Interferon-α response in chronic hepatitis B-transfected HepG2.2.15 cells is partially restored by lamivudine treatment

AIM：To characterize the IFN-response and its modulation by the antiviral compound lamivudine in HBV- transfected HepG2.2.15 cells. METHODS： HepG2.2.15 and HepG2 cells were stimulated with various concentrations of IFN-α 2a in the presence or absence of lamivudine. Then, total RNA was extracted and analysed by customised cDNA arrays and northern blot for interferon-inducible genes （ISGs）. In addition, cellular proteins were extracted for EMSA and western blot. HBV replication was assessed by southern blot or ELISAs for HBsAg and HBeAg. RESULTS： Two genes （MxA, CigS） with completely abolished and 4 genes （IFITM1, -2, -3, and 6-16） with partially reduced IFN-responses were identified in HepG2.2.15 cells. In 2 genes （IFITM1, 6-16）, the response to IFN-α could be restored by treatment with lamivudine. This effect could not be explained by a direct modulation of the Jak/Stat signalling pathway since EMSA and western blot experiments revealed no suppression of Statl activation and ISGF3 formation after stimulation with IFN-α in HepG2.2.15 compared to HepG2 cells. CONCLUSION： These results are consistent with the assumption that chronic hepatitis B may specifically modulate the cellular response to IFN by a selective blockage of some ISGs. Antiviral treatment with lamivudine may partially restore ISG expressionby reducing HBV gene expression and replication.

Combination of small interfering RNA and lamivudine on inhibition of human B virus replication in HepG2.2.15 cells

AIM: To observe the inhibition of hepatitis B virus (HBV) replication and expression by combination of siRNA and lamivudine in HepG2.2.15 cells. METHODS: Recombinant plasmid psil-HBV was constructed and transfected into HepG2.2.15 cells. The transfected cells were cultured in lamivudine-containing medium (0.05 μmol/L) and harvested at 48, 72 and 96 h. The concentration of HBeAg and HBsAg was determined using ELISA. HBV DNA replication was examined by real- time PCR and the level of HBV mRNA was measured by RT-PCR. RESULTS: In HepG2.2.15 cells treated with combination of siRNA and lamivudine, the secretion of HBeAg and HBsAg into the supernatant was found to be inhibited by 91.80% and 82.40% (2.89 ± 0.48 vs 11.73 ± 0.38, P < 0.05; 4.59 ± 0.57 vs 16.25 ± 0.48, P < 0.05) at 96 h, respectively; the number of HBV DNA copies within culture medium was also significantly decreased at 96 h (1.04 ± 0.26 vs 8.35 ± 0.33, P < 0.05). Moreover, mRNA concentration in HepG2.2.15 cells treated with combination of siRNA and lamivudine was obviously lower compared to those treated either with siRNA or lamivudine (19.44 ± 0.17 vs 33.27 ± 0.21 or 79.9 ± 0.13, P < 0.05). CONCLUSION: Combination of siRNA and lamivudine is more effective in inhibiting HBV replication as compared to the single use of siRNA or lamivudine in HepG2.2.15 cells.