title: Stimulating basal mitochondrial respiration decreases doxorubicin apoptotic signaling in H9c2 cardiomyoblasts.
abstract: Doxorubicin (DOX) is currently used in cancer chemotherapy, however, its use often results in adverse effects highlighted by the development of cardiomyopathy and ultimately heart failure. Interestingly, DOX cardiotoxicity is decreased by resveratrol or by physical activity, suggesting that increased mitochondrial activity may be protective. Conversely, recent studies showed that troglitazone, a PPARγ agonist, increases the cytotoxicity of DOX against breast cancer cells by up-regulating mitochondrial biogenesis. The hypothesis for the current investigation was that DOX cytotoxicity in H9c2 cardiomyoblasts is decreased when mitochondrial capacity is increased. We focused on several end-points for DOX cytotoxicity, including loss of cell mass, apoptotic signaling and alterations of autophagic-related proteins. Our results show that a galactose-based, modified cell culture medium increased H9c2 basal mitochondrial respiration, protein content, and mtDNA copy number without increasing maximal or spare respiratory capacity. H9c2 cardiomyoblasts cultured in the galactose-modified media showed lower DOX-induced activation of the apoptotic pathway, measured by decreased caspase-3 and -9 activation, and lower p53 expression, although ultimately loss of cells was not prevented. Treatment with the PPARγ agonist troglitazone had no effect on DOX toxicity in this cardiac cell line, which agrees with the fact that troglitazone did not increase mitochondrial DNA content or capacity at the concentrations and duration of exposure used in this investigation. Our results show that mitochondrial remodeling caused by stimulating basal rates of oxidative phosphorylation decreased DOX-induced apoptotic signaling and increased DOX-induced autophagy in H9c2 cardiomyoblasts. The differential effect on cytotoxicity in cardiac versus breast cancer cell lines suggests a possible overall improvement in the clinical efficacy for doxorubicin in treating cancer.
authors.affiliation: CNC-Center for Neuroscience and Cell Biology, University of Coimbra, UC Biotech Building, Biocant Park, 3060-197 Cantanhede, Portugal.
authors.forename: Cláudia M
authors.initials: CM
authors.lastname: Deus
authors.affiliation: Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, USA.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Zehowski
authors.affiliation: Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, USA.
authors.forename: Kendra
authors.initials: K
authors.lastname: Nordgren
authors.affiliation: Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, USA.
authors.forename: Kendall B
authors.initials: KB
authors.lastname: Wallace
authors.affiliation: Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Skildum
authors.affiliation: CNC-Center for Neuroscience and Cell Biology, University of Coimbra, UC Biotech Building, Biocant Park, 3060-197 Cantanhede, Portugal. Electronic address: pauloliv@cnc.uc.pt.
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Oliveira
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D019069:Cell Respiration / Q000187:drug effects; D002839:Chromans / Q000494:pharmacology; D003470:Culture Media / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D004272:DNA, Mitochondrial / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000633:toxicity*; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D063269:Mitochondrial Turnover / Q000187:drug effects*; D032386:Myoblasts, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D045162:Thiazolidinediones / Q000494:pharmacology; D013997:Time Factors; D000077288:Troglitazone; D015854:Up-Regulation
chemical_list: D000903:Antibiotics, Antineoplastic; D051017:Apoptosis Regulatory Proteins; D002839:Chromans; D003470:Culture Media; D004272:DNA, Mitochondrial; D045162:Thiazolidinediones; D004317:Doxorubicin; D000077288:Troglitazone
keywords: Doxorubicin; H9c2 myoblasts; Mitochondrial capacity; Toxicity; Troglitazone