ABSTRACT: MYC favors the onset of tumorigenesis by inducing epigenetic reprogramming of mammary epithelial cells towards a stem cell-like state [ChIP-seq]
Project description:MYC favors the onset of tumorigenesis by inducing epigenetic reprogramming of mammary epithelial cells towards a stem cell-like state
Project description:MYC favors the onset of tumorigenesis by inducing epigenetic reprogramming of mammary epithelial cells towards a stem cell-like state [microarray]
Project description:Changing the somatic cell transcriptome to a pluripotent state using exogenous reprogramming factors needs transcriptional co-regulators that help activate or suppress gene expression and rewrite the epigenome. Here, we show that reprogramming-specific engagement of the NCoR/SMRT co-repressor complex at key pluripotency loci creates an epigenetic block to reprogramming. HDAC3 executes the repressive function of NCoR/SMRT in reprogramming by inducing histone deacetylation at these loci. Recruitment of NCoR/SMRT-HDAC3 to pluripotency genes is facilitated by all 4 Yamanaka factors (OCT4, SOX2, KLF4 and c-MYC) but mostly by c-MYC. Class IIa HDACs further potentiate this recruitment by interacting with both the reprogramming factors and NCoR/SMRT. Consequently, depleting NCoR/SMRT-HDAC3 function enables high efficiency of reprogramming, while elevating NCoR/SMRT-HDAC3 recruitment at pluripotency loci by over-expressing constitutively active class IIa HDACs derails it. Our findings thus uncover an unexpected epigenetic mechanism involving c-MYC, whose manipulation greatly enhances reprogramming efficiency.
Project description:Changing the somatic cell transcriptome to a pluripotent state using exogenous reprogramming factors needs transcriptional co-regulators that help activate or suppress gene expression and rewrite the epigenome. Here, we show that reprogramming-specific engagement of the NCoR/SMRT co-repressor complex at key pluripotency loci creates an epigenetic block to reprogramming. HDAC3 executes the repressive function of NCoR/SMRT in reprogramming by inducing histone deacetylation at these loci. Recruitment of NCoR/SMRT-HDAC3 to pluripotency genes is facilitated by all 4 Yamanaka factors (OCT4, SOX2, KLF4 and c-MYC) but mostly by c-MYC. Class IIa HDACs further potentiate this recruitment by interacting with both the reprogramming factors and NCoR/SMRT. Consequently, depleting NCoR/SMRT-HDAC3 function enables high efficiency of reprogramming, while elevating NCoR/SMRT-HDAC3 recruitment at pluripotency loci by over-expressing constitutively active class IIa HDACs derails it. Our findings thus uncover an unexpected epigenetic mechanism involving c-MYC, whose manipulation greatly enhances reprogramming efficiency.
Project description:Mouse embryonic stem cells can be maintained in a naive state of pluripotency by culture conditions containing inhibitors of Mek and Gsk3. Myc activity is essential for efficient cellular reprogramming. We genetically addressed the role of c-myc and N-myc in naive ESCs cultured in 2i by inducing the deletion of both genes using CRE-mediated recombination. Our findings show that myc activity controls the biosynthetic and proliferative machines of ESCs without significantly affecting the pluripotency network.
Project description:We address the molecular mechanisms through which MYC promotes loss of cell identity and acquisition of stem cell-like traits, favouring the onset of tumorigenesis, by performing epigenetic profile analyses in a transition from WT IMEC, IMEC over-expressing MYC and mammospeheres formed from IMEC-MYC (named M2).
Project description:Embryonic stem cells are maintained in a self-renewing and pluripotent state by multiple regulatory pathways. Pluripotent-specific transcriptional networks are sequentially reactivated as somatic cells reprogram to achieve pluripotency. How epigenetic regulators modulate this process and contribute to somatic cell reprogramming is not clear. Here we perform a functional RNAi screen to identify the earliest epigenetic regulators required for reprogramming. We identify components of the SAGA histone acetyltransferase complex, in particular Gcn5, as critical regulators of reprogramming initiation. Furthermore, we show in mouse pluripotent stem cells that Gcn5 strongly associates with Myc and that upon initiation of somatic reprogramming, Gcn5 and Myc form a positive feed forward loop that activates a distinct alternative splicing network and the early acquisition of pluripotency-associated splicing events. These studies expose a Myc-SAGA pathway that drives expression of an essential alternative splicing regulatory network during somatic cell reprogramming. Examination of Myc-chromatin interactions in reprogramming cells
Project description:Using transgenic mouse models of breast cancer, we demonstrate that loss of ShcA signaling within mammary tumors results in extensive CD4+ T cell infiltration, activation and induction of a humoral immune response. Our studies reveal that ShcA signaling during early breast cancer progression is required to establish and maintain an immunosuppressive state that favors tumor growth. Consistent with these transgenic studies, high ShcA levels correlate with poor outcome and reduced CTL infiltration in primary human breast cancers. Conversely, elevated expression of a ShcA-regulated immune signature, generated from ShcA-null mammary tumors, is a predictor of good prognosis in HER2-positive and basal breast cancer patients. These observations define a novel role for ShcA in polarizing the immune response to facilitate tumorigenesis NIC SHC null Tumors vs. pooled MMPV-NIC reference, some replicate dye swaps
Project description:Background. Oncogene overexpression in primary cells often triggers the induction of a cellular safeguard response promoting senescence or apoptosis. Secondary cooperating genetic events are generally required for oncogene induced tumorigenesis to overcome these biologic obstacles. We employed array CGH for 8 genetically-engineered mouse models of mammary cancer to identify loci that might harbor genes that enhance oncogene-induced tumorigenesis. Results. Unlike many other mammary tumor models, the MMTV-Myc tumors displayed few CNVs except for amplification of distal mouse chromosome 11 in 80% of the tumors (syntenic to human 17q23-qter often amplified in human breast cancer). Analyses of candidate genes located in this region identified JMJD6 as an epigenetic regulatory gene that cooperates with Myc to enhance tumorigenesis. It suppresses Myc-induced apoptosis under varying stress conditions through inhibition of p19ARF mRNA and protein, leading to reduced levels of p53. JMJD6 binds to the p19ARF promoter and exerts its inhibitory function through demethylation of H4R3me2a. JMJD6 overexpression in MMTV-Myc cell lines increases tumor burden, induces EMT and greatly enhances tumor metastasis. Importantly, we demonstrate that co-expression of high levels of JMJD6 and MYC is associated with poor prognosis for human ER+ breast cancer patients. Conclusions. A novel epigenetic mechanism has been identified for how JMJD6 cooperates with Myc during oncogenic transformation. Combined high expression of Myc and JMJD6 confers a more aggressive phenotype in mouse and human tumors. Given the pleotropic pro-tumorigenic activities of JMJD6, it may be useful as a prognostic factor and a therapeutic target for Myc-driven mammary tumorigenesis.
Project description:This SuperSeries is composed of the following subset Series: GSE32727: EMT inducers catalyze malignant transformation of mammary epithelial cells and drive tumorigenesis towards claudin-low tumors [human] GSE32904: EMT inducers catalyze malignant transformation of mammary epithelial cells and drive tumorigenesis towards claudin-low tumors [mouse] Refer to individual Series