Abstract: Objective The aim of this study was to investigate the clinical significance of cancerous family with sequence similarity 49 member B (FAM49B) gene in patients with hepatocellular carcinoma (HCC). Methods The Oncomine and GEPIA databases were applied to analyze the gene level of FAM49B in HCC tissues and normal liver tissues. HCC dataset was collected from the Cancer Genome Atlas (TCGA) database. The gene levels of FAM49B in patients with different clinic-pathological features were analyed by SPSS 21.0. The impact of FAM49B gene on prognosis was analyzed by Kaplan Meier Plotter. The MethHC database was used to analyze the FAM49B promoter methylation. The String database was used to analyze the network of protein interaction between FAM49B and others, and gene set enrichment analysis (GSEA) was used to predict the possible signal pathways of FAM49B in HCC. Results Studies on Oncomine and GEPIA database showed that FAM49B gene level in HCC tissues was higher than that in normal liver tissues (both P<0.01); the gene levels of FAM49B were different significantly between different gender(P=0.001), with or without cirrhosis(P=0.003) and degree of tumor differentiation(P=0.004), but not between ages, tumor sizes, pathological stages, serum alpha-fetoprotein levels and with or without vascular invasion (all P>0.05); the patients with high cancerous FAM49B level had shorter overall survival than those with low gene level (HR=1.8, P=0.0012); the FAM49B promoter methylation in cancerous tissues was lower than that in normal liver tissues (P<0.005); the proteins interaction with FAM49B included SERPINA1, ISLR and FERMT3, etc.; the samples with high level of FAM49B mRNA showed enrichment of genes in the pathways of apoptosis, cell cycle, regulation of autophagy and P53 signaling pathway (all P<0.05). Conclusion FAM49B is highly expressed in cancerous tissues in patients with HCC, showing a oncogene feature, and those with higher FAM49B gene level is associated with the poor prognosis.

Key words: Hepatocellular carcinoma, Family with sequence similarity 49 member B, Data mining, Oncogene