High activity of mitochondrial glycerol phosphate dehydrogenase in insulinomas and carcinoid and other tumors of the amine precursor uptake decarboxylation system

• Published in: Cancer research (Chicago, Ill.) Vol. 50; no. 22; pp. 7203 - 7205
• Main Authors: MACDONALD, M. J, WARNER, T. F, MERTZ, R. J
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 15-11-1990
• Subjects: APUD Cells - enzymology; Biological and medical sciences; Carcinoid Tumor - enzymology; Gastroenterology. Liver. Pancreas. Abdomen; Glycerolphosphate Dehydrogenase - metabolism; Humans; Insulinoma - enzymology; Medical sciences; Mitochondria - enzymology; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Succinate Dehydrogenase - metabolism; Tumors; Endocrinopathy; Human; Nervous system diseases; Glycerol-3-phosphate dehydrogenase; Enzyme; Insulinoma; Paraganglioma; Carcinoid tumor; Gastrinoma; Mitochondria; Enzymatic activity; Thyroid nodule; Digestive diseases; Parathyroid glands; Tumor
• ISSN: 0008-5472; 1538-7445

The activity of the mitochondrial glycerol phosphate dehydrogenase (EC 1.1.99.5), the enzyme unique to the glycerol phosphate hydrogen shuttle, was measured in normal human tissues and tumors and compared with the activity of succinate dehydrogenase, another enzyme that transfers electrons to ubiquinone at site II of the electron transport chain. Six of 7 insulinomas and 10 of 12 carcinoid tumors showed high glycerol phosphate dehydrogenase activity. The activity was also increased in 3 of 4 gastrinomas, 2 paraganglionomas, 1 of 4 thyroid nodules, and 1 parathyroid tumor. These tissues belong to the amine precursor uptake decarboxylation system. The activity of glycerol phosphate dehydrogenase was generally unremarkable in non-amine precursor uptake decarboxylation system tumors and in normal tissues studied. However, 1 of 2 breast carcinomas, 1 submandibular tumor, and 2 of 3 melanomas were enriched in glycerol phosphate dehydrogenase activity. In general, succinate dehydrogenase activity exceeded that of glycerol phosphate dehydrogenase in all tissues except some of the tissues in which glycerol phosphate dehydrogenase activity was high. Normal tissues, such as the pancreatic beta-cell, which aerobically metabolize glucose rapidly utilize the glycerol phosphate shuttle to oxidize the large amount of NADH formed from glucose metabolism in the cytosol. Whether this is the reason for the enriched activity of the glycerol phosphate dehydrogenase in certain amine precursor uptake decarboxylation system tumors is unknown.