Fig. 1

Metformin enhances the anticancer effects of cisplatin in TNBC cells. a, b Hs 578T and MDA-MB-231 cells were treated with metformin (1~10 mM) for 24 or 48 h in DMEM supplemented with 10% FBS and 5 mM glucose (i.e., normoglycemic conditions), followed by MTT assay. c, d Hs 578T and MDA-MB-231 cells were treated for 24 h with 5 mM metformin, 5 μM cisplatin, or a combination of metformin + cisplatin, followed by MTT assay. Cell viability was expressed as the percentage of viable cells in treated wells relative to the percentage of viable cells in control wells (100% viability). e, f 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 5 mM metformin + 5 μM cisplatin. Representative images of wound healing were obtained at the time of the scratch and after 24 h. g, h Invasiveness of Hs 578T and MDA-MB-231 cells was measured using a Matrigel Transwell assay following treatment with metformin (5 mM), cisplatin (5 μM), or a combination of 5 mM metformin + 5 μM cisplatin for 24 h. Cell invasion was quantified by staining and counting membrane-associated cells in 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, by one-way ANOVA followed by Bonferroni’s post hoc test