Project description:IMR90 ER:RAS cells were transfected with scramble siRNA or 2 deconvoluted siRNAs targeting each of 38 candidate genes or positive control siRNAs targeting the senescence regulators p16 and p53 and the SASP regulators NF-kappaB, p38alpha and CEBPbeta. The next day the cells were treated with 4OHT to induce senescence. 6 days later the cells were collected for total mRNA analysis. Our previous experiments had shown that these 38 genes regulate the secretome of senescent cells without affecting other senescence phenotypes such as the growth arrest. By performing RNA-seq we confirmed that knockdown of these genes affected the expression of multiple pro-inflammatory factors in senescence. More importantly, the secreted factors were differentially regulated across the different knockdown conditions indicating potential for specific manipulation of immune response genes.
Project description:Oncogene-induced senescence (OIS) and therapy-induced senescence (TIS), while tumor-suppressive, also promote procarcinogenic effects by activating the DNA damage response (DDR), which in turn induces inflammation. This inflammatory response prominently includes an array of cytokines known as the senescence-associated secretory phenotype (SASP). Previous observations link the transcription-associated methyltransferase and oncoprotein MLL1 to the DDR, leading us to investigate the role of MLL1 in SASP expression. Our findings reveal direct MLL1 epigenetic control over proproliferative cell cycle genes: MLL1 inhibition represses expression of proproliferative cell cycle regulators required for DNA replication and DDR activation, thus disabling SASP expression. Strikingly, however, these effects of MLL1 inhibition on SASP gene expression do not impair OIS and, furthermore, abolish the ability of the SASP to enhance cancer cell proliferation. More broadly, MLL1 inhibition also reduces âÂÂSASP-likeâ inflammatory gene expression from cancer cells in vitro and in vivo independently of senescence. Taken together, these data demonstrate that MLL1 inhibition may be a powerful and effective strategy for inducing cancerous growth arrest through the direct epigenetic regulation of proliferation-promoting genes and the avoidance of deleterious OIS- or TIS-related tumor secretomes, which can promote both drug resistance and tumor progression. This study consists of a single replicate of RNA-seq from oncogene-induced senescent (or control) IMR90 cells in a MLL1 knockdown (or WT) background, for a total of four samples
Project description:Senescent cells release a variety of cytokines, proteases and growth factors collectively defined as the Senescent Secretory Associated Phenotype (SASP). Sustained SASP induces a pattern of chronic inflammation associated with aging and implicated in multiple age-related diseases. Here, we investigated the expression and function of the immunomodulatory cytokine BAFF (B-cell activating factor), a SASP factor, in multiple senescence models. First, we characterized BAFF production across different senescence models, including senescent human diploid fibroblasts (WI-38, IMR-90) and monocytic leukemia cells (THP-1), and tissues of mice induced to undergo senescence. We identified IRF1 (interferon response factor 1) as a transcription factor required for promoting BAFF mRNA transcription in senescence, and found that suppressing BAFF production decreased the senescent phenotype in both monocytes and fibroblasts. Importantly, the influence of BAFF on the senescence program was cell type-specific: in monocytes, BAFF promoted the early activation of NF-κB and general SASP secretion, while in fibroblasts, BAFF contributed to the production and function of TP53 (p53). Overall, BAFF silencing affected shared senescence-associated phenotypes including IL6 secretion, SA-beta-Gal staining, and γ-H2AX accumulation. We propose that BAFF is a novel biomarker of senescence and a potential target for senotherapy.
Project description:Cellular senescence due to telomere dysfunction has been hypothesized to play a role in age-associated diseases including idiopathic pulmonary fibrosis (IPF). It has been postulated that paracrine mediators originating from senescent alveolar epithelia signal to surrounding mesenchymal cells and contribute to disease pathogenesis. However, murine models of telomere-induced alveolar epithelial senescence fail to display the canonical senescence-associated secretory phenotype (SASP) that is observed in senescent human cells. In an effort to understand human-specific responses to telomere dysfunction, we modelled telomere dysfunction-induced senescence in a human alveolar epithelial cell line. We hypothesized that this system would enable us to probe for differences in transcriptional and proteomic senescence pathways in vitro and to identify novel secreted protein (secretome) changes that potentially contribute to the pathogenesis of IPF. Following induction of telomere dysfunction, a robust senescence phenotype was observed. RNA-Seq analysis of the senescent cells revealed the SASP and comparisons to previous murine data highlighted species-specific responses to telomere dysfunction. We then conducted a proteomic analysis of the senescent cells using a novel biotin ligase capable of labeling secreted proteins. Candidate biomarkers selected from our transcriptional and secretome data were then evaluated in IPF and control patient plasma. Four novel proteins were found to be differentially expressed between the patient groups: stanniocalcin-1, contactin-1, tenascin C, and total inhibin. Our data show that human telomere-induced, alveolar epithelial senescence results in a transcriptional SASP that is distinct from that seen in analogous murine cells. Our findings suggest that studies in animal models should be carefully validated given the species-specific responses to telomere dysfunction. We also describe a pragmatic approach for the study of the consequences of telomere-induced alveolar epithelial cell senescence in humans.
Project description:Senescent cells no longer divide, but remain metabolically active and secrete an array of cytokines, growth factors, and proteases termed the senescence-associated secretory phenotype (SASP). Previous studies have indicated that the SASP factor IL-1α may be an upstream regular of the SASP. We show here that knockdown of the IL-1α receptor IL-1R results in a sizable reduction of SASP expression late in senescence induction. Our results suggest that targeting the IL-1 signaling pathway is a reliable method to dissociate the SASP from cell-cycle exit.
Project description:Senescence in WI-38 cell context was induce by RASv12 over expression Cellular senescence is a permanent cell cycle arrest that is triggered by cancer- initiating or promoting events in mammalian cells and is now considered a major tumour suppressor mechanism. Here, we did a transcriptomic analysis and compared WI-38 contol wich is a human fibroblaste cell line and WI-38 that overexpressed RASv12 a G protein that induce senescence. The goal of our project is to compare transciptomic profile of human growing fibroblast (WI-38 control) and senescent human fibroblast (WI-38 OERAS) Comparaison WI-38 vs WI-38 OE RAS
Project description:Acute Pten loss initiates prostate tumorigenesis characterized by cellular senescence response. Senescent cells secrete a variety of pro inflammatory factors in the tumor microenvironment, which can support the survival, outgrowth and migration of tumor cells. Here we examine cytokines and cytokines-related factors gene expression in Ptenpc-/- senescent and in Ptenpc-/-; Trp53pc-/- non senescent tumors. RNAseq analysis confirmed the presence of cytokines, which were specifically up- and down-regulated in Ptenpc-/- senescent tumors (“core-SASP”) we also found a number of upregulated secreted factors that were “senescence-unrelated” both present in both Ptenpc-/- and Ptenpc-/-; Trp53pc-/- tumors.