Protective effect of the Y220C mutant p53 against steatosis: good news?

Nonalcoholic fatty liver disease (NAFLD) ranges from simple steatosis to steatohepatitis, which may progress to fibrosis, and cirrhosis, leading eventually to hepatocarcinoma development. Recently, cases of hepatocarcinoma have been diagnosed in steatotic patients without nonalcoholic steatohepatitis (NASH) and cirrhosis. The p53 protein, besides its function as tumor suppressor, is emerging as an important regulator of cellular metabolism, but its role in steatosis remains unclear. We induced steatosis in HepG2 (wt-p53) and Huh7.5.1 (Y220C-mutant p53) cells using free fatty acids. We observed a different modulation of p53, different intracellular lipid content, and similar down-regulation of the de novo lipid synthesis genes but opposite modulation of the fatty acid β-oxidation pathway between HepG2 and Huh7.5.1. Accordingly, we found a diverse amount of apoptosis and reactive oxygen species between the two cell lines. Transfection of the wt-p53 in Huh7.5.1 cells reverted the different lipid metabolism behavior observed in these cells. In conclusion, unlike the wt-p53, the Y220C mutant provides a specific protection against steatosis and potentially against its progression. Our findings highlight for the first time an unknown role of a p53 mutant in the setting of steatosis. Being this mutation very frequent in human cancers, this study could be a breakthrough in explaining the occurrence of hepatocarcinoma in steatotic patients without NASH and cirrhosis.