Abstract: Objective To investigate the role of wild—type XPD in HepG2 hepatoma cells，its relationship with P52 and P21．And the apoptosis mechanism of HepG2 hepatoma cells． Methods The experiment were classified three groups: pEGFP-N2-XPD group, pEGFP-N2 group, with the same genetic background and the generations of HepG2 cells as normal group. pEGFP-N2 and pEGFP-N2-XPD were transfected into HepG2 cell line by Lipofectamine 2000. The expression of green fluorescent protein(GFP) were observed with fluorescence microscope. The expression of wild-type XPD，P52 ,P21 was detected by RT-PCR，Western blot．Cell growth was detected by MTT. Results ①HepG2-pEGFP-N2-XPD and HepG2-pEGFP-N2 express the green fluorescence protein which could be detected under the immunofluorescence microscope．②RT-PCR The relative expression of P21 mRNA, XPD mRNA in the HepG2, HepG2-pEGFP-N2-XPD and HepG2-pEGFP-N2: the relative expression of P21 mRNA, XPD mRNA in the HepG2-pEGFP-N2-XPD was significantly higher than other two controls(P<0.01). Otherwise, the relative expression of P52 mRNA was significantly lower than other two controls (P<0.01), the difference of two controls was not significant(P>0.05)③Western blot The relative expression of XPD protein,P21 protein were significantly higher than other two controls (P<0．01)．Otherwise，the relative expression of P52 protein was significantly lower than other two controls(P<0.01)，the difference of two controls was not significant(P>0.05)．④MTT The -XPD was much more decreased than other two controls (P<0．05)，the other two controls were not different(P>0．05)． Conclusions The wild-type XPD could inhibit the proliferation of HepG2 cells in vitro. The wild-type XPD could decrease the expression of P52 and increase the expression of P21.

Key words: Carcinoma, hepatocellular, DNA repair, genes, transfection