ABSTRACT
BACKGROUND & AIMS: 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. METHODS: 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 in vitro investigations of the underlying CTNNB1 S45P driver mutation. A syngeneic immunocompetent mouse model was used to further test the involvement of CTNNB1mutand TNFRSF19 in reshaping the tumor microenvironment. RESULTS: 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. Somatic events common in HCCs arising from NAFLD and viral hepatitis B infection underscore similar driver pathways, although an incidence shift highlights CTNNB1mut dominance in NAFLD-HCC (33%). Immune exclusion correlated evidently with CTNNB1mut. Chromatin immunoprecipitation-sequencing integrated with transcriptome and immune profiling revealed a unique transcriptional axis, wherein CTNNB1mut leads to an upregulation of TNFRSF19 which subsequently represses senescence-associated secretory phenotype-like cytokines (including IL6 and CXCL8). This phenomenon could be reverted by the Wnt-modulator ICG001. CONCLUSIONS: 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 CTNNB1 mutations in immune exclusion. LAY SUMMARY: 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 ß-catenin was involved in reshaping the tumor-immune microenvironment.
Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , Metabolic Syndrome , Non-alcoholic Fatty Liver Disease , Receptors, Tumor Necrosis Factor , beta Catenin , Adult , Animals , Carcinoma, Hepatocellular/genetics , Carcinoma, Hepatocellular/metabolism , Hepatitis B , Humans , Immune Evasion , Liver Neoplasms/genetics , Liver Neoplasms/metabolism , Mice , Mutation , Non-alcoholic Fatty Liver Disease/genetics , Receptors, Tumor Necrosis Factor/genetics , Tumor Microenvironment , beta Catenin/genetics , beta Catenin/metabolismABSTRACT
Zinc finger protein X-linked (ZFX) is a zinc finger protein of Zfy family, which is highly conserved in vertebrates. This transcriptional regulator is not only highly expressed in embryonic stem cells (ESC) and hematopoietic stem cells, but is also upregulated in a number of human cancers where it is functional related to cell proliferation and survival. Hepatocellular carcinoma (HCC) is highly aggressive cancer that commonly resistant to most chemotherapies and displays stemness characteristics. In this study, we examined the expression of ZFX in HCC and its possible functional implications in liver tumorigenesis. Quantitative RT-PCR analysis showed common overexpressions of ZFX in 51.8% HCC tumors when compared with their adjacent nonmalignant liver (n = 43/83; p = 0.004). Inline with the pluripotency role of ZFX, we found silencing of ZFX readily inhibited self-renewal capability (p = 0.0022), colony formation ability (p < 0.0001) and cell proliferation (p < 0.0001) through G0/G1 cell cycle arrest of HCC cells (p = 0.0038). In addition, suppression of ZFX sensitized HCC cells to chemotherapeutic agent cisplatin (p < 0.0001). Further investigations suggested that ZFX bind on the promoter of two important mediators, namely Nanog and SOX-2, activating their expressions in HCC (p < 0.0001). Moreover, in vivo xenograft study demonstrated that overexpression of ZFX would promote the tumor growth (p = 0.031). Taken together, our results show, for the first time, commonly overexpressions of ZFX in HCC, where it likely contributes to the stemness and pluripotent behavior of this highly malignant cancer.
