Distinct effects of the antiestrogen Faslodex on the stability of estrogen receptors-α and -β in the breast cancer cell line MCF-7

Abstract

The effects of estrogen receptor (ER) ligands on the stability and transcriptional activity of ERβ in the breast cancer cell lines MCF-7 and HeLa were examined. We found that ERβ was degraded in the presence of 17β-estradiol. Tamoxifen and Faslodex (ICI 182,780) prevented ERβ receptor destabilization. In contrast to ERα, ERβ degradation was not abolished by inhibitors of the proteasome-mediated protein degradation pathway. Furthermore, single point mutations in helix 12 of the receptor dramatically affected the stability and subsequent transcriptional activation of ERβ. © 2004 Society for Endocrinology.