Fig. 5

Metformin and cisplatin inhibit subcutaneous tumor growth in xenograft mice. Two to 4 weeks after subcutaneous injection of ovarian SKOV3 cancer cells, the treatments were started when the tumor size reached approximately 150 mm³. Four groups of mice (n = 6) were treated with saline, metformin, cisplatin, or the combination of metformin and cisplatin for 4 weeks. Tumor size and body weight were measured weekly throughout the experiment period. Three mice of each group were sacrificed after 4 weeks of treatment for analysis and the other three mice were kept to observe for an additional 5 weeks. Representative experiment showing the actual resected tumor of each treatment group (a). Summary results from three separate experiments are presented (b). After 4 weeks of treatment, tumor tissues from each group were digested with ultrapure collagenase IV to obtain single cell suspensions. Flow cytometry was performed to isolate CD44⁺CD117⁺ CSCs of each treatment group. Metformin treatment significantly reduced the CD44⁺CD117⁺ CSC population (c). Total RNA was isolated from CD44⁺CD117⁺cells and mRNA was quantitated by real-time RT-PCR. Metformin significantly reduced snail 2, twist, and vimentin, but not the snail1 expression level, and upregulated E-cadherin expression (d). * Significant difference compared with control (P < 0.05)