Abstract: Objective To analyze the effect of hepatitis B virus X protein on the expression of DKK2 in different hepatoma cell lines and its possible mechanism. Methods HepG2 and SMMC7721 cells were infected by Ad-HBx, and X gene expression was detected by immunofluorescence and PCR, and protein level of DKK2 was detected by Western blot. The hepatoma cell lines were incubated with methylated transferase inhibitor (DAC), the expressions of DKK2, Dnmt1, Dnmt3a and Dnmt3b were detected by Western blot. By silencing the methyltransferase, the expression of DKK2 was detected by Western blot. Results After HepG2 and SMMC7721 being infected with Ad-HBx, the relative expression of HBx mRNA was up-regulated by 61.12 times and 50.24 times respectively (P＜0.05), the protein expression of DKK2 was down-regulated by 1.61 times (P＜0.05) and 3.33 times (P＜0.05), and the protein expression of Dnmt1 and Dnmt3a was significantly increased. Compared with the Ad-HBx infection group, DKK2 protein expression was up-regulated by 2.27 times(P＜0.05), Dnmt3a protein expression was significantly down-regulated, Dnmt1 and Dnmt3b protein level was not significantly changed after DAC treatment. By silencing Dnmt1 and Dnmt3a, DKK2 protein expression was significantly up-regulated. Conclusions HBx inhibits the expression of DKK2 by up-regulation of Dnmt3a and Dnmt1, and then activates the Wnt/β-catenin signaling pathway, which is involved in the occurrence of HBV related liver cancer.

Key words: Hepatic carcinoma, HBx, DKK2, Wnt/β-catenin, Methyltransferase