development of hepatocellular cancer in a murine model of nonalcoholic steatohepatitis induced by use of low-fat/high carbohydrate diet

Introduction Hepatocellular carcinoma (HCC) is one of the most common liver tumors. Nonalcoholic fatty liver disease (NAFLD) is a frequent chronic liver disorder. It can progress through the more severe nonalcoholic steatohepatitis (NASH), cirrhosis and, lastly, HCC. Some studies have discussed the role of high-fat and/or high-fructose/sucrose diets on lipid accumulation and liver injury induction, but mechanisms remain unclear. In this study, a mouse model predisposed to NAFLD was used to analyze the long-term effects of hypercaloric high-fat (HF) or low fat (LF)-high carbohydrate (HC) diet during the transition from steatosis to hepatitis, fibrosis and then cancer development. MiRNA analysis was also performed to identify molecules involved in the process. Materials and method C57BL/6J mice were fed a HF (protein kcal 16.4%, carbohydrate kcal 25.5%, fat-hydrogenated coconut oil- kcal 58%; kcal/g 5.56) or LF-HC (protein kcal% 16.4, carbohydrate –sucrose- kcal% 73.1, fat kcal% 10.5; kcal/g 4.07) diet for 3, 6, 12, and 18 months. Control mice were standard diet fed for the same time points. At sacrifice, blood and hepatic tissues were collected. Histological analyses were performed. TaqMan qRT-PCR was used to analyze miRNAs in liver tissues. Results Increasing livers’ volume and weight was detected in HF and, less pronounced, in LF-HC mice after 3, 6, 12 and 18 months. Histological analysis revealed earlier liver damage in HF mice. Both groups showed increasing incidence of steatosis, inflammation and fibrosis during the treatment, demonstrating liver injury progression from NAFLD-NASH-fibrosis. Macroscopic nodules, with neoplastic features, were revealed in 20% and 50% of HF after 12 and 18 months, respectively, and, interestingly, in 30% of 18 months LF-HC mice. No nodular lesions were found in 12 and 18 months controls. MiRNAs analysis showed several differentially expressed during the progression of liver damage and in tumors (i.e. miR-155, miR-182, miR-125a-5p, miR-193b, miR-27a). Conclusions The effects of long term HF and LF-HC hypercaloric diets on liver damage were assessed in C57BL/6J mice. NAFLD-NASH-fibrosis progression was detected in both HF and LF-HC groups, although in the latter injury appeared later. Cancer was detected in 12 and 18 months HF and, for the first time, in 18 months LF-HC mice, indicating a role of carbohydrate rich diet in this process. Several miRNAs differentially expressed during the progression of the damage were identified.