Proliferative effects of BPs in MCF-7 breast cancer cells.

<p>(<b>A</b>) After 48 h of steroid deprivation, MCF-7 cells were cultured in medium containing 2.5% dextran-treated charcoal stripped FBS and treated during 5 days with vehicle, 10⁻⁸ M estradiol (E2) or different concentrations of BPs (10⁻⁸, 10⁻⁷ and 10⁻⁶ M). In addition, cells were treated with 10⁻⁷ M of the anti-estrogen ICI_182,780 (ICI) alone or in combination with 10⁻⁸ M E2 (hatched bar) or 10⁻⁶ M of each one of the BPs (open bars). Cell growth was evaluated using methylene blue assays and the results were expressed as fold induction between treated cells and vehicle-treated cells (considered as one-fold induction). (<b>B and C</b>) As in panel A, MCF-7 cells were cultured in medium containing 2.5% dextran-treated charcoal stripped FBS and treated with different concentrations of estradiol (10⁻¹², 10⁻¹¹, 10⁻¹⁰ M, illustrated by color gradations) or different concentrations of BPs (10⁻⁸, 10⁻⁷ and 10⁻⁶ M, illustrated by color gradations). The percentage of cells in S phase was evaluated 48 hours later using BrdU incorporation assays. Data are the mean values from triplicate experiments ± SEM (* P<0.05, **P<0.01, ***P<0.001). (<b>D</b>) Equal amounts of whole cell extracts from MCF-7 cells were loaded on denaturing gels. The ERα and β-actin protein levels were detected with specific antibodies as described in the Materials and Methods.