Hepatocellular carcinoma is induced by a subnecrogenic dose of diethylnitrosamine in previously fasted-refed rats

We reported elsewhere that diethylnitrosamine (DENA) at 20 mg/kg triggered the development of liver foci in fasted-refed rats. Here we investigate whether liver cancer is induced by this dose of DENA when administered to previously fasted-refed animals. Fischer 344 rats, fasted for four days, were given 20 mg/kg DENA after one day of refeeding; regularly fed animals receiving 20 or 200 mg/kg DENA were used as negative and positive controls, respectively. The rats were selected by the promoting regimen of Solt and Farber. Focal proliferative lesions, nodules, and carcinomas developed in the liver of fasted-refed rats given 20 mg/kg DENA and, as expected, in the liver of positive controls. Neither preneoplastic nor neoplastic lesions were found in the negative controls. The liver initiation in fasted-refed rats was steadily irreversible, as reflected by the growth of foci, even when the promoting regimen was postponed. The data show that fasting-refeeding can substitute for any compensatory proliferative stimulus to make the subnecrogenic dose of DENA able to initiate hepatocytes, eventually leading to the development of liver cancer.