Tanshinone IIA inhibits cardiomyocyte apoptosis and rescues cardiac function during doxorubicin-induced cardiotoxicity by activating the DAXX/MEK/ERK1/2 pathway

Heart failure (HF) is a common cardiovascular syndrome. Tanshinone IIA (Tan IIA) is a pharmacologically active monomer that exerts a significant cardioprotective effect in the clinic; however, the specific mechanisms are not fully understood.We mainly investigated the protective effects of Tan IIA on doxorubicin (DOX)-induced HF.In an in vitro study, H9C2 and HL-1 cells were cultured and treated with DOX and Tan IIA for 24 h, we investigated the mechanism underlying Tan IIA-mediated protection. In an in vivo study, a model of DOX-induced HF was established in C57BL/6 mice that were divided into the six groups randomly: a control group, a DOX group, DOX groups treated with Tan IIA (DOX+Tan IIA) at dosages of 2.5, 5 and 10 mg/kg/day and DOX groups treated with N-acetylcysteine (NAC) at dosages of 200 mg/kg/day.The results demonstrated that Tan IIA significantly increased cell viability and protected against DOX-induced apoptosis. RNA-sequencing showed that the genes expression associated with the apoptotic signaling pathway was altered by Tan IIA. Among the differentially expressed genes, death-domain associated protein (DAXX), which plays an critical role in apoptotic signaling, exhibited increased expression under Tan IIA treatment. In addition, RNA interference was used to silence the expression of DAXX, which abolished Tan IIA-mediated protection against DOX-induced apoptosis; this effect was associated with extracellular signal-regulated protein kinase 1/2 (ERK1/2) and mitogen-activated protein kinase (MEK) expression. In the in vivo study, the echocardiography results revealed that heart function was rescued by Tan IIA, and the histomorphology results showed that Tan IIA prevented myocardial structural alteration and myofibril disruption. Furthermore, Tan IIA induced the expressions of DAXX, p-ERK1/2 and p-MEK. Tan IIA also inhibited apoptosis by suppressing the expression of cleaved caspase-8, p-P38 and cleaved caspase-3.Our results provide novel interpretations into the important role of DAXX in DOX-induced cardiotoxicity and show that Tan IIA may be a novel agent strategy for HF treatment via activating the DAXX/MEK/ERK1/2 pathway.