Objective To observe the effects of hepatitis B virus(HBV)X gene muhifunctional protein(HBx)on the biological characteristics of QSG7701 and the transformational effects on QSG7701 cell.Methods QSG7701 ceils were stably transformed by recombinant plasmid pCMV/X and eukaryotic expressed plasmid pRc/CMV2 by liposome-based assay,respectively.Non-transfeeted QSG7701 cells were employed as controls.The expressions of HBx,c-Myc and Bel-2 proteins in QSG7701 cells were detected by Western blot.MTT colorimetric analysis,flow cytometry and soft agar clone-forming assay were performed tO detect the biolo~dcal activity of cells.Results HBx Drotein was highly expressed in pCMV X/QSG7701 cells.The expression level of c-Myc protein in the pCMV X/QSG7701 cells was much higher than those in the other tWO groups of cells.The expression of Bcl2 protein was detected in the three groups of cells,but the expression levels were similar.Percentage of S stage cells in pCMV X/QSG7701 ceils was significantly higher than those in pRcCMV2/QSG7701 and non-transfected QSG7701 cells E(28.80±2.32)%,(15.5±2.64)%and(21.5±3.66)%,LSD 0.05=3.95%,LSD 0.01=5.47%,P<0.01].While percentage of G1 stage cells in pCMV X/QSG7701 cells was significantly lower than those in pRcCMV2/QSG7701 and non-transfected QSG7701 cells[(62.30±3.85)%,(78.70±4.12)%and(78.10q±4.45)%,LSD 0.05=5.63%,LSD 0.01-7.79 %,P<0.01].The apoptosis rate of pCMV X/QSG7701 cells was much higher than those in pRcCMV2/QSG770t and non-transfected QSG7701 cells[(14.90±1.01)%,(8.91±0.48)%and (4.03±0.47)%,LSD 0.05=O.94%,LSD 0.01=1.31%,P<0.01].The population doubling time of pCMV X/QSG7701 cells was shorter than those in pRcCMV2/QSG and non-trarmfected cells(14 h,29 h,38 h,respectively).The cloning ratio in soft agar of pCMV X/QSG7701 cells WaS significantly higher than those of pRcCMV2/QSG and non-transfected QSG7701 cells[(19.83±1.96)%,(1.76±0.03)%and (1.33±0.18)%,LSD 0.05=1.53%,LSD 0.01=2.11%,P<0.01].Conclusion HBx may transform human non-tumor hepatoeyte QSG7701,which makes the cell growth malignizeA.