title: Erythropoietin protects against doxorubicin-induced cardiomyopathy via a phosphatidylinositol 3-kinase-dependent pathway.
abstract: Doxorubicin (DOX) is an effective antineoplastic agent whose use has been limited by its cardiotoxic side effects. Recent studies have established that erythropoietin (EPO), a cytokine essential for red blood cell production, protects against ischemic injury in the heart and other organs. The purpose of this study was to assess whether EPO protects the heart against cardiotoxicity induced by DOX. We found that DOX-induced apoptosis and impaired heart function in mice were largely prevented by EPO administration. To investigate the mechanism of protection by EPO, cultured neonatal mouse ventricular myocytes were treated with EPO at therapeutic levels (i.e., 1 U/ml), before application of DOX (0.1-1.0 microM). EPO protected against DOX-induced cardiomyocyte death (by approximately 50%) and apoptosis assessed by annexin-V labeling, DNA fragmentation, and caspase-3 activity. DOX-mediated increases in reactive oxygen species, which trigger cardiotoxicity, were also reversed by preconditioning with EPO. These functional effects of EPO correlated with increased Akt/protein kinase B ( approximately 2-fold) and glycogen synthase kinase 3 (GSK-3; approximately 1.3-fold) phosphorylations, suggesting protection by EPO was mediated by phosphatidylinositol 3-kinase activation. Indeed, preventing Akt and GSK-3beta phosphorylations by phosphatidylinositol 3-kinase (PI3K) inhibition abolished protection by EPO against cardiomyocyte loss, apoptosis, and oxidative stress. Thus, pretreatment with therapeutic levels of EPO can protect the myocardium against DOX-induced impaired heart function and cardiomyocyte apoptosis by activating PI3K-Akt cell survival pathways.
authors.affiliation: Departments of Physiology and Medicine, Heart and Stroke/Richard Lewar Centre of Excellence, Room 71, FitzGerald Bldg. 150 College St., Toronto, ON M5S 3E2, Canada.
authors.forename: Kyoung-Han
authors.initials: KH
authors.lastname: Kim
authors.forename: Gavin Y
authors.initials: GY
authors.lastname: Oudit
authors.forename: Peter H
authors.initials: PH
authors.lastname: Backx
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D009202:Cardiomyopathies / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D002316:Cardiotonic Agents / Q000627:therapeutic use*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004317:Doxorubicin / Q000633:toxicity*; D004921:Erythropoietin / Q000627:therapeutic use*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D017467:Receptors, Erythropoietin / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D002316:Cardiotonic Agents; D017382:Reactive Oxygen Species; D017467:Receptors, Erythropoietin; D004921:Erythropoietin; D004317:Doxorubicin; D019869:Phosphatidylinositol 3-Kinases; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3