Reactive oxygen species-independent apoptosis in doxorubicin-treated H9c2 cardiomyocytes: role for heme oxygenase-1 down-modulation.
Increased oxidative stress and apoptosis have been implicated in the cardiotoxicity that limits the clinical use of doxorubicin (DOX) as an anti-tumoral drug, but the mechanism of DOX-mediated apoptosis remains unclear. We examined the interplay between oxidative stress and cell death in cardiac-derived H9c2 myocytes exposed to DOX doses in the range of the plasma levels found in patients undergoing chemotherapy. A low DOX concentration (0.25 microM) induced apoptosis, whereas the cells treated with the high dose of 2 microM also showed necrosis. The production of reactive oxygen species (ROS) and induction of oxidative stress markers was increased in the cells treated with 2 microM DOX but not in those treated with the low dose. Surprisingly, heme oxygenase (HO-1) expression was down-modulated in the cells exposed to 0.25 microM DOX, and its Bach 1 transcriptional repressor was induced. In line with the role of HO-1 as an anti-apoptotic protein, inhibiting HO-1 activity with SnPPIX was sufficient to induce apoptosis and increased DOX-mediated apoptosis, whereas hemin-induced HO-1 activation prevented DOX-mediated apoptotic cell death. In brief, our findings do not support the hypothesis that oxidative stress plays a role in the apoptotic cell death occurring in cardiomyocytes exposed to low concentrations of DOX, but suggest that DOX may facilitate the apoptosis of cardiomyocytes by inhibiting the anti-apoptotic HO-1.
Institute of General Pathology, University of Milan, Via Mangiagalli 31, 20133 Milan, Italy.
Francesca
F
Bernuzzi
Stefania
S
Recalcati
Alessandra
A
Alberghini
Gaetano
G
Cairo
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects*; D004317:Doxorubicin / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D009336:Necrosis / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D004317:Doxorubicin; D051547:Heme Oxygenase-1