| Background: Doxorubicin(DOX)is a broad-spectrum and efficient anthracycline chemotherapeutic agent,which is one of the most commonly used antineoplastic drugs in clinic.However,DOX-induced cardiotoxicity has become increasingly prominent due to the prolonged survival period of cancer patients after the advancement of modern cancer remedy,which has become the main reason to blunt the clinical application of DOX.Previous studies have confirmed that oxidative stress and cell apoptosis are the key pathophysiological mechanisms of DOX-elicited cardiomyocytes injury and cardiac dysfunction.Exercise is an effective non-drug therapy to reduce DOX-induced cardiotoxicity.Efficient aerobic exercise can maintain the redox homeostasis of cardiomyocytes,reduce DOX-caused pathological damage and significantly improve cardiac systolic/diastolic function.Moreover,exercise does not affect the chemotherapeutic effect of DOX on tumors,unfortunately,cancer patients often can’t tolerate general physical endurence because of cachexia or chemotherapy.Myokine is the key way to mediate the biological function of exercise,meteorin-like protein(METRNL)was recently identified as a myokine mainly derived from skeletal muscle,which is involved in the regulation of energy metabolism and immune response.Yet,the role of METRNL in DOX-induced cardiotoxicity remains unclear.In this study,we respectively generated DOX-induced cardiotoxicity models in vivo and in vitro,and investigated the possible role and molecular basis of METRNL on DOX-induced oxidative stress,cell apoptosis and cardiac dysfunction.Methods: Mice were exposed to adeno-associated virus 9(AAV9)injection via tail vein or intramyocardial adenovirus(AdV)injection to specifically overexpress or knock down METRNL in murine hearts,which were then intraperitoneally injected with DOX(4mg/kg/week)for consecutive four weeks to establish DOX-induced cardiotoxicity mouse model.Echocardiography and hemodynamic analysis were performed to assess the role of METRNL in DOX-induced cardiac dysfunction.Molecular detection and histological measurements were used to determine the role of METRNL on DOX-elicited oxidative stress and cell apoptosis.H9C2 cardiomyocytes were cultured to further confirm the protective role of METRNL on DOX-induced cardiomyocyte injury in vitro via transfecting with the adenovirus or small interefering RNA(si RNA)to overexpress and delete METRNL respectively.We also used the neutralizing antibody of METRNL in vivo and in vitro to explore whether METRNL from cardiomyocytes could exert the anti-oxidant and anti-apoptotic effect in a secretion-dependent manner.Finally,we constructed breast tumor-bearing mice to evaluate the effect of METRNL on DOX-mediated chemotherapeutic capacity.Mechanistically,cardiomyocyte-specific SIRT1 knockout mice,si RNA and small molecular inhibitors were used to elucidate the particular mechanism of METRNL in preventing DOX-induced cardiotoxicity.Results: METRNL was abundantly expressed in cardiac muscle,and its expression was significantly downregulated in DOX-treated cardiac muscle and cells compared with the control groups.In DOX-treated mice,cardiac-specific overexpression of METRNL markedly inhibited oxidative stress,cell apoptosis and improved the cardiac dysfunction and survival status.Whereas knockdown of endogenous METRNL in the heart further aggravated DOX-induced cardiotoxicity,and the mice motality rate was also increased.We also confirmed that METRNL overexpression could increase the survival rate of H9C2 cardiomyocytes,reduce oxidative stress and cell apoptosis caused by DOX stimulation,while METRNL knockdown promoted DOX-mediatede damageto H9C2 cardiomyocytes.Application of METRNL neutralizing antibody in vivo exacerbated DOX-triggered cardiac injury and dysfunction,which were notably improved by cardiomyocyte-specific METRNL overexpression.In addition,METRNL could be detected from myocardial perfusion fluid and the culture medium of cardiomyocytes,and its secretion was significantly reduced after DOX treatment.Moreover,the beneficial effect of METRNL on cardiomyocyte injury was also disappeared after the incubation with METRNL neutralizing antibody.At last,data from 4T1 breast cancer cells and tumor-bearing mice model confirmed that METRNL treatment did not affect the anti-tumor effect of DOX.In terms of mechanism,we found that METRNL can activate SIRT1 via the cAMP/PKA pathway to exert the cardio-protective effect,whereas SIRT1 specific knockout in cardiomyocytes notably blocked the anti-oxidant and anti-apoptotic capacity of MENRTL.Conclusion: Cardiomyocyte-derived METRNL can activate SIRT1 via cAMP/PKA pathway in an autocrine manner,which ultimately improved DOX-elicited oxidative stress,cell apoptosis and cardiac dysfunction.Therefore,targeting METRNL might help to develop safe and effective interventions for the treatment of DOX-induced cardiotoxicity. |
