Dietary factors can modify metabolic events involved in the initiation, promotion, or progression of tumors. To determine whether a high-sucrose diet has any effect on the development of enzyme-altered foci during the promotion step of chemical hepatocarcinogenesis in rats, 1-day-old Sprague-Dawley rats were given a single i.p. dose of diethylnitrosamine; controls received an equivalent i.p. volume of 0.9% NaCl solution. At 21 days of age, the rats were weaned, segregated by sex, separated in groups, and fed modified AIN76A diets containing either 65% glucose or 65% sucrose, with or without 0.05% phenobarbital. At the end of a 4-week treatment period, the sucrose-fed control rats of either sex had significantly heavier livers than did those on the glucose diet. Enlarged livers were found also in the sucrose-fed diethylnitrosamine-treated female rats, which developed twice as many γ-glutamyltranspeptidase-positive foci per sq cm of liver section than did those on the glucose diet. Addition of phenobarbital augmented the number of foci 3-fold in the sucrose group and 5-fold in the glucose group. Focus count per sq cm was similar in animals on the two phenobarbital-supplemented diets. Despite the absence of statistically significant liver enlargement, results analogous to those in females were obtained in carcinogen-treated males. Differences between treatments, however, were smaller. In both female and male rats, the DNA-synthesizing activity of hepatocytes in enzyme-altered foci was significantly higher than in the surrounding normal parenchymal cells, as determined by autoradiography. These studies indicate that a high-sucrose diet has a promoting effect during hepatocarcinogenesis induced in the rat by diethylnitrosamine and that this effect is weaker than that of 0.05% phenobarbital.
Supported in part by Grant CA 25164 from the National Cancer Institute. Some of the data were presented in abstract form at the 68th Annual Meeting of the Federation of American Societies for Experimental Biology, St. Louis, MO, April 1984.