title: MAPK superfamily plays an important role in daunomycin-induced apoptosis of cardiac myocytes.
abstract: BACKGROUND
  Although anthracyclines, such as daunomycin (DM) and adriamycin, are potent chemotherapeutic agents, they have serious adverse effects, including cardiac toxicity. In the present study, we investigated the molecular mechanisms of DM-induced cardiomyocyte impairment.
  
  
  RESULTS
  When cultured cardiac myocytes of neonatal rats were exposed to 1 micromol/L DM for 24 hours, many cells became positive for TUNEL staining, with morphological changes characteristic of apoptosis. Fragmentation of DNA into oligonucleosome-size fragments was recognized by agarose gel electrophoresis in DM-treated myocytes. DM activated 3 members of the mitogen-activated protein kinase (MAPK) family dose-dependently, such as extracellular signal-regulated protein kinases (ERKs), c-Jun NH(2)-terminal kinases, and p38 MAPK in cardiac myocytes. Oxyradical scavengers or Ca(2+) chelators inhibited DM-induced activation of ERKs and p38 MAPK. DM-induced activation of ERKs was also inhibited by overexpression of dominant negative mutants of Ras (D.N.Ras), and the p38 MAPK activation was attenuated by D.N.Rho. The number of DM-induced apoptotic cells was markedly increased when the ERK signaling pathway was selectively blocked by a specific MAPK/ERK kinase inhibitor, PD98059, whereas pretreatment with a specific inhibitor of p38 MAPK, SB203580, significantly reduced the amount of apoptosis.
  
  
  CONCLUSIONS
  These results suggest that DM activates MAPKs through reactive oxygen species and Ca(2+) and that the MAPK family plays important roles in DM-induced apoptosis in cardiac myocytes. ERKs protect cardiomyocytes from apoptosis, whereas p38 MAPK is involved in the induction of cardiomyocyte apoptosis.
authors.affiliation: Department of Cardiovascular Medicine, University of Tokyo Graduate School of Medicine, Japan.
authors.forename: W
authors.initials: W
authors.lastname: Zhu
authors.forename: Y
authors.initials: Y
authors.lastname: Zou
authors.forename: R
authors.initials: R
authors.lastname: Aikawa
authors.forename: K
authors.initials: K
authors.lastname: Harada
authors.forename: S
authors.initials: S
authors.lastname: Kudoh
authors.forename: H
authors.initials: H
authors.lastname: Uozumi
authors.forename: D
authors.initials: D
authors.lastname: Hayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Gu
authors.forename: T
authors.initials: T
authors.lastname: Yamazaki
authors.forename: R
authors.initials: R
authors.lastname: Nagai
authors.forename: Y
authors.initials: Y
authors.lastname: Yazaki
authors.forename: I
authors.initials: I
authors.lastname: Komuro
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003630:Daunorubicin / Q000627:therapeutic use*; D004789:Enzyme Activation; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000903:Antibiotics, Antineoplastic; D011505:Protein-Tyrosine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium; D003630:Daunorubicin