title: Over-expression of calpastatin aggravates cardiotoxicity induced by doxorubicin.
abstract: OBJECTIVE
  Doxorubicin causes damage to the heart, which may present as cardiomyopathy. However, the mechanisms by which doxorubicin induces cardiotoxicity remain not fully understood and no effective prevention for doxorubicin cardiomyopathy is available. Calpains, a family of calcium-dependent thiol-proteases, have been implicated in cardiovascular diseases. Their activities are tightly controlled by calpastatin. This study employed transgenic mice over-expressing calpastatin to investigate the role of calpain in doxorubicin-induced cardiotoxicity.
  
  
  RESULTS
  Doxorubicin treatment decreased calpain activities in cultured neonatal mouse cardiomyocytes and in vivo mouse hearts, which correlated with down-regulation of calpain-1 and calpain-2 proteins. Over-expression of calpastatin or incubation with pharmacological calpain inhibitors enhanced apoptosis in neonatal and adult cardiomyocytes induced by doxorubicin. In contrast, over-expression of calpain-2 but not calpain-1 attenuated doxorubicin-induced apoptosis in cardiomyocytes. The pro-apoptotic effects of calpain inhibition were associated with down-regulation of protein kinase B (AKT) protein and mRNA expression, and a concomitant reduction in glycogen synthase kinase-3beta (GSK-3β) phosphorylation (Ser9) in doxorubicin-treated cardiomyocytes. Blocking AKT further increased doxorubicin-induced cardiac injuries, suggesting the effects of calpain inhibition may be mediated by inactivating the AKT signalling. In an in vivo model of doxorubicin-induced cardiotoxicity, over-expression of calpastatin exacerbated myocardial dysfunction as assessed by echocardiography and haemodynamic measurement in transgenic mice 5 days after doxorubicin injection. The 5-day mortality was higher in transgenic mice (29.16%) compared with their wild-type littermates (8%) after doxorubicin treatment.
  
  
  CONCLUSIONS
  Over-expression of calpastatin enhances doxorubicin-induced cardiac injuries through calpain inhibition and thus, calpains may protect cardiomyocytes against doxorubicin-induced cardiotoxicity.
authors: Department of Cardiology, Shanghai 6th People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200233, China.
authors: Yanpeng
authors: Y
authors: Wang
authors: Dong
authors: D
authors: Zheng
authors: Meng
authors: M
authors: Wei
authors: Jian
authors: J
authors: Ma
authors: Yong
authors: Y
authors: Yu
authors: Ruizhen
authors: R
authors: Chen
authors: James C
authors: JC
authors: Lacefield
authors: Huaxi
authors: H
authors: Xu
authors: Tianqing
authors: T
authors: Peng
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002154:Calpain / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000633:toxicity*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006331:Heart Diseases / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014463:Ultrasonography; D015854:Up-Regulation; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D000903:Antibiotics, Antineoplastic; D002135:Calcium-Binding Proteins; D015853:Cysteine Proteinase Inhibitors; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; C033668:calpastatin; D004317:Doxorubicin; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D002154:Calpain; C112682:Capn1 protein, mouse; C570925:Capn2 protein, mouse
keywords: Calpain; Calpastatin; Cardiotoxicity; Doxorubicin; Protein kinase B