Non-alcoholic steatohepatitis (NASH)-related hepatocellular carcinoma (HCC) is increasing globally, but its molecular features are not well defined. We aimed to identify unique molecular traits characterizing NASH-HCC compared to other HCC aetiologies. We collected 80 NASH-HCC and 125 NASH samples from 5 institutions. Expression array (n=53 NASH-HCC; n=74 NASH) and whole exome sequencing (n=50 NASH-HCC) data were compared to HCCs of other aetiologies (n=184). Three NASH-HCC mouse models were analysed with RNAseq/expression-array (n=20). ACVR2A was silenced in HCC cells and proliferation assessed by MTT and colony formation assays. Mutational profiling of NASH-HCC tumours revealed TERT-promoter (56%), CTNNB1 (28%), TP53 (18%) and ACVR2A (10%) as the most-frequently mutated genes. ACVR2A mutation rates were higher in NASH-HCC than in other HCC aetiologies (10% versus 3%, p<0.05). In vitro, ACVR2A silencing prompted a significant increase in cell proliferation in HCC cells. We identified a novel mutational signature (MutSig-NASH-HCC) significantly associated with NASH-HCC (16% vs 2% in viral/alcohol-HCC, p=0.03). Tumour mutational burden (TMB) was higher in non-cirrhotic than in cirrhotic NASH-HCCs (1.45 versus 0.94 mutations/Mb; p<0.0017). Compared to other aetiologies of HCC, NASH-HCCs were enriched in bile and fatty acid signalling, oxidative stress and inflammation, and presented a higher fraction of Wnt/TGF-β proliferation subclass tumours (42% versus 26%, p=0.01) and a lower prevalence of the CTNNB1 subclass. Compared to other aetiologies, NASH-HCC showed a significantly higher prevalence of immunosuppressive cancer field. In three murine models of NASH-HCC key features of human NASH-HCC were preserved. NASH-HCCs display unique molecular features including higher rates of ACVR2A mutations and the presence of a newly identified mutational signature.
Overall design
53 NASH-HCCs, 29 adjacent non-tumor NASH liver samples and 74 NASH samples were analysed, as well as 6 healthy livers and 8 cirrhotic livers as a control.
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