Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy.
Mol Syst Biol. 2011 Aug 16;7:523. doi: 10.1038/msb.2011.56.
Oncogenes such as K-ras mediate cellular and metabolic transformation during tumorigenesis. To analyze K-Ras-dependent metabolic alterations, we employed ¹³C metabolic flux analysis (MFA), non-targeted tracer fate detection (NTFD) of ¹⁵N-labeled glutamine, and transcriptomic profiling in mouse fibroblast and human carcinoma cell lines. Stable isotope-labeled glucose and glutamine tracers and computational determination of intracellular fluxes indicated that cells expressing oncogenic K-Ras exhibited enhanced glycolytic activity, decreased oxidative flux through the tricarboxylic acid (TCA) cycle, and increased utilization of glutamine for anabolic synthesis. Surprisingly, a non-canonical labeling of TCA cycle-associated metabolites was detected in both transformed cell lines. Transcriptional profiling detected elevated expression of several genes associated with glycolysis, glutamine metabolism, and nucleotide biosynthesis upon transformation with oncogenic K-Ras. Chemical perturbation of enzymes along these pathways further supports the decoupling of glycolysis and TCA metabolism, with glutamine supplying increased carbon to drive the TCA cycle. These results provide evidence for a role of oncogenic K-Ras in the metabolic reprogramming of cancer cells.
癌基因如 K-ras 在肿瘤发生过程中介导细胞和代谢转化。为了分析 K-Ras 依赖性代谢改变，我们采用了 ¹³C 代谢通量分析（MFA）、¹⁵N 标记谷氨酰胺的非靶向示踪物命运检测（NTFD）和小鼠成纤维细胞和人癌细胞系的转录组谱分析。稳定同位素标记的葡萄糖和谷氨酰胺示踪剂以及细胞内通量的计算确定表明，表达致癌 K-Ras 的细胞表现出增强的糖酵解活性、减少三羧酸（TCA）循环中的氧化通量以及增加对用于合成代谢的谷氨酰胺的利用。令人惊讶的是，在两种转化细胞系中都检测到 TCA 循环相关代谢物的非典型标记。转录组谱分析检测到在致癌 K-Ras 转化后，与糖酵解、谷氨酰胺代谢和核苷酸生物合成相关的几个基因的表达水平升高。沿着这些途径的酶的化学扰动进一步支持糖酵解和 TCA 代谢的解耦，谷氨酰胺提供增加的碳来驱动 TCA 循环。这些结果为致癌 K-Ras 在癌细胞的代谢重编程中发挥作用提供了证据。
