Study On Protective Effect And Its Mechanism Of Metformin On Cardiotoxicity Induced By Doxorubicin

Doxorubicin(DOX)is an effective anthracycline anticancer drug.However,the clinical usage of it is limited due to its severe cardiotoxicity side effects.Metformin(Met)is a kind of first-line antihyperglycemic drug which has a potential protective effect on the heart,it is often used for oral treatment of type 2 diabetes.This article is to explore the possible protective effect of Met against DOX-induced cardiotoxicity and underlying mechanisms.In the study,for the sake of exploring the Met protective effect and mechanism,we established the DOX-induced cardiotoxicity models both in H9C2 cells incubated with DOX in vitro and Sprague–Dawley rats treated with DOX.The protective effect of Met on DOX-induced H9C2 cells was investigated by determining cell viability via the MTT assay and performing cell apoptosis via flow cytometry analysis.The protective effect of Met on DOX-induced SD rats were examined by measuring serum myocardial function damage indicators creatine kinase-MB(CK-MB)and Lactic dehydrogenase(LDH)using serum biochemical analyzer,evaluating cardiac function indicators by electrocardiogram and echocardiography,and observing heart tissue morphology and myocardial apoptosis under microscope.Then,the mechanism of protective effects of Met on DOX-induced cardiotoxicity was initially explored by detecting oxidative stress indicators,Western-blotting and other methods.In the results,Met can inhibit growth inhibition and apoptosis of H9C2 cells induced by DOX.The heart indexes of rats were examined to evaluate the Met cardiotoxicity protection.Met improved the abnormal indexes,serum markers of cardiac heart injury,echocardiography,electrocardiogram,cardiac pathology,cardiomyocyte apoptosis,and oxidative stress markers induced by DOX.Furthermore,in vivo and in vitro studies demonstrated that Met significantly inhibited the upregulation of cleaved-caspase-3 and pro-apoptotic protein Bax caused by DOX,significantly promotes the down-regulation of DOX-induced anti-apoptotic protein Bcl-2,reduced cardiac oxidative stress.Met inhibited mitogen-activated protein kinase(MAPK)pathway and activated AMP-activated protein kinase(AMPK)signaling pathway,as revealed by prominent attenuation of phosphorylation of ERK,JNK,p38,whereas overt enhancement of phosphorylation of AMPK.In the DOX-induced autophagy model of H9C2 cells,Met can regulate autophagy proteins,significantly inhibited the up-regulation of the expression of LC3 II,Beclin1,and P62 proteins caused by DOX,relieved DOX-induced inhibition of lysosomal acidification and improve DOX-induced autophagy.In vivo experiments,Met can significantly inhibit DOXinduced increase in LC3 II,Beclin1 and P62 protein expression,and improve DOXinduced autophagy.The protective effects of Met were systematically studied in vitro and in vivo models,including DOX-induced H9C2 cells and DOX-induced cardiac toxicity in rats.The protective mechanism of Met was related to reduction of oxidative stress and apoptosis,regulation of autophagy and regulation of AMPK and MAPK signal pathways.