A-769662 Protects Osteoblasts from Hydrogen Dioxide-Induced Apoptosis through Activating of AMP-Activated Protein Kinase (AMPK)

Here we report that 5'-monophosphate (AMP)-activated protein kinase (AMPK) agonist A-769662 inhibited hydrogen peroxide (H(2)O(2))-induced viability loss and apoptosis of human and mouse osteoblast cells. H(2)O(2)-induced moderate AMPK activation in osteoblast cells, which was enhanced by A-769662. Inactivation of AMPK by its inhibitor compound C, or by target shRNA-mediated silencing and kinase dead (KD) mutation exacerbated H(2)O(2)-induced cytotoxicity in osteoblast cells. A-769662-mediated protective effect against H(2)O(2) was also blocked by AMPK inhibition or depletion. A-769662 inhibited reactive oxygen species (ROS) accumulation by H(2)O(2) in osteoblast cells. Meanwhile, H(2)O(2)-induced ATP depletion was inhibited by A-769662, but was aggravated by compound C. Further, H(2)O(2) induced AMPK-dependent and pro-survival autophagy in cultured osteoblast cells, which was enhanced by A-769662. Our results suggested that activation of AMPK by H(2)O(2) is anti-apoptosis and pro-survival in osteoblast cells, probably due to its anti-oxidant, pro-autophagy and ATP preservation abilities, and A-769662-mediated cell-protective effect in osteoblast cells requires AMPK activation. Our study suggests that A-769662 might be further investigated as a novel anti-osteonecrosis agent.