Journal article

Unliganded estrogen receptor-beta regulation of genes is inhibited by tamoxifen

Nitzan Levy, Sreenivasan Paruthiyil, Xiaoyue Zhao, Omar I Vivar, Elise F Saunier, Chandi Griffin, Mary Tagliaferri, Isaac Cohen, Terence P Speed, Dale C Leitman

MOLECULAR AND CELLULAR ENDOCRINOLOGY | ELSEVIER IRELAND LTD | Published : 2010

Abstract

Tamoxifen can stimulate the growth of some breast tumors and others can become resistant to tamoxifen. We previously showed that unliganded ERbeta inhibits ERalpha-mediated proliferation of MCF-7 cells. We investigated if tamoxifen might have a potential negative effect on some breast cancer cells by blocking the effects of unliganded ERbeta on gene regulation. Gene expression profiles demonstrated that unliganded ERbeta upregulated 196 genes in MCF-7 cells. Tamoxifen significantly inhibited 73 of these genes by greater than 30%, including several growth-inhibitory genes. To explore the mechanism whereby unliganded ERbeta activates genes and how tamoxifen blocks this effect, we used doxycycl..

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University of Melbourne Researchers