title: Role of hypoxia-inducible factors in the dexrazoxane-mediated protection of cardiomyocytes from doxorubicin-induced toxicity.
abstract: OBJECTIVE
  Iron aggravates the cardiotoxicity of doxorubicin, a widely used anticancer anthracycline, and the iron chelator dexrazoxane is the only agent protecting against doxorubicin cardiotoxicity; however, the mechanisms underlying the role of iron in doxorubicin-mediated cardiotoxicity and the protective role of dexrazoxane remain to be established. As iron is required for the degradation of hypoxia-inducible factors (HIF), which control the expression of antiapoptotic and protective genes, we tested the hypothesis that dexrazoxane-dependent HIF activation may mediate the cardioprotective effect of dexrazoxane.
  
  
  METHODS
  Cell death, protein levels (by immunoblotting) and HIF-mediated transcription (using reporter constructs) were evaluated in the rat H9c2 cardiomyocyte cell line exposed to low doses of doxorubicin with or without dexrazoxane pretreatment. HIF levels were genetically manipulated by transfecting dominant-negative mutants or short hairpin RNA.
  
  
  RESULTS
  Treatment with dexrazoxane induced HIF-1α and HIF-2α protein levels and transactivation capacity in H9c2 cells. It also prevented the induction of cell death and apoptosis by exposure of H9c2 cells to clinically relevant concentrations of doxorubicin. Suppression of HIF activity strongly reduced the protective effect of dexrazoxane. Conversely, HIF-1α overexpression protected against doxorubicin-mediated cell death and apoptosis also in cells not exposed to the chelator. Exposure to dexrazoxane increased the expression of the HIF-regulated, antiapoptotic proteins survivin, Mcl1 and haem oxygenase.
  
  
  CONCLUSIONS
  Our results showing HIF-dependent prevention of doxorubicin toxicity in dexrazoxane-treated H9c2 cardiomyocytes suggest that HIF activation may be a mechanism contributing to the protective effect of dexrazoxane against anthracycline cardiotoxicity.
authors.affiliation: Department of Human Morphology and Biomedical Sciences 'Città Studi', University of Milan, Milano, Italy.
authors.forename: R D
authors.initials: RD
authors.lastname: Spagnuolo
authors.forename: S
authors.initials: S
authors.lastname: Recalcati
authors.forename: L
authors.initials: L
authors.lastname: Tacchini
authors.forename: G
authors.initials: G
authors.lastname: Cairo
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects; D051792:Basic Helix-Loop-Helix Proteins / Q000502:physiology*; D002460:Cell Line; D004317:Doxorubicin / Q000633:toxicity*; D020869:Gene Expression Profiling; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology*; D007502:Iron Chelating Agents / Q000494:pharmacology*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D011929:Razoxane / Q000494:pharmacology*; D015533:Transcriptional Activation; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D000903:Antibiotics, Antineoplastic; D051792:Basic Helix-Loop-Helix Proteins; D004317:Doxorubicin; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007502:Iron Chelating Agents; D011929:Razoxane; D000099162:Endothelial PAS Domain-Containing Protein 1