Figure 2. Downregulation of HEXIM1 expression resulted in the attenuation of repressive effects of tamoxifen on ERα transcription.

A. HEXIM1 miRNA- or control miRNA-transfected MCF-7 cells were treated with 10 nM E₂ ± 100 nM TOT for 3 hours. Proteins were extracted from cells and processed for western blot analyses as described in the “Materials and Methods”. Image shown is representative of three independent replicates. B. HEXIM1 miRNA- or control miRNA-transfected MCF-7 cells were treated with 100 nM E₂ ± 1 uM TOT for 90 minutes and processed for ChIP assays. ChIP assays were performed with antibodies against HEXIM1 or non-specific rabbit IgG (as a control for immunoprecipitation). Panel on the left, DNA fragments were analyzed by PCR using primers specific for the promoter region of pS2. Panel on the right, Quantifications of HEXIM1 enrichment at the pS2 promoter. bars, SE. a, P < 0.05 vs. control-transfected cells with the same treatment. C. ChIP assays were performed with antibodies against cyclin T1 or non-specific rabbit IgG (as a control for immunoprecipitation). Shown are quantifications of cyclin T1 enrichment at the pS2 coding region. Columns represent mean of three replicates; bars, SE. a, P < 0.05 vs. E₂-treated cells. D. ChIP assays were performed with antibodies against serine 2 phosphorylated RNAP II or non-specific rabbit IgG (as a control for immunoprecipitation). Shown are quantifications of RNAP II enrichment at the pS2 coding region. Columns represent mean of three replicates; bars, SE. a, P < 0.05 vs. E₂-treated cells; b, P < 0.05 vs. control-transfected cells with the same treatment.