Acceleration of papilloma growth in mice fed high-fat diets during promotion of two-stage skin carcinogenesis.

The effect of feeding a high-fat diet during the promotion phase of skin tumorigenesis was assessed in SENCAR mice. Tumors were initiated on the backs of mice by application of 10 nmol 7,12-dimethylbenz[a]anthracene (DMBA); the tumors were then promoted beginning one week later with twice weekly treatments of 2 micrograms 12-O-tetradecanoylphorbol-13-acetate (TPA) each in 0.2 ml acetone. Control diet containing 5% corn oil was fed from four weeks before until one week after DMBA treatment in all groups. A high-fat diet (24.6% corn oil) was fed from one week after DMBA treatment; the other groups continued on the control diet. Mice were fed ad libitum, and those given the high-fat diet consumed more calories early in the study than the controls did. Treatment with TPA increased calorie consumption throughout the study. Body weights were elevated in mice fed high-fat diets and reduced by TPA treatment. The average number of papillomas per mouse did not differ between the low- and high-fat groups, but papillomas grew more rapidly on the mice fed a high-fat diet than those fed a low-fat diet. The feeding of a high-fat diet following DMBA treatment, in the absence of TPA administration, did not result in promotion of skin tumors. Therefore, a high-fat diet acted as a copromoter of skin tumors in SENCAR mice.