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Level of macroautophagy drives senescent keratinocytes into cell death or neoplastic evasion.

ABSTRACT: Senescence is a non-proliferative state reached by normal cells in response to various stresses, including telomere uncapping, oxidative stress or oncogene activation. In previous reports, we have highlighted that senescent human epidermal keratinocytes have two opposite outcomes: either they die by autophagic programmed cell death or they evade in the form of neoplastic postsenescence emergent (PSNE) cells. Herein, we show that partially reducing macroautophagy in senescent keratinocytes using 3-methyl adenine or anti-Atg5 siRNAs increases the PSNE frequency, suggesting that senescent keratinocytes have to escape autophagic cell death to generate PSNE cells. However, totally inhibiting macroautophagy impairs PSNE and leads to a huge accumulation of oxidative damages, indicating that senescent keratinocytes need to achieve quality-control macroautophagy for PSNE to occur. In accordance, we demonstrate that the progenitors of PSNE cells display a level of macroautophagy slightly lower than that of the average senescent population, which is directly dictated by their level of reactive oxygen species, their level of upregulation of MnSOD, their level of activation of NF-κB transcription factors and their level of dysfunctional mitochondria. Macroautophagy thus has antagonistic roles during senescence, inducing cell death or promoting neoplastic transformation, depending on its level of activation. Taken together, these data suggest that levels of oxidative damages and ensuing macroautophagic activity could be two main determinants of the very initial phases of neoplastic transformation by senescence evasion.

SUBMITTER: Deruy E

PROVIDER: S-EPMC4649843 | biostudies-other | 2014 Dec

REPOSITORIES: biostudies-other

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Senescent keratinocytes die by autophagic programmed cell death.

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MnSOD upregulation induces autophagic programmed cell death in senescent keratinocytes.

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EHBP1L1 Drives Immune Evasion in Renal Cell Carcinoma through Binding and Stabilizing JAK1.

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Extracellular Galectin 4 Drives Immune Evasion and Promotes T-cell Apoptosis in Pancreatic Cancer.

Project description:Pancreatic ductal adenocarcinoma (PDAC) is characterized by rich deposits of extracellular matrix (ECM), affecting the pathophysiology of the disease. Here, we identified galectin 4 (gal 4) as a cancer cell-produced protein that was deposited into the ECM of PDAC tumors and detected high-circulating levels of gal 4 in patients with PDAC. In orthotopic transplantation experiments, we observed increased infiltration of T cells and prolonged survival in immunocompetent mice transplanted with cancer cells with reduced expression of gal 4. Increased survival was not observed in immunodeficient RAG1-/- mice, demonstrating that the effect was mediated by the adaptive immune system. By performing single-cell RNA-sequencing, we found that the myeloid compartment and cancer-associated fibroblast (CAF) subtypes were altered in the transplanted tumors. Reduced gal 4 expression associated with a higher proportion of myofibroblastic CAFs and reduced numbers of inflammatory CAFs. We also found higher proportions of M1 macrophages, T cells, and antigen-presenting dendritic cells in tumors with reduced gal 4 expression. Using a coculture system, we observed that extracellular gal 4 induced apoptosis in T cells by binding N-glycosylation residues on CD3ε/δ. Hence, we show that gal 4 is involved in immune evasion and identify gal 4 as a promising drug target for overcoming immunosuppression in PDAC.

| S-EPMC9808371 | biostudies-literature

Cylindromatosis drives synapse pruning and weakening by promoting macroautophagy through Akt-mTOR signaling.

Project description:The lysine-63 deubiquitinase cylindromatosis (CYLD) is long recognized as a tumor suppressor in immunity and inflammation, and its loss-of-function mutations lead to familial cylindromatosis. However, recent studies reveal that CYLD is enriched in mammalian brain postsynaptic densities, and a gain-of-function mutation causes frontotemporal dementia (FTD), suggesting critical roles at excitatory synapses. Here we report that CYLD drives synapse elimination and weakening by acting on the Akt-mTOR-autophagy axis. Mice lacking CYLD display abnormal sociability, anxiety- and depression-like behaviors, and cognitive inflexibility. These behavioral impairments are accompanied by excessive synapse numbers, increased postsynaptic efficacy, augmented synaptic summation, and impaired NMDA receptor-dependent hippocampal long-term depression (LTD). Exogenous expression of CYLD results in removal of established dendritic spines from mature neurons in a deubiquitinase activity-dependent manner. In search of underlying molecular mechanisms, we find that CYLD knockout mice display marked overactivation of Akt and mTOR and reduced autophagic flux, and conversely, CYLD overexpression potently suppresses Akt and mTOR activity and promotes autophagy. Consequently, abrogating the Akt-mTOR-autophagy signaling pathway abolishes CYLD-induced spine loss, whereas enhancing autophagy in vivo by the mTOR inhibitor rapamycin rescues the synaptic pruning and LTD deficits in mutant mice. Our findings establish CYLD, via Akt-mTOR signaling, as a synaptic autophagy activator that exerts critical modulations on synapse maintenance, function, and plasticity.

| S-EPMC9278694 | biostudies-literature

Silencing of circCRIM1 Drives IGF2BP1-Mediated NSCLC Immune Evasion.

Project description:ObjectivesCircular RNAs (circRNAs) have been found to have significant impacts on non-small cell lung cancer (NSCLC) progression through various mechanisms. However, the mechanism of circRNAs modulating tumor immune evasion in NSCLC has yet to be well-revealed.Materials and methodsThrough analyzing the expression profiles of circRNAs in NSCLC tissues, RNA FISH, pull-down assay, mass spectrometry analysis, and RIP, circCRIM1 was identified, and its interaction with IGF2BP1 was confirmed. The effects of circCRIM1 on modulating tumor immune evasion were explored via co-culture in vitro and in tumor xenograft models. Subsequently, we evaluated the regulatory effects of circCRIM1 on IGF2BP1 and screened its target genes through RNA sequencing. Finally, we explored the underlying molecular mechanisms that circCRIM1 could regulate the stability of target mRNA.ResultscircCRIM1 was downregulated in NSCLC, and its expression was positively correlated with favorable prognoses. Furthermore, circCRIM1 was more stable than its linear transcript and was mainly localized in the cytoplasm. Mechanistically, circCRIM1 destabilized HLA-F mRNA via competitive binding to IGF2BP1. Importantly, the overexpression of circCRIM1 suppressed the immune evasion of NSCLC and promoted the expressions of Granzyme B, IFN-γ, and TNF-α of CD8+ T and NK cell in vitro co-culture assays and tumor xenograft models.ConclusionsThis study identifies circCRIM1 as a new tumor suppressor that inhibits tumor immune evasion through a competitive combination with IGF2BP1 to destabilize HLA-F mRNA.

| S-EPMC9856323 | biostudies-literature

Beta-cell death and dysfunction drives hyperglycaemia in organ donors.

Project description:BackgroundDonor hyperglycaemia following brain death has been attributed to reversible insulin resistance. However, our islet and pancreas transplant data suggest that other mechanisms may be predominant. We aimed to determine the relationships between donor insulin use and markers of beta-cell death and beta-cell function in pancreas donors after brain death.MethodsIn pancreas donors after brain death, we compared clinical and biochemical data in 'insulin-treated' and 'not insulin-treated donors' (IT vs. not-IT). We measured plasma glucose, C-peptide and levels of circulating unmethylated insulin gene promoter cell-free DNA (INS-cfDNA) and microRNA-375 (miR-375), as measures of beta-cell death. Relationships between markers of beta-cell death and islet isolation outcomes and post-transplant function were also evaluated.ResultsOf 92 pancreas donors, 40 (43%) required insulin. Glycaemic control and beta-cell function were significantly poorer in IT donors versus not-IT donors [median (IQR) peak glucose: 8 (7-11) vs. 6 (6-8) mmol/L, p = .016; C-peptide: 3280 (3159-3386) vs. 3195 (2868-3386) pmol/L, p = .046]. IT donors had significantly higher levels of INS-cfDNA [35 (18-52) vs. 30 (8-51) copies/ml, p = .035] and miR-375 [1.050 (0.19-1.95) vs. 0.73 (0.32-1.10) copies/nl, p = .05]. Circulating donor miR-375 was highly predictive of recipient islet graft failure at 3 months [adjusted receiver operator curve (SE) = 0.813 (0.149)].ConclusionsIn pancreas donors, hyperglycaemia requiring IT is strongly associated with beta-cell death. This provides an explanation for the relationship of donor IT with post-transplant beta-cell dysfunction in transplant recipients.

| S-EPMC10947469 | biostudies-literature

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