CD95/Fas increases stemness in cancer cells by inducing a STAT1 dependent Type I interferon response
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE81860 | GEO | 2017/02/16
SECONDARY ACCESSION(S): PRJNA322761
REPOSITORIES: GEO
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Project description:Stimulation of CD95/Fas drives and maintains cancer stem cells (CSCs). We now report that this involves activation of signal transducer and activator of transcription 1 (STAT1) and induction of STAT1-regulated genes and that this process is inhibited by active caspases. STAT1 is enriched in CSCs in cancer cell lines, patient-derived human breast cancer, and CD95high-expressing glioblastoma neurospheres. CD95 stimulation of cancer cells induced secretion of type I interferons (IFNs) that bind to type I IFN receptors, resulting in activation of Janus-activated kinases, activation of STAT1, and induction of a number of STAT1-regulated genes that are part of a gene signature recently linked to therapy resistance in five primary human cancers. Consequently, we identified type I IFNs as drivers of cancer stemness. Knockdown or knockout of STAT1 resulted in a strongly reduced ability of CD95L or type I IFN to increase cancer stemness. This identifies STAT1 as a key regulator of the CSC-inducing activity of CD95.
| S-EPMC5474321 | biostudies-literature
Project description:CD95 was found to be important for both the formation of CSCs and their maintenance. Using a stable isotope labeling by amino acids in cell culture (SILAC) analysis we have now identified STAT1 as a critical gene that mediates the CSC-driving activity of CD95. We report that chronic stimulation of CD95 by either agonist antibodies, soluble CD95L or stably expressed membrane CD95L causes both serine and tyrosine phosphorylation of STAT1 and activation of STAT1 regulated genes. The genes most significantly induced were part of an interferon (IFN)-related DNA damage resistance signature (IRDS) recently identified in a radiation resistant squamous cell carcinoma cell line Nu61 when compared to parental SCC61 cells. The IRDS was found to strongly correlate with therapy resistance (chemotherapy and radiation) in multiple cancer cells as well as in 5 human primary cancers. We now report that CD95 stimulation of breast cancer cell lines or the SCC61 cells induces the upregulation of Type I IFNs that bind to both Type I receptors IFNAR1 and IFNR2 resulting in activation of JAK kinases, activation of STAT1 and induction of a number of STAT1-regulated genes. This process can be inhibited by active caspases. Consequently, we identified Type I IFNs as drivers of cancer stemness. Knockdown of STAT1 using either siRNAs or shRNAs, or deleting two independent sites in the STAT1 gene in MCF-7 cells using the CRIPSR/Cas9 gene editing system resulted in a loss of the ability of CD95 to increase stemness. This identifies STAT1 as a critical mediator of the CSCs-inducing activity of CD95.
2017-02-16 | GSE81853 | GEO
Project description:CD95 was found to be important for both the formation of CSCs and their maintenance. Using a stable isotope labeling by amino acids in cell culture (SILAC) analysis we have now identified STAT1 as a critical gene that mediates the CSC-driving activity of CD95. We report that chronic stimulation of CD95 by either agonist antibodies, soluble CD95L or stably expressed membrane CD95L causes both serine and tyrosine phosphorylation of STAT1 and activation of STAT1 regulated genes. The genes most significantly induced were part of an interferon (IFN)-related DNA damage resistance signature (IRDS) recently identified in a radiation resistant squamous cell carcinoma cell line Nu61 when compared to parental SCC61 cells. The IRDS was found to strongly correlate with therapy resistance (chemotherapy and radiation) in multiple cancer cells as well as in 5 human primary cancers. We now report that CD95 stimulation of breast cancer cell lines or the SCC61 cells induces the upregulation of Type I IFNs that bind to both Type I receptors IFNAR1 and IFNR2 resulting in activation of JAK kinases, activation of STAT1 and induction of a number of STAT1-regulated genes. This process can be inhibited by active caspases. Consequently, we identified Type I IFNs as drivers of cancer stemness. Knockdown of STAT1 using either siRNAs or shRNAs, or deleting two independent sites in the STAT1 gene in MCF-7 cells using the CRIPSR/Cas9 gene editing system resulted in a loss of the ability of CD95 to increase stemness. This identifies STAT1 as a critical mediator of the CSCs-inducing activity of CD95. androgen receptor (AR) activation independently of androgen. We have previously reported that AR can directly repress the expression of many target genes, one of which is NOV/CCN3. Here we show that NOV, primarily localized in the cytoplasm, physically interacts with AR at its Nterminus and sequesters AR and AR variants in the cytoplasm, thereby reducing AR chromatintargeting. This negative feedback loop, however, is disrupted in CRPC due to epigenetic silencing of NOV by the Polycomb group protein EZH2, rendering AR transcriptional activities and drug-resistant prostate cancer progression. Our findings thus suggest a working model wherein AR-repressed genes critically prevent CRPC through negative feedback loops inhibiting AR signaling.
2017-02-16 | GSE81859 | GEO
Project description:CD95/Fas increases stemness in cancer cells by inducing a STAT1 dependent Type I interferon response
| PRJNA322761 | ENA
Project description:CD95/Fas is an apoptosis inducing death receptor. However, it also has multiple nonapoptotic activities that are tumorigenic. Chronic stimulation of CD95 on breast cancer cells can increase their cancer initiating capacity through activation of a type I interferon (IFN-I)/STAT1 pathway when caspases are inhibited. We now show that this activity relies on the canonical components of the CD95 death-inducing signaling complex, FADD and caspase-8, and on the activation of NF-κB. We identified caspase-2 as the antagonistic caspase that downregulates IFN-I production. Once produced, IFN-Is bind to their receptors activating both STAT1 and STAT2 resulting in upregulation of the double stranded (ds)RNA sensor proteins RIG-I and MDA5, and a release of a subset of endogenous retroviruses. Thus, CD95 is part of a complex cell autonomous regulatory network that involves activation of innate immune components that drive cancer stemness and contribute to therapy resistance.
| S-EPMC6987111 | biostudies-literature
Project description:Alpha/beta interferons (IFNs-alpha/beta) are cytokines that play an essential role in the host defense against viral infection. Our previous studies have shown that the key IFN signaling molecule STAT1 is highly elevated and activated in central nervous system neurons during viral infection and in transgenic mice with astrocyte production of IFN-alpha (glial fibrillary acidic protein [GFAP]-IFN-alpha), suggesting that neurons are a very responsive target cell population for IFNs. To elucidate the genomic response of neurons to IFN-alpha, we undertook studies both in vitro and in vivo. Gene chip analysis was applied to RNA from IFN-alpha-treated or untreated primary cortical neuronal cultures derived from embryonic day 15 fetal wild-type or STAT1 knockout (KO) mice. The expression of 51 known and 5 unknown genes was increased significantly by more than twofold after exposure of wild-type but not STAT1 KO neurons to IFN-alpha. Some more highly expressed genes included IFN-induced 15-kDa protein, ubiquitin-specific protease 18, glucocorticoid attenuated response genes, IFN-induced GTPases, and the chemokine CXCL10. For several of these genes, the gene chip findings were confirmed by RNase protection assays. In addition, examination of the expression of some of these selected genes revealed that they were increased in neurons in the brain of either GFAP-IFN-alpha mice or mice infected with lymphocytic choriomeningitis virus. In conclusion, our study revealed a robust STAT1-dependent genomic response of neurons to IFN-alpha, highlighting an innate potential of these cells to defend against viral infection in the brain.
| S-EPMC1143744 | biostudies-literature
Project description:BackgroundIn humans, interferon-α treatment for chronic viral hepatitis is a well-recognized clinical model for inflammation-induced depression, but the molecular mechanisms underlying these effects are not clear. Following peripheral administration in rodents, interferon-α induces signal transducer and activator of transcription-1 (STAT1) within the hippocampus and disrupts hippocampal neurogenesis.MethodsWe used the human hippocampal progenitor cell line HPC0A07/03C to evaluate the effects of 2 concentrations of interferon-α, similar to those observed in human serum during its therapeutic use (500 pg/mL and 5000 pg/mL), on neurogenesis and apoptosis.ResultsBoth concentrations of interferon-α decreased hippocampal neurogenesis, with the high concentration also increasing apoptosis. Moreover, interferon-α increased the expression of interferon-stimulated gene 15 (ISG15), ubiquitin-specific peptidase 18 (USP18), and interleukin-6 (IL-6) via activation of STAT1. Like interferon-α, co-treatment with a combination of ISG15, USP18, and IL-6 was able to reduce neurogenesis and enhance apoptosis via further downstream activation of STAT1. Further experiments showed that ISG15 and USP18 mediated the interferon-α-induced reduction in neurogenesis (potentially through upregulation of the ISGylation-related proteins UBA7, UBE2L6, and HERC5), while IL-6 mediated the interferon-α-induced increase in apoptosis (potentially through downregulation of aquaporin 4). Using transcriptomic analyses, we showed that interferon-α regulated pathways involved in oxidative stress and immune response (e.g., Nuclear Factor (erythroid-derived 2)-like 2 [Nrf2] and interferon regulatory factor [IRF] signaling pathway), neuronal formation (e.g., CAMP response element-binding protein [CREB] signaling), and cell death regulation (e.g., tumor protein(p)53 signaling).ConclusionsWe identify novel molecular mechanisms mediating the effects of interferon-α on the human hippocampus potentially involved in inflammation-induced neuropsychiatric symptoms.
| S-EPMC5793815 | biostudies-literature
Project description:CD95/Fas ligand binds to the death receptor CD95 to induce apoptosis in sensitive cells. We previously reported that CD95L mRNA is enriched in sequences that, when converted to si/shRNAs, kill all cancer cells by targeting critical survival genes (Putzbach et al., 2017). We now report expression of full-length CD95L mRNA itself is highly toxic to cells and induces a similar form of cell death. We demonstrate that small (s)RNAs derived from CD95L are loaded into the RNA induced silencing complex (RISC) which is required for the toxicity and processing of CD95L mRNA into sRNAs is independent of both Dicer and Drosha. We provide evidence that in addition to the CD95L transgene a number of endogenous protein coding genes involved in regulating protein translation, particularly under low miRNA conditions, can be processed to sRNAs and loaded into the RISC suggesting a new level of cell fate regulation involving RNAi.
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Project description:African swine fever virus (ASFV) is an extensive and intricate double-stranded DNA virus with approximately 100% lethality in domestic swine. There is no effective vaccine to combat this virus, and this has led to substantial economic losses in the swine industry. ASFV encodes various proteins that impede interferon-based immune defenses in the host by employing diverse mechanisms. However, the roles of most of these proteins remain unknown. Therefore, understanding the immune evasion mechanisms employed by ASFV may facilitate the development of effective measures against the virus. In this study, we discovered a negative regulation of the type I interferon (IFN) response by the ASFV ribonuclease reductase large subunit pF778R. This novel type Ⅰ IFN response antagonist significantly inhibits IFN-α-induced interferon-stimulated response element promoter activation, precludes the upregulation of various interferon-stimulated genes, and prevents STAT1 nuclear translocation. Mechanistically, pF778R did not affect the protein levels of crucial molecules in the JAK/STAT signaling pathway or engage in direct interactions. However, pF778R expression impedes type I IFN responses mediated by the JAK/STAT signaling pathway. Further investigations revealed that pF778R did not interfere with STAT1 phosphorylation or dimerization, but it inhibited IFN signaling by weakening the nuclear accumulation of activated STAT1. The critical role of the ASFV protein pF778R in evading IFN-I-mediated innate immunity highlights a unique mode of ASFV evasion and provides insights into the pathogenic mechanism of the virus.
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Project description:Heterozygous mutations in the CD95 (APO-1/Fas) receptor occur in most individuals with autoimmune lymphoproliferative syndrome (ALPS) and dominantly interfere with apoptosis by an unknown mechanism. We show that local or global alterations in the structure of the cytoplasmic death domain from nine independent ALPS CD95 death-domain mutations result in a failure to bind the FADD/MORT1 signaling protein. Despite heterozygosity for the abnormal allele, lymphocytes from ALPS patients showed markedly decreased FADD association and a loss of caspase recruitment and activation after CD95 crosslinking. These data suggest that intracytoplasmic CD95 mutations in ALPS impair apoptosis chiefly by disrupting death-domain interactions with the signaling protein FADD/MORT1.
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