NASH time course

Current models of hepatocellular tumorigenesis propose that the chronic injury and inflammation in NASH are mutagenic and growth promoting which can eventually lead to HCC. However, contrary to this model, here we show that NASH suppresses the early development of liver cancers in mice. We found that NASH did not hinder the malignant reprogramming of oncogene expressing hepatocytes but suppressed their clonal expansion and led to their elimination. This elimination was not caused by a direct effect of NASH on malignant cells but due to the stimulation of cell competition in tumor-surrounding hepatocytes. Mechanistically, NASH activated the Hippo pathway effectors Yap and Taz in hepatocytes, which elevated their cellular fitness. Thus, deletion of Yap/Taz in tumor-surrounding hepatocytes abolished the elimination of tumor cells by NASH, while experimental hyperactivation of Yap in malignant cells protected them from NASH-induced elimination We purified hepatocytes from control mice (ND = normal diet) and mice that were fed a NASH diet for different lengths of time and determined their gene expression profile by RNA sequencing.