Chromatin enrichment of TRIM24, estrogen receptor and H3K4me2 in estrogen-treated and -untreated MCF7 cells
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ABSTRACT: TRIM24 PHD-Bromo domains exhibit preferential binding to unmethylated H3K4 and acetylated H3K27. TRIM24 is a co-activator of estrogen receptor (ER). The results suggest that specific ER-binding sites are depleted of H3K4me2 with estrogen treatment. TRIM24 binds these sites preferentially and facilitates ER-regulated gene expression, cell survival and proliferation.
Project description:TRIM24 PHD-Bromo domains exhibit preferential binding to unmethylated H3K4 and acetylated H3K27. TRIM24 is a co-activator of estrogen receptor (ER). The results suggest that specific ER-binding sites are depleted of H3K4me2 with estrogen treatment. TRIM24 binds these sites preferentially and facilitates ER-regulated gene expression, cell survival and proliferation. ChIP performed on MCF7 cells +/- estrogen with antibodies against ER, TRIM24 and H3K4me2. ChIP assays of ER, co-activator TRIM24 and H3K4me2 were performed with two concentrations of antibody, without and 6h with estrogen treatment of MCF7 cells. Antibody-enriched samples were sequenced two times, and compared to an IgG negative control and Input. Enriched DNA sequenced by Illumina Solexa.
Project description:The role of histone lysine methylation in estrogen receptor-alpha (ERα)-activated transcription is highly context-specific and poorly understood. Here, we show that lysine demethylase 1 (LSD1) mediates loss of H3 lysine 4 dimethylation (H3K4me2) in coordination with tripartite-motif-containing protein 24 (TRIM24)- regulated growth of breaset cancer-derived cells. We performed global profiling of histone H3K4me2 in comparison to genome-wide binding of TRIM24 in MCF7 cells when estrogen is depleted or added. We found specific subsets of genes with functions in transcription and cell proliferation are depleted of H3K4me2 at TRIM24 binding sites. Chromatin immunoprecipitation (ChIP) analyses over a time course of estrogen induction revealed cyclic demethylation of H3K4me2, LSD1, TRIM24 and ERα binding. Inhibition of LSD1 enzymatic activity led to increased H3K4me2 and decreased estrogen response of TRIM24-dependent genes. Additon of a small molecule inhibitor of the TRIM24 bromodomain or depletion of TRIM24 expression amplified the impact of LSD1 inhbition as measured by survival and proliferation of MCF7 cells, suggesting that combinatorial inhibition of LSD1 and TRIM24 may be effective in targeting ER-positive breast cancers.
Project description:Global profiling of tumor expression revealed increased RING-PHD-Bromodomain protein TRIM24 levels in numerous human cancers. Conditional over-expression of Trim24 was sufficient to drive murine mammary tumor development, 70% of which were ER, PR and HER2-negative carcinosarcomas with coexisting malignant epithelial and mesenchymal compartments, offering a unique model of human triple-negative, metaplastic breast cancer (MpBC). Both in vivo and in cellulo, TRIM24 induced EMT, repressing CDH1 and activating EMT factors. Whole exome sequencing of human MpBC tumors and Trim24-driven carcinosarcomas defined a TRIM24-like subclass of MpBC patients with worse overall and relapse-free survival. Among 40 MpBC patients, 43% had robust expression of TRIM24. These studies implicate TRIM24 as a potential biomarker and therapeutic target for a subset of MpBC.
Project description:The genomic binding sites of the transcription factor (TF) and tumour suppressor p53 are unusually diverse in regards to their chromatin features, including histone modifications, opening the possibility that chromatin provides context-dependence for p53 regulation. Here, we show that the ability of p53 to open chromatin and activate its target genes is indeed locally restricted by its cofactor Trim24. Trim24 binds to both p53 and unmethylated lysine 4 of histone H3, thereby preferentially locating to those p53 sites that reside in closed chromatin, while it is deterred from accessible chromatin by lysine 4 methylation. The presence of Trim24 increases cell viability upon stress and enables p53 to impact gene expression as a function of the local chromatin state. These findings link histone methylation to p53 function and illustrate how specificity in chromatin can be achieved, not by TF-intrinsic sensitivity to histone modifications, but by employing chromatin-sensitive cofactors which locally modulate TF function.
Project description:Conditional overexpression of histone reader Tripartite motif containing protein 24 (TRIM24) in mouse mammary epithelia (Trim24COE) drives spontaneous development of carcinosarcoma tumors, lacking ER, PR and HER2. Human carcinosarcomas or metaplastic breast cancers (MpBC) are a rare, chemorefractory subclass of triple-negative breast cancers (TNBC). Comparison of Trim24COE carcinosarcoma morphology, TRIM24 protein levels and a derived Trim24COE gene signature revealed strong correlation with human MpBC tumors and MpBC xenograft (PDX) models. Global and single-cell tumor profiling revealed Met as a direct oncogenic target of TRIM24, leading to aberrant PI3K/mTOR activation. Pharmacological inhibition of these pathways in primary Trim24COE tumor cells and TRIM24-PROTAC treatment of MpBC PDX tumorspheres revealed the therapeutic potential of targeting TRIM24. Altogether, global expression, single-cell immunophenotyping and mechanistic studies of tumors and MpBC PDX nominated TRIM24-activated c-MET/PI3K/mTOR pathways and TRIM24, which were validated as potential MpBC therapeutic targets.
Project description:Identification of Estrogen Receptor alpha (ERa) binding sites by ChIP-seq in MCF-7 breast cancer cells following an estrogen treatment. This study describes molecular effects of estradiol treatment and subsequent regulation by ER for a single gene/locus. A public ER chipseq (available in SRA as ERR011973), in addition to our own data, guided us to regulatory regions were ER was binding that were then analyzed in detail using "manual" ChIP.
Project description:Estrogen Receptor ? (ER?) has central role in hormone-dependent breast cancer and its ligand-induced functions have been extensively characterized. However, evidence exists that ER? has functions which are independent of ligands. In the present work, we investigated the binding of ER? to chromatin in absence of ligands, and its function(s) on gene regulation. We demonstrated that in MCF7 breast cancer cells unliganded ER? binds to more than four thousands chromatin sites. Unexpectedly, although almost entirely comprised in the larger group of estrogen-induced binding sites, we found that unliganded-ER? binding is specifically linked to genes with developmental functions, as compared to estrogen-induced binding. Moreover, we found that siRNA-mediated downregulation of ER? in absence of estrogen is accompanied by changes in the expression levels of hundreds of coding and noncoding RNAs. Downregulated mRNAs showed enrichment in genes related to epithelial cell growth and development. Stable ER? downregulation using shRNA, which caused cell-growth arrest, was accompanied by increased H3K27me3 at ER? binding sites. Finally, we found that FOXA1 and AP2? binding to several sites is decreased upon ER? silencing, suggesting that unliganded ER? participates, together with other factors, to the maintenance of the luminal-specific cistrome in breast cancer cells. Examination of unligandend estrogen receptor alpha (apoER?) DNA interactions in control and ER? siRNA treated MCF7 cells.
Project description:Identification of Estrogen Receptor alpha (ERa) binding sites by ChIP-seq in MCF-7 breast cancer cells following an estrogen treatment. This study describes molecular effects of estradiol treatment and subsequent regulation by ER for a single gene/locus. A public ER chipseq (available in SRA as ERR011973), in addition to our own data, guided us to regulatory regions were ER was binding that were then analyzed in detail using "manual" ChIP. MCF-7 cells were treated for 1 h either 10 nm estradiol (E2) or vehicle (ethanol) and subjected to ChIP using antibodies against ERa or IgG.
Project description:Transcriptomic changes and estrogen and progesterone receptor binding in multiple ER+/PR+ models (eight ER+/PR+ patient tumors, various T47Ds, ZR75) and multiple ER+/PR-negative models (four ER+/PR- patient tuumors, PR-deficient T47D and MCF7 cells) treated with various hormone combinations. Results: In isolation, estrogen and progestin act as genomic agonists by regulating the expression of common target genes in similar directions, but at different levels. Similarly, in isolation, progestin is also a weak phenotypic agonist of estrogen action. However, in the presence of both hormones, progestin behaves as a phenotypic estrogen antagonist. PR remodels nucleosomes to noncompetitively redirect ER genomic binding to distal enhancers enriched for BRCA1 binding motifs and sites that link PR and ER/PR complexes. Importantly, when both hormones are present, progestin modulates estrogen action such that responsive transcriptomes, cellular processes and ER/PR recruitment to genomic sites correlate with those observed with PR alone, but not ER alone. Conclusions: Genomic Agonism and Phenotypic Antagonism between Estrogen and Progesterone Receptors in Breast Cancer. Individual and concerted actions of ER and PR highlight the prognostic and therapeutic value of PR in ER+/PR+ breast cancers.