Objective:To investigate the effect of DExH-box helicase 9(DHX9)O-linked N-acetylglucosamine(O-GlcNAc)modifi-cation(O-GlcNAcylation)on the proliferation of hepatitis B virus(HBV)-associated hepatoma cells.Methods:The pAdTrack-TO4-DHX9-3Flag recombinant adenovirus plasmid was constructed by molecular cloning and transfected into HEK293 cells for packaging and amplification of the recombinant adenovirus AdDHX9.The interaction between DHX9 and O-GlcNAc transferase(OGT)was con-firmed using co-immunoprecipitation.The co-localization between DHX9 and OGT was measured by immunofluorescence.The level of DHX9 O-GlcNAcylation was determined using succinylated wheat germ agglutinin(sWGA)and glycosylated immunoprecipitation(IP).The effect of DHX9 O-GlcNAcylation on the proliferation of HBV-associated hepatoma cells was assessed using the colony-forming assay and cell growth curves.Results:The recombinant adenovirus AdDHX9 was successfully obtained,and DHX9 expression was confirmed by Western blot.DHX9 interacted with OGT,and the two proteins were co-localized on the nucleus.The sWGA and gly-cosylated IP experiments showed that DHX9 underwent O-GlcNAcylation,which was further enhanced by HBV infection.The colony-forming assay demonstrated that the number of cell clones was increased in the AdDHX9 group(386.667±15.630)compared with the AdGFP control group(142.667±7.572,P<0.001).Moreover,cell growth curves demonstrated that the overall cell growth rate was en-hanced in the AdDHX9 group(22.860±0.770)compared with the AdGFP control group(13.670±0.517,P<0.001).Conclusion:HBV infection promotes DHX9 O-GlcNAcylation,which enhances the proliferation of HBV-associated hepatoma cells.

Chronic hepatitis B virus (HBV) infection is one of the leading causes of hepatocellular carcinoma (HCC). Ubiquitin-proteasome system (UPS) mediates the post-translational modification and degradation of protein in eukaryotic cells. Recent studies have revealed that UPS plays an important role in HBV infection and hepatocarcinogenesis. Targeting HBx to intervene in the progression of HBV infection or HBV-related HCC has become a research hotspot both domestically and internationally in recent years. This article reviewed the progress in HBx promoting HBV infection and hepatocarcinogenesis through UPS.