FIG. 6.

(A) Analysis of CCND1 promoter responsiveness to progesterone upon stable transfection of the indicated luciferase reporter genes in MCF-7 cells, reported as fold induction by 50 nM R5020 for 18 to 24 h versus the activity assayed in hormone-starved cells transfected with the same construct, arbitrarily set to 1. Plasmids used for transfections are named as shown in Fig. 1. MMTV-luc, progesterone-responsive reporter gene including the mouse mammary tumor virus long terminal repeat. Results reported represent the means of three to five independent experiments carried out several times. F.i., fold induction. Bars indicate standard deviations. (B) EMSAs with nuclear extracts from hormone-responsive hBC cells treated, where indicated (+), with 50 nM E2 or R5020 for 2 h and challenged with ³²P-labeled AP-1/dE oligonucleotide. Data are representative of multiple experiments carried out with at least two different nuclear extracts from either MCF-7 or ZR 75.1 cells. (C) ChIP analysis of in vivo binding of progesterone receptors and other transcription regulatory factors to the upstream element of the CCND1 gene in ZR-75.1 cells. Input, total chromatin before immunoprecipitation. Data are representative of three experiments, one of which was carried out with MCF-7 cells.