The hybrid energy metabolism profile of human colorectal cancer cells.

In a continuous effort to characterize the energy metabolism of colorectal cancer, the glycolytic and oxidative phosphorylation fluxes of human colorectal cancer Caco2 cells, cultured and incubated under various conditions, were assessed. Furthermore, the activities and kinetic parameters of several glycolytic and antioxidant enzymes were determined. Both pathways made similar contributions to the cell ATP supply, indicating a hybrid energy metabolism in these colorectal cancer cells, rather than the widely assumed "glycolytic phenotype" commonly associated with this type of cancer. The kinetic analysis of glycolysis and antioxidant pathway revealed no significant differences in enzyme activities and kinetic parameters among Caco2 cells grown under different conditions. However, (a) the glycolytic LDH/PyK, PyK/PFK-1 and PFK-1/HK, and antioxidant G6PD/IDH and CAT/SOD activity ratios, and (b) the strong HPI inhibition exerted by Ery4P indicated clear regulatory differences between cancer and non-cancer cells, which may be considered as potential metabolic biomarkers and suitable drug targets.