p16 deficiency promotes nonalcoholic steatohepatitis via regulation of hepatic oxidative stress.

Nonalcoholic steatohepatitis (NASH) is characterized by excess accumulation of lipids in liver, accompanied with hepatocyte injury, cell death and inflammation. Although p16 is known as tumor suppressor in multiple cancer types, it remains unclear whether p16 plays a critical role in NASH. To determine whether p16 could play a role in the pathogenesis of NASH, wild-type mice and p16-/- mice were fed on a methionine and choline-deficient (MCD) diet for 3 weeks, and liver steatosis, fibrosis, and inflammation were evaluated. Our data show that p16-/- mice fed with MCD diet displayed more significant hepatic steatosis, hepatocyte damage, increased oxidative stress and inflammatory cell infiltration compared to MCD-fed WT mice. It was also clear that the increased ROS and the accumulation of lipid in BEL-7402 cells occurred when p16 expression was depleted with siRNA. These findings indicate that p16 may play a critical role in the development of NASH by reining in ROS production and by inhabiting inflammatory response.