tumours, but primary and acquired resistance limits its long-term benefit1,2. Here we show that in mouse models of hormone-receptor-positive breast cancer, periodic fasting or a fasting-mimicking diet3-5 enhances the activity of the endocrine therapeutics tamoxifen and fulvestrant by lowering circulating IGF1, insulin and leptin and by inhibiting AKT-mTOR signalling via upregulation of EGR1 and PTEN. When fulvestrant is combined with palbociclib (a cyclin-dependent kinase 4/6 inhibitor), adding periodic cycles of a fasting-mimicking diet promotes long-lasting tumour regression and reverts acquired resistance to drug treatment. Moreover, both fasting and a fasting-mimicking diet prevent tamoxifen-induced endometrial hyperplasia. In patients with hormone-receptor-positive breast cancer receiving oestrogen therapy, cycles of a fasting-mimicking diet cause metabolic changes analogous to those observed in mice, including reduced levels of insulin, leptin and IGF1, with the last two remaining low for extended periods. In mice, these long-lasting effects are associated with long-term anti-cancer activity. These results support further clinical studies of a fasting-mimicking diet as an adjuvant to oestrogen therapy in hormone-receptor-positive breast cancer.
    DOI:  https://doi.org/10.1038/s41586-020-2502-7
  32. Mol Cell. 2020 Jul 16. pii: S1097-2765(20)30436-6. [Epub ahead of print]79(2): 293-303.e4
    ATP-Driven Separation of Liquid Phase Condensates in Bacteria.
    Baptiste Guilhas, Jean-Charles Walter, Jerome Rech, Gabriel David, Nils Ole Walliser, John Palmeri, Celine Mathieu-Demaziere, Andrea Parmeggiani, Jean-Yves Bouet, Antoine Le Gall, Marcelo Nollmann.
      Liquid-liquid phase-separated (LLPS) states are key to compartmentalizing components in the absence of membranes; however, it is unclear whether LLPS condensates are actively and specifically organized in the subcellular space and by which mechanisms. Here, we address this question by focusing on the ParABS DNA segregation system, composed of a centromeric-like sequence (parS), a DNA-binding protein (ParB), and a motor (ParA). We show that parS and ParB associate to form nanometer-sized, round condensates. ParB molecules diffuse rapidly within the nucleoid volume but display confined motions when trapped inside ParB condensates. Single ParB molecules are able to rapidly diffuse between different condensates, and nucleation is strongly favored by parS. Notably, the ParA motor is required to prevent the fusion of ParB condensates. These results describe a novel active mechanism that splits, segregates, and localizes non-canonical LLPS condensates in the subcellular space.
    Keywords:  ParABS; liquid droplets; liquid phase condensation; phase separation; photo-activated localization microscopy; plasmid partition; single particle tracking
    DOI:  https://doi.org/10.1016/j.molcel.2020.06.034
  33. Cancer Cell. 2020 Jul 06. pii: S1535-6108(20)30311-1. [Epub ahead of print]
    IL6/STAT3 Signaling Hijacks Estrogen Receptor α Enhancers to Drive Breast Cancer Metastasis.
    Rasmus Siersbæk, Valentina Scabia, Sankari Nagarajan, Igor Chernukhin, Evangelia K Papachristou, Rebecca Broome, Simon J Johnston, Stacey E P Joosten, Andrew R Green, Sanjeev Kumar, Julia Jones, Soleilmane Omarjee, Ruben Alvarez-Fernandez, Silvia Glont, Sarah J Aitken, Kamal Kishore, Danya Cheeseman, Emad A Rakha, Clive D'Santos, Wilbert Zwart, Alasdair Russell, Cathrin Brisken, Jason S Carroll.
      The cytokine interleukin-6 (IL6) and its downstream effector STAT3 constitute a key oncogenic pathway, which has been thought to be functionally connected to estrogen receptor α (ER) in breast cancer. We demonstrate that IL6/STAT3 signaling drives metastasis in ER+ breast cancer independent of ER. STAT3 hijacks a subset of ER enhancers to drive a distinct transcriptional program. Although these enhancers are shared by both STAT3 and ER, IL6/STAT3 activity is refractory to standard ER-targeted therapies. Instead, inhibition of STAT3 activity using the JAK inhibitor ruxolitinib decreases breast cancer invasion in vivo. Therefore, IL6/STAT3 and ER oncogenic pathways are functionally decoupled, highlighting the potential of IL6/STAT3-targeted therapies in ER+ breast cancer.
    Keywords:  FOXA1; IL6; STAT3; breast cancer; estrogen receptor; metastasis; mouse intraductal xenograft model; pioneer factor
    DOI:  https://doi.org/10.1016/j.ccell.2020.06.007
  34. Nat Commun. 2020 Jul 16. 11(1): 3568
    Dissemination of RasV12-transformed cells requires the mechanosensitive channel Piezo.
    Jiae Lee, Alejandra J H Cabrera, Cecilia M T Nguyen, Young V Kwon.
      Dissemination of transformed cells is a key process in metastasis. Despite its importance, how transformed cells disseminate from an intact tissue and enter the circulation is poorly understood. Here, we use a fully developed tissue, Drosophila midgut, and describe the morphologically distinct steps and the cellular events occurring over the course of RasV12-transformed cell dissemination. Notably, RasV12-transformed cells formed the Actin- and Cortactin-rich invasive protrusions that were important for breaching the extracellular matrix (ECM) and visceral muscle. Furthermore, we uncovered the essential roles of the mechanosensory channel Piezo in orchestrating dissemination of RasV12-transformed cells. Collectively, our study establishes an in vivo model for studying how transformed cells migrate out from a complex tissue and provides unique insights into the roles of Piezo in invasive cell behavior.
    DOI:  https://doi.org/10.1038/s41467-020-17341-y
  35. Nature. 2020 Jul 15.
    Ageing hallmarks exhibit organ-specific temporal signatures.
    Tabula Muris Consortium
      Ageing is the single greatest cause of disease and death worldwide, and understanding the associated processes could vastly improve quality of life. Although major categories of ageing damage have been identified-such as altered intercellular communication, loss of proteostasis and eroded mitochondrial function1-these deleterious processes interact with extraordinary complexity within and between organs, and a comprehensive, whole-organism analysis of ageing dynamics has been lacking. Here we performed bulk RNA sequencing of 17 organs and plasma proteomics at 10 ages across the lifespan of Mus musculus, and integrated these findings with data from the accompanying Tabula Muris Senis2-or 'Mouse Ageing Cell Atlas'-which follows on from the original Tabula Muris3. We reveal linear and nonlinear shifts in gene expression during ageing, with the associated genes clustered in consistent trajectory groups with coherent biological functions-including extracellular matrix regulation, unfolded protein binding, mitochondrial function, and inflammatory and immune response. Notably, these gene sets show similar expression across tissues, differing only in the amplitude and the age of onset of expression. Widespread activation of immune cells is especially pronounced, and is first detectable in white adipose depots during middle age. Single-cell RNA sequencing confirms the accumulation of T cells and B cells in adipose tissue-including plasma cells that express immunoglobulin J-which also accrue concurrently across diverse organs. Finally, we show how gene expression shifts in distinct tissues are highly correlated with corresponding protein levels in plasma, thus potentially contributing to the ageing of the systemic circulation. Together, these data demonstrate a similar yet asynchronous inter- and intra-organ progression of ageing, providing a foundation from which to track systemic sources of declining health at old age.
    DOI:  https://doi.org/10.1038/s41586-020-2499-y
  36. Nature. 2020 Jul;583(7816): 332
    Mitochondrial genome editing: another win for curiosity-driven research.
      
    Keywords:  Biological techniques; CRISPR-Cas9 genome editing; Genetics; Metabolism
    DOI:  https://doi.org/10.1038/d41586-020-02094-x
  37. Cancer Res. 2020 Jul 13. pii: canres.0014.2020. [Epub ahead of print]
    ΔNp63 regulated epithelial-to-mesenchymal transition state heterogeneity confers a leader-follower relationship that drives collective invasion.
    Jill M Westcott, Sharon Camacho, Apsra Nasir, Molly E Huysman, Raneen Rahhal, Tuyen T Dang, Anna T Riegel, Rolf A Brekken, Gray W Pearson.
      Defining how interactions between tumor subpopulations contribute to invasion is essential for understanding how tumors metastasize. Here, we find that the heterogeneous expression of the transcription factor ΔNp63 confers distinct proliferative and invasive EMT states in subpopulations that establish a leader-follower relationship to collectively invade. A ΔNp63-high EMT program coupled the ability to proliferate with an interleukin 1α (IL-1α) and miR-205-dependent suppression of cellular protrusions that are required to initiate collective invasion. An alternative ΔNp63-low EMT program conferred cells with the ability to initiate and lead collective invasion. However, this ΔNp63-low EMT state triggered a collateral loss of fitness. Importantly, rare growth-suppressed ΔNp63-low EMT cells influenced tumor progression by leading the invasion of proliferative ΔNp63-high EMT cells in heterogeneous primary tumors. Thus, heterogeneous activation of distinct EMT programs promotes a mode of collective invasion that overcomes cell intrinsic phenotypic deficiencies to induce the dissemination of proliferative tumor cells.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-20-0014
  38. FEBS J. 2020 Jul 18.
    Model membrane systems to reconstitute immune cell signaling.
    Pablo F Céspedes, Daniel Beckers, Michael L Dustin, Erdinc Sezgin.
      Understanding the broad variety of functions encoded in cellular membranes requires experimental systems mimicking both their biochemical composition and biophysical properties. Here, we review the interplay between membrane components and the physical properties of the plasma membrane worth considering for biomimetic studies. Later, we discuss the main advantages and caveats of different model membrane systems. We further expand on how the use of model systems has contributed to the understanding of immune cell signaling, with a specific focus on the immunological synapse. We discuss the similarities of immune synapses observed for innate and adaptive immune cells and focus on the physical principles underlying these similarities.
    Keywords:  giant vesicles; immune synapse; model membranes; reconstitution; supported lipid bilayers
    DOI:  https://doi.org/10.1111/febs.15488
  39. Trends Cancer. 2020 Jul 15. pii: S2405-8033(20)30189-8. [Epub ahead of print]
    Targeting EMT in Cancer with Repurposed Metabolic Inhibitors.
    Vignesh Ramesh, Thomas Brabletz, Paolo Ceppi.
      Epithelial-to-mesenchymal transition (EMT) determines the most lethal features of cancer, metastasis formation and chemoresistance, and therefore represents an attractive target in oncology. However, direct targeting of EMT effector molecules is, in most cases, pharmacologically challenging. Since emerging research has highlighted the distinct metabolic circuits involved in EMT, we propose the use of metabolism-specific inhibitors, FDA approved or under clinical trials, as a drug repurposing approach to target EMT in cancer. Metabolism-inhibiting drugs could be coupled with standard chemo- or immunotherapy to combat EMT-driven resistant and aggressive cancers.
    Keywords:  chemoresistance; drug repurposing; epithelial–mesenchymal transition; metabolic inhibitor; partial EMT
    DOI:  https://doi.org/10.1016/j.trecan.2020.06.005
  40. Sci Signal. 2020 Jul 14. pii: eaay5024. [Epub ahead of print]13(640):
    Functional anatomy of the full-length CXCR4-CXCL12 complex systematically dissected by quantitative model-guided mutagenesis.
    Bryan S Stephens, Tony Ngo, Irina Kufareva, Tracy M Handel.
      Because of their prominent roles in development, cancer, and HIV, the chemokine receptor CXCR4 and its ligand CXCL12 have been the subject of numerous structural and functional studies, but the determinants of ligand binding, selectivity, and signaling are still poorly understood. Here, building on our latest structural model, we used a systematic mutagenesis strategy to dissect the functional anatomy of the CXCR4-CXCL12 complex. Key charge swap mutagenesis experiments provided evidence for pairwise interactions between oppositely charged residues in the receptor and chemokine, confirming the accuracy of the predicted orientation of the chemokine relative to the receptor and providing insight into ligand selectivity. Progressive deletion of N-terminal residues revealed an unexpected contribution of the receptor N terminus to chemokine signaling. This finding challenges a longstanding "two-site" hypothesis about the essential features of the receptor-chemokine interaction in which the N terminus contributes only to binding affinity. Our results suggest that although the interaction of the chemokine N terminus with the receptor-binding pocket is the key driver of signaling, the signaling amplitude depends on the extent to which the receptor N terminus binds the chemokine. Together with systematic characterization of other epitopes, these data enable us to propose an experimentally consistent structural model for how CXCL12 binds CXCR4 and initiates signal transmission through the receptor transmembrane domain.
    DOI:  https://doi.org/10.1126/scisignal.aay5024
  41. Trends Endocrinol Metab. 2020 Jul 13. pii: S1043-2760(20)30134-X. [Epub ahead of print]
    Role of Energy Excretion in Human Body Weight Regulation.
    Jens Lund, Zachary Gerhart-Hines, Christoffer Clemmensen.
      Food intake and energy expenditure are the typical determinants of body weight. Yet, recent observations underscore that a third and often-neglected factor, fecal energy loss, can influence energy balance. Here, we explore how macronutrient excretion modulates human energy homeostasis and highlight its potential impact on the propensity to gain weight.
    Keywords:  Luxuskonsumption; constitutional thinness; fecal and urinary energy loss; obesity; overfeeding; spendthrift and thrifty phenotypes
    DOI:  https://doi.org/10.1016/j.tem.2020.06.002
  42. Nature. 2020 Jul 15.
    A single-cell transcriptomic atlas characterizes ageing tissues in the mouse.
    Tabula Muris Consortium
      Ageing is characterized by a progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death1. Despite rapid advances over recent years, many of the molecular and cellular processes that underlie the progressive loss of healthy physiology are poorly understood2. To gain a better insight into these processes, here we generate a single-cell transcriptomic atlas across the lifespan of Mus musculus that includes data from 23 tissues and organs. We found cell-specific changes occurring across multiple cell types and organs, as well as age-related changes in the cellular composition of different organs. Using single-cell transcriptomic data, we assessed cell-type-specific manifestations of different hallmarks of ageing-such as senescence3, genomic instability4 and changes in the immune system2. This transcriptomic atlas-which we denote Tabula Muris Senis, or 'Mouse Ageing Cell Atlas'-provides molecular information about how the most important hallmarks of ageing are reflected in a broad range of tissues and cell types.
    DOI:  https://doi.org/10.1038/s41586-020-2496-1
  43. Biomolecules. 2020 Jul 15. pii: E1055. [Epub ahead of print]10(7):
    Vitamin D Prevents Pancreatic Cancer-Induced Apoptosis Signaling of Inflammatory Cells.
    Stefania Moz, Nicole Contran, Monica Facco, Valentina Trimarco, Mario Plebani, Daniela Basso.
      Combined approaches based on immunotherapy and drugs supporting immune effector cell function might increase treatment options for pancreatic ductal adenocarcinoma (PDAC), vitamin D being a suitable drug candidate. In this study, we evaluated whether treatment with the vitamin D analogue, calcipotriol, counterbalances PDAC induced and SMAD4-associated intracellular calcium [Ca2+]i alterations, cytokines release, immune effector function, and the intracellular signaling of peripheral blood mononuclear cells (PBMCs). Calcipotriol counteracted the [Ca2+]i depletion of PBMCs induced by SMAD4-expressing PDAC cells, which conditioned media augmented the number of calcium flows while reducing whole [Ca2+]i. While calcipotriol inhibited spontaneous and PDAC-induced tumor necrosis factor alpha (TNF-α) release by PBMC and reduced intracellular transforming growth factor beta (TGF-β), it did not counteract the lymphocytes proliferation induced in allogenic co-culture by PDAC-conditioned PBMCs. Calcipotriol mainly antagonized PDAC-induced apoptosis and partially restored PDAC-inhibited NF-κB signaling pathway. In conclusion, alterations induced by PDAC cells in the [Ca2+]i of immune cells can be partially reverted by calcipotriol treatment, which promotes inflammation and antagonizes PBMCs apoptosis. These effects, together with the dampening of intracellular TGF-β, might result in an overall anti-tumor effect, thus supporting the administration of vitamin D in PDAC patients.
    Keywords:  PDAC; cytokines; immune system; intracellular calcium; intracellular signaling pathways; vitamin D
    DOI:  https://doi.org/10.3390/biom10071055
  44. EMBO Rep. 2020 Jul 12. e49807
    Hypothalamic CDK4 regulates thermogenesis by modulating sympathetic innervation of adipose tissues.
    Judit Castillo-Armengol, Valentin Barquissau, Sarah Geller, Honglei Ji, Ilenia Severi, Wiebe Venema, Eric Aria Fenandez, Catherine Moret, Katharina Huber, Lucia C Leal-Esteban, Anita Nasrallah, Laia Martinez-Carreres, Guy Niederhäuser, Patricia Seoane-Collazo, Sylviane Lagarrigue, Miguel López, Antonio Giordano, Sophie Croizier, Bernard Thorens, Isabel C Lopez-Mejia, Lluis Fajas.
      This study investigated the role of CDK4 in the oxidative metabolism of brown adipose tissue (BAT). BAT from Cdk4-/- mice exhibited fewer lipids and increased mitochondrial volume and expression of canonical thermogenic genes, rendering these mice more resistant to cold exposure. Interestingly, these effects were not BAT cell-autonomous but rather driven by increased sympathetic innervation. In particular, the ventromedial hypothalamus (VMH) is known to modulate BAT activation via the sympathetic nervous system. We thus examined the effects of VMH neuron-specific Cdk4 deletion. These mice display increased sympathetic innervation and enhanced cold tolerance, similar to Cdk4-/- mice, in addition to browning of scWAT. Overall, we provide evidence showing that CDK4 modulates thermogenesis by regulating sympathetic innervation of adipose tissue depots through hypothalamic nuclei, including the VMH. This demonstrates that CDK4 not only negatively regulates oxidative pathways, but also modulates the central regulation of metabolism through its action in the brain.
    Keywords:  CDK4; adrenergic innervation; brown adipose tissue; hypothalamus; mitochondria; thermogenesis
    DOI:  https://doi.org/10.15252/embr.201949807
  45. EMBO Mol Med. 2020 Jul 15. e11908
    Characterization of circulating breast cancer cells with tumorigenic and metastatic capacity.
    Claudia Koch, Andra Kuske, Simon A Joosse, Gökhan Yigit, George Sflomos, Sonja Thaler, Daniel J Smit, Stefan Werner, Kerstin Borgmann, Sebastian Gärtner, Parinaz Mossahebi Mohammadi, Laura Battista, Laure Cayrefourcq, Janine Altmüller, Gabriela Salinas-Riester, Kaamini Raithatha, Arne Zibat, Yvonne Goy, Leonie Ott, Kai Bartkowiak, Tuan Zea Tan, Qing Zhou, Michael R Speicher, Volkmar Müller, Tobias M Gorges, Manfred Jücker, Jean-Paul Thiery, Cathrin Brisken, Sabine Riethdorf, Catherine Alix-Panabières, Klaus Pantel.
      Functional studies giving insight into the biology of circulating tumor cells (CTCs) remain scarce due to the low frequency of CTCs and lack of appropriate models. Here, we describe the characterization of a novel CTC-derived breast cancer cell line, designated CTC-ITB-01, established from a patient with metastatic estrogen receptor-positive (ER+ ) breast cancer, resistant to endocrine therapy. CTC-ITB-01 remained ER+ in culture, and copy number alteration (CNA) profiling showed high concordance between CTC-ITB-01 and CTCs originally present in the patient with cancer at the time point of blood draw. RNA-sequencing data indicate that CTC-ITB-01 has a predominantly epithelial expression signature. Primary tumor and metastasis formation in an intraductal PDX mouse model mirrored the clinical progression of ER+ breast cancer. Downstream ER signaling was constitutively active in CTC-ITB-01 independent of ligand availability, and the CDK4/6 inhibitor Palbociclib strongly inhibited CTC-ITB-01 growth. Thus, we established a functional model that opens a new avenue to study CTC biology.
    Keywords:  breast cancer; circulating tumor cells; functional studies; liquid biopsy; metastasis
    DOI:  https://doi.org/10.15252/emmm.201911908
  46. Nat Cell Biol. 2020 Jul 13.
    Persistence of a regeneration-associated, transitional alveolar epithelial cell state in pulmonary fibrosis.
    Yoshihiko Kobayashi, Aleksandra Tata, Arvind Konkimalla, Hiroaki Katsura, Rebecca F Lee, Jianhong Ou, Nicholas E Banovich, Jonathan A Kropski, Purushothama Rao Tata.
      Stem cells undergo dynamic changes in response to injury to regenerate lost cells. However, the identity of transitional states and the mechanisms that drive their trajectories remain understudied. Using lung organoids, multiple in vivo repair models, single-cell transcriptomics and lineage tracing, we find that alveolar type-2 epithelial cells undergoing differentiation into type-1 cells acquire pre-alveolar type-1 transitional cell state (PATS) en route to terminal maturation. Transitional cells undergo extensive stretching during differentiation, making them vulnerable to DNA damage. Cells in the PATS show an enrichment of TP53, TGFβ, DNA-damage-response signalling and cellular senescence. Gain and loss of function as well as genomic binding assays revealed a direct transcriptional control of PATS by TP53 signalling. Notably, accumulation of PATS-like cells in human fibrotic lungs was observed, suggesting persistence of the transitional state in fibrosis. Our study thus implicates a transient state associated with senescence in normal epithelial tissue repair and its abnormal persistence in disease conditions.
    DOI:  https://doi.org/10.1038/s41556-020-0542-8
  47. Anal Chem. 2020 Jul 14.
    A Mitochondria-Immobilized Unimolecular Fluorescent Probe for Multiplexing Imaging of Living Cancer Cells.
    Nansong Zhu, Xiaolei Guo, Shirui Pang, Yulei Chang, Xiaomin Liu, Zhan Shi, Shouhua Feng.
      Cancer incidence and mortality are fast growing worldwide. Recently, multiplexing imaging methods have been reported to be vital for cancer diagnosis and therapy. Fluorescence imaging, which has intrinsic capabilities for multiplexing imaging, is suitable and ripe for cancer imaging. In biomedical research, using a single probe for multiplexing imaging can avoid larger invasive effects and ensure the same spatio-temporal distributions and metabolisms of the probes, which has advantages over using multiple probes. Therefore, developing unimolecular fluorescent probes for multiplexing imaging of living cancer cells is meaningful. We herein report a unimolecular fluorescent probe (ZED) that simultaneously detects cysteine/homocysteine, hypochlorous acid, mitochondrial membrane potential (Δψm) and opening of the mitochondrial permeability transition (MPT) pore in cells. These four analytes are key indicators predominantly associated with multiple aspects of carcinogenesis and cancer therapy in living cells. Besides, ZED also differentiates MCF-7 cells from HBL-100 cells. The sensing process is fast, selective and sensitive in living cancer cells. As far as we know, ZED is the first probe that simultaneously detects four analytes in cells and the first probe that simultaneously detects Δψm and opening of the MPT pore in mitochondria.
    DOI:  https://doi.org/10.1021/acs.analchem.0c01046
  48. Cancer Cell. 2020 Jul 13. pii: S1535-6108(20)30323-8. [Epub ahead of print]38(1): 3-8
    Clinical Trials in the Evolving Landscape of Precision Medicine.
      Landmark discoveries in cancer research improve clinical therapies. To bring these therapies to the right patients quickly and safely requires well-designed clinical trials. Harmony Turk of Cancer Cell and Sara Hamilton of Cell Reports Medicine spoke with Dr. Lillian Siu of Princess Margaret Cancer Center, Dr. Carl June of the University of Pennsylvania's Perelman School of Medicine, and Dr. Patrick Ott of Dana-Farber Cancer Institute on improving the design of oncology clinical trials in the evolving landscape of precision medicine. Excerpts from this conversation are presented below, and the full conversation is available with the article online. Editor's note: Some text was subsequently revised for clarity and conciseness.
    DOI:  https://doi.org/10.1016/j.ccell.2020.06.016
  49. Nature. 2020 Jul 14.
    Telomere-to-telomere assembly of a complete human X chromosome.
    Karen H Miga, Sergey Koren, Arang Rhie, Mitchell R Vollger, Ariel Gershman, Andrey Bzikadze, Shelise Brooks, Edmund Howe, David Porubsky, Glennis A Logsdon, Valerie A Schneider, Tamara Potapova, Jonathan Wood, William Chow, Joel Armstrong, Jeanne Fredrickson, Evgenia Pak, Kristof Tigyi, Milinn Kremitzki, Christopher Markovic, Valerie Maduro, Amalia Dutra, Gerard G Bouffard, Alexander M Chang, Nancy F Hansen, Amy B Wilfert, Françoise Thibaud-Nissen, Anthony D Schmitt, Jon-Matthew Belton, Siddarth Selvaraj, Megan Y Dennis, Daniela C Soto, Ruta Sahasrabudhe, Gulhan Kaya, Josh Quick, Nicholas J Loman, Nadine Holmes, Matthew Loose, Urvashi Surti, Rosa Ana Risques, Tina A Graves Lindsay, Robert Fulton, Ira Hall, Benedict Paten, Kerstin Howe, Winston Timp, Alice Young, James C Mullikin, Pavel A Pevzner, Jennifer L Gerton, Beth A Sullivan, Evan E Eichler, Adam M Phillippy.
      After two decades of improvements, the current human reference genome (GRCh38) is the most accurate and complete vertebrate genome ever produced. However, no one chromosome has been finished end to end, and hundreds of unresolved gaps persist1,2. Here we present a de novo human genome assembly that surpasses the continuity of GRCh382, along with the first gapless, telomere-to-telomere assembly of a human chromosome. This was enabled by high-coverage, ultra-long-read nanopore sequencing of the complete hydatidiform mole CHM13 genome, combined with complementary technologies for quality improvement and validation. Focusing our efforts on the human X chromosome3, we reconstructed the ~3.1 megabase centromeric satellite DNA array and closed all 29 remaining gaps in the current reference, including new sequence from the human pseudoautosomal regions and cancer-testis ampliconic gene families (CT-X and GAGE). These novel sequences will be integrated into future human reference genome releases. Additionally, a complete chromosome X, combined with the ultra-long nanopore data, allowed us to map methylation patterns across complex tandem repeats and satellite arrays for the first time. Our results demonstrate that finishing the entire human genome is now within reach and the data presented here will enable ongoing efforts to complete the remaining human chromosomes.
    DOI:  https://doi.org/10.1038/s41586-020-2547-7
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