Figure 1.

Metformin suppressed cell proliferation and colony formation, with the most pronounced inhibitory effects seen under low glucose conditions. The endometrial cancer cell lines, ECC-1 and Ishikawa, were cultured in glucose-free media supplemented with 25 mM glucose (HG), 5 mM glucose (NG) and 1 mM glucose (LG) for 24 h and then treated with the indicated concentration of metformin in 96-well plates for 48 h. Cell proliferation was assessed by MTT assay. LG increased sensitivity to metformin in the inhibition of cell proliferation in both cell lines (A and B). The effect of metformin on the long term growth in ECC-1 and Ishikawa was assessed through a colony-forming assay. LG increased sensitivity to metformin in the inhibition of colony formation in both cell lines (C and D). The results are shown as the mean of ± SE of triplicate samples and are representative of three independent experiments. *P < 0.05, **P < 0.01.