Figure 2. ERα induces the transcriptional activity of the human FOXM1 gene through a ERE consensus proximal to the transcription start site.

A) Effect of treatment with E2 and expression of ER on FOXM1 promoter activity. Schematic representation of the full-length, HindIII and ApaI FOXM1-luciferase reporter constructs. In upper panel, COS-1 cells cultured in 5% double-charcoal striped FCS and phenol red free medium were transiently transfected with 20 ng of either the empty pGL3-basic, pGL3-FOXM1(Trident), pGL3-FOXM1(ApaI), or the control pGL3-ERE-pS2 promoter/reporter and 0 ng or 10 ng of ERα expression vector (pHEGO) in the absence or presence of E2 and with OHT treatment in the presence of E2 induction (E2+OHT). Cells were harvested 24 h after transfection and assayed for luciferase activity. All relative luciferase activity values are corrected for cotransfected Renilla activity. All data shown represent the averages of data from three independent experiments, and the error bars show the standard deviations. In lower panel, COS-1 cells were transfected with pGL3-FOXM1(Trident), pGL3-FOXM1(ApaI), or pGL3-ERE promoter/reporter constructs, together with increasing amounts (0, 0.1, 1, 10, and 20 ng) of ERα expression vector (pHEGO), and processed as described above. B) Schematic representation of the ApaI FOXM1-luciferase reporter construct, showing the consensus, the wild-type, and the mutant ERE (mERE) sequences. COS-1 cells were transfected with pGL3-basic, pGL3-FOXM1(ApaI) wild-type (WT) or mutant ERE, or the control pGL3-ERE-PS2 promoter/reporter and with or without E2 treatment and 20 ng of ERα expression vector. The transfected cells were processed and assayed as described above.