- Glutamine is the most abundant amino acid in the body. It has a key role in nitrogen metabolism and is a major source of energy for the enterocyte and many other cells. Glutamine is also essential for tumor growth, and marked changes in organ glutamine metabolism are characteristic in cancer patients. We have investigated the catabolism of glutamine in a classic premalignant condition: the colonic adenomatous polyp. The content of glutamine and activity of two catabolic enzymes, glutamine transferase and phosphate-dependent glutaminase, were studied in normal colon and in polyp mucosa. Free glutamine content and activity of glutaminase were significantly lower in polyps than in their adjacent mucosa. Glutamine transferase activity was significantly lower in polyp mucosa than in normal colon controls. Adenomatous polyps might behave as a glutamine trap, channeling glutamine to protein and nucleic acid synthesis. These changes in glutamine catabolism could play a role in colonic neoplasia pathogenesis.