Up-regulation of microRNA-203 inhibits myocardial fibrosis and oxidative stress in mice with diabetic cardiomyopathy through the inhibition of PI3K/Akt signaling pathway via PIK3CA

Diabetic cardiomyopathy (DCM) refers to the myocardial dysfunction in the absence of coronary artery disease and hypertension. Recently, the role of microRNAs (miRs) in gene expression regulation has attracted much more attention. Studies have shown that the PI3K/Akt signaling pathway is involved in the growth, metabolism and apoptosis of myocardial cells. Therefore, this study aimed to explore the regulatory role of miR-203 in myocardial fibrosis in mice with DCM via involvement of the PI3K/Akt signaling pathway. Firstly, mouse model of diabetes mellitus (DM) was established and injected with agomir, antagomir or IGF-1 (PI3K/Akt signaling pathway activator) for investigating the role of miR-203 in PIK3CA and the PI3K/Akt signaling pathway. PIK3CA was identified as a target gene of miR-203, and overexpressed miR-203 inhibited the activation of PI3K/Akt signaling pathway. The obtained results indicated that up-regulation of miR-203 reduced myocardial hypertrophy, myocardial fibrosis, myocardial apoptosis, and levels of PIK3CA, PI3K, Akt, Cal I, CoI III, ANP, MDA and ROS in the myocardial tissues, by which DM-induced cardiac dysfunction and pathological changes could be ameliorated. Collectively, our present study highlighted that overexpression of miR-203 may function as a cardioprotective regulator in DCM by targeting PIK3CA via inactivation of PI3K/Akt signaling pathway.