Biological Testing Branch, Developmental Therapeutics Program, SAIC-Frederick Inc., NCI-Frederick, Frederick, MD 21702, USA.
Int J Cancer. 2010 Dec 1;127(11):2510-9. doi: 10.1002/ijc.25499.
The "Warburg effect," also termed aerobic glycolysis, describes the increased reliance of cancer cells on glycolysis for ATP production, even in the presence of oxygen. Consequently, there is continued interest in inhibitors of glycolysis as cancer therapeutics. One example is dichloroacetate (DCA), a pyruvate mimetic that stimulates oxidative phosphorylation through inhibition of pyruvate dehydrogenase kinase. In this study, the mechanistic basis for DCA anti-cancer activity was re-evaluated in vitro using biochemical, cellular and proteomic approaches. Results demonstrated that DCA is relatively inactive (IC(50) ≥ 17 mM, 48 hr), induces apoptosis only at high concentrations (≥ 25 mM, 48 hr) and is not cancer cell selective. Subsequent 2D-PAGE proteomic analysis confirmed DCA-induced growth suppression without apoptosis induction. Furthermore, DCA depolarizes mitochondria and promotes reactive oxygen species (ROS) generation in all cell types. However, DCA was found to have selective activity against rho(0) cells [mitochondrial DNA (mtDNA) deficient] and to synergize with 2-deoxyglucose in complex IV deficient HCT116 p53(-/-) cells. DCA also synergized in vitro with cisplatin and topotecan, two antineoplastic agents known to damage mitochondrial DNA. These data suggest that in cells "hardwired" to selectively utilize glycolysis for ATP generation (e.g., through mtDNA mutations), the ability of DCA to force oxidative phosphorylation confers selective toxicity. In conclusion, although we provide a mechanism distinct from that reported previously, the ability of DCA to target cell lines with defects in the electron transport chain and to synergize with existing chemotherapeutics supports further preclinical development.
“沃伯格效应”，又称有氧糖酵解，描述了癌细胞对糖酵解产生 ATP 的依赖性增加，即使在有氧气的情况下也是如此。因此，人们一直对糖酵解抑制剂作为癌症治疗药物感兴趣。其中一个例子是二氯乙酸（DCA），它是一种丙酮酸类似物，通过抑制丙酮酸脱氢酶激酶来刺激氧化磷酸化。在这项研究中，使用生化、细胞和蛋白质组学方法在体外重新评估了 DCA 的抗癌活性的机制基础。结果表明，DCA 的活性相对较低（IC50≥17mM，48 小时），仅在高浓度（≥25mM，48 小时）下诱导细胞凋亡，并且对癌细胞没有选择性。随后的 2D-PAGE 蛋白质组学分析证实，DCA 诱导生长抑制而不诱导细胞凋亡。此外，DCA 使线粒体去极化并促进所有细胞类型中活性氧（ROS）的产生。然而，发现 DCA 对 rho(0)细胞（线粒体 DNA（mtDNA）缺失）具有选择性活性，并与 complex IV 缺陷的 HCT116 p53(-/-)细胞中的 2-脱氧葡萄糖协同作用。DCA 还与顺铂和拓扑替康在体外协同作用，顺铂和拓扑替康是两种已知破坏线粒体 DNA 的抗肿瘤药物。这些数据表明，在细胞中“硬连线”以选择性地利用糖酵解产生 ATP（例如，通过 mtDNA 突变），DCA 迫使氧化磷酸化的能力赋予了选择性毒性。总之，尽管我们提供了与以前报道的不同的机制，但 DCA 靶向电子传递链有缺陷的细胞系并与现有化疗药物协同作用的能力支持进一步的临床前开发。
