Quantitative Metabolome Profiling of Colon and Stomach Cancer Microenvironment by Capillary Electrophoresis Time-of-Flight Mass Spectrometry

TLDR

Cancer cells preferentially use glycolysis (Warburg effect) even with oxygen, yet direct global metabolite measurements in clinical tumor tissues are scarce. The study applied capillary electrophoresis time‑of‑flight mass spectrometry to quantify charged metabolites in tumor and adjacent normal tissues from 16 colon and 12 stomach cancer patients. Quantification of 94–95 metabolites across glycolysis, the pentose phosphate pathway, the TCA and urea cycles, and amino‑acid and nucleotide metabolism revealed several cancer‑specific metabolic traits. Tumor tissues showed markedly low glucose, high lactate and glycolytic intermediates, widespread amino‑acid accumulation (except glutamine), organ‑specific TCA differences, and overall poor nutrition, confirming the Warburg effect and underscoring CE‑TOFMS as a powerful tool for developing metabolism‑targeted anticancer agents.

Abstract

Most cancer cells predominantly produce energy by glycolysis rather than oxidative phosphorylation via the tricarboxylic acid (TCA) cycle, even in the presence of an adequate oxygen supply (Warburg effect). However, little has been reported regarding the direct measurements of global metabolites in clinical tumor tissues. Here, we applied capillary electrophoresis time-of-flight mass spectrometry, which enables comprehensive and quantitative analysis of charged metabolites, to simultaneously measure their levels in tumor and grossly normal tissues obtained from 16 colon and 12 stomach cancer patients. Quantification of 94 metabolites in colon and 95 metabolites in stomach involved in glycolysis, the pentose phosphate pathway, the TCA and urea cycles, and amino acid and nucleotide metabolisms resulted in the identification of several cancer-specific metabolic traits. Extremely low glucose and high lactate and glycolytic intermediate concentrations were found in both colon and stomach tumor tissues, which indicated enhanced glycolysis and thus confirmed the Warburg effect. Significant accumulation of all amino acids except glutamine in the tumors implied autophagic degradation of proteins and active glutamine breakdown for energy production, i.e., glutaminolysis. In addition, significant organ-specific differences were found in the levels of TCA cycle intermediates, which reflected the dependency of each tissue on aerobic respiration according to oxygen availability. The results uncovered unexpectedly poor nutritional conditions in the actual tumor microenvironment and showed that capillary electrophoresis coupled to mass spectrometry-based metabolomics, which is capable of quantifying the levels of energy metabolites in tissues, could be a powerful tool for the development of novel anticancer agents that target cancer-specific metabolism.