Ionizing Radiation Activates AMP-Activated Kinase (AMPK): A Target for Radiosensitization of Human Cancer Cells

We provide evidence that IR activates AMPK in human cancer cells in an LKB1-independent manner, leading to induction of p21waf/cip and regulation of the cell cycle and survival. AMPK appears to (1) participate in an ATM-AMPK-p21waf/cip pathway, (2) be involved in regulation of the IR-induced G2/M checkpoint, and (3) may be targeted by metformin to enhance IR responses.