Enzymes, nucleic acids, and lipids in human breast cancer and normal breast tissue.

Abstract

Summary Some of the biochemical characteristics of human breast cancer were defined by examining the activities of several specific enzymes associated with carbohydrate, lipid, and amino acid metabolism in forty-nine samples of infiltrating ductal carcinoma of the breast. In addition, the levels of RNA, DNA, cholesterol, free fatty acids, and triglycerides were determined. Samples of normal breast tissue and fibrocystic disease of the breast were also analyzed for the same parameters. Compared with normal breast tissue, the activities of pyruvate kinase, glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, phosphoglucomutase, glutamate dehydrogenase, and hexokinase in the carcinomas were elevated 10- to 30-fold, when enzyme activity was expressed per 100 mg of tissue weight, or from 2- to 8-fold, when enzyme activity was expressed per mg DNA. RNA and DNA levels were increased in neoplastic tissues, as were those of cholesterol and free fatty acids, whereas α-glycerophosphate dehydrogenase activity and triglyceride levels were significantly reduced in the tumors. In fibrocystic disease, only the activity of phosphoglucomutase, expressed per mg DNA, was higher than in normal breast tissue. Significant correlations between pairs of biochemical parameters were found; some were common to all tissues investigated, whereas others were present only in carcinomas. No differences in the biochemical profile of neoplastic tissues were attributable to either the menopausal status of the patient or to the presence of metastases. Thus, certain unique biochemical changes were associated with frank carcinoma and, in this limited study, we were able to identify a tissue sample as cancer or noncancer on the basis of the observed biochemical profile.