FGF9 Recruits β-Catenin to Increase Hepatic ECM Synthesis and Promote NASH-Driven HCC

Most nonalcoholic steatohepatitis (NASH) patients develop severe fibrosis through extracellular matrix (ECM) accumulation, which can lead to hepatocellular carcinoma (HCC). Fibroblast growth factor 9 (FGF9) is involved in serial types of cancer; however, the specific role of FGF9 in NASH-driven HCC is not fully understood. This study finds that FGF9 is increased in patients with NASH-associated HCC. Furthermore, NASH-driven HCC mice models by feeding wildtype mice with high-fat/high-cholesterol (HFHC) diet and low dose carbon tetrachloride (CCl₄ ) treatment is established; and identified that hepatic FGF9 is increased; with severe fibrosis. Additionally, AAV-mediated knockdown of FGF9 reduced the hepatic tumor burden of NASH-driven HCC mice models. Hepatocyte-specific FGF9 transgenic mice (FGF9^Alb ) fed with a HFHC diet without CCl₄ treatment exhibited an increased hepatic ECM and tumor burden. However, XAV-939 treatment blocked ECM accumulation and NASH-driven HCC in FGF9^Alb mice fed with HFHC diet. Molecular mechanism studies show that FGF9 stimulated the expression of ECM related genes in a β-catenin dependent manner; and FGF9 exerts its effect on β-catenin stability via the ERK1/2-GSK-3β signaling pathway. In summary, the data provides evidence for the critical role of FGF9 in NASH-driven HCC pathogenesis; wherein it promotes the tumors formation through the ECM pathway.