bims-cagime Biomed News
on Cancer, aging and metabolism
Issue of 2021‒08‒29
forty-three papers selected by
Kıvanç Görgülü
Technical University of Munich

  1. J Cell Sci. 2021 Jan 15. pii: jcs247056. [Epub ahead of print]134(2):
      Autophagy is deregulated in many cancers and represents an attractive target for therapeutic intervention. However, the precise contributions of autophagy to metastatic progression, the principle cause of cancer-related mortality, is only now being uncovered. While autophagy promotes primary tumor growth, metabolic adaptation and resistance to therapy, recent studies have unexpectedly revealed that autophagy suppresses the proliferative outgrowth of disseminated tumor cells into overt and lethal macrometastases. These studies suggest autophagy plays unexpected and complex roles in the initiation and progression of metastases, which will undoubtedly impact therapeutic approaches for cancer treatment. Here, we discuss the intricacies of autophagy in metastatic progression, highlighting and integrating the pleiotropic roles of autophagy on diverse cell biological processes involved in metastasis.
    Keywords:  Autophagy; Cancer; Metastasis; Selective Autophagy
  2. J Cachexia Sarcopenia Muscle. 2021 Aug 23.
      BACKGROUND: Cancer cachexia (CCx) is a multifactorial wasting disorder characterized by involuntary loss of body weight that affects many cancer patients and implies a poor prognosis, reducing both tolerance to and efficiency of anticancer therapies. Actual challenges in management of CCx remain in the identification of tumour-derived and host-derived mediators involved in systemic inflammation and tissue wasting and in the discovery of biomarkers that would allow for an earlier and personalized care of cancer patients. The aim of this study was to identify new markers of CCx across different species and tumour entities.METHODS: Quantitative secretome analysis was performed to identify specific factors characteristic of cachexia-inducing cancer cell lines. To establish the subsequently identified phospholipase PLA2G7 as a marker of CCx, plasma PLA2G7 activity and/or protein levels were measured in well-established mouse models of CCx and in different cohorts of weight-stable and weight-losing cancer patients with different tumour entities. Genetic PLA2G7 knock-down in tumours and pharmacological treatment using the well-studied PLA2G7 inhibitor darapladib were performed to assess its implication in the pathogenesis of CCx in C26 tumour-bearing mice.
    RESULTS: High expression and secretion of PLA2G7 were hallmarks of cachexia-inducing cancer cell lines. Circulating PLA2G7 activity was increased in different mouse models of CCx with various tumour entities and was associated with the severity of body wasting. Circulating PLA2G7 levels gradually rose during cachexia development. Genetic PLA2G7 knock-down in C26 tumours only partially reduced plasma PLA2G7 levels, suggesting that the host is also an important contributor. Chronic treatment with darapladib was not sufficient to counteract inflammation and tissue wasting despite a strong inhibition of the circulating PLA2G7 activity. Importantly, PLA2G7 levels were also increased in colorectal and pancreatic cancer patients with CCx.
    CONCLUSIONS: Overall, our data show that despite no immediate pathogenic role, at least when targeted as a single entity, PLA2G7 is a consistent marker of CCx in both mice and humans. The early increase in circulating PLA2G7 levels in pre-cachectic mice supports future prospective studies to assess its potential as biomarker for cancer patients.
    Keywords:  Biomarker; Cancer cachexia; Cancer patients; Darapladib; Mouse models; PLA2G7
  3. Nat Commun. 2021 08 24. 12(1): 5103
      Hypercholesterolemia and dyslipidemia are associated with an increased risk for many cancer types and with poor outcomes in patients with established disease. Whereas the mechanisms by which this occurs are multifactorial we determine that chronic exposure of cells to 27-hydroxycholesterol (27HC), an abundant circulating cholesterol metabolite, selects for cells that exhibit increased cellular uptake and/or lipid biosynthesis. These cells exhibit substantially increased tumorigenic and metastatic capacity. Notably, the metabolic stress imposed upon cells by the accumulated lipids requires sustained expression of GPX4, a negative regulator of ferroptotic cell death. We show that resistance to ferroptosis is a feature of metastatic cells and further demonstrate that GPX4 knockdown attenuates the enhanced tumorigenic and metastatic activity of 27HC resistant cells. These findings highlight the general importance of ferroptosis in tumor growth and metastasis and suggest that dyslipidemia/hypercholesterolemia impacts cancer pathogenesis by selecting for cells that are resistant to ferroptotic cell death.
  4. Cancers (Basel). 2021 Aug 19. pii: 4173. [Epub ahead of print]13(16):
      Pancreatic ductal adenocarcinoma (PDAC), the most common malignancy of the pancreas, shows a dismal and grim overall prognosis and survival rate, which have remained virtually unchanged for over half a century. PDAC is the most lethal of all cancers, with the highest mortality-to-incidence ratio. PDAC responds poorly to current therapies and remains an incurable malignancy. Therefore, novel therapeutic targets and drugs are urgently needed for pancreatic cancer treatment. Selective induction of apoptosis in cancer cells is an appealing approach in cancer therapy. Apoptotic cell death is highly regulated by different signaling routes that involve a variety of subcellular organelles. Endoplasmic reticulum (ER) stress acts as a double-edged sword at the interface of cell survival and death. Pancreatic cells exhibit high hormone and enzyme secretory functions, and thereby show a highly developed ER. Thus, pancreatic cancer cells display a prominent ER. Solid tumors have to cope with adverse situations in which hypoxia, lack of certain nutrients, and the action of certain antitumor agents lead to a complex interplay and crosstalk between ER stress and autophagy-the latter acting as an adaptive survival response. ER stress also mediates cell death induced by a number of anticancer drugs and experimental conditions, highlighting the pivotal role of ER stress in modulating cell fate. The alkylphospholipid analog prototype edelfosine is selectively taken up by tumor cells, accumulates in the ER of a number of human solid tumor cells-including pancreatic cancer cells-and promotes apoptosis through a persistent ER-stress-mediated mechanism both in vitro and in vivo. Here, we discuss and propose that direct ER targeting may be a promising approach in the therapy of pancreatic cancer, opening up a new avenue for the treatment of this currently incurable and deadly cancer. Furthermore, because autophagy acts as a cytoprotective response to ER stress, potentiation of the triggering of a persistent ER response by combination therapy, together with the use of autophagy blockers, could improve the current gloomy expectations for finding a cure for this type of cancer.
    Keywords:  alkylphospholipid analog; cancer therapy; edelfosine; endoplasmic reticulum stress; endoplasmic reticulum targeting; pancreatic cancer
  5. Exp Cell Res. 2021 Aug 21. pii: S0014-4827(21)00332-3. [Epub ahead of print] 112779
      Skeletal muscle wasting drives negative clinical outcomes and is associated with a spectrum of pathologies including cancer. Cancer cachexia is a multi-factorial syndrome that encompasses skeletal muscle wasting and remains understudied, despite being a frequent and serious co-morbidity. Deviation from the homeostatic balance between breakdown and regeneration leads to muscle wasting disorders, such as cancer cachexia. Muscle stem cells (MuSCs) are the cellular compartment responsible for muscle regeneration, which makes MuSCs an intriguing target in the context of wasting muscle. Molecular studies investigating MuSCs and skeletal muscle wasting largely focus on transcriptional changes, but our group and others propose that metabolic changes are another layer of cellular regulation underlying MuSC dysfunction in CC. In the present study, we combined gene expression and non-targeted metabolomic profiling of myoblasts exposed to wasting conditions (cancer cell conditioned media) to derive a more complete picture of the myoblast response to wasting factors. After mapping these features to annotated pathways, we found that more than half of the mapped pathways were amino acid-related, linking global amino acid metabolic disruption to conditioned media-induced myoblast defects. Notably, arginine metabolism was a highly enriched pathway in combined metabolomic and transcriptomic data. Arginine catabolism generates nitric oxide (NO), an important signaling molecule known to have negative effects on mature muscle. We hypothesize that tumor-derived disruptions in Nitric Oxide Synthase (NOS)2-regulated arginine catabolism impair differentiation of MuSCs. The work presented here further investigates the effect of NOS2 overactivity on myoblast proliferation and differentiation. We show that NOS2 inhibition is sufficient to rescue wasting phenotypes associated with inflammatory cytokines. Ultimately, this work provides new insights into MuSC biology and opens up potential therapeutic avenues for addressing disrupted MuSC dynamics in cancer cachexia.
    Keywords:  IFNγ; NOS2; TNFα; cancer cachexia; myoblast; nitric oxide
  6. Clin Cancer Res. 2021 Aug 23. pii: clincanres.3925.2020. [Epub ahead of print]
      PURPOSE: Precision medicine approaches in pancreatic ductal adenocarcinoma (PDAC) are imperative for improving disease outcomes. With molecular subtypes of PDAC gaining relevance in the context of therapeutic stratification, the ability to characterize heterogeneity of cancer specific gene expression patterns is of great interest. Additionally, understanding patterns of immune evasion within PDAC is of importance as novel immunotherapeutic strategies are developed.EXPERIMENTAL DESIGN: Single-cell RNA sequencing (scRNA-seq) is readily applicable to limited biopsies from human primary and metastatic PDAC and identifies most cancers as being an admixture of previously described epithelial transcriptomic subtypes.
    RESULTS: Integrative analyses of our data provide an in-depth characterization of the heterogeneity within the tumor microenvironment, including cancer-associated fibroblast (CAF) subclasses, and predicts for a multitude of ligand-receptor interactions, revealing potential targets for immunotherapy approaches.
    CONCLUSIONS: Our analysis demonstrates that the use of de novo biopsies from PDAC patients paired with scRNA-seq may facilitate therapeutic prediction from limited biopsy samples.
  7. Cell. 2021 Aug 20. pii: S0092-8674(21)00943-0. [Epub ahead of print]
      Engineering new functionality into living eukaryotic systems by enzyme evolution or de novo protein design is a formidable challenge. Cells do not rely exclusively on DNA-based evolution to generate new functionality but often utilize membrane encapsulation or formation of membraneless organelles to separate distinct molecular processes that execute complex operations. Applying this principle and the concept of two-dimensional phase separation, we develop film-like synthetic organelles that support protein translation on the surfaces of various cellular membranes. These sub-resolution synthetic films provide a path to make functionally distinct enzymes within the same cell. We use these film-like organelles to equip eukaryotic cells with dual orthogonal expanded genetic codes that enable the specific reprogramming of distinct translational machineries with single-residue precision. The ability to spatially tune the output of translation within tens of nanometers is not only important for synthetic biology but has implications for understanding the function of membrane-associated protein condensation in cells.
    Keywords:  2D phase separation; enzyme engineering; genetic code expansion; membrane signaling; orthogonal translation; synthetic biology; synthetic biomolecular condensates
  8. Biomolecules. 2021 Jul 22. pii: 1082. [Epub ahead of print]11(8):
      Pancreatic cancer is the third leading cause of cancer-related deaths in the United States. Pancreatic ductal adenocarcinoma (PDA) is the most common (90%) and aggressive type of pancreatic cancer. Genomic analyses of PDA specimens have identified the recurrent genetic mutations that drive PDA initiation and progression. However, the underlying mechanisms that further drive PDA metastasis remain elusive. Despite many attempts, no recurrent genetic mutation driving PDA metastasis has been found, suggesting that PDA metastasis is driven by epigenetic fluctuations rather than genetic factors. Therefore, establishing epigenetic mechanisms of PDA metastasis would facilitate the development of successful therapeutic interventions. In this review, we provide a comprehensive overview on the role of epigenetic mechanisms in PDA as a critical contributor on PDA progression and metastasis. In particular, we explore the recent advancements elucidating the role of nucleosome remodeling, histone modification, and DNA methylation in the process of cancer metastasis.
    Keywords:  DNA methylation; epigenetics; metastasis; pancreatic cancer
  9. Sci Adv. 2021 Aug;pii: eabg7287. [Epub ahead of print]7(35):
      Changes in metabolism that affect mitochondrial and glycolytic networks are hallmarks of cancer, but their impact in disease is still elusive. Using global proteomics and ubiquitome screens, we now show that Parkin, an E3 ubiquitin ligase and key effector of mitophagy altered in Parkinson's disease, shuts off mitochondrial dynamics and inhibits the non-oxidative phase of the pentose phosphate pathway. This blocks tumor cell movements, creates metabolic and oxidative stress, and inhibits primary and metastatic tumor growth. Uniformly down-regulated in cancer patients, Parkin tumor suppression requires its E3 ligase function, is reversed by antioxidants, and is independent of mitophagy. These data demonstrate that cancer metabolic networks are potent oncogenes directly targeted by endogenous tumor suppression.
  10. J Cell Sci. 2021 Aug 27. pii: jcs.258824. [Epub ahead of print]
      Degradation of aggregates by selective autophagy is important as damaged proteins may impose a threat to cellular homeostasis. Although the core components of the autophagy machinery are well-characterized, the spatiotemporal regulation of many selective autophagy processes, including aggrephagy, remains largely unexplored. Furthermore, because most live-cell imaging studies have so far focused on starvation-induced autophagy, little is known about the dynamics of aggrephagy. Here, we describe the development and application of the mKeima-PIM assay, which enables live-cell observation of autophagic turnover and degradation of inducible protein aggregates in conjunction with key autophagy players. This allowed us to quantify the relative timing and duration of different steps of aggrephagy and revealed the short-lived nature of the autophagosome. The assay furthermore showed the spatial distribution of omegasome formation, highlighting that autophagy initiation is directly instructed by the cargo. Moreover, we found that nascent autophagosomes mostly remain immobile until acidification occurs. Thus, our assay provides new insights into the spatiotemporal regulation and dynamics of aggrephagy.
    Keywords:  Aggregates; Autophagy; Live-cell imaging
  11. Cancers (Basel). 2021 Aug 07. pii: 3990. [Epub ahead of print]13(16):
      Nearly half of cancer patients suffer from cachexia, a metabolic syndrome characterized by progressive atrophy of fat and lean body mass. This state of excess catabolism decreases quality of life, ability to tolerate treatment and eventual survival, yet no effective therapies exist. Although the central nervous system (CNS) orchestrates several manifestations of cachexia, the precise mechanisms of neural dysfunction during cachexia are still being unveiled. Herein, we summarize the cellular and molecular mechanisms of CNS dysfunction during cancer cachexia with a focus on inflammatory, autonomic and neuroendocrine processes and end with a discussion of recently identified CNS mediators of cachexia, including GDF15, LCN2 and INSL3.
    Keywords:  GDF15; INSL3; LCN2; autonomic nervous system; cachexia; cancer; cytokines; neuroendocrinology; neuroinflammation
  12. Cells. 2021 Jul 29. pii: 1928. [Epub ahead of print]10(8):
      Pancreatic stellate cells (PSCs) are important pancreatic fibrogenic cells that interact with pancreatic cancer cells to promote the progression of pancreatic ductal adenocarcinoma (PDAC). In the tumor microenvironment (TME), several factors such as cytokines and nucleotides contribute to this interplay. Our aim was to investigate whether there is an interaction between IL-6 and nucleotide signaling, in particular, that mediated by the ATP-sensing P2X7 receptor (P2X7R). Using human cell lines of PSCs and cancer cells, as well as primary PSCs from mice, we show that ATP is released from both PSCs and cancer cells in response to mechanical and metabolic cues that may occur in the TME, and thus activate the P2X7R. Functional studies using P2X7R agonists and inhibitors show that the receptor is involved in PSC proliferation, collagen secretion and IL-6 secretion and it promotes cancer cell migration in a human PSC-cancer cell co-culture. Moreover, conditioned media from P2X7R-stimulated PSCs activated the JAK/STAT3 signaling pathway in cancer cells. The monoclonal antibody inhibiting the IL-6 receptor, Tocilizumab, inhibited this signaling. In conclusion, we show an important mechanism between PSC-cancer cell interaction involving ATP and IL-6, activating P2X7 and IL-6 receptors, respectively, both potential therapeutic targets in PDAC.
    Keywords:  IL-6; P2X7R; PDAC; STAT3; Tocilizumab; eATP; fibrosis; pancreatic cancer; pancreatic stellate cells
  13. Int J Mol Sci. 2021 Aug 18. pii: 8873. [Epub ahead of print]22(16):
      The phenomenon of how oncogenes and tumor-suppressor mutations can synergize to promote tumor fitness and cancer progression can be studied in relatively simple animal model systems such as Drosophila melanogaster. Almost two decades after the landmark discovery of cooperative oncogenesis between oncogenic RasV12 and the loss of the tumor suppressor scribble in flies, this and other tumor models have provided new concepts and findings in cancer biology that has remarkable parallels and relevance to human cancer. Here we review findings using the RasV12; scrib-/- tumor model and how it has contributed to our understanding of how these initial simple genetic insults cooperate within the tumor cell to set in motion the malignant transformation program leading to tumor growth through cell growth, cell survival and proliferation, dismantling of cell-cell interactions, degradation of basement membrane and spreading to other organs. Recent findings have demonstrated that cooperativity goes beyond cell intrinsic mechanisms as the tumor interacts with the immediate cells of the microenvironment, the immune system and systemic organs to eventually facilitate malignant progression.
    Keywords:  cold-blooded cancer; cooperative oncogenesis; tumor/stroma interactions
  14. Metabolites. 2021 Aug 05. pii: 517. [Epub ahead of print]11(8):
      Skeletal muscle is a highly responsive tissue, able to remodel its size and metabolism in response to external demand. Muscle fibers can vary from fast glycolytic to slow oxidative, and their frequency in a specific muscle is tightly regulated by fiber maturation, innervation, or external causes. Atrophic conditions, including aging, amyotrophic lateral sclerosis, and cancer-induced cachexia, differ in the causative factors and molecular signaling leading to muscle wasting; nevertheless, all of these conditions are characterized by metabolic remodeling, which contributes to the pathological progression of muscle atrophy. Here, we discuss how changes in muscle metabolism can be used as a therapeutic target and review the evidence in support of nutritional interventions and/or physical exercise as tools for counteracting muscle wasting in atrophic conditions.
    Keywords:  diet; epigenetics; muscle wasting; physical exercise; skeletal muscle metabolism
  15. United European Gastroenterol J. 2021 Aug 25.
      BACKGROUND: Pancreatic ductal adenocarcinoma is the deadliest cancer worldwide with a 98% loss-of-life expectancy and a 30% increase in the disability-adjusted life years during the last decade in Europe. The disease cannot be effectively prevented nor being early detected. When diagnosed, 80% of patients have tumors that are in incurable stages, while for those who undergo surgery, 80% of patients will present with local or distant metastasis. Importantly, chemotherapies are far from being effective.OBJECTIVE: Pancreatic cancer represents a great challenge and, at the same time, a huge opportunity for advancing our understanding on the basis of the disease, the molecular profiles, that would lead to develop tools for early detection and effective treatments, thus, boosting patient survival.
    RESULTS: Research on pancreatic cancer has being receiving little or minimal funds from European funding bodies. UEG is calling for public-private partnerships that would effectively fund research on pancreatic cancer.
    CONCLUSION: This would increase our understanding of this disease and better treatment, through pan-European efforts that take advantage of the strong academic European research landscape on pancreatic cancer, and the contribution by the industry of all sizes.
    Keywords:  Horizon Europe; chronic pancreatitis; familial pancreatic cancer; funding; intraductal papillary mucinous neoplasm; pancreatic cancer; pancreatic ductal adenocarcinoma
  16. STAR Protoc. 2021 Sep 17. 2(3): 100730
      Isolation of autophagosomes, autolysosomes, and lysosomes allows mechanistic studies into the pathophysiology of autophagy-a lysosomal quality control pathway. Here, we outline a Nycodenz density gradient ultracentrifugation approach for high-yield isolation of autophagic fractions from mouse liver. These fractions can be used for immunoblotting, transmission electron microscopy, and proteomic and lipidomic analyses. For complete details on the use and execution of this protocol, please refer to Toledo et al. (2018).
    Keywords:  cell biology; cell separation/fractionation; metabolism
  17. Cell Rep. 2021 Aug 24. pii: S2211-1247(21)01012-3. [Epub ahead of print]36(8): 109578
      Tumor genotype can influence the immune microenvironment, which plays a critical role in cancer development and therapy resistance. However, the immune effects of gain-of-function Trp53 mutations have not been defined in pancreatic cancer. We compare the immune profiles generated by KrasG12D-mutated mouse pancreatic ductal epithelial cells (PDECs) engineered genetically to express the Trp53R172H mutation with their p53 wild-type control. KrasG12D/+;Trp53R172H/+ tumors have a distinct immune profile characterized by an influx of CD11b+Ly6G+ neutrophils and concomitant decreases in CD3+ T cells, CD8+ T cells, and CD4+ T helper 1 cells. Knockdown of CXCL2, a neutrophil chemokine, in the tumor epithelial compartment of CRISPR KrasG12D/+;Trp53R172H/+ PDEC tumors reverses the neutrophil phenotype. Neutrophil depletion of mice bearing CRISPR KrasG12D/+;Trp53R172H/+ tumors augments sensitivity to combined CD40 immunotherapy and chemotherapy. These data link Trp53R172H to the presence of intratumoral neutrophils in pancreatic cancer and suggest that tumor genotypes could inform selection of affected individuals for immunotherapy.
    Keywords:  immune microenvironment; mutant p53; neutrophils; pancreatic cancer
  18. J Natl Compr Canc Netw. 2021 Aug 27. pii: jnccn20577. [Epub ahead of print] 1-8
      BACKGROUND: Metastatic pancreatic ductal adenocarcinoma (PDAC) is characterized by a poor survival rate, which can be improved by systemic treatment. Consensus on the most optimal first- and second-line palliative systemic treatment is lacking. The aim of this study was to describe the use of first- and second-line systemic treatment, overall survival (OS), and time to failure (TTF) of first- and second-line treatment in metastatic PDAC in a real-world setting.PATIENTS AND METHODS: Patients with synchronous metastatic PDAC diagnosed between 2015 and 2018 who received systemic treatment were selected from the nationwide Netherlands Cancer Registry. OS and TTF were evaluated using Kaplan-Meier curves with log-rank test and multivariable Cox proportional hazard analyses.
    RESULTS: The majority of 1,586 included patients received FOLFIRINOX (65%), followed by gemcitabine (18%), and gemcitabine + nab-paclitaxel (13%) in the first line. Median OS for first-line FOLFIRINOX, gemcitabine + nab-paclitaxel, and gemcitabine monotherapy was 6.6, 4.7, and 2.9 months, respectively. Compared to FOLFIRINOX, gemcitabine + nab-paclitaxel showed significantly inferior OS after adjustment for confounders (hazard ratio [HR], 1.20; 95% CI, 1.02-1.41), and gemcitabine monotherapy was independently associated with a shorter OS and TTF (HR, 1.98; 95% CI, 1.71-2.30 and HR, 2.31; 95% CI, 1.88-2.83, respectively). Of the 121 patients who received second-line systemic treatment, 33% received gemcitabine + nab-paclitaxel, followed by gemcitabine (31%) and FOLFIRINOX (10%).
    CONCLUSIONS: Based on population-based data in patients with metastatic PDAC, treatment predominantly consists of FOLFIRINOX in the first line and gemcitabine with or without nab-paclitaxel in the second line. FOLFIRINOX in the first line shows superior OS compared with gemcitabine with or without nab-paclitaxel.
  19. Proc Natl Acad Sci U S A. 2021 Aug 31. pii: e2023909118. [Epub ahead of print]118(35):
      The trace element zinc is essential for many aspects of physiology. The mitochondrion is a major Zn2+ store, and excessive mitochondrial Zn2+ is linked to neurodegeneration. How mitochondria maintain their Zn2+ homeostasis is unknown. Here, we find that the SLC-30A9 transporter localizes on mitochondria and is required for export of Zn2+ from mitochondria in both Caenorhabditis elegans and human cells. Loss of slc-30a9 leads to elevated Zn2+ levels in mitochondria, a severely swollen mitochondrial matrix in many tissues, compromised mitochondrial metabolic function, reductive stress, and induction of the mitochondrial stress response. SLC-30A9 is also essential for organismal fertility and sperm activation in C. elegans, during which Zn2+ exits from mitochondria and acts as an activation signal. In slc-30a9-deficient neurons, misshapen mitochondria show reduced distribution in axons and dendrites, providing a potential mechanism for the Birk-Landau-Perez cerebrorenal syndrome where an SLC30A9 mutation was found.
    Keywords:  Birk–Landau–Perez cerebrorenal syndrome; SLC-30A9; Zn2+ transporters; mitochondria
  20. Cell Rep. 2021 Aug 24. pii: S2211-1247(21)01037-8. [Epub ahead of print]36(8): 109599
      Both tumors and aging alter the immune landscape of tissues. These interactions may play an important role in tumor progression among elderly patients and may suggest considerations for patient care. We leverage large-scale genomic and clinical databases to perform comprehensive comparative analysis of molecular and cellular markers of immune checkpoint blockade (ICB) response with patient age. These analyses demonstrate that aging is associated with increased tumor mutational burden, increased expression and decreased promoter methylation of immune checkpoint genes, and increased interferon gamma signaling in older patients in many cancer types studied, all of which are expected to promote ICB efficacy. Concurrently, we observe age-related alterations that might be expected to reduce ICB efficacy, such as decreases in T cell receptor diversity. Altogether, these changes suggest the capacity for robust ICB response in many older patients, which may warrant large-scale prospective study on ICB therapies among patients of advanced age.
    Keywords:  TCGA; aging; cancer; genomics; immune; immunotherapy
  21. Trials. 2021 Aug 26. 22(1): 568
      BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease, and multimodal strategies, such as surgery plus neoadjuvant chemotherapy (NAC)/adjuvant chemotherapy, have been attempted to improve survival in patients with localized PDAC. To date, there is one prospective study providing evidence for the superiority of a neoadjuvant strategy over upfront surgery for localized PDAC. However, which NAC regimen is optimal remains unclear.METHODS: A randomized, exploratory trial is performed to examine the clinical benefits of two chemotherapy regimens, gemcitabine plus S-1 (GS) and gemcitabine plus nab-paclitaxel (GA), as NAC for patients with planned PDAC resection. Patients are enrolled after the diagnosis of resectable or borderline resectable PDAC. They are randomly assigned to either NAC regimen. Adjuvant chemotherapy after curative resection is highly recommended for 6 months in both arms. The primary endpoint is tumor progression-free survival time, and secondary endpoints include the rate of curative resection, the completion rate of protocol therapy, the recurrence type, the overall survival time, and safety. The target sample size is set as at least 100.
    DISCUSSION: This study is the first randomized phase II study comparing GS combination therapy with GA combination therapy as NAC for localized pancreatic cancer.
    TRIAL REGISTRATION: UMIN Clinical Trials Registry UMIN000021484 . This trial began in April 2016.
    Keywords:  Gemcitabine plus S-1; Gemcitabine plus nab-paclitaxel; Neoadjuvant chemotherapy; Pancreatic cancer
  22. Cancers (Basel). 2021 Aug 23. pii: 4235. [Epub ahead of print]13(16):
      To date, extensive efforts to harness immunotherapeutic strategies for the treatment of pancreatic ductal adenocarcinoma (PDAC) have yielded disappointing results in clinical trials. These strategies mainly focused on cancer vaccines and immune checkpoint inhibitors alone or in combination with chemotherapeutic or targeted agents. However, the growing preclinical and clinical data sets from these efforts have established valuable insights into the immunological characteristics of PDAC biology. Most notable are the immunosuppressive role of the tumour microenvironment (TME) and PDAC's characteristically poor immunogenicity resulting from tumour intrinsic features. Moreover, PDAC tumour heterogeneity has been increasingly well characterized and may additionally limit a "one-fits-all" immunotherapeutic strategy. In this review, we first outline mechanisms of immunosuppression and immune evasion in PDAC. Secondly, we summarize recently published data on preclinical and clinical efforts to establish immunotherapeutic strategies for the treatment of PDAC including diverse combinatorial treatment approaches aiming at overcoming this resistance towards immunotherapeutic strategies. Particularly, these combinatorial treatment approaches seek to concomitantly increase PDAC antigenicity, boost PDAC directed T-cell responses, and impair the immunosuppressive character of the TME in order to allow immunotherapeutic agents to unleash their full potential. Eventually, the thorough understanding of the currently available data on immunotherapeutic treatment strategies of PDAC will enable researchers and clinicians to develop improved treatment regimens and to design innovative clinical trials to overcome the pronounced immunosuppression of PDAC.
    Keywords:  PDAC; cancer vaccine; checkpoint inhibition; immunosuppression; translational research; tumour microenvironment
  23. Cancers (Basel). 2021 Aug 20. pii: 4187. [Epub ahead of print]13(16):
      Tumor heterogeneity is a hallmark of many solid tumors, including pancreatic ductal adenocarcinoma (PDAC), and an inherent consequence of the clonal evolution of cancers. As such, it is considered the underlying concept of many characteristics of the disease, including the ability to metastasize, adapt to different microenvironments, and to develop therapy resistance. Undoubtedly, the high mortality of PDAC can be attributed to a high extent to these properties. Despite its apparent importance, studying tumor heterogeneity has been a challenging task, mainly due to its complexity and lack of appropriate methods. However, in recent years molecular DNA barcoding has emerged as a sophisticated tool that allows mapping of individual cells or subpopulations in a cell pool to study heterogeneity and thus devise new personalized treatment strategies. In this review, we provide an overview of genetic and non-genetic inter- and intra-tumor heterogeneity and its impact on (personalized) treatment strategies in PDAC and address how DNA barcoding technologies work and can be applied to study this clinically highly relevant question.
    Keywords:  PDAC; metastasis; molecular barcoding; therapy resistance; tumor heterogeneity
  24. Metabolites. 2021 Jul 27. pii: 481. [Epub ahead of print]11(8):
      Autophagy is an essential protective mechanism that allows mammalian cells to cope with a variety of stressors and contributes to maintaining cellular and tissue homeostasis. Due to these crucial roles and also to the fact that autophagy malfunction has been described in a wide range of pathologies, an increasing number of in vivo studies involving animal models targeting autophagy genes have been developed. In mammals, total autophagy inactivation is lethal, and constitutive knockout models lacking effectors of this route are not viable, which has hindered so far the analysis of the consequences of a systemic autophagy decline. Here, we take advantage of atg4b-/- mice, an autophagy-deficient model with only partial disruption of the process, to assess the effects of systemic reduction of autophagy on the metabolome. We describe for the first time the metabolic footprint of systemic autophagy decline, showing that impaired autophagy results in highly tissue-dependent alterations that are more accentuated in the skeletal muscle and plasma. These changes, which include changes in the levels of amino-acids, lipids, or nucleosides, sometimes resemble those that are frequently described in conditions like aging, obesity, or cardiac damage. We also discuss different hypotheses on how impaired autophagy may affect the metabolism of several tissues in mammals.
    Keywords:  ATG4; ATG8; GABARAP; LC3; aging; autophagin; autophagosome; autophagy; metabolome
  25. Physiol Rep. 2021 Aug;9(16): e15016
      This study aimed to examine the effects of voluntary wheel running on cancer cachexia-induced mitochondrial alterations in mouse skeletal muscle. Mice bearing colon 26 adenocarcinoma (C26) were used as a model of cancer cachexia. C26 mice showed a lower gastrocnemius and plantaris muscle weight, but 4 weeks of voluntary exercise rescued these changes. Further, voluntary exercise attenuated observed declines in the levels of oxidative phosphorylation proteins and activities of citrate synthase and cytochrome c oxidase in the skeletal muscle of C26 mice. Among mitochondrial morphology regulatory proteins, mitofusin 2 (Mfn2) and dynamin-related protein 1 (Drp1) were decreased in the skeletal muscle of C26 mice, but exercise resulted in similar improvements as seen in markers of mitochondrial content. In isolated mitochondria, 4-hydroxynonenal and protein carbonyls were elevated in C26 mice, but exercise blunted the increases in these markers of oxidative stress. In addition, electron microscopy revealed that exercise alleviated the observed increase in the percentage of damaged mitochondria in C26 mice. These results suggest that voluntary exercise effectively counteracts mitochondrial dysfunction to mitigate muscle loss in cachexia.
    Keywords:  cancer cachexia; mitochondria; oxidative stress; skeletal muscle; voluntary exercise
  26. FEBS J. 2021 Aug 26.
      Enzymes play essential roles in all life processes and are used extensively in the biomedical and biotechnological fields. However, enzyme-related information is spread across multiple resources making its retrieval time-consuming. In response to this challenge, the Enzyme Portal has been established to facilitate enzyme research, by providing a freely available hub where researchers can easily find and explore enzyme-related information. It integrates relevant enzyme data for a wide range of species from various resources such as UniProtKB, PDB and ChEMBL. Here, we describe what type of enzyme-related data the Enzyme Portal provides, how the information is organised and, by show-casing two potential use cases, how to access and retrieve it.
    Keywords:  EC number; database; enzyme; metabolite
  27. Hepatobiliary Surg Nutr. 2021 Aug;10(4): 530-533
  28. Gastroenterology. 2021 Aug 18. pii: S0016-5085(21)03402-8. [Epub ahead of print]
      BACKGROUND & AIM: Tumor-microenvironment (TME) factors and cancer stem cells (CSCs) play a critical role in the aggressiveness of pancreatic cancer (PC). However, the degree to which TME factors promote stemness remains unexplored. Here, we examined whether cancer-associated fibroblasts (CAFs) promote CSC features in PC.METHODS: PC cells were treated long-term (30, 60, and 90 days) with conditioned media (CM)-derived from normal human fibroblasts (NFs) and CAFs. The stemness features of tumorsphere formation and stemness populations, along with CSCs markers, were analyzed using 2D and 3D sodium alginate bead-based co-culture models. Immunohistochemistry and immunofluorescence staining were performed for CSCs and fibroblast markers in autochthonous KrasG12D/+; Trp53R172H/+; Pdx1-Cre (KPC) mice and human pancreatic tumors. PCR-array and gene knockdown were performed to identify the mechanism of stemness enrichment.
    RESULTS: Long-term treatment of PC cells with CAF-CM enriched stemness, as demonstrated by significantly higher CD44+, ALDH+, and AF+ populations in PC cells. Increased tumorsphere formation and elevated CSC, self-renewal, and drug-resistance markers in CAF-CM-treated PC cells were observed. In addition, CAF co-cultured with PC cells in the 3D model showed a substantial increase in stemness features. CD44 and α-SMA were positively correlated, and their expressions progressively increased from the early to late stages of KPC mice and human pancreatic tumors. OPN/SPP1 was identified as the top-differentially overexpressed gene in CAF-CM-treated PC cells, and knockdown of OPN/SPP1 significantly reduced stemness characteristics in CAF-CM-treated PC cells.
    CONCLUSIONS: Our data uncover novel insight into the interplay between CAF and enrichment of stemness population through SPP1-CD44 axis in PC.
    Keywords:  CD44; Cancer-associated Fibroblast; OPN/SPP1; Pancreatic Cancer; cancer stem cells
  29. FEBS J. 2021 Aug 26.
      ATP is the most universal and essential energy molecule in cells. This is due to its ability to store cellular energy in form of high energy phosphate bonds, which are extremely stable and readily usable by the cell. This energy is key for a variety of biological functions such as cell growth and division, metabolism, signaling, and for the turnover of biomolecules. Understanding how ATP is produced and hydrolyzed with a spatiotemporal resolution is necessary to understand its functions both in physiological and pathological contexts. In this review, we will first describe the organization of the electron transport chain and ATP synthase, the main molecular motor for ATP production in mitochondria. Second, we will review the biochemical assays currently available to estimate ATP quantities in cells, and we will compare their readouts, strengths and weaknesses. Finally, we will explore the palette of genetically-encoded biosensors designed for microscopy-based approaches, and show how their spatiotemporal resolution opened up the possibility to follow ATP levels in living cells.
    Keywords:  ATP; ATP synthase; biochemical assays; fluorescence-based tools; mitochondria
  30. Autophagy. 2021 Aug 26. 1-3
      Targeted protein degradation (TPD) provides unprecedented drug discovery strategies, but it is incapable of degrading non-protein pathogenic biomolecules. We have previously developed the concept of autophagosome-targeting compounds (ATTEC), which can target pathogenic proteins to autophagic degradation. Since macroautophagy (autophagy hereafter) is capable of degrading a wide spectrum of substrates including non-protein biomolecules, ATTEC should also be capable of targeting those non-protein biomolecules for autophagic degradation. Here in our most recent study, we have demonstrated this possibility using lipid droplets (LDs) as an exemplar target. LDs are intracellular structures storing neutral lipids, which can be degraded by autophagy. Based on the concept of ATTEC, compounds binding with both the LDs and the key phagophore and autophagosome protein LC3 may target LDs to autophagic degradation. We designed and synthesized such compounds by connecting the identified LC3-binding molecules to known LD-binding probes via a chemical linker. At micromolar concentrations, these compounds drastically reduced LDs via autophagy through the predicted mechanism, and rescued LD-related phenotypes in cells and in two independent mouse models with hepatic lipidosis. Our proof-of-concept study demonstrates the possibility of harnessing autophagy to degrade non-protein biomolecules by ATTEC.
    Keywords:  ATTEC; NASH; autophagy; degrader; lipid droplets; obesity
  31. Sci Rep. 2021 Aug 26. 11(1): 17220
      Primary cilia protrude from the apical surface of many cell types and act as a sensory organelle that regulates diverse biological processes ranging from chemo- and mechanosensation to signaling. Ciliary dysfunction is associated with a wide array of genetic disorders, known as ciliopathies. Polycystic lesions are commonly found in the kidney, liver, and pancreas of ciliopathy patients and mouse models. However, the pathogenesis of the pancreatic phenotype remains poorly understood. Chibby1 (Cby1), a small conserved coiled-coil protein, localizes to the ciliary base and plays a crucial role in ciliogenesis. Here, we report that Cby1-knockout (KO) mice develop severe exocrine pancreatic atrophy with dilated ducts during early postnatal development. A significant reduction in the number and length of cilia was observed in Cby1-KO pancreta. In the adult Cby1-KO pancreas, inflammatory cell infiltration and fibrosis were noticeable. Intriguingly, Cby1-KO acinar cells showed an accumulation of zymogen granules (ZGs) with altered polarity. Moreover, isolated acini from Cby1-KO pancreas exhibited defective ZG secretion in vitro. Collectively, our results suggest that, upon loss of Cby1, concomitant with ciliary defects, acinar cells accumulate ZGs due to defective exocytosis, leading to cell death and progressive exocrine pancreatic degeneration after birth.
  32. Biochem J. 2021 Aug 27. 478(16): 3125-3143
      Mitochondria import about 1000 proteins that are produced as precursors on cytosolic ribosomes. Defects in mitochondrial protein import result in the accumulation of non-imported precursor proteins and proteotoxic stress. The cell is equipped with different quality control mechanisms to monitor protein transport into mitochondria. First, molecular chaperones guide unfolded proteins to mitochondria and deliver non-imported proteins to proteasomal degradation. Second, quality control factors remove translocation stalled precursor proteins from protein translocases. Third, protein translocases monitor protein sorting to mitochondrial subcompartments. Fourth, AAA proteases of the mitochondrial subcompartments remove mislocalized or unassembled proteins. Finally, impaired efficiency of protein transport is an important sensor for mitochondrial dysfunction and causes the induction of cellular stress responses, which could eventually result in the removal of the defective mitochondria by mitophagy. In this review, we summarize our current understanding of quality control mechanisms that govern mitochondrial protein transport.
    Keywords:  TIM23 complex; TOM complex; mitochondria; protein sorting; protein transport
  33. Cells. 2021 Aug 13. pii: 2077. [Epub ahead of print]10(8):
      BACKGROUND: Cancers of the pancreas and biliary tree remain one of the most aggressive oncological malignancies, with most patients relying on systemic chemotherapy. However, effective biomarkers to predict the best therapy option for each patient are still lacking. In this context, an assay able to evaluate individual responses prior to treatment would be of great value for clinical decisions. Here we aimed to develop such a model using zebrafish xenografts to directly challenge pancreatic cancer cells to the available chemotherapies.METHODS: Zebrafish xenografts were generated from a Panc-1 cell line to optimize the pancreatic setting. Pancreatic surgical resected samples, without in vitro expansion, were used to establish zebrafish patient-derived xenografts (zAvatars). Upon chemotherapy exposure, zAvatars were analyzed by single-cell confocal microscopy.
    RESULTS: We show that Panc-1 zebrafish xenografts are able to reveal tumor responses to both FOLFIRINOX and gemcitabine plus nanoparticle albumin-bound (nab)-paclitaxel in just 4 days. Moreover, we established pancreatic and ampullary zAvatars with patient-derived tumors representative of different histological types.
    CONCLUSION: Altogether, we provide a short report showing the feasibility of generating and analyzing with single-cell resolution zAvatars from pancreatic and ampullary cancers, with potential use for future preclinical studies and personalized treatment.
    Keywords:  ampullary tumors; chemotherapy; pancreatic cancer; personalized medicine; zAvatars; zebrafish xenografts
  34. Cell Metab. 2021 Aug 17. pii: S1550-4131(21)00365-X. [Epub ahead of print]
      Adipocytes undergo intense energetic stress in obesity resulting in loss of mitochondrial mass and function. We have found that adipocytes respond to mitochondrial stress by rapidly and robustly releasing small extracellular vesicles (sEVs). These sEVs contain respiration-competent, but oxidatively damaged mitochondrial particles, which enter circulation and are taken up by cardiomyocytes, where they trigger a burst of ROS. The result is compensatory antioxidant signaling in the heart that protects cardiomyocytes from acute oxidative stress, consistent with a preconditioning paradigm. As such, a single injection of sEVs from energetically stressed adipocytes limits cardiac ischemia/reperfusion injury in mice. This study provides the first description of functional mitochondrial transfer between tissues and the first vertebrate example of "inter-organ mitohormesis." Thus, these seemingly toxic adipocyte sEVs may provide a physiological avenue of potent cardio-protection against the inevitable lipotoxic or ischemic stresses elicited by obesity.
    Keywords:  adipocyte; cardiovascular disease; diabetes; exosomes; extracellular vesicles; mitochondria; mitochondrial dysfunction; mitohormesis; obesity; stress response
  35. Pancreatology. 2021 Aug 18. pii: S1424-3903(21)00529-9. [Epub ahead of print]
      BACKGROUND: Glucose-regulated protein 78 (GRP78) plays an essential role in protein folding, transportation, and degradation, thus regulates ER homeostasis and promotes cell survival, proliferation and invasion. GRP78 expression in PDAC patients who received neoadjuvant therapy has not been reported.METHODS: This retrospective study of resected PDAC patients included 125 patients treated with neoadjuvant therapy (NAT) and 140 patients treated with surgery first (SF). The expression of GRP78 was evaluated by immunohistochemistry on tissue microarrays and the results were correlated with clinicopathologic parameters and survival.
    RESULTS: GRP78 expression was higher in SF patients compared to NAT patients (P < 0.001). In SF cohort, the median disease-free survival (DFS) and overall survival (OS) for patients with GRP78-positive tumors were 11.2 months and 25.0 months, respectively, compared to DFS of 52.1 months (P = 0.008) and OS of 69.5 months (P = 0.02) for those with GRP78-negative tumors. GRP78 expression correlated with higher frequency of recurrent/metastasis (P = 0.045). In NAT cohort, GRP78 expression correlated with shorter OS (P = 0.03), but not DFS (P = 0.08). GRP78 expression was an independent prognosticator for both DFS (P = 0.02) and OS (P = 0.049) in SF cohort and was an independent prognosticator for OS (P = 0.03), but not for DFS (P = 0.06) in NAT cohort by multivariate analysis.
    CONCLUSIONS: Our study showed that GRP78 expression in NAT cohort is lower than that in SF cohort. GRP78 expression correlated with shorter survival in both SF and NAT patients. Our findings suggest that targeting GRP78 may help to improve the prognosis in PDAC patients.
    Keywords:  GRP78; Neoadjuvant therapy; Pancreatic cancer; Survival; Tumor response grading
  36. Cancer Sci. 2021 Aug 22.
      Tumor growth and progression are complex processes mediated by mutual interactions between cancer cells and their surrounding stroma that includes diverse cell types and acellular components, which form the tumor microenvironment. In this environment, direct intercellular communications play important roles in the regulation of the biological behaviors of tumors. However, the underlying molecular mechanisms are insufficiently defined. We used an in vitro coculture system to identify genes that were specifically expressed at higher levels in cancer cells associated with stromal cells. Major examples included epithelial membrane protein 1 (EMP1) and stomatin, which positively and negatively regulate tumor progression, respectively. EMP1 promotes tumor cell migration and metastasis via activation of the small GTPase Rac1, while stomatin strongly suppresses cell proliferation and induces apoptosis of cancer cells via inhibition of Akt signaling. Here we highlight important aspects of EMP1, stomatin, and their family members in cancer biology. Furthermore, we consider the molecules that participate in intercellular communications and signaling transduction between cancer cells and stromal cells, which may affect the phenotypes of cancer cells in the tumor microenvironment.
    Keywords:  Intercellular communication; Signal transduction; Stroma; Tumor invasion; Tumor microenvironment
  37. Clin Cancer Res. 2021 Aug 25. pii: clincanres.1906.2021. [Epub ahead of print]
      BACKGROUND: The clinical behavior of ampullary adenocarcinoma varies widely. Targeted tumor sequencing may better define biologically distinct subtypes to improve diagnosis and management.METHODS: The hidden genome algorithm, a multilevel meta-feature regression model, was trained on a prospectively sequenced cohort of 3,411 patients (1,001 pancreatic adenocarcinoma, 165 distal bile duct adenocarcinoma, 2,245 colorectal adenocarcinoma) and subsequently applied to targeted panel DNA sequencing data from ampullary adenocarcinomas. Genomic classification (i.e., colorectal vs. pancreatic) was correlated with standard histological classification (i.e., intestinal [INT] vs. pancreatobiliary [PB]) and clinical outcome.
    RESULTS: Colorectal genomic subtype prediction was primarily influenced by mutations in APC and PIK3CA, tumor mutational burden, and DNA mismatch repair (MMR) deficiency signature. Pancreatic genomic subtype prediction was dictated by KRAS gene alterations, particularly KRAS G12D, KRAS G12R, and KRAS G12V. Distal bile duct adenocarcinoma genomic subtype was most influenced by copy number gains in the MDM2 gene. Despite high (73%) concordance between immunomorphologic subtype and genomic category, there was significant genomic heterogeneity within both histologic subtypes. Genomic scores with higher colorectal probability were associated with greater survival compared to those with a higher pancreatic probability.
    CONCLUSIONS: The genomic classifier provides insight into the heterogeneity of ampullary adenocarcinoma and improves stratification, which is dictated by the proportion of colorectal and pancreatic genomic alterations. This approach is reproducible with available molecular testing and obviates subjective histologic interpretation.
  38. J Comput Biol. 2021 Aug 23.
       Increasing genome-wide data in biological sciences and medicine has contributed to the development of a variety of visualization tools. Several automatic, semiautomatic, and manual visualization tools have already been developed. Some even have integrated flux balance analysis (FBA), but in most cases, it depends on separately installed third party software that is proprietary and does not allow customization of its functionality and has many restrictions for easy data distribution and analysis. In this study, we present an interactive metabolic flux analyzer and visualizer (IMFLer)-a static single-page web application that enables the reading and management of metabolic model layout maps, as well as immediate visualization of results from both FBA and flux variability analysis (FVA). IMFLer uses the Escher Builder tool to load, show, edit, and save metabolic pathway maps. This makes IMFLer an attractive and easily applicable tool with a user-friendly interface. Moreover, it allows to faster interpret results from FBA and FVA and improves data interoperability by using a standardized file format for the genome-scale metabolic model. IMFLer is a fully open-source tool that enables the rapid visualization and interpretation of the results of FBA and FVA with no time setup and no programming skills required, available at
    Keywords:  cellular metabolism; flux balance analysis; flux variability analysis; genome-scale metabolic models; network visualization
  39. J Cell Physiol. 2021 Aug 26.
      Evidence accumulated from past findings indicates that defective proteostasis may contribute to risk factors for cancer generation. Irregular assembly of abnormal proteins catalyzes the disturbance of cellular proteostasis and induces the ability of abnormal cellular proliferation. The autophagy mechanism plays a key role in the regular clearance of abnormal/poor lipids, proteins, and various cellular organelles. The results of functional and effective autophagy deliver normal cellular homeostasis, which establishes supportive metabolism and avoids unexpected tumorigenesis events. Still, the precise molecular mechanism of autophagy in tumor suppression has not been clear. How autophagy triggers selective or nonselective bulk degradation to dissipate tumor promotion under stress conditions is not clear. Under proteotoxic insults to knockdown the drive of tumorigenesis, it is critical for us to figure out the detailed molecular functions of autophagy in human cancers. The current article summarizes autophagy-based theragnostic strategies targeting various phases of tumorigenesis and suggests the preventive roles of autophagy against tumor progression. A better understanding of various molecular partners of autophagic flux will improve and innovate therapeutic approaches based on autophagic-susceptible effects against cellular oncogenic transformation.
    Keywords:  apoptosis; autophagy; cancer; diseases; tumor
  40. J Cell Biol. 2021 Nov 01. pii: e202104107. [Epub ahead of print]220(11):
      The intrinsic genetic program of a cell is not sufficient to explain all of the cell's activities. External mechanical stimuli are increasingly recognized as determinants of cell behavior. In the epithelial folding event that constitutes the beginning of gastrulation in Drosophila, the genetic program of the future mesoderm leads to the establishment of a contractile actomyosin network that triggers apical constriction of cells and thereby tissue folding. However, some cells do not constrict but instead stretch, even though they share the same genetic program as their constricting neighbors. We show here that tissue-wide interactions force these cells to expand even when an otherwise sufficient amount of apical, active actomyosin is present. Models based on contractile forces and linear stress-strain responses do not reproduce experimental observations, but simulations in which cells behave as ductile materials with nonlinear mechanical properties do. Our models show that this behavior is a general emergent property of actomyosin networks in a supracellular context, in accordance with our experimental observations of actin reorganization within stretching cells.
  41. Cancer Res. 2021 Aug 24.
      The paradigm of metastasis has been significantly remodeled by the incorporation of cancer dormancy as a mechanism to explain long-term remission intervals followed by relapse. There is overall consensus on the potential impact of better understanding dormancy. Key cancer-cell autonomous and microenvironmental mechanisms might explain this biology and, in turn, the timing of metastasis. However, the approach and feasibility to apply this biology to clinical trials has been controversial. The discussion here provides insight into how these controversies are being resolved by the development of active clinical trials, thus bringing to reality opportunities to target cancer dormancy.
  42. Nat Med. 2021 Aug 23.
      Mitochondrial DNA (mtDNA) variants influence the risk of late-onset human diseases, but the reasons for this are poorly understood. Undertaking a hypothesis-free analysis of 5,689 blood-derived biomarkers with mtDNA variants in 16,220 healthy donors, here we show that variants defining mtDNA haplogroups Uk and H4 modulate the level of circulating N-formylmethionine (fMet), which initiates mitochondrial protein translation. In human cytoplasmic hybrid (cybrid) lines, fMet modulated both mitochondrial and cytosolic proteins on multiple levels, through transcription, post-translational modification and proteolysis by an N-degron pathway, abolishing known differences between mtDNA haplogroups. In a further 11,966 individuals, fMet levels contributed to all-cause mortality and the disease risk of several common cardiovascular disorders. Together, these findings indicate that fMet plays a key role in common age-related disease through pleiotropic effects on cell proteostasis.
  43. Curr Opin Cell Biol. 2021 Aug 23. pii: S0955-0674(21)00091-0. [Epub ahead of print]72 131-136
      Cell migration is an essential process that controls many physiological functions ranging from development to immunity. In vivo, cells are guided by a combination of physical and chemical cues. Chemokines have been the center of attention for years, but the role of physical properties of tissues has been under-investigated, despite the fact that these properties can be drastically modified in pathology. Here, we discuss the role of one important tissue physical property, hydraulic resistance, in cell guidance, a phenomenon referred to as barotaxis, and describe the underlying physical principles and molecular mechanisms. Finally, we speculate on the putative role of barotaxis in physiological processes involving immune and cancer cells.