Fig. 2
Tamoxifen-resistant cells are resistant to DNA-damaging chemotherapy. a Cell viability assay showing the effect of tamoxifen on MCF7-Re cells when transfected with negative control siRNA (nc), BARD1, and/or BRCA1 siRNAs. b MCF7-Pa and MCF7-Re cells were treated with different concentrations of cisplatin (cis), adriamycin (ADM), or paclitaxel, and the proportions of viable cells were examined by cell viability assay. c Apoptosis assay by AnnexinV-FITC/PI staining showing the percentages of apoptotic cells when MCF7-Pa and MCF7-Re cells were treated with cisplatin. d Comet assay showing the DNA damage when MCF7-Pa and MCF7-Re cells were treated with cisplatin. Scale bar indicated 100 μm. e Western blot showing the expression of γH2AX when MCF7-Pa and MCF7-Re cells were treated with cisplatin. f Representative immunofluorescence staining of γH2AX, Rad51, and BRCA1 in MCF7-Pa and MCF7-Re cells treated with cisplatin at 0 h, 2 h, 8 h. Scale bar indicated 25 μm. g Percentages of positive nuclei (10 foci or more per nucleus being considered positive) from three fields per sample are indicated. In a–d, g, data show means ± s.d. (n = 3) *p < 0.05; **p < 0.01; compared with control or indicated lines by Student’s t test
