title: Doxorubicin increases oxidative metabolism in HL-1 cardiomyocytes as shown by 13C metabolic flux analysis.
abstract: Doxorubicin (DXR), an anticancer drug, is limited in its use due to severe cardiotoxic effects. These effects are partly caused by disturbed myocardial energy metabolism. We analyzed the effects of therapeutically relevant but nontoxic DXR concentrations for their effects on metabolic fluxes, cell respiration, and intracellular ATP. (13)C isotope labeling studies using [U-(13)C(6)]glucose, [1,2-(13)C(2)]glucose, and [U-(13)C(5)]glutamine were carried out on HL-1 cardiomyocytes exposed to 0.01 and 0.02 μM DXR and compared with the untreated control. Metabolic fluxes were calculated by integrating production and uptake rates of extracellular metabolites (glucose, lactate, pyruvate, and amino acids) as well as (13)C-labeling in secreted lactate derived from the respective (13)C-labeled substrates into a metabolic network model. The investigated DXR concentrations (0.01 and 0.02 μM) had no effect on cell viability and beating of the HL-1 cardiomyocytes. Glycolytic fluxes were significantly reduced in treated cells at tested DXR concentrations. Oxidative metabolism was significantly increased (higher glucose oxidation, oxidative decarboxylation, TCA cycle rates, and respiration) suggesting a more efficient use of glucose carbon. These changes were accompanied by decrease of intracellular ATP. We conclude that DXR in nanomolar range significantly changes central carbon metabolism in HL-1 cardiomyocytes, which results in a higher coupling of glycolysis and TCA cycle. The myocytes probably try to compensate for decreased intracellular ATP, which in turn may be the result of a loss of NADH electrons via either formation of reactive oxygen species or electron shunting.
authors: Biochemical Engineering Institute, Saarland University, Saarbruecken, Germany.
authors: Alexander
authors: A
authors: Strigun
authors: Judith
authors: J
authors: Wahrheit
authors: Jens
authors: J
authors: Niklas
authors: Elmar
authors: E
authors: Heinzle
authors: Fozia
authors: F
authors: Noor
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D002247:Carbon Isotopes; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002952:Citric Acid Cycle / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects*; D005947:Glucose / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects; D019344:Lactic Acid / Q000378:metabolism; D051379:Mice; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D010084:Oxidation-Reduction; D019289:Pyruvic Acid / Q000378:metabolism; D013997:Time Factors
chemical_list: D000596:Amino Acids; D000903:Antibiotics, Antineoplastic; D002247:Carbon Isotopes; D005973:Glutamine; D019344:Lactic Acid; D004317:Doxorubicin; D019289:Pyruvic Acid; D000255:Adenosine Triphosphate; D005947:Glucose