The elevated D-2-hydroxyglutarate level found as a characteristic metabolic change of colon cancer in both in vitro and in vivo models.

The D-2-hydroxyglutarate (D-2-HG), whose normal cellular concentration is low, can be accumulated 10-100 times natural levels in some cancer types and participates in the carcinogenesis process. D-2-HG is produced by different pathways specific to cancer type. In this study, the level of significant metabolites produced in some metabolic pathways related to D-2-HG in the energy metabolism was determined in colon adenocarcinoma cell lines at different stages. Then, the differences in TCA and Cori cycle, glutaminolysis, and Glycolysis were investigated in the brain, colon, liver, and tumor tissues extracted from xenograft models. The levels of glucose, pyruvate, lactate, all TCA cycle intermediates, and D-2-HG were determined by the HPLC analysis, DNS method, and pyruvate assay. The intracellular D-2-HG level was found at 22.6 μmol/mg in primary (Caco-2) and 152.6 μmol/mg in metastatic (SW620) colon adenocarcinoma cells, whereas it could not be detected in colon epithelial cell line (CCD-18Co). In the xenograft models, D-2-HG could not be detected in CCD-18Co colon and brain tissues, whereas it was produced in Caco-2 and SW620 tissues. Most importantly, the level of D-2-HG was 7.4 and 19.9-fold increased in Caco-2 and SW620 tumor tissues compared to healthy tissue, respectively. In addition, the D-2-HG production pathways were investigated. The results revealed that the carbon source of D-2-HG is glucose, and the imbalance of wt-IDH1/2 enzymes plays a role in its production. Overall, the in vitro and in vivo results show that the enhanced production of endogenous D-2-HG is a characteristic change in the metabolism of colon cancer.