Project description:High-grade serous ovarian cancer (HGSOC) is an aggressive disease with few available targeted therapies. Despite high expression of estrogen receptor-alpha (ER) in ~80% of HGSOC and some small but promising clinical trials of endocrine therapy, ER has been understudied as a target in this disease. Results: Proliferation is ER-regulated in HGSOC cells in vitro and in vivo, and is in part dependent on 3-D context. Transcriptomic studies identified genes shared by cell lines and PDX explants as ER targets. The selective ER down-regulator (SERD) fulvestrant is more effective than tamoxifen in blocking ER action. ER H-score was predictive of efficacy of endocrine therapy, and this prediction could be further improved by inclusion of target gene expression, especially that of IGFBP3. Conclusion: Laboratory models corroborate intertumor heterogeneity of endocrine response in HGSOC but identify features associated with functional ER and endocrine responsiveness. Assessing ER function (e.g. IGFBP3 expression) in conjunction with ERH-score may help select patients who would benefit from endocrine therapy. Our preclinical data suggest that SERDs might be more effective than tamoxifen.
Project description:Orphan nuclear receptor estrogen-related receptor alpha (ERRα) has recently been shown to carry negative prognostic significance in breast and ovarian cancers. The specific role of ERRα in tumor growth and progression, however, is yet to be fully understood. The significant homology between estrogen receptor alpha (ERα) and ERRα initially suggested that these receptors may share similar transcriptional targets. Using the well-characterized ERα-positive MCF-7 breast cancer cell line, we sought to gain a genome-wide picture of ERα-ERRα cross-talk using an unbiased microarray approach. Since a small molecule ligand has not been identified for ERRα, its transcriptional activity in these studies was induced using its known coactivator PGC-1α (peroxisome proliferator-activated receptor-γ coactivator-1α) as a protein ligand. Both wild-type PGC1, as well as ERRa-specific variant (PGC1 2x9) were used to activate ERRa. Non-NR-dependent activities of PGC-1α were controlled for using a variant PGC-1α in which the leucines within the NR-interacting domain had been mutated to alanines (L2L3M). Beta-galactosidase (BGAL) overexpression was used as a non-specific background control. Activation of endogenous ER was achieved by treatment with 10 nM estadiol. Keywords: Response to stimulus
Project description:Retinoic acid receptor-alpha (RAR alpha) is a known estrogen target gene in breast cancer cells. The consequence of RAR alpha induction by estrogen was previously unknown. We now show that RAR alpha is required for efficient estrogen receptor-alpha (ER)-mediated transcription and cell proliferation. RAR alpha can interact with ER-binding sites, but this occurs in an ER-dependent manner, providing a novel role for RAR alpha that is independent of its classic role. We show, on a genome-wide scale, that RAR alpha and ER can co-occupy regulatory regions together within the chromatin. This transcriptionally active co-occupancy and dependency occurs when exposed to the predominant breast cancer hormone, estrogen--an interaction that is promoted by the estrogen-ER induction of RAR alpha. These findings implicate RAR alpha as an essential component of the ER complex, potentially by maintaining ER-cofactor interactions, and suggest that different nuclear receptors can cooperate for effective transcriptional activity in breast cancer cells. RAR alpha silenced breast cancer MCF-7 cell lines or control siRNA in the presence of estrogen or a vehicle. MCF-7 cells were hormone-depleted for 3 d and treated with 100 nM estrogen for 12 h. There were three biological replicates for each of the four different groups.
Project description:Here we investigate the impact of epigenetic therapy with Decitabine in endocrine-resistant ER+ breast cancer by using patient-derived xenograft (PDX) models. Decitabine treatment restrained tumour growth, inhibited cell proliferation and resulted in significant loss of DNA methylation, particularly at enhancers and repetitive elements. Systematic integration of matched in situ Hi-C / PCHi-C, EPIC, RNA-seq and ChIP–seq datasets revealed widespread differences in epigenome regulation and enhancer-promoter communication with Decitabine. We find that loss of DNA methylation with Decitabine strongly affects the open (A) and closed (B) compartment structure and TAD boundary insulation. Our study identified and focused on key DNA methylation-dependent, enhancer ER binding sites that are activated in Decitabine-treated PDX tumours, enabling direct interactions between promoters and multiple distal enhancers, inducing expression of ER target genes and pathways. Overall, we demonstrate that epigenetic therapy inhibits tumour progression through to rewiring of ER-mediated 3D chromatin interactions and transcriptome programs. Our findings suggest that targeting the 3D epigenome with epigenetic therapies represents a promising strategy for anti-cancer treatment in ER+ endocrine resistant breast cancer patients.
Project description:Phosphorylation of estrogen receptor α (ER) at serine 118 (pS118-ER) is induced by estrogen and is the most abundant post-translational mark associated with a transcriptionally active receptor. Cistromic analysis of pS118-ER from our group found enrichment of the GRHL2 motif near pS118-ER binding sites. In this report we use cistromic and transcriptomic analyses to interrogate the relationship between GRHL2 and pS118-ER. We found that GRHL2 is bound to chromatin at pS118-ER/GRHL2 co-occupancy sites prior to ligand treatment, and GRHL2 binding is required for maximal pS118-ER recruitment. pS118-ER/GRHL2 co-occupancy sites were enriched at active enhancers marked by H3K27ac and H3K4me1, along with FOXA1 and p300. Transcriptomic analysis yielded four subsets of ER/GRHL2 co-regulated genes revealing that GRHL2 can both enhance and antagonize E2-mediated ER transcriptional activity. Gene ontology analysis identified several coregulated genes involved in cell migration. Accordingly, knockdown of GRHL2 combined with estrogen treatment resulted in increased cell migration but no change in proliferation. These results support a model in which GRHL2 binds to select enhancers and facilitates pS118-ER recruitment to chromatin which then results in differential activation and repression of genes that control ER-positive breast cancer cell migration.
Project description:Retinoic acid receptor-alpha (RAR alpha) is a known estrogen target gene in breast cancer cells. The consequence of RAR alpha induction by estrogen was previously unknown. We now show that RAR alpha is required for efficient estrogen receptor-alpha (ER)-mediated transcription and cell proliferation. RAR alpha can interact with ER-binding sites, but this occurs in an ER-dependent manner, providing a novel role for RAR alpha that is independent of its classic role. We show, on a genome-wide scale, that RAR alpha and ER can co-occupy regulatory regions together within the chromatin. This transcriptionally active co-occupancy and dependency occurs when exposed to the predominant breast cancer hormone, estrogen--an interaction that is promoted by the estrogen-ER induction of RAR alpha. These findings implicate RAR alpha as an essential component of the ER complex, potentially by maintaining ER-cofactor interactions, and suggest that different nuclear receptors can cooperate for effective transcriptional activity in breast cancer cells.
Project description:Estrogen Receptor-alpha (ER) is the key driver of 75% of all breast cancers. Upon stimulation by its ligand estra-2-diol, ER forms a transcriptionally active complex binding chromatin. Previous studies have reported that ER binding follows a cyclical binding pattern with a periodicity of 90 minutes. However, these studies have been limited to individual ER target genes and most were done without replicates. Thus, the robustness and generality of ER cycling are not well understood. Here we present a comprehensive genome-wide analysis of the time dependence of ER binding affinity up to 90 minutes after activation, based on 6 replicates at 10 time points using our previously reported method for precise quantification of binding, Parallel-Factor ChIP-seq (pfChIP-seq). In contrast to previously described cyclical binding, our approach identifies a unidirectional sustained increase in ER binding affinity, as well as a class of estra-2-diol independent binding sites. Our results are corroborated by a quantitative re-analysis of data from multiple independent studies. Our new model reconciles the results of multiple conflicting studies into the activation of ER at the TFF1 promoter. We provide a detailed understanding of ER's response to estra-2-diol in the context of the receptor's fundamental role as both the main driver and therapeutic target of breast cancer
Project description:We report that neurofibromin, a tumor suppressor and Ras-GAP (GTPase Activating Protein), is also an estrogen receptor-alpha (ER) transcriptional co-repressor through leucine/isoleucine-rich motifs that are functionally independent of GAP activity. GAP activity, in turn, does not impact ER binding. Consequently, neurofibromin-depletion causes estradiol hypersensitivity and tamoxifen agonism, explaining the poor prognosis associated with neurofibromin-loss in endocrine therapy-treated ER+ breast cancer. Neurofibromin-deficient ER+ breast cancer cells initially retain sensitivity to selective estrogen receptor degraders (SERDs). However, Ras activation does play a role in acquired SERD resistance, which can be reversed upon MEK inhibitor addition, and SERD/MEK inhibitor combinations induce tumor regression. Thus, neurofibromin is a dual repressor for both Ras and ER signaling, and co-targeting may treat neurofibromin-deficient ER+ breast tumors.
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.