Project description:Senescent cells secrete a plethora of factors with potent paracrine signaling capacity. Strikingly, senescence, which acts as a defense against cell transformation, exerts pro-tumorigenic activities through its secretome by promoting numerous tumor-specific features, such as cellular proliferation, epithelial-mesenchymal transition and invasiveness. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has the unique activity of activating cell death exclusively in tumor cells. Given that the senescence-associated secretome supports cell transformation, we asked whether factor(s) of this secretome would establish a program required for the acquisition of TRAIL sensitivity. We found that conditioned media from several types of senescent cells (CMS) efficiently sensitized pre-transformed cells to TRAIL, while the same was not observed with normal or immortalized cells. Dynamic transcription profiling analysis of CMS-exposed pre-transformed cells revealed paracrine autoregulatory loop of senescence-associated secretome factors and a dominant role of CMS-induced MYC. Sensitization to TRAIL coincided with MYC upregulation and massive changes in gene regulation. CMS-induced MYC silenced its target gene CFLAR, encoding the apoptosis inhibitor FLIPL, thus leading to the acquisition of TRAIL sensitivity. Altogether, our results reveal that senescent cell-secreted factors exert a TRAIL sensitizing effect on pre-transformed cells by modulating the expression of MYC and CFLAR. Notably, CMS dose-dependent sensitization to TRAIL was observed with TRAIL-insensitive cancer cells and confirmed in co-culture experiments. Dissection and characterization of TRAIL-sensitizing CMS factors and the associated signaling pathway(s) may provide a mechanistic insight in the acquisition of TRAIL sensitivity and lead to novel concepts for the apoptogenic therapy of pre-malignant and TRAIL-resistant tumors. Pre-transformed BJEL cells were incubated with CMS for 0, 1, 3, 6, 8, 16 or 24 h respectively. Total RNA has been extracted from each time point and used for gene expression analysis (Affymetrix Human Gene 1.0 ST Arrays).
Project description:Senescent cells secrete a plethora of factors with potent paracrine signaling capacity. Strikingly, senescence, which acts as a defense against cell transformation, exerts pro-tumorigenic activities through its secretome by promoting numerous tumor-specific features, such as cellular proliferation, epithelial-mesenchymal transition and invasiveness. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has the unique activity of activating cell death exclusively in tumor cells. Given that the senescence-associated secretome supports cell transformation, we asked whether factor(s) of this secretome would establish a program required for the acquisition of TRAIL sensitivity. We found that conditioned media from several types of senescent cells (CMS) efficiently sensitized pre-transformed cells to TRAIL, while the same was not observed with normal or immortalized cells. Dynamic transcription profiling analysis of CMS-exposed pre-transformed cells revealed paracrine autoregulatory loop of senescence-associated secretome factors and a dominant role of CMS-induced MYC. Sensitization to TRAIL coincided with MYC upregulation and massive changes in gene regulation. CMS-induced MYC silenced its target gene CFLAR, encoding the apoptosis inhibitor FLIPL, thus leading to the acquisition of TRAIL sensitivity. Altogether, our results reveal that senescent cell-secreted factors exert a TRAIL sensitizing effect on pre-transformed cells by modulating the expression of MYC and CFLAR. Notably, CMS dose-dependent sensitization to TRAIL was observed with TRAIL-insensitive cancer cells and confirmed in co-culture experiments. Dissection and characterization of TRAIL-sensitizing CMS factors and the associated signaling pathway(s) may provide a mechanistic insight in the acquisition of TRAIL sensitivity and lead to novel concepts for the apoptogenic therapy of pre-malignant and TRAIL-resistant tumors.
Project description:Oncogenic levels of Myc expression sensitize cells to multiple apoptotic stimuli and this protects long-lived organisms from cancer development. How cells discriminate physiological from supra-physiological levels of Myc is largely unknown. Here we show that induction of apoptosis by Myc in breast epithelial cells requires association of Myc with Miz1. Gene expression and ChIP-sequencing experiments show that oncogenic levels of Myc, but not of MycV394D, a point mutant that does not bind Miz1, recruit Miz1 to core promoters and enable binding of Myc/Miz1 complexes to low-affinity target sites, correlating with repression of a specific set of target genes. Repressed genes encode proteins involved in cell adhesion, migration and wound healing; their promoters are enriched for binding sites of the serum response (SRF) factor. Restoring SRF activity attenuates Myc-induced apoptosis in response to glutamine starvation, exposure to Trail and to DNA damage. We propose that supra-physiological levels of Myc engage Miz1 in repressive DNA binding complexes and suppress transcriptional progress. MIZ1, MYC-ER and MYC-ERVD ChIP-Seq with 10E2 and HC20 anti-ERalpha antibodies in MCF10A cells, performed on an Illumina IIx Genome Analyzer. Input sample is accessioned as GSM1423726.
Project description:Oncogenic levels of Myc expression sensitize cells to multiple apoptotic stimuli and this protects long-lived organisms from cancer development. How cells discriminate physiological from supra-physiological levels of Myc is largely unknown. Here we show that induction of apoptosis by Myc in breast epithelial cells requires association of Myc with Miz1. Gene expression and ChIP-sequencing experiments show that oncogenic levels of Myc, but not of MycV394D, a point mutant that does not bind Miz1, recruit Miz1 to core promoters and enable binding of Myc/Miz1 complexes to low-affinity target sites, correlating with repression of a specific set of target genes. Repressed genes encode proteins involved in cell adhesion, migration and wound healing; their promoters are enriched for binding sites of the serum response (SRF) factor. Restoring SRF activity attenuates Myc-induced apoptosis in response to glutamine starvation, exposure to Trail and to DNA damage. We propose that supra-physiological levels of Myc engage Miz1 in repressive DNA binding complexes and suppress transcriptional progr 4 different experimental conditions were analyzed: MYC-ER 4-OHT treated versus MYC-ER ctr-treated (EtOH), MYC-ER V394D 4-OHT treated versus MYC-ER V394D ctr-treated; 3 biological replicates for every condition.
Project description:Oncogenic levels of Myc expression sensitize cells to multiple apoptotic stimuli and this protects long-lived organisms from cancer development. How cells discriminate physiological from supra-physiological levels of Myc is largely unknown. Here we show that induction of apoptosis by Myc in breast epithelial cells requires association of Myc with Miz1. Gene expression and ChIP-sequencing experiments show that oncogenic levels of Myc, but not of MycV394D, a point mutant that does not bind Miz1, recruit Miz1 to core promoters and enable binding of Myc/Miz1 complexes to low-affinity target sites, correlating with repression of a specific set of target genes. Repressed genes encode proteins involved in cell adhesion, migration and wound healing; their promoters are enriched for binding sites of the serum response (SRF) factor. Restoring SRF activity attenuates Myc-induced apoptosis in response to glutamine starvation, exposure to Trail and to DNA damage. We propose that supra-physiological levels of Myc engage Miz1 in repressive DNA binding complexes and suppress transcriptional progress.
Project description:Oncogenic levels of Myc expression sensitize cells to multiple apoptotic stimuli and this protects long-lived organisms from cancer development. How cells discriminate physiological from supra-physiological levels of Myc is largely unknown. Here we show that induction of apoptosis by Myc in breast epithelial cells requires association of Myc with Miz1. Gene expression and ChIP-sequencing experiments show that oncogenic levels of Myc, but not of MycV394D, a point mutant that does not bind Miz1, recruit Miz1 to core promoters and enable binding of Myc/Miz1 complexes to low-affinity target sites, correlating with repression of a specific set of target genes. Repressed genes encode proteins involved in cell adhesion, migration and wound healing; their promoters are enriched for binding sites of the serum response (SRF) factor. Restoring SRF activity attenuates Myc-induced apoptosis in response to glutamine starvation, exposure to Trail and to DNA damage. We propose that supra-physiological levels of Myc engage Miz1 in repressive DNA binding complexes and suppress transcriptional progr
Project description:Therapy-induced senescence (TIS) is a DNA damage-triggered irreversible cell-cycle block that terminates further expansion of (pre-)malignant lesions. Utilizing the Eµ-myc transgenic mouse lymphoma model (apoptosis protected by retroviral Bcl2-overexpression), we sought to elucidate the biological properties, long-term fate of senescent tumor cells and their impact on the microenvironment. We used global gene expression profiling by microarrays to gain insight into the molecular program underlying the treatment-induced senescence in Emu-myc transgenic B-cell lymphomas (apoptosis protected by Bcl2 overexpression), which robustly enter senescence in response to DNA-damaging anticancer agents such as Adriamycin (ADR).
Project description:Cellular senescence is a stress or damage response that causes a permanent proliferative arrest and secretion of numerous factors with potent biological activities. This senescence-associated secretory phenotype (SASP) has been characterized largely for secreted proteins that participate in embryogenesis, wound healing, inflammation and many age-related pathologies. By contrast, lipid components of the SASP are understudied. We show that senescent cells activate the biosynthesis of several oxylipins that promote segments of the SASP and reinforce the proliferative arrest. Notably, senescent cells synthesize and accumulate an unstudied intracellular prostaglandin, 1a,1b-dihomo-15-deoxy-delta-12,14-prostaglandin J2. Released 15-deoxy-delta-12,14-prostaglandin J2 is a biomarker of senolysis in culture and in vivo. This and other prostaglandin D2-related lipids promote the senescence arrest and SASP by activating RAS signaling. These data identify an important aspect of cellular senescence and a method to detect senolysis
Project description:Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease involving primarily the synovial membranes and articular structures of multiple joints. A hallmark of RA is the pseudo-tumoral expansion of fibroblast-like synoviocytes (FLS), as these cells invade and finally destroy the joint structure. RA FLS have been therefore proposed as a therapeutic target. > TNF-related apoptosis-inducing ligand (TRAIL) has been described as a pro-apoptotic factor on malignant cells. The fact that fibroblasts-like-synoviocytes (FLS) in rheumatoid arthritis RA patients exhibit tumor like features led us to investigate the effect of TRAIL on ex-vivo RA FLS. We have previously described that TRAIL induces apoptosis only in a subset of RA FLS, but an induction of proliferation in the surviving cells. This observation corresponds to the pleiotropic effects of TRAIL observed on primary human tumor cells. We also observed that sensitivity to TRAIL-induced apoptosis varied in RA FLS from one patient to another, and was correlated with disease severity. We therefore screened for genes that were differentially expressed in RA FLS sensitive and resistant to TRAIL induced apoptosis in order to understand molecular factors making cells resistant or sensitive to TRAIL induced apoptosis.