FIGURE 6.

Many Sp1-binding sites on the BRCA2 promoter region appear to be important for ERα-, ERβ-induced transcription activation or p53-induced transcription inhibition. A, effects of mutations of Sp1-binding sites on ERα-induced BRCA2 promoter activity in MCF-7 cells. Single or combined mutations of Sp1A, Sp1B, and Sp1C sites were separately made in pGL3-BRCA2 as described under “Experimental Procedures.” Cells were co-transfected in duplicate with either the wild-type pGL3-BRCA2 plasmid or one of the mutant pGL3-BRCA2 constructs with ERα expression vector and then incubated for 40 h. Luciferase assays were performed as described under “Experimental Procedures.” Luciferase activity in the cells transfected with the mutant pGL3-BRCA2 constructs was compared with that in the cells transfected with the wild-type pGL3-BRCA2 plasmid. *, p < 0.05; **, p < 0.01. B, effects of mutations of Sp1-binding sites on ERβ-induced BRCA2 promoter activity in MCF-7 cells. Cells were co-transfected in duplicate with either the wild-type pGL3-BRCA2 plasmid or one of the mutant pGL3-BRCA2 constructs with ERβ expression vector and then incubated for 40 h. Luciferase assays were performed as described under “Experimental Procedures.” Luciferase activity in the cells transfected with the mutant pGL3-BRCA2 constructs was compared with that in the cells transfected with the wild-type pGL3-BRCA2 plasmid. *, p < 0.05; ** p < 0.01. C, effects of mutations of Sp1-binding sites on p53-induced BRCA2 promoter activity in MCF-7 cells. Cells were co-transfected in duplicate with either the wild-type pGL3-BRCA2 plasmid or one of the mutant pGL3-BRCA2 constructs with p53 expression vector and then incubated for 40 h. Luciferase assays were performed as described under “Experimental Procedures.” Luciferase activity in the cells transfected with the mutant pGL3-BRCA2 constructs was compared with that in the cells transfected with the wild-type pGL3-BRCA2 plasmid. *, p < 0.05; **, p < 0.01.