Figure 1.
Metformin inhibits MEC mammosphere formation and CD61high/CD49fhigh subpopulation. A, representative mammary whole mounts of control (A1) and metformin-treated (A2) mice. MMTV-ErbB2 mice were treated with saline (control) or metformin (250 mg/kg/day via i.p.) starting from 8 weeks of age. Mammary glands were harvested and processed at 18 weeks of age. Whole mounts from 3 mice of each group were examined. B, mammosphere-forming efficiency of MECs from metformin-treated mice was reduced. Primary MECs were isolated from 18-week-old mice with above treatments, followed by mammosphere-formation assay. C, metformin selectively inhibits CD61high/CD49fhigh subpopulation in mammary tissues of MMTV-ErbB2 transgenic mice. MECs were isolated from 18-week-old mammary tissues with above treatments. CD49f and CD61 expression profile were analyzed by FACS. D, metformin inhibits CD61high/CD49fhigh subpopulation in 78617 cells. These MMTV-ErbB2 tumor-derived cells were cultured in the absence/presence of 1 mmol/L of metformin for 72 hours, followed by FACS analysis of CD49f and CD61 expression. E, quantitative analysis of CD61high/CD49fhigh subpopulation in 78617 cells as in D.