Figure 2.

Induction of apoptosis by metformin is glucose-dependent. The ECC-1 and Ishikawa cells were treated with metformin for 12 h in 25 (HG), 5 (NG) and 1 (LG) mM glucose containing media. Cleaved caspase 3 activity was assayed by ELISA assay. Metformin increased cleaved caspase 3 activity under LG conditions in both cell lines (A and B); metformin increased cleaved caspase 3 activity under NG and HG conditions for ECC-1 but not Ishikawa. Western blotting was used to evaluate the expression of BCL-2 and MCL-2 in both cell lines after treatment with metformin under varying glucose conditions for 18 h. Metformin decreased expression of the BCL-2 and MCL-2 proteins under all glucose conditions (C). Metformin decreased BCL-2 and MCL-2 expression in a dose-dependent manner in both cell lines (D). The results are shown as the mean ± SD and are representative of three independent experiments. *P < 0.05, **P < 0.01.