MicroRNA-320 involves in the cardioprotective effect of insulin against myocardial ischemia by targeting survivin.

It is generally accepted that insulin exerts an antiapoptotic effect against ischemia/reperfusion through the activation of PI3K/Akt/mTOR pathway. MicroRNAs involve in multiple cardiac pathophysiological processes, including ischemia/reperfusion-induced cardiac injury. However, the regulation of microRNAs in the cardioprotective effect of insulin is rarely discussed. In this study, using a cell model of ischemia through culturing H9C2 cardiac myocytes in serum-free medium with hypoxia, we demonstrated that pretreatment with insulin significantly inhibited cell apoptosis and downregulated microRNA-320 (miR-320) expression. Interestingly, miR-320 mimic impaired the cardioprotective effect of insulin against myocardial ischemia injury by targeting survivin, which is a member of the family of inhibitor of apoptosis proteins. Suppression miR-320 expression by miR-320 inhibitor in H9C2 cells with myocardial ischemia mimics the cardioprotective effect of insulin by maintaining survivin expression. Taken together, miR-320-mediated survivin expression involves in cardioprotective effect of insulin against myocardial ischemia injury.

SIGNIFICANCE OF THIS STUDY: Myocardial ischemia/reperfusion (I/R) injury remains an important clinical problem with extremely deficient clinical therapies. Insulin exerts an antiapoptotic effect against I/R through the activation of PI3K/Akt/mTOR pathway. Here, we provided evidences to show that microRNA-320 involves in the cardioprotective effect of insulin by targeting survivin, which is an inhibitor of apoptosis protein and functions as a key regulator in cell apoptosis and involves in the tumour genesis and progression. Our findings may provide a new potential therapeutic strategy for I/R injury and ischemic heart disease.