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Effect of hepatitis B virus X protein on the expression of retinoblastoma gene product.
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1997
Year
ImmunologyHepatitis BPathologyViral HepatitisHepatobiliary TumorRetinoblastoma Gene ProductSynthesized HbxVirus GeneViral GeneticsLiver PhysiologyVirologyGene ExpressionCell BiologyCmv-hbx CloneTumor MicroenvironmentHepatologyNatural SciencesHepatitisLiver CancerPrb ExpressionLiverMedicineViral OncologyHepatocellular Carcinoma
Hepatitis B virus X protein (HBX) was studied for its capacity to form a specific complex with the retinoblastoma tumour suppressor protein (pRB), and for its effect on the expression of pRB. HBX was synthesized by in vitro transcription and translation in the presence of [35S]methionine. The synthesized HBX was assayed for its binding to a glutathione-S-transferase (GST)-pRB fusion protein bound to Sepharose beads. The in vivo binding was investigated by a co-immunoprecipitation and Western blot analysis of the cell extract from a CMV-HBX-transfected hepatoblastoma cell line, Hep G2 cells. These experiments demonstrated that HBX was unable to form a detectable complex with pRB. However, the level of pRB increased considerably in Hep G2 cells transfected with CMV-HBX clone. The alteration of pRB expression by HBX could be a mechanism, contributing to the development of hepatocellular carcinoma (HCC) in human.