Carcinogenesis in the hamster cheek pouch. II. Changes in enzymes of glucose-6-phosphate oxidation.

Summary The activities of the enzymes, hexokinase, glucose-6-phosphate dehydrogenase, and phosphogluconate dehydrogenase were determined in extracts prepared from hamster cheek pouches which were being painted thrice weekly with 9,10-dimethyl-1,2-benzanthracene. Histology revealed five periods: I, no change, approximately 1 week; II, inflammation, 2d and 3d week; III, hyperplasia after the 3d week; IV, preneoplastic hyperplasia and appearance of papillomas after about 7 weeks; and V, appearance of malignant tumors. The specific activities of all three enzymes were significantly higher in tumors than in unpainted cheek pouches or in controls painted with mineral oil. The patterns of change in enzyme activities in the cheek pouches during the course of carcinogenesis were different for each enzyme. These differences were especially evident in periods III to V. Hexokinase was low in period III and returned to the control range in period V. Glucose-6-phosphate dehydrogenase increased during periods IV and V. Phosphogluconate dehydrogenase was low during periods III and IV. A difference between the sexes was evident especially in the inflammatory reaction as well as in patterns of changes in enzyme activities. It was concluded that changes of phosphogluconate show the greatest degree of correlation with the neoplastic state as compared with the hyperplastic state.