Objective      To explore the role of BARF1 gene encoded by Epstein-Barr virus (EBV) in malignant transformation of human gastric epithelial cells.      Methods      BARF1 gene carried by the eukaryotic vector pIRES2-EGFP/BARF1 was transfected into human gastric epithelial cell line GES-1; the transfected cells were screened by G418; and through this process obtained human gastric epithelial cells that stably expressed BARF1 gene. The colony formation in soft agar and tumorigenicity in SCID mice of the stably transfected cells were examined. GES-1 cells were divided into 4 groups including a BARF1 group (cells transfected with BARF1 gene)

a TPA group (cells transfected with BARF1 gene and treated with TPA)

a vector group (cells transfected with vector plasmid) and a control group (cells with no transfection). The SCID mice were given different groups of cells through subcutaneous inoculation

and each treatment included 3 mice.      Results      The cells of the BARF1 group and the TPA group formed colonies in soft agar

and the clony-forming efficiency were 24.2% (58/240) and 40.0% (96/240)

respectively

while cells of the vector group and the control group did not form any colonies in soft agar. Tumors were formed in the SCID mice that were given the cells of the TPA group

while no tumor was formed in the SCID mice that were given the cells of the other groups. However

nodules were formed in the SCID mice that were given the cells of the BARF1 group.      Conclusion     BARF1 gene

as an oncogene of EBV

can induce malignant transformation and gain of tumor cell characteristics in cells and plays an important role in the malignant transformation of gastric epithelial cells.