[Small interfering RNA targeting to hepatitis B virus X gene and 5-aza-2'-deoxycytidineon inhibited growth of the subcutaneous implanted tumor of hepatocellular carcinoma in nude mice].

Objective: To investigate the anti-tumor effect of small interfering RNA targeting to HBV X gene (X-siRNA) and 5-aza-2'-deoxycytidine (5-aza-dC) on HBV-related hepatocellular carcinoma.

Methods: X-siRNA and control siRNA were synthesized. HepG2/GFP-HBx cells were treated with X-siRNA, and the levels of HBV X mRNA were detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Nude mice were inoculated with HepG2/GFP and HepG2/GFP-HBx cells subcutaneous respectively to establish implant models of hepatocellular carcinoma, and were treated with X-siRNA, 5-aza-dC alone or in combination, and tumor growth was observed. The methylation of p16 gene promoter was detected by methylation specific polymerase chain reaction (MSP).

Results: RT-PCR showed the expression of HBV X mRNA in HepG2/GFP-HBx cells was inhibited markedly by X-siRNA. The nude mice experiment showed that the gross tumor volume was much bigger in HepG2/GFP-HBx group than that in HepG2/GFP group (P < 0.05). The growth of palpable tumors in X-siRNA or 5-aza-dC treatment group notably decreased (P < 0.05). MSP analysis showed that p16 gene methylation was observed in HepG2/ GFP-HBx-caused palpable tumors, while no methylation was detected in HepG2/GFP group. However, after treatment with X-siRNA or 5-aza-dC, p16 gene methylation reduced.

Conclusions: HBV X-siRNA and methylation inhibitor can inhibit the growth of hepatoma cells via reversing p16 methylation.