The upregulation of expressed proteins in HepG2 cells transfected by the recombinant plasmid-containing HBx gene.

It is known that the hepatitis B virus X protein (HBx) plays a crucial role in the pathogenesis of HCC, but the exact functions and molecular mechanisms of HBx in HCC are not well understood. In the present study, HepG2 cell lines were cultured and transfected with pEGFP-N1 and pEGFP-N1-X. Twenty-four hours after transfection, cells were harvested and total RNA was extracted using TRIzol reagent. The expression of HBx in HepG2 cell line was assayed by real-time polymerase chain reaction and was detected by Western blotting. Moreover, proteomic analysis was performed for the HepG2-pEGFP-X cells and HepG2-pEGFP control cells. The combination of 2DE and MALDI-TOF-MS/MS revealed that SEC13L1 (SEC13-like 1 isoform b), PA28 alpha (proteasome activator REG alpha), serine-threonine kinase receptor-associated protein (STRAP) and nm23/nucleoside diphosphate kinase (NME) were upregulated in HepG2-pEGFP-X cells. STRAP is known to be a WD40 domain-containing protein, which interacts with TbetaR-I and TbetaR-II and negatively regulates TGF-beta signalling, was also found increased in human cancers. NME is known to be involved in the regulation of cancer cell progression and metastasis. These results would help the understanding of how HBx maintains tumorigenicity and progression of HCC.