Oxygen and glucose consumption in gastrointestinal adenocarcinomas: Correlation with markers of hypoxia, acidity and anaerobic glycolysis

This study gives an insight into tumor metabolic activity by investigating oxygen and glucose content, together with their metabolic products carbon dioxide and acids-pH, in the arterial and venous blood of a tumor. Nineteen patients with gastrointestinal adenocarcinomas undergoing surgery were studied. Biochemical analysis showed that in a large subgroup of tumors, oxygen consumption was reduced while that of glucose was increased in malignant, as compared to normal tissues; these features were more evident in tumors overexpressing lactate dehydrogenase (LDH-5) and hypoxia inducible factors (HIF1 alpha/2 alpha). An increase in carbon dioxide production in the tumor environment was linked with overexpression of carbonic anhydrase 9 (CA9). The simultaneous overexpression of CA9 and LDH-5 was related to very low pH levels in the veins draining the tumor, suggesting an intense acidification of the tumor microenvironment in such cases. These in vivo data confirm the importance of HIFs and their downstream regulated genes in tumor metabolism, particularly in glycolysis and carbon dioxide buffering.