Project description:The nuclear hormone receptor, estrogen receptor-alpha (ERα), and MAP kinases both play key roles in hormone-dependent cancers, yet their interplay and the integration of their signaling inputs remain poorly understood. In these studies, we document that estrogen-occupied ERα activates and interacts with ERK2, a downstream effector in the MAPK pathway, resulting in ERK2 and ERα colocalization at chromatin binding sites across the genome of breast cancer cells. KEYWORDS: siRNA knock-down, ligand treatment
Project description:The nuclear hormone receptor, estrogen receptor-alpha (ERα), and MAP kinases both play key roles in hormone-dependent cancers, yet their interplay and the integration of their signaling inputs remain poorly understood. In these studies, we document that estrogen-occupied ERα activates and interacts with ERK2, a downstream effector in the MAPK pathway, resulting in ERK2 and ERα colocalization at chromatin binding sites across the genome of breast cancer cells. KEYWORDS: siRNA knock-down, ligand treatment MCF-7 human breast adenocarcinoma cells were tranfected with control, ERK1 and ERK2 siRNA for 60 hours and treated with 0.1% EtOH (Vehicle) or 10 nM E2 for 4 hours or 24 hours, and cDNA microarray analyses were carried out using Affymetrix [HG-U133A_2] Affymetrix Human Genome U133A 2.0 Array.
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:The closely related transcription factors (TFs), estrogen receptors ER? and ER?, regulate divergent gene expression programs and proliferative outcomes in breast cancer. Utilizing MCF-7 breast cancer cells with ER?, ER?, or both receptors as a model system to define the basis of differing response specification by related TFs, we show that these TFs and their key coregulators, SRC3 and RIP140, generate overlapping as well as unique chromatin-binding and transcription-regulating modules. Cistrome and transcriptome analyses and use of clustering algorithms delineated 11 clusters representing different chromatin-bound receptor and coregulator assemblies that could be functionally associated through enrichment analysis with distinct patterns of gene regulation and preferential coregulator usage, RIP140 with ER? and SRC3 with ER?. The receptors modified each other’s transcriptional effect, and ER? countered the proliferative drive of ER? through several novel mechanisms associated with specific binding site clusters. Our findings delineate distinct TF-coregulator assemblies that function as control nodes specifying precise patterns of gene regulation, proliferation, and metabolism, as exemplified by two of the most important nuclear hormone receptors in human breast cancer. Examination of Estrogen Receptors alpha and beta and their coregulators SRC3 and RIP140 in different cell types
Project description:Estrogen receptor alpha (ERalpha) is a ligand-dependent transcription factor that plays an important role in breast cancer. Estrogen-dependent gene regulation by ERalpha can be mediated by interaction with other DNA-binding proteins, such as activator protein-1 (AP-1). The nature of such interactions in mediating the estrogen response in breast cancer cells remains unclear. Here we show that knockdown of c-Fos, a component of the transcription factor AP-1, attenuates the expression of 37% of all estrogen-regulated genes, suggesting that AP-1 is a fundamental factor for ERalpha-mediated transcription. Additionally, knockdown of c-Fos affected the expression of a number of genes that were not regulated by estrogen. Pathway analysis reveals that silencing of c-Fos downregulates an E2F1-dependent pro-proliferative gene network. Thus, modulation of the E2F1 pathway by c-Fos represents a novel mechanism by which c-Fos enhances breast cancer cell proliferation. Furthermore, we show that c-Fos and ERalpha can cooperate in regulating E2F1 gene expression by binding to regulatory elements in the E2F1 promoter. To start to dissect the molecular details of the cross-talk between AP-1 and estrogen signaling, we identify a novel ERalpha/AP-1 target, PKIB (cAMP-dependent protein kinase inhibitor-beta), which is overexpressed in ERalpha-positive breast cancer tissues. Knockdown of PKIB by siRNA results in drastic growth suppression of breast cancer cells. Collectively, our findings support AP-1 as a critical factor that governs estrogen-dependent gene expression and breast cancer proliferation programs. MCF-7 cells were transfected with a control siRNA or with the pool of siRNAs targeting c-Fos for 72 h and were then treated with vehicle or E2 for 24 h, and global gene expression profiles were assessed. Three or four biological replicates were used for each group.
Project description:Estrogen receptor α (ERα) is the major driving transcription factor in normal mammary gland development as well as breast cancer initiation and progression.However,the fundamental mechanisms,including global cistromic and genomic transcriptional responses that are required to elicit mammary epithelial cell proliferation in response to ERα, have not been elucidated. We used chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) to identify estrogen regulated genes that directly recruit ERα in the WT mouse mammary gland
Project description:The ERK/MAPK signal transduction cascade is one of the key pathways regulating proliferation and differentiation in development and disease. In human embryonic stem cells (hESCs), ERK signaling is required for their self-renewing property. Here we studied the convergence of the ERK signaling cascade at the DNA by mapping genome-wide kinase-chromatin interactions for ERK2 in hESCs. We observe that ERK2 targets genes coding for small RNAs, histones, and genes involved in cellular metabolism and cell cycle. We find that the transcription factor ELK1 is essential in hESCs and that ERK2 co-occupies promoters bound by ELK1. Strikingly, promoters bound by ELK1 without ERK2 are occupied by Polycomb group proteins that repress genes involved in lineage commitment. In summary, we propose a model where extracellular signaling-stimulated proliferation and intrinsic repression of differentiation is integrated to maintain the identity of hESCs.
Project description:The ERK/MAPK signal transduction cascade is one of the key pathways regulating proliferation and differentiation in development and disease. In human embryonic stem cells (hESCs), ERK signaling is required for their self-renewing property. Here we studied the convergence of the ERK signaling cascade at the DNA by mapping genome-wide kinase-chromatin interactions for ERK2 in hESCs. We observe that ERK2 targets genes coding for small RNAs, histones, and genes involved in cellular metabolism and cell cycle. We find that the transcription factor ELK1 is essential in hESCs and that ERK2 co-occupies promoters bound by ELK1. Strikingly, promoters bound by ELK1 without ERK2 are occupied by Polycomb group proteins that repress genes involved in lineage commitment. In summary, we propose a model where extracellular signaling-stimulated proliferation and intrinsic repression of differentiation is integrated to maintain the identity of hESCs.
Project description:To better characterize group IE like human breast cancer based on the gene profiles of estrogen actions through estrogen receptor alpha (ER alpha), we identified an ER alpha transcriptional regulatory network for cell cycle in silico. We used two datasets from cell line (Data 1) and clinical samples (Data 2), respectively. Analyses on Data 1 via trajectory clustering and Pathway-Express confirmed the significant estrogen effect on up-regulating cell cycle activities. The gene expression relationships between ER alpha and cell cycle genes were re-identified in Data 2 by three statistical methods – Galton-Pearson’s correlation coefficient, Student’s t-test and the coefficient of intrinsic dependence. They were mostly (56.09%)(46/82) re-confirmed by literature search. E2F1 was found to be the major ER alpha target in regulating cell cycle gene expressions (83.72%)(36/43) via suppressive mode. However, enhanced cell cycle progression via up-regulating some cell cycle genes was predicted in silico possibly involving E2F2, in part. Both tumorigenic and tumor suppressing activities indicated by this network were predicted. This network clearly provides a robust way for uncovering estrogen actions in an ER(+) subtype specific manner. Experiment Overall Design: Two clinical datasets were used in this study. One, the 37 clinical arrays (abbreviated as 37A) consist of 26 A for patients positive in estrogen receptor alpha (ER) and in progesterone receptor (PR) immunohistochemical stain (IHC) and 11A for patients negative in ER IHC. This dataset was designated as Data 2. The 31 clinical arrays (31A) consist of 20A for patients positive in ER status but negative in PR status and 11A which are the same as in 37A. This dataset was used for data comparison. All the signals from the mRNA profile of each sample in the experiments were normalized using the internal control RNA- Stratagene's human common reference RNA via statistical method 'rank consistant lowess. Finally, those ratios were transformed by Log2.