Project description:Estrogens are steroid hormones that play critical roles in the initiation, development, and metastasis of breast and uterine cancers. The estrogen (E2) response in breast cancer cells is predominantly mediated by the estrogen receptor-alpha (ER alpha), a ligand-activated transcription factor. ER alpha regulates transcription of target genes through direct binding to its cognate recognition sites, known as estrogen response elements (EREs), or by modulating the activity of other DNA-bound transcription factors at alternative DNA sequences. The proto-oncogene c-myc is upregulated by ER¦à in response to E2 and encodes a transcription factor, c-MYC, which regulates a cascade of gene targets whose products mediate cellular transformation. This study aims at mapping the binding sites of these two transcription factors (ER alpha and c-MYC) in one ER alpha positive breast cancer cell line (MCF7 cell line). Keywords: ChIP-Chip Analysis This series contains ChIP-on-Chip data sets for two transcription factors (ER alpha and c-MYC) and control samples (INPUT). All the experiments are done in triplicates. MCF7 Cells were E2-deprived for 3 days and then were treated with 10 nM E2 (45 minutes and 2 hours for mapping ER alpha and c-MYC binding sites, respectively) at 80% confluence.
Project description:Estrogens are steroid hormones that play critical roles in the initiation, development, and metastasis of breast and uterine cancers. The estrogen (E2) response in breast cancer cells is predominantly mediated by the estrogen receptor-alpha (ER alpha), a ligand-activated transcription factor. ER alpha regulates transcription of target genes through direct binding to its cognate recognition sites, known as estrogen response elements (EREs), or by modulating the activity of other DNA-bound transcription factors at alternative DNA sequences. The proto-oncogene c-myc is upregulated by ER¦Á in response to E2 and encodes a transcription factor, c-MYC, which regulates a cascade of gene targets whose products mediate cellular transformation. This study aims at mapping the binding sites of these two transcription factors (ER alpha and c-MYC) in one ER alpha positive breast cancer cell line (MCF7 cell line). Keywords: ChIP-Chip Analysis
Project description:The Estrogen Receptor alpha (ERa) is the key transcriptional regulator in luminal breast cancer and the main target for adjuvant treatment. Luminal gene signatures are dictated by the transcriptional capacities of ERa, which are a direct consequence of the receptors binding preference at specific sites on the chromatin. The identification of ERa binding signatures on a genome-wide level has greatly enhanced our understanding of Estrogen Receptor biology in cell lines, but the technique has its limitations with respect its applicability in limit amounts of tumor tissue. Here, we present a refinement of the ChIP-seq procedures to enable transcription factor mapping on limited amounts of tissue culture cells and illustrate the applicability of this refined technology by mapping the ERa genome-wide chromatin binding landscape in core needle biopsy material from primary breast tumors.
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:Estrogen receptor-{alpha} (ER{alpha}) and its ligand estradiol play critical roles in breast cancer growth and are important therapeutic targets for this disease. Using chromatin immunoprecipitation (ChIP)-on-chip, ligand-bound ER{alpha} was recently found to function as a master transcriptional regulator via binding to many cis-acting sites genome-wide. Here, we used an alternative technology (ChIP cloning) and identified 94 ER{alpha} target loci in breast cancer cells. The ER{alpha}-binding sites contained both classic estrogen response elements and nonclassic binding sequences, showed specific transcriptional activity in reporter gene assay, and interacted with the key transcriptional regulators, including RNA polymerase II and nuclear receptor coactivator-3. The great majority of the binding sites were located in either introns or far distant to coding regions of genes. Forty-three percent of the genes that lie within 50 kb to an ER{alpha}-binding site were regulated by estradiol. Most of these genes are novel estradiol targets encoding receptors, signaling messengers, and ion binders/transporters. mRNA profiling in estradiol-treated breast cancer cell lines and tissues revealed that these genes are highly ER{alpha} responsive both in vitro and in vivo. Among estradiol-induced genes, Wnt11 was found to increase cell survival by significantly reducing apoptosis in breast cancer cells. Taken together, we showed novel genomic binding sites of ER{alpha} that regulate a novel set of genes in response to estradiol in breast cancer. Our findings suggest that at least a subset of these genes, including Wnt11, may play important in vivo and in vitro biological roles in breast cancer. Experiment Overall Design: This Series currently contains the gene expression data accompanying Zhihong Lin et al. Cancer Research 67,5017-5024(2007). MCF7 cells were treated with vehicle or E2 at a concentration of 10E-9 mol/L for 3 and 6 h. All experiments were performed in triplicate.
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{alpha}) and its ligand estradiol play critical roles in breast cancer growth and are important therapeutic targets for this disease. Using chromatin immunoprecipitation (ChIP)-on-chip, ligand-bound ER{alpha} was recently found to function as a master transcriptional regulator via binding to many cis-acting sites genome-wide. Here, we used an alternative technology (ChIP cloning) and identified 94 ER{alpha} target loci in breast cancer cells. The ER{alpha}-binding sites contained both classic estrogen response elements and nonclassic binding sequences, showed specific transcriptional activity in reporter gene assay, and interacted with the key transcriptional regulators, including RNA polymerase II and nuclear receptor coactivator-3. The great majority of the binding sites were located in either introns or far distant to coding regions of genes. Forty-three percent of the genes that lie within 50 kb to an ER{alpha}-binding site were regulated by estradiol. Most of these genes are novel estradiol targets encoding receptors, signaling messengers, and ion binders/transporters. mRNA profiling in estradiol-treated breast cancer cell lines and tissues revealed that these genes are highly ER{alpha} responsive both in vitro and in vivo. Among estradiol-induced genes, Wnt11 was found to increase cell survival by significantly reducing apoptosis in breast cancer cells. Taken together, we showed novel genomic binding sites of ER{alpha} that regulate a novel set of genes in response to estradiol in breast cancer. Our findings suggest that at least a subset of these genes, including Wnt11, may play important in vivo and in vitro biological roles in breast cancer. Keywords: time course
Project description:The nuclear receptor, estrogen receptor alpha (ERα), controls the expression of hundreds of genes responsible for target cell phenotypic properties, but the relative importance of direct vs. tethering mechanisms of DNA binding has not been established. In this first report, we examine the genome-wide chromatin localization of an altered-specificity mutant ER with a DNA-binding domain deficient in binding to estrogen response element (ERE)-containing DNA (DBDmut ER) vs. wild type ERα. Using high-throughput sequencing of ER chromatin immunoprecipitations (ChIP-Seq) and mRNA transcriptional profiling, we show that direct ERE binding is required for most (75%) estrogen-dependent gene regulation and 90% of hormone-dependent recruitment of ER to genomic binding sites. De novo motif analysis of the chromatin binding regions in MDA-MB-231 human breast cancer cells defined unique transcription factor profiles responsible for genes regulated through tethering vs. direct DNA (ERE) binding, with Runx motifs enriched in ER-tethered sites. We confirmed a role for Runx1 in mediating ERa genomic recruitment and regulation of tethering genes. Our findings delineate the contributions of ERE binding vs. binding through response elements for other transcription factors in chromatin localization and ER-dependent gene regulation, paradigms likely to underlie the gene regulatory actions of other nuclear receptors as well. This SuperSeries is composed of the following subset Series: GSE22593: WT and DBDmut Breast Cancer Cells GSE22609: Genome-Wide Maps of WT and DBDmut Estrogen Receptor in Human Breast Cancer Cells Refer to individual Series
Project description:This SuperSeries is composed of the following subset Series: GSE22533: Breast cancer cells resistant to hormone deprivation maintain an estrogen receptor alpha-dependent, E2F-directed transcriptional program GSE27300: Estrogen-independent genomic ER binding analysis Refer to individual Series