Aberrant acetylated modification of FGF21-KLB signaling contributes to hepatocellular carcinoma metastasis through the β-catenin pathway

beta-Klotho (KLB) is a vital element of the fibroblast growth factor (FGF) receptor complex and acts as a co-receptor to facilitate the binding of FGF19 and FGF21 to the FGFRs on the target cells. The present study aimed to determine the contribution of FGF21-KLB signaling to hepatocellular carcinoma (HCC) metastasis. KLB expression was measured in HCC tissues and cell lines using western blot and reverse transcription-quantitative PCR. Furthermore, the proliferation, apoptosis and metastasis capacity of KLB-knockdown Huh7 cells (human HCC cell line) were assessed by Cell Counting Kit-8 assay, 5-ethynyl-2'-deoxyuridine assay, flow cytometry, wound-healing assay and Transwell assay. Enrichment analysis was used to explore the underlying regulatory mechanisms of KLB. The metastasis potential of human HCC cells in the context of FGF21 with or without KLB inhibition was determined in vitro and in vivo. Acetylated modification of KLB was determined using a co-immunoprecipitation assay. The results indicated a significant upregulation of KLB in HCC tissues compared with the corresponding normal tissues. In addition, KLB expression was closely associated with HCC metastasis. Migration and invasion assays revealed that KLB knockdown promoted the metastatic capability of HCC cells. Gene set variation analysis and subsequent mechanistic investigations revealed that KLB is the upstream regulatory factor of beta-catenin signaling. Furthermore, FGF21 was indicated to suppress HCC metastasis by inhibiting beta-catenin signaling-driven epithelial-mesenchymal transition ( EMT), while KLB knockdown and simultaneous FGF21 overexpression promoted HCC cell motility. Histone deacetylase 3 (HDAC3) was further characterized as the potential deacetylase for KLB. Furthermore, the results revealed that HDAC3 inhibitor-mediated acetylated modification led to KLB inactivation, resulting in the blockade of FGF21-KLB signaling, which further triggered the expression of EMT induction-related genes in Huh7 cells. In conclusion, the present study demonstrated that aberrant acetylated modification of KLB inhibited FGF21-KLB signaling, thereby promoting beta-catenin signaling-driven EMT and HCC metastasis.