Genome wide analysis of the transcription induced by estrogen and tamoxifen in MCF-7 cells

The aim of this study is to understand the role of tamoxifen in the transcription regulation of estrogen receptor positive breast cancer cells using GRO-seq experiment. ER positive MCF-7 cells was depleted with lipid hormone in stripped culture media for 4 days, and stimulated with 17-ß-estradiol (100nM), 4-OH-tamoxifen (1µM), and the combination of both for 40min. Each treatment was generated in duplicates. Then nuclei was isolated and used as the starting material for GRO-seq experiments. Sequencing data was analyzed and differential gene expression analysis was performed. A rapid induction of gene expression by 17-ß-estradiol was observed as previous studies reported. While also a number of genes were also up-regulated by 4-OH-tamoxifen treatment which is considered as a ER antagnist. The data strongly indicate that as a recpressor of estrogen receptor induced transcription, tamoxifen could also perform as a partial agnist at the same time. Overall design: Transcriptome profiling of hormone depleted MCF-7 cells treated with vehicle (control), 17-ß-estradiol (100nM), 4-OH-tamoxifen (1µM) and combination of both for 40min. 2 replicates for each