Knockdown of miR-665 Protects Against Cardiomyocyte Ischemia/Reperfusion Injury-Induced ROS Accumulation and Apoptosis Through the Activation of Pak1/Akt Signaling in Myocardial Infarction.

Myocardial infarction (MI) is one of the major causes of death worldwide, and the therapeutic strategies of MI are still limited. In this study, we investigated the function of miR-665 in MI. In the present study, an ischemia/reperfusion (I/R) rat model and a hypoxia/reoxygenation (H/R)-induced H9c2 cell model were successfully established to mimic the MI for in vivo and in vitro studies. The concentrations of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), tumor necrosis factor alpha (TNF-α), IL-6, and reactive oxygen species (ROS) were then measured. Moreover, cell viability and apoptosis were detected by MTT assay, TdT-mediated dUTP nick end labeling (TUNEL), and PI/FITC-annexin V assay. The binding of miR-665 and Pak1 was determined by luciferase assay. miR-665 was upregulated in I/R rats, and the overexpression of miR-665 significantly increased LDH, CK-MB, TNF-α, IL-6, and ROS concentrations and induced cell apoptosis, while knockdown of miR-665 had opposite results. Consistent with in vivo results, miR-665 induced cell apoptosis and ROS generation in H/R-treated H9c2 cells. More importantly, Pak1 was the target gene of miR-665, and knockdown of miR-665 depressed the accumulation of ROS and cell apoptosis by targeting Pak1 and promoting the phosphorylation of Akt, whereas knockdown of Pak1 could attenuate the protection of miR-665 inhibitor in H/R-treated H9c2 cells. Therefore, knockdown of miR-665 protects against cardiomyocyte ischemia/reperfusion injury-induced ROS accumulation and apoptosis through activating Pak1/Akt signaling in MI. In general, understanding the biology and modulation of miR-665 may have the potential to counteract the development of MI.