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: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:About one-third of oestrogen receptor alpha- positive breast cancer patients treated with tamoxifen relapse. Here we identify the nuclear receptor retinoic acid receptor alpha as a marker of tamoxifen resistance. Using quantitative mass spectrometry-based proteomics, we show that retinoic acid receptor alpha protein networks and levels differ in a tamoxifen-sensitive (MCF7) and a tamoxifen-resistant (LCC2) cell line. High intratumoural retinoic acid receptor alpha protein levels also correlate with reduced relapse-free survival in oestrogen receptor alpha-positive breast cancer patients treated with adjuvant tamoxifen solely. A similar retinoic acid receptor alpha expression pattern is seen in a comparable independent patient cohort. An oestrogen receptor alpha and retinoic acid receptor alpha ligand screening reveals that tamoxifen-resistant LCC2 cells have increased sensitivity to retinoic acid receptor alpha ligands and are less sensitive to oestrogen receptor alpha ligands compared with MCF7 cells. Our data indicate that retinoic acid receptor alpha may be a novel therapeutic target and a predictive factor for oestrogen receptor alpha-positive breast cancer patients treated with adjuvant tamoxifen. Peptide and protein identification data set 1: Peptide identification from the MALDI-TOF/TOF data was carried out using the Paragon algorithm in the ProteinPilot 2.0 software package (Applied Biosystems) 46. Default settings for a 4800 instrument were used (i.e., no manual settings for mass tolerance was given). The following parameters were selected in the analysis method: iTRAQ 4plex peptide labelled as sample type, MMTS as alkylating agent of cysteine, trypsin as digesting enzyme, 4800 as instrument, gel based ID and Urea denaturation as special factors, biological modifications as ID focus, and thorough ID as search effort. Peptide identification from the Q-TOF data was carried out using the Spectrum Mill Protein Identification software (Agilent). Data was extracted between MH+ 600 and 4000 Da (Agilent's definition). Scans with the same precursor m/z 90 sec, 0.05 m/z matching with a minimum of 20 peaks in MS2 were merged. Peptide and protein identification data set 2: Proteome discoverer 1.3 with sequest-percolator was used for protein identification. Precursor mass tolerance was set to 10 ppm and for fragments 0.8 Da and 0.02 Da were used for detection in the linear iontrap and the orbitrap, respectively. Oxidized methionine and phosphorylation on S,T and Y was set as dynamic modifications, and carbamidomethylation, N-terminal 8plex iTRAQ, and lysyl 8plex iTRAQ as fixed modifications. Spectra were matched to ensembl 68 limited to human protein sequences, and results were filtered to 1% FDR.
Project description:Previous studies have identified an interaction between RUNX1 and estrogen receptor alpha and its potential role in estrogen signaling in breast cancer. To determine the transcriptomic actions of RUNX1, we knocked down its expression by using siRNAs, both in the absence and presence of estradiol (E2).
Project description:The overall study explores differential sensitivity of estrogen-receptor-positive and -negative breast carcinoma cells to retinoids via gene expression and microRNA profiling in MCF7 and MDA-MB-231 cells. This Series reports results of transcriptional profiling of breast carcinoma cell lines comparing the effects of retinoic acid treatment (6 and 48 hours) on estrogen-receptor-positive (MCF7) and estrogen-receptor-negative (MDA-MB-231) cells. mRNA profiling: Retinoic-acid-treated (1microM) vs vehicle-treated cells, two time points (6 and 48h), two cell lines (MCF7 and MDA-MB-231). Two biological replicates for each condition, balanced dye design.
Project description:The Estrogen Receptor alpha (ERα) controls key cellular functions in hormone responsive breast cancer by assembling in large functional multiprotein complexes. ERα ligands are classified as agonists and antagonist, according to the response they elicit, thus the molecular characterization of the of ERα nuclear iteractome composition following estrogen and antiestrogen stimulation whose is needed to understand their effects on estrogen target tissues, in particular breast cancer. To this aim interaction proteomics coupled to mass spectrometry (MS) was applied to map the ERα nuclear interacting partners in MCF7 breast cancer cell nuclei following estrogen and antiestrogen stimuli.
Project description:This study is to identify estrogen receptor alpha targeting in liver cancer and breast cancer using RNA-Seq and ChIP-Seq and reveal the mechanisms underlying estrogen receptor alpha in the regulation of liver cancer and breast cancer.
Project description:We have previously demonstrated that endoxifen is the most important tamoxifen metabolite responsible for eliciting the anti-estrogenic effects of this drug in breast cancer cells expressing estrogen receptor-alpha. However, the relevance of estrogen receptor-beta in mediating endoxifen action has yet to be explored. Therefore, the goals of this study were to determine the differences in the global gene expression profiles elicited by estradiol treatment and endoxifen between parental MCF7 breast cancer cells (expressing estrogen receptor alpha only) and MCF7 cells stably expressing estrogen receptor beta.
Project description:The overall study explores differential sensitivity of estrogen-receptor-positive and -negative breast carcinoma cells to retinoids via gene expression and microRNA profiling in MCF7 and MDA-MB-231 cells. This Series reports results of transcriptional profiling of breast carcinoma cell lines comparing the effects of retinoic acid treatment (6 and 48 hours) on estrogen-receptor-positive (MCF7) and estrogen-receptor-negative (MDA-MB-231) cells.