Preventive effect of fermented brown rice and rice bran on diethylnitrosoamine and phenobarbital-induced hepatocarcinogenesis in male F344 rats

Abstract

Epidemiological and preclinical studies have suggested that nutrition plays an important role in the etiology of cancer. Our group previously demonstrated that rice germ or fermented brown rice has a preventive effect on colorectal carcinogenesis. The experiment described here was examined for the potential anticancer properties of brown rice fermented by Aspergillus Oryzae (FBRA) in male F344 rats using inhibition of diethylnitrosoamine (DEN) and phenobarbital (PB)-induced hepatocarcinogenesis as the measure of preventive efficacy when this agent was administered at 5% and 10% levels in diet during initiation phase (during and until 1 week after carcinogen treatment) or post-initiation phase (beginning 1 week after carcinogen treatment) of the carcinogenesis. Rats were sacrificed 20 weeks after the initiation of DEN treatment (200 mg/kg body weight, once weekly for 3 weeks). Expression of liver tumors was evaluated histopathologically. Administration of 10% FBRA in the diet during the initiation phase significantly decreased the incidence (43% vs. 8%) and multiplicity (0.5+/-0.6 vs. 0.1+/-0.3) of hepatocellular carcinoma (HCC) as compared to those given the control diet. In addition, 5% and 10% of FBRA in the diet during post-initiation phase significantly decreased the incidence of HCC (43% vs. 15% and 9%, respectively) and multiplicity of hepatocellular adenoma (4.7+/-3.7 vs. 2.1+/-2.2 and 2.4+/-1.4, respectively) and HCC (0.5+/-0.6 vs. 0.2+/-0.4 and 0.1+/-0.3, respectively). These data prove that FBRA has an inhibitory effect on the hepatocarcinogenesis in rats. FBRA could be a promising chemopreventive agent for human liver as well as colorectal neoplasia.