Enhanced- autophagy by exenatide mitigates doxorubicin-induced cardiotoxicity in vitro and in vivo

Objective: Exenatide, glucagon-like peptide-1 analogue, mitigates myocardial injury caused by ischemia/reperfusion injury via survival signaling pathway. We investigated that exenatide would also provide a protective effect in doxorubicin-induced cardiotoxicity. Design and Method: H9c2 cardiomyocytes were incubated after treatment with doxorubicin (DOX, 1, 10 uM) or pre-treatment with exenatide (3, 30 nM) followed by DOX in vitro. Incubated cells were measured with cell viability and autophagosome staining. In vivo, SD rat was treated with exenatide (10 ug/kg, subcutaneous injection) or control saline 1 hour prior to every DOX (accumulative dose, 20 mg/kg) intraperitoneal injection, and left ventricular (LV) function and performance were assessed by echocardiography. Western blot, TUNEL staining and ROS study to determine the intracellular changes. Autophagic process was visualized by Cyto-ID staining in H9c2. Results: In vivo, echocardiography shows that reduced LV function by DOX treatment was significantly improved by pre-treatment of exenatide. Doxorubicin significantly increased myocyte apotosis by TUNEL and ratio of activated caspase-3, which also decreased by pre-treatment exenatide. However, the oxidative stress in cardiac tissue and serum did not significant differ between each groups. Autophagic markers, LC3 II, Beclin, and ATG5 signal increased in exenatide combination group. Also, number of autophagosomes increasedappreciably with more exenatide pre-treated H9c2 cells than DOX treated cells. When suppress the formation of autophagosome by Bafilomycin A1, apoptosis regulated under the exenatide-mediated autophagy inhibition in H9c2. Conclusions: Exenatide reduces DOX-induced cardiomyocytes apoptosis by upregulating autophagy and improves cardiac function. These novel results highlight the therapeutic potential of exenatide to prevent doxorubicin cardiotoxicity.