Background: V-set and immunoglobulin domain containing protein 4 (VSIG4) was reported to play an important role in tumorigenesis. However, the expression and clinical relevance in hepatocellular carcinoma (HCC) remain unknown.
Materials and methods: First, the mRNA profiles of HCC were screened from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus databases. VSIG4 , a differentially expressed gene that has not been reported in HCC, was distinguished. Second, the correlation between VSIG4  expression and the prognosis of HCC patients from TCGA was analyzed. Third, VSIG4  mRNA level was detected in 36 pairs of HCC tissues and 4 HCC cell lines by PCR assay. And finally, prognosis analysis was assessed for 36 HCC patients with different expression levels of VSIG4 .
Results: Bioinformatics analysis showed that VSIG4  expression was downregulated in HCC tissues, and the expression level of VSIG4  was negatively correlated with serum alpha fetal protein (AFP) level and tumor distant metastasis. Survival analysis of all HCC patients in TCGA indicated that the overall survival and disease-free survival were not significantly associated with VSIG4  expression. However, subgroup analysis showed that in the patients with hepatitis B virus-related HCC, both overall survival and disease-free survival were shorter in the low VSIG4  expression group. Our PCR results further showed that VSIG4  expression was significantly decreased in HCC tissues and HCC cell lines, and the disease-free survival in hepatitis B virus-related HCC patients with low VSIG4  expression was shorter than in those with high VSIG4  expression, which was consistent with the bioinformatics analysis results.
Conclusion: Our study suggests that VSIG4 is downregulated in HCC, and low expression of VSIG4 is associated with poor prognosis in hepatitis B virus-related HCC patients.
Keywords: hepatocellular carcinoma, VSIG4, hepatitis B infection, bioinformatics analysis