Regulation of Breast Cancer Cell Lines

Parental and ERβ1-expressing MCF7 cells [12 (link)] and doxycycline-inducible Hs578T-ERβ1 cells [8 (link)] were cultured as previously described. Doxycycline-inducible ERβ1-expressing MDA-MB-231 cell lines were established using the T-REx™ System (Invitrogen) as previously described [9 (link)] and were maintained in DMEM/F12 medium supplemented with 10% FBS, 1% AA, 5 mg/L blasticidin S and 500 mg/L zeocin. Charcoal-stripped fetal bovine serum (CS-FBS) was purchased from Gemini Bio-Products (West Sacramento, CA). 17β-estradiol (E2), (Z)-tamoxifen, (Z)-4-hydroxy-tamoxifen and doxycycline (Dox) were purchased from Sigma-Aldrich (St. Louis, MO). (Z)-endoxifen was synthesized by the National Cancer Institute (Bethesda, MD). The ERβ-specific agonists; DPN, WAY200070, FERb 033 and Liquiritigenin, as well as the pure ER antagonist ICI 182,780, were purchased from Tocris Bioscience (Bristol, United Kingdom).