Biochemical Engineering Institute, Saarland University, Saarbruecken, Germany.
Toxicol Sci. 2012 Feb;125(2):595-606. doi: 10.1093/toxsci/kfr298. Epub 2011 Nov 1.
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.
阿霉素（DXR）是一种抗癌药物，但由于其严重的心脏毒性作用而限制了其使用。这些作用部分是由心肌能量代谢紊乱引起的。我们分析了治疗相关但无毒的 DXR 浓度对代谢通量、细胞呼吸和细胞内 ATP 的影响。使用 [U-（13）C（6）]葡萄糖、[1,2-（13）C（2）]葡萄糖和 [U-（13）C（5）]谷氨酰胺对暴露于 0.01 和 0.02 μM DXR 的 HL-1 心肌细胞进行了（13）C 同位素标记研究，并与未处理的对照组进行了比较。通过整合细胞外代谢物（葡萄糖、乳酸、丙酮酸和氨基酸）的产生和摄取率以及来自相应（13）C 标记底物的分泌乳酸中的（13）C 标记，将代谢通量计算到代谢网络模型中。研究的 DXR 浓度（0.01 和 0.02 μM）对 HL-1 心肌细胞的活力和搏动没有影响。在测试的 DXR 浓度下，糖酵解通量在处理过的细胞中显着降低。氧化代谢显着增加（更高的葡萄糖氧化、氧化脱羧、TCA 循环速率和呼吸），表明葡萄糖碳的利用效率更高。这些变化伴随着细胞内 ATP 的减少。我们得出结论，纳摩尔范围内的 DXR 显着改变了 HL-1 心肌细胞中的中央碳代谢，导致糖酵解和 TCA 循环的耦合更高。心肌细胞可能试图补偿细胞内 ATP 的减少，这反过来可能是由于形成活性氧或电子分流而导致 NADH 电子损失的结果。
