title: Modulation of anthracycline-induced myofibrillar disarray in rat ventricular myocytes by neuregulin-1beta and anti-erbB2: potential mechanism for trastuzumab-induced cardiotoxicity.
abstract: BACKGROUND
  There is an increased incidence of heart failure in patients treated concurrently with anthracyclines and the chemotherapeutic anti-erbB2 agent trastuzumab (Herceptin). On the basis of our previous studies with recombinant neuregulin-1beta (NRG-1beta), a ligand for the erbB2 receptor tyrosine kinase, we hypothesized that activation of erbB2 by anti-erbB2 versus NRG-1 would cause differential effects on myocyte intracellular signaling as well as anthracycline-induced myofibrillar injury and might potentially account for the clinical toxicity of trastuzumab in the setting of concurrent anthracycline therapy.
  
  
  RESULTS
  We tested this hypothesis using adult rat ventricular myocytes (ARVMs) in culture, assessing myofibrillar structure by immunostaining for myomesin and filamentous actin. Activation of erbB2, extracellular signal-regulated kinase 1/2 (Erk1/2), and Akt was assessed by use of antibodies to phosphorylated activated receptor or kinase detected by immunoblot. ARVMs treated with doxorubicin (0.1 to 0.5 micromol/L) showed a concentration-dependent increase in myofilament disarray. NRG-1beta (10 ng/mL) activated erbB2, Erk1/2, and Akt in ARVMs and significantly reduced anthracycline-induced disarray. In contrast to NRG-1beta, anti-erbB2 (1 microg/mL) caused rapid phosphorylation of erbB2 but not Erk1/2 or Akt, with downregulation of erbB2 by 24 hours. Concomitant treatment of myocytes with anti-erbB2 and doxorubicin caused a significant increase in myofibrillar disarray versus doxorubicin alone.
  
  
  CONCLUSIONS
  NRG-1beta/erbB signaling regulates anthracycline-induced myofilament injury. The increased susceptibility of myofilaments to doxorubicin in the presence of antibody to erbB2 may explain the contractile dysfunction seen in patients receiving concurrent trastuzumab and anthracyclines.
authors.affiliation: Cardiovascular Medicine Section, Department of Medicine, Boston Medical Center and Myocardial Biology Unit, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Sawyer
authors.forename: Christian
authors.initials: C
authors.lastname: Zuppinger
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Miller
authors.forename: Hans M
authors.initials: HM
authors.lastname: Eppenberger
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Suter
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000648:ultrastructure*; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D000906:Antibodies / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000494:pharmacology / Q000633:toxicity; D061067:Antibodies, Monoclonal, Humanized; D002478:Cells, Cultured; D004317:Doxorubicin / Q000494:pharmacology*; D004357:Drug Synergism; D005260:Female; D006352:Heart Ventricles / Q000187:drug effects / Q000648:ultrastructure; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000648:ultrastructure*; D020890:Neuregulin-1 / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology* / Q000378:metabolism; D000068878:Trastuzumab
chemical_list: D000903:Antibiotics, Antineoplastic; D000906:Antibodies; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D004317:Doxorubicin; D020928:Mitogen-Activated Protein Kinases; D020890:Neuregulin-1; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D018719:Erb-b2 Receptor Tyrosine Kinases; D000068878:Trastuzumab; C117467:neuregulin beta; C494920:Akt1 protein, rat