Inhibition of 6-phosphogluconate dehydrogenase by glucose 1,6-diphosphate in human normal and malignant colon extracts.

Increased activity of 6-phosphogluconate dehydrogenase was found in human colon tumors as compared to the adjacent unaffected mucosa. Glucose 1,6-diphosphate (Glc-1,6-P2), an endogenous potent regulator of glucose metabolism, markedly inhibited the activity of 6-phosphogluconate dehydrogenase (6-PGD) in extracts of the normal and malignant human colon. Glc-1,6-P2 also inhibited the activity of hexokinase in these extracts. The endogenous levels of Glc-1,6-P2 in the colon and tumors were measured. Since the pentose cycle can be inhibited by Glc-1,6-P2, means to increase endogenous levels of Glc-1,6-P2 or to introduce it into cells, might result in antitumor effects.