Fig. 8

Metformin potentiates cisplatin-mediated inhibition of breast cancer growth in an orthotopic murine breast cancer model. a Schematic representation of the experiment. Briefly, 4T1 murine breast cancer cells were implanted in the mammary fat pad of female BALB/c mice, following which the mice were randomly allocated to four treatment groups. Treatments comprised administration of saline, metformin (IP, 150 mg/kg, daily), cisplatin (IP, 3 mg/ kg, q3d), or a combination of both for 3 weeks. b The body weight of the mice was measured daily. Data represent the mean ± SEM (n = 10/group). No significant difference was observed (P > 0.05). c Tumor growth was monitored by measuring tumor size with calipers every other day. Data represent the mean ± SEM (n = 10/group). ***P < 0.001 by one-way ANOVA followed by Bonferroni’s post hoc test. d Net tumor weights and representative tumor images upon necropsy are shown. Statistical analyses were performed using GraphPad Prism 7. All data were tested for normality by the Shapiro-Wilk test. Student’s t test (for normally distributed samples) and the Mann-Whitney U test (for nonparametric analyses) were performed to compare groups. All statistical analyses were two-tailed. Linear regression analysis was performed to test whether slopes and intercepts in tumor growth curves were significantly different. e Tumor lysates were analyzed for RAD51 expression by western blot. The bar graph represents quantification of band intensities (n = 3) *P < 0.05, ***P < 0.001 based on one-way ANOVA followed by Bonferroni’s post hoc test. f Immunohistochemical staining of the tumors confirms RAD51 expression (× 200 magnification)