Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Intense efforts have been made to elucidate the pathogeny, but the molecular mechanisms of HCC are still not well understood. To identify the candidate genes in the carcinogenesis and progression of HCC, microarray datasets GSE19665, GSE33006 and GSE41804 were downloaded from Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified, and function enrichment analyses were performed. The protein-protein interaction network (PPI) was constructed and the module analysis was performed using STRING and Cytoscape. A total of 273 DEGs were identified, consisting of 189 downregulated genes and 84 upregulated genes. The enriched functions and pathways of the DEGs include protein activation cascade, complement activation, carbohydrate binding, complement and coagulation cascades, mitotic cell cycle and oocyte meiosis. Sixteen hub genes were identified and biological process analysis revealed that these genes were mainly enriched in cell division, cell cycle and nuclear division. Survival analysis showed that BUB1, CDC20, KIF20A, RACGAP1 and CEP55 may be involved in the carcinogenesis, invasion or recurrence of HCC. In conclusion, DEGs and hub genes identified in the present study help us understand the molecular mechanisms underlying the carcinogenesis and progression of HCC, and provide candidate targets for diagnosis and treatment of HCC.
Ubiquitin-specific protease 18 (USP18, also known as UBP43) has both interferon stimulated gene 15 (ISG15) dependent and ISG15-independent functions. By silencing the expression of USP18 in HepG2.2.15 cells, we studied the effect of USP18 on the anti-HBV activity of IFN-α and demonstrated that knockdown of USP18 significantly Inhibited the HBV expression and increased the expression of ISGs. Levels of hepatitis B virus surface antigen (HBsAg), hepatitis B virus e antigen (HBeAg), HBV DNA and intracellular hepatitis B virus core antigen (HBcAg) were dramatically decreased with or without treatment of indicated dose of IFN-α. Suppression of USP18 activated the JAK/STAT signaling pathway as shown by the increased and prolonged expression of phosphorylated signal transducer and activator of transcription 1 (p-STAT1) in combination with enhanced expression of several interferon stimulated genes (ISGs). Our results indicated that USP18 modulates the anti-HBV activity of IFN-α via activation of the JAK/STAT signaling pathway in Hepg2.2.15 cells.
Hepatitis E is the most common type of acute hepatitis prevalent worldwide. The open reading frame 3 protein of HEV (HEV ORF3) is proposed to create a favorable environment for viral replication and pathogenesis. However, the mechanisms by which HEV overcomes the effects of host immunity, particularly the role of ORF3, remain to be established. Expression of IFNα and IFNβ in supernatant and cell samples was examined via ELISA and quantitative RT-PCR. The protein levels of specific signaling factors in cells overexpressing HEV ORF3 were examined via western blot. Analyses of cells transfected with vectors expressing ORF3 demonstrated that HEV ORF3 significantly impairs the generation of endogenous type I interferon through downregulating TLR3 and TLR7 as well as their corresponding downstream signaling pathways. Moreover, inhibition of NFκB, JAK/STAT and JNK/MAPK signaling pathways contributed significantly to suppression of increased levels of TLR7. Levels of p-P65, p-STAT1 and p-JNK were markedly impaired in ORF3-expressing cells, even upon treatment with the respective agonists. HEV ORF3 inhibits the production of endogenous type I interferon through downregulation of TLR3 and TLR7. Furthermore, suppression of TLR7 is achieved through impairment of multiple signaling pathways, including NFκB, JAK/STAT and JNK/MAPK.
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