Fig. 7

RAD51 regulates metformin- and cisplatin-mediated cell invasion. a MDA-MB-231 cells were transfected with a RAD51-flag expression plasmid for 48 h, followed by western blotting using antibodies against RAD51 and β-actin (control). b Hs 578T and MDA-MB-231 cells overexpressing RAD51 were seeded into a six-well plate for a scratch wound migration assay. Cells were treated with metformin (5 mM) and cisplatin (5 μM), either alone or in combination, for 12 h. c Cell invasion was measured by the Matrigel Transwell assay following treatment with metformin (5 mM), cisplatin (5 μM), or a combination of both, and quantified by staining and counting viable cells on the lower surface of the Transwell. d MDA-MB-231 cells were transfected with either a scrambled sequence control or RAD51-targeting siRNA for 48 h. Western blotting was performed using antibodies against RAD51 and β-actin to confirm the reduction in RAD51 levels. e Hs 578T (upper panel) and MDA-MB-231 (lower panel) cells were transfected with non-target or RAD51 siRNA for 24 h. Cultures of Hs 578T and MDA-MB-231 cells were wounded by scratching with a pipette tip and incubated with metformin (5 mM), cisplatin (5 μM), or a combination of both. Representative images of wound healing were obtained at the time of the scratch and after 24 h. Bar graphs (n = 5) are shown. f Hs 578T (upper panel) and MDA-MB-231 (lower panel) cells were transfected with non-target or RAD51 siRNA for 24 h. Invasiveness of RAD51 knockdown or control cells was evaluated using the Matrigel-covered Transwell invasion assay following treatment with metformin (5 mM), cisplatin (5 μM), or a combination of both. Cell invasion was quantified by staining and counting viable cells on the lower surface of the Transwell. Results represent the mean ± SEM of five independent experiments. #, ##, ## vs. no treatment; ^#P < 0.05, ^##P < 0.01, ^###P < 0.001, *P < 0.05, **P < 0.01, **P < 0.001 by one-way ANOVA followed by Bonferroni’s post hoc test