Sterol Metabolism in Tumor-Mice

Abstract

Wolter (1) in 1913 found the cholesterol content of a primary liver carcinoma to be 1.4 per cent of its dry weight, an observation confirmed by Loeper, Debray, and Tonnet (2) and by Roffo and his collaborators (3). Roffo believed that the malignancy of a tumor is proportionate to its sterol content and observed also that cutaneous cancer has a predilection for areas of the body exposed to light, by which the cholesterol content of the skin is increased. Several investigators (4–7) reported that addition of cholesterol to the diet exerted a stimulating effect on the incidence and growth of transplantable and tar tumors, but no such effect was observed on the incidence of spontaneous neoplasms in the mouse (8). The present experiments were undertaken to determine whether or not the sterol metabolism of tumor-bearirig mice differs from that of normal animals. The sterol metabolism of normal mice is well known from earlier studies by Schoenheimer and Breusch (9) and by Breusch (10). Using a method specially devised for the purpose, they found that normal mice daily synthesize about 13.6 mg. of sterol per 100 gm. of body weight, which is about 3 mg. for an animal of 20 to 25 gm. If, however, there is added to the daily diet 12 mg. of cholesterol, synthesis is not complete and some destruction of the sterol is observed, amounting to about 0.9 mg. per day per mouse. This effect is produced only by the absorbable sterol—cholesterol. The various plant sterols, as sitosterol, dihydrocholesterol, etc., which are not absorbable, have no effect on sterol balance.