Transcriptomic Effects of Estrogen Starvation and Induction in the MCF7 Cells. The Meta-analysis of Microarray...

Estrogen is one of the most important signaling molecules which targets a number of genes. Estrogen levels regulate cell proliferation and a plethora of metabolic processes, which may interfere with a range of medical conditions and drug metabolism. The MCF7 breast cancer cell line, expressing the estrogen receptor α, is a well-studied model of cellular answer to estrogen. The aim of this study was to characterize transcriptomic responses to estrogen in a broad time range. We performed a meta-analysis of microarray data on gene expression in the MCF7 cells under estrogen exposure and deprivation. As the result we distinguished three major phases of transcriptomic response to stimulation with 17β- estradiol: the early (1-2 h), with the activation of the MAPK signaling pathway; the intermediate (3-12 h), with enhanced expression of genes participating in cell surface receptor linked signal transduction and cellular homeostasis; and the late one (24-48 h), with the induction of genes involved in mitotic cell division. Two main phases under estrogen starvation were indicated as the early (1-3 days), with elevated expression of genes associated with cell projection and repression of those responsible for cell cycle regulation, and the late (15-180 days), with increased expression of genes of cell adhesion proteins. The meta-analysis displayed how different gene sets are either induced or repressed following either estrogen exposure or deprivation, and how the gene expression changes are orchestrated by estrogen in time dependent manner, indicating that proper understanding of estrogen impact on transcriptional gene activity requires an extensive time perspective.