FIGURE 2.

TPSF specifically inhibits expression of endogenous ER-regulated genes. A, TPSF inhibits E₂ induction of PI-9 mRNA. For studies of PI-9 mRNA (filled squares), MCF-7 cells were incubated for 24 h with the indicated concentrations of TPSF and maintained for 4 h in 10 nm E₂ and TPSF. PI-9 mRNA was quantitated by RT-PCR as described (23). B, TPSF inhibition of E₂-ERα induction of cyclin D1 mRNA is shown. MCF-7 cells were plated and 24 h later treated with ethanol and DMSO vehicles, 10 nm E₂, or 10 nm E₂ and 10 μm TPSF. After 24 h, RNA was extracted, and cyclin D1 mRNA levels were measured by qRT-PCR. The level of cyclin D1 mRNA in the vehicle only sample was set to 1. -Fold induction of cyclin D1 in the presence of 10 μm TPSF was significantly different from the control (p < 0.05 using Student's t test). C, TPSF does not inhibit NF-κB induction of IL-8 mRNA. MCF-7 cells were maintained for 24 h in medium without TNF-α or with 10 ng/ml TNF-α with and without 30 μm TPSF and harvested, and IL-8 mRNA levels were determined by qRT-PCR. D, dose-response studies of inhibition of ERα, AR, and GR transactivation are shown. For each receptor, induction of luciferase reporter gene expression (AR and GR) or endogenous PI-9 mRNA (ER) in the presence of an appropriate ligand with DMSO minus TPSF was set to 100%. Cells were incubated for 24 h with 0.2 nm E₂ for ERα (filled squares), 5 nm dexamethasone for GR (filled triangles), 1 μm dihydrotestosterone for AR (filled circles), and the indicated concentrations of TPSF. Data are the average ± S.E. for three experiments.