Unique molecular characteristics of NAFLD-associated liver cancer accentuate β-catenin/TNFRSF19-mediated immune evasion

Abstract

<h3>Background & Aims</h3><p>The hepatic manifestation of the metabolic syndrome, non-alcoholic fatty liver disease (NAFLD), can lead to the development of hepatocellular carcinoma (HCC). Despite a strong causative link, NAFLD-HCC is often underrepresented in systematic genome explorations.</p><h3>Methods</h3><p>Herein, tumor-normal pairs from 100 patients diagnosed with NAFLD-HCC were subject to next-generation sequencing. Bioinformatic analyses were performed to identify key genomic, epigenomic and transcriptomic events associated with the pathogenesis of NAFLD-HCC. Establishment of primary patient-derived NAFLD-HCC culture was used as a representative human model for downstream <em>in vitro</em> investigations of the underlying <em>CTNNB1</em> S45P driver mutation. A syngeneic immunocompetent mouse model was used to further test the involvement of <em>CTNNB1</em>^mut <em>and TNFRSF19</em> in reshaping the tumor microenvironment.</p><h3>Results</h3><p>Mutational processes operative in the livers of patients with NAFLD inferred susceptibility to tumor formation through defective DNA repair pathways. Dense promoter mutations and dysregulated transcription factors accentuated activated transcriptional regulation in NAFLD-HCC, in particular the enrichment of MAZ-MYC activities<em>.</em> Somatic events common in HCCs arising from NAFLD and viral hepatitis B infection underscore similar driver pathways, although an incidence shift highlights <em>CTNNB1</em>^mut dominance in NAFLD-HCC (33%). Immune exclusion correlated evidently with <em>CTNNB1</em>^mut. Chromatin immunoprecipitation-sequencing integrated with transcriptome and immune profiling revealed a unique transcriptional axis, wherein <em>CTNNB1</em>^mut leads to an upregulation of <em>TNFRSF19</em> which subsequently represses senescence-associated secretory phenotype-like cytokines (including <em>IL6</em> and <em>CXCL8</em>). This phenomenon could be reverted by the Wnt-modulator ICG001.</p><h3>Conclusions</h3><p>The unique mutational processes in the livers of patients with NAFLD and NAFLD-HCC allude to a “field effect” involving a gain-of-function role of <em>CTNNB1</em> mutations in immune exclusion.</p><h3>Lay summary</h3><p>The increasing prevalence of metabolic syndrome in adult populations means that NAFLD is poised to be the major cause of liver cancer in the 21st century. We showed a strong “field effect” in the livers of patients with NAFLD, wherein activated β-catenin was involved in reshaping the tumor-immune microenvironment.</p>