title: Blockade of the erbB2 receptor induces cardiomyocyte death through mitochondrial and reactive oxygen species-dependent pathways.
abstract: Overexpression of the receptor tyrosine kinase erbB2 (Her2 in humans) is correlated with a poor prognosis in breast and ovarian cancers. Treatment with trastuzumab (a monoclonal antibody against erbB2) improves survival; however, it also causes cardiomyopathy. We hypothesized that blockade of the erbB2 receptor induces cardiomyocyte death through a mitochondrial pathway that is dependent on the production of reactive oxygen species (ROS). We first showed that levels of erbB2 receptor are significantly decreased in an animal model of ischemic heart disease and in human ischemic cardiomyopathy. We treated neonatal rat cardiomyocytes with an inhibitory erbB2 antibody to study the mechanism behind the deleterious effects of erbB2 blockade. These cells displayed a dose-dependent increase in ROS production and cell death compared with control IgG-treated cells; these processes were reversed by the antioxidant, N-acetylcysteine. The effects of erbB2 antibody on both cell death and ROS production were also reversed by cyclosporine A and diazoxide, chemicals that regulate the pro- and anti-apoptotic channels in the mitochondria, respectively. Furthermore, mouse embryonic fibroblasts lacking Bax and Bak (proteins that mediate cell death through a mitochondrial pathway) were resistant to the deleterious effects of erbB2 antibody. These effects of erbB2 blockade appear to occur through a pathway involving AKT and PKC-alpha. Our results suggest that erbB2 plays a role in cardiomyocyte survival, and that the deleterious effects of trastuzumab on the heart occur through a mitochondrial pathway and is mediated by ROS production. Manipulation of redox signaling may be beneficial in cancer patients receiving trastuzumab.
authors.affiliation: Division of Hematology/Oncology, Department of Medicine, Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Leo I
authors.initials: LI
authors.lastname: Gordon
authors.forename: Michael A
authors.initials: MA
authors.lastname: Burke
authors.forename: Amareshwar T K
authors.initials: AT
authors.lastname: Singh
authors.forename: Sheila
authors.initials: S
authors.lastname: Prachand
authors.forename: Elliot D
authors.initials: ED
authors.lastname: Lieberman
authors.forename: Lin
authors.initials: L
authors.lastname: Sun
authors.forename: Tejaswitha Jairaj
authors.initials: TJ
authors.lastname: Naik
authors.forename: Sathyamangla V Naga
authors.initials: SV
authors.lastname: Prasad
authors.forename: Hossein
authors.initials: H
authors.lastname: Ardehali
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D016923:Cell Death; D004285:Dogs; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D017202:Myocardial Ischemia / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D051571:Protein Kinase C-alpha / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors
chemical_list: D000906:Antibodies; D051571:Protein Kinase C-alpha; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D018719:Erb-b2 Receptor Tyrosine Kinases