OBJECTIVE: To investigate the mechanisms for inhibitory effect of aldehyde dehydrogenase 2 (ALDH2) on doxorubicin (DOX)-induced cytotoxicity in C2C12 myogenic cell line.
 METHODS: Cell apoptosis was evaluated by flow cytometry and the activity of capase-3/7. The relative content of reactive oxygen species (ROS) and 4-hydroxynonenal (4-HNE) were detected by chemical fluorometric enzyme immunoassay. The protein and mRNA expression of ALDH2, Bcl-2, NADPH oxidase 2 (NOX2) and the cytoplasmic subunit p-p47PHOX were evaluated by Western blot and quantitative PCR, respectively. 
 RESULTS: Overexpression of ALDH2 attenuated DOX-induced cell toxicity (increase in apoptosis and inhibition of proliferation), which were reversed by downregulation of ALDH2. Overexpression of ALDH2 reduced p47PHOX phosphorylation levels, and suppressed activation of NOX2 and ROS production, which were reversed by downregulation of ALDH2. Moreover, apocynin, an inhibitor of NOX, reduced the cytotoxicity of DOX concomitantly with a decrease in phosphorylation of p47PHOX, ROS production and caspase-3/7 activity, and an increase in the activity and expression of ALDH2. 
 CONCLUSION DOX-induced cytotoxicity is related to increase of intracellular oxidative stress, which is involved in unregulation of NOX2 and downregulation of ALDH2. Activation of ALDH2 could exert cytoprotection via inhibiting NOX2-dependent ROS production.
Aldehyde Dehydrogenase, Mitochondrial ; Aldehydes ; Animals ; Apoptosis ; Caspase 3 ; Cell Line ; Cell Survival ; Down-Regulation ; Doxorubicin ; Mice ; Oxidative Stress ; Phosphorylation ; Reactive Oxygen Species