Abstract: Objective The aim of this experiment was to investigate tumor-promoting elements, e.g., ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2) and enhancer of Zeste homolog 2 (EZH2) in HepG2 and HepG2.2.15 cells and their impact on cell proliferation and invasiveness. Methods For inhibition of ENPP2 and EZH2 expression, siRNAs were synthesized, and HepG2, HepG2.2.15, pSM2 plasmid-transfected HepG2(HepG2/pSM2) and siENPP2 or siEZH2-transfected HepG2.2.15 cells were harvested. ENPP2 and EZH2 mRNAs were detected by real-time PCR and their expression was detected by Western blot. Proliferation and invasion of cells were detected by CCK-8 and Trans-well movement. Results ENPP2 and EZH2 mRNA loads in transient HBV-plasmid transfected HepG2 cells or HepG2.2.15 cells with stable HBV infection increased greatly, compared to those in HepG2 cells (P<0.001), and ENPP2 and EZH2 protein expression also intensified (P<0.001); proliferation and invasiveness of HepG2.2.15 cells were obviously elevated compared to in HepG2 cells (P<0.01), while inhibition of ENPP2 or EZH2 expression in HepG2.2.15 cells greatly weakened proliferation and invasiveness of the cells (P<0.01). Conclusion The intensified expressions of ENPP2 and EZH2 in HepG2 cells and in HepG2.2.15 cells might play a pivotal role in carcinogenesis, which needs further investigation.

Key words: HepG2 cells, HepG2.2.15 cells, Ectonucleotide pyrophosphatase/phosphodiesterase 2, Enhancer of Zeste homolog 2, Proliferation, Invasion, In vitro