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Accumulation of 8-hydroxy-2'-deoxyguanosine adducts in HBx recombinant HepG2 cells and HBx transgenic mice.

Author	Ralph Gehrke, Maria A Brauchle, Kurt Reifenberg, Eberhard Hildt, Uwe Gruetzner, Volker Schmitz, Hans-Jürgen Schlicht, Peter Hans Hofschneider, Wolfgang H Caselmann, Christian Rabe
Citation Information	Digestion, 70:117-26 (2004)
Keywords	Acetylcysteine, Animals, Blotting, Western, Carcinoma, Hepatocellular, Cell Line, Tumor, DNA Adducts, DNA, Recombinant, Deoxyguanosine, Humans, Liver, Liver Neoplasms, Mice, Mice, Transgenic, Trans-Activators
Related Products	MAB8419
Pub Med ID	15375340

BACKGROUND/AIMS: Transgenic mice overexpressing hepatitis B x protein (HBx) show an increased susceptibility to mutations if exposed to mutagens. Also involved in HBx signalling, reactive oxygen intermediates (ROI) can induce DNA adducts such as 8-hydroxy-2'-deoxyguanosine that can in turn lead to G/T transversion mutations. Therefore, we investigated whether HBx expression increases the level of the mutational precursor 8-hydroxy-2'-deoxyguanosine in hepatocellular DNA. METHODS: 8-hydroxy-2'-deoxyguanosine concentrations of DNA hydrolysates of HBx protein expressing HepG2 cells and livers of HBx transgenic mouse lines were determined electrochemically after HPLC fractionation. RESULTS: 8-hydroxy-2'-deoxyguanosine concentrations in genomic DNA of HBx protein expressing cell lines correlated with the factor of transactivation. The 8-hydroxy-2'-deoxyguanosine levels were reduced after incubation of HBx recombinant cell lines with 0.1 or 1 mM of the antioxidant N-acetylcysteine. Hepatic 8-hydroxy-2'-deoxyguanosine concentrations in DNA of old transgenic mice were significantly, i.e. twofold, (p 0.01) increased as compared to those of old nontransgenic or young transgenic controls and of control mice expressing a second HBV transactivator (MHBs(t76)). Conclusion: HBx expression results in elevated DNA adduct levels. This could reflect a direct inhibitory interaction of HBx with cellular repair mechanisms. Alternatively, this may be an effect of an increased generation of reactive oxygen intermediates through HBx.