ABSTRACT
Although sorafenib is the first-line therapeutic agent for advanced hepatocellular carcinoma (HCC), the development of drug resistance in HCC cells limits its clinical efficacy. However, the key factors involved in mediating the sorafenib resistance of HCC cells and the underlying mechanisms have not been elucidated. In this study, we generated sorafenib-resistant HCC cell lines, and our data demonstrate that HLA-F locus-adjacent transcript 10 (FAT10), a ubiquitin-like protein, is markedly upregulated in sorafenib-resistant HCC cells and that reducing the expression of FAT10 in sorafenib-resistant HCC cells increases sensitivity to sorafenib. Mechanistically, FAT10 stabilizes the expression of the PTEN-specific E3 ubiquitin ligase NEDD4 that causes downregulation of PTEN, thereby inducing AKT-mediated autophagy and promoting the resistance of HCC cells to sorafenib. Moreover, we screened the small molecule Compound 7695-0983, which increases the sensitivity of sorafenib-resistant HCC cells to sorafenib by inhibiting the expression of FAT10 to inhibit NEDD4-PTEN/AKT axis-mediated autophagy. Collectively, our preclinical findings identify FAT10 as a key factor in the sorafenib resistance of HCC cells and elucidate its underlying mechanism. This study provides new mechanistic insight for the exploitation of novel sorafenib-based tyrosine kinase inhibitor (TKI)-targeted drugs for treating advanced HCC.
ABSTRACT
BarH-like homeobox 2 (BARX2) has been identified to play a key role in the development of multiple cancers. Meanwhile, BARX2 may be an independent prognostic biomarker for patients suffering from hepatocellular carcinoma (HCC). Nevertheless, the regulatory role of BARX2 in HCC is still unclear and needs to be unveiled. In this study, the expressions of BARX2 and N-acetylgalactosaminyltransferase 4 (GALNT4) were evaluated by quantitative real-time PCR (qRT-PCR) as well as western blot. Besides, the abilities of cells to proliferate, migrate, invade, and angiogenesis were assessed with CCK-8, colony formation, wound-healing, Transwell, and tube formation assays, separately. Cell apoptosis was determined by flow cytometry analysis. The binding relationship between BARX2 and GALNT4 was predicted by JASPAR website and verified using Chromatin immunoprecipitation (ChIP) and luciferase report assay. It was discovered that BARX2 was reduced in HCC cell lines, while its overexpression greatly repressed cell proliferation, migration, invasion, and angiogenesis and promoted cell apoptosis in HuH7 and MHCC97-H cells. BARX2 could bind to GALNT4 promoter and positively regulate GALNT4 expression. In addition, GALNT4 deficiency partly abolished the inhibitory effects of BARX2 on the progression of HCC. In summary, this study highlights that BARX2 may hold promise for serving as a potential therapeutic target, facilitating the development of a novel therapeutic strategy against HCC.
ABSTRACT
The transcription factor BarH-like homeobox 2 (BARX2), a member of the Bar-like homeobox gene family, is involved in cell proliferation, differentiation, immune responses and tumorigenesis. However, the potential role of BARX2 in the development of liver hepatocellular carcinoma (LIHC) remains unclear. Therefore, we aimed to study the biological role of BARX2 in hepatocellular carcinoma. Through the UALCAN, GTEx PORTAL, TIMER 2.0, LinkedOmics, SMART, MethSurv, Metascape, GSEA and STRING public databases, the BARX2 mRNA level, prognostic value, coexpressed genes, associated differentially expressed genes, DNA methylation and functional enrichment of LIHC patients were studied. The relationships between BARX2 expression and various clinical or genetic parameters of LIHC patients were determined using data from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and BEAT LIHC databases. In addition, the biological function of BARX2 in LIHC was studied in vitro. Through large-scale data mining, our study showed that BARX2 was differentially expressed between different normal and tumour tissues.BARX2 expression in LIHC tissues was significantly lower than that in corresponding controls, especially in patients with T2-4 stage disease. In patients with LIHC, overexpression of BARX2 was an independent poor prognostic factor associated with poor cytogenetic risk and gene mutations. Genomic hypermethylation of the BARX2 gene was associated with upregulated BARX2 expression and poor overall survival (OS) in LIHC. Functional enrichment analysis showed that BARX2 had an immunomodulatory role and was involved in the inflammatory response in LIHC occurrence. In conclusion, the oncogene BARX2 may serve as a new biomarker and prognostic factor for patients with LIHC. The immunomodulatory function of BARX2 deserves further validation in LIHC.
