Tanshinone IIA protects against heart failure post-myocardial infarction via AMPKs/mTOR-dependent autophagy pathway

Heart failure (HF) leads to an increase in morbidity and mortality globally. Tanshinone IIA is an important traditional Chinese medicine monomer and has been shown to have remarkable protective effect against HF. Autophagy is critically involved in the progression of HF. The effect of Tanshinone IIA on autophagy has not been clarified yet. In this study, left anterior descending (LAD) ligation was used to induce HF model and a hydrogen peroxide-(H₂O₂-)-induced H9C2 cell injury model was established. in vivo, echocardiography results showed that Tanshinone IIA could significantly improve heart function. Western Blot result showed that Tanshinone IIA treatment enhanced autophagy and regulated expressions of key autophagy-related molecules, including protein 1 light chain 3 (LC3), p62 and Beclin1. Tanshinone IIA also inhibited apoptosis and regulated expressions of key apoptotic protein, including B cell lymphoma-2 (Bcl-2) and Bcl-2 Associated X Protein (Bax) and cleaved caspase-3 and -7. Further experiments demonstrated that the effects of Tanshinone IIA were mediated through upregulation of AMP-activated protein kinase (AMPK) and downregulation of mammalian target of rapamycin (mTOR) simultaneously. The mTOR agonist MHY1485 could abrogate the therapeutic effect of Tanshinone IIA in vitro. In conclusion, Tanshinone IIA protects cardiomyocytes and improves cardiac function by inhibiting apoptosis and inducing autophagy via activation of the AMPK-mTOR signaling pathway.