Figure 3

Effects of AMPK siRNA on the cytotoxic and radiosensitizing effects of metformin.

(A) Transfection of MCF-7 and FSaII ells with siRNA against AMPK markedly reduced the AMPK levels in the cells. (B) Transfection of cells with AMPK siRNA markedly reduced the clonogenic cell death caused by 48 h incubation with various concentrations of metformin. (C) Transfection of cells with AMPK siRNA reduced the efficacy of metformin to sensitize the cells to radiation. Cells were incubated with 1 or 5 mM metformin for 24 h, irradiated with various doses of X-rays, further incubated with metformin for 24 h and then cultured for colony formation. The radiation survival curves were normalized for the cell death caused by metformin alone.