Inhibitory Effect Of Xeroderma Pigmentosum D Gene On Proliferation Of Human Hepatocellular Carcinoma Cell Line SMMC-7721

Objective The Xeroderma Pigmentosum D(XPD)gene plays an important function in DNA repair path ,because it is a key factor of DNA nucleotide excision repair-dependent signaling. Research shows that when the XPD gene mutations in the gene ,a higher susceptibility to tumor. This project studied that the XPD gene represses hepatoma carcinoma cell(HCC). To investigate the mechanism of the XPD gene inhibits the HCC.Methods pEGFP-N2 and pEGFP-N2-XPD were transfected into SMMC-7721 cell line by LipofectAMINE 2000.The expression of green fluorescent protein(GFP) were observed with fluorescence microscope. The expression of wild-type XPD,c-myc,cdc25A ,and cdK2 were detected by Reverse Transcription-Polymerase Chain Reaction(RT-PCR) and Western blot . Flow cytometry(FCM)were employed for examining the cell cycle of the transfected SMMC-7721 cells.Cell proliferation was detected by MTT.Results The recombinational plasmid pEGFP-N2-XPD was generated and identified.SMMC-7721-pEGFP-N2 and SMMC-7721-pEGFP-N2-XPD expressed the green fluorescence protein which could be detected under the immunofluorescence microscope. The relative expression of XPD in SMMC-7721- pEGFP- N2-XPD was significantly higher than those in control SMMC-7721 and SMMC-7721-pEGFP-N2. The relative expressions of c-myc, cdc25A and cdK2 were significantly lower in SMMC-7721-pEGFP-N2-XPD cells than in controls . The Wild type XPD gene prevented the hepatoma cells from entering the S period, suspending in the G1 period . The proliferative ability of SMMC-7721-pEGFP-N2-XPD was much more inhibited than in control(sP<0.05).Conclusion The wild-type XPD could decrease the expression of c-myc,cdc25A ,and cdK2 and play an important role in S period DNA damage checkpoint.However, inhibit the proliferation of SMMC-7721 cells in vitro.