Project description:Affymetrix microarray data was generated from MCF7 breast cancer cells treated in vitro with siRNAs against estrogen receptor alpha (ESR1). Gene expresion of estrogen receptor alpha (ESR1) was knocked down in MCF7 breast cancer cells using siRNA. Then the gene expression profiles of these MCF7 cells, along with non-targetting control treated cells were analysed using Affymetrix Human Genome U133 Plus 2.0 microarrays.
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:Affymetrix microarray data was generated from MCF7 breast cancer cells treated in vitro with siRNAs against estrogen receptor alpha (ESR1).
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. Total RNA was isolated from parental or estrogen-receptor beta expressing MCF7 cells following 24 hour treatments with either ethanol vehicle, 1nM 17-beta-estradiol or 1nM estradiol plus 40nM endoxifen. All studies were conducted in biological replicates of 2.
Project description:Cholinergic Receptor Nicotinic Alpha 5 (CHRNA5), an important susceptibility locus for nicotine addiction and lung cancer, is not well studied in breast cancer. In our study, CHRNA5 was transiently depleted in MCF7 cells and transcriptomic changes were compared to siRNA controls. We for the first time showed by microarray analysis that silencing of CHRNA5 in MCF7 breast cancer cells, downregulated genes involved in the cell cycle and proliferation while resulting in reduced cell viability, DNA synthesis and G1 growth arrest. In addition, simultaneous treatment of CHRNA5 siRNA and topoisomerase inhibitors showed an important role of CHRNA5 in increased drug sensitivity. Phalloidin stained CHRNA5 siRNA treated cells on the other hand exhibited a distinct cellular morphotype with increased cellular extensions and a transcriptome characterized by mixed expression of epithelial-mesenchymal genes. Through bioinformatics analysis of the public transcriptome data we demonstrated a strong positive association of expression signature of CHRNA5 RNAi with that of a differentiated cell as well as hormone starvation. Hence, our study implicates CHRNA5 as an antiproliferative differentiation marker in breast cancer.
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.