Objective To transfect antisense vector of human cyclooxygenase-2 (COX-2) gene into COX-2 highly expressing chol-angiocarcinoma cell line QBC939 and explore its biological activities and role in carcinogenesis. Methods QBC939 cells were transfected with antisense vector of human COX-2 gene using LipoVecTM transfecting te-chnique. Transfected cells were selected with G418; COX-2 mRNA was examined using reverse transcription polymerase chain reaction (RT-PCR) and COX-2 protein expression was detected by immunocytochemistry using isozyme selective anti-bodies. The proliferative status of transfected cells was measured by using methabenzthiazuron (MTT) assay; Cell cycle and apoptosis were analyzed by using flow cytometry. Results RT-PCR showed a lower COX-2 mRNA level in antisense vector transfected cells and immunocytochemistry showed a weaker COX-2 protein expression in antisense vector transfected cells. The antisense vector transfected cells proli-ferative index decreased significantly (P< 0.01), the percentage of S phase decreased remarkably (P< 0.05) in antisense vec-tor transfected cells (9.27% ±1.91%) compared with that in QBC939 cells without transfection(16.35% ±2.87%), and the percentage of G0/G1 phase increased remarkably (P< 0.05) in antisense vector transfected cells (75.16%±4.13%) compared with that in QBC939 cells without transfection (57.31% ±10.16%). Transfection with antisense vector of human COX-2 gene had no significant influence on the apoptosis in QBC939 cells (P> 0.05). Conclusion Transfection with antisense vector of human COX-2 gene could inhibit the proliferation of human cholan-giocarcinoma QBC939 cells. Objective To transfect antisense vector of human cyclooxygenase-2 (COX-2) gene into COX-2 highly expressing chol-angiocarcinoma cell line QBC939 and explore its biological activities and role in carcinogenesis. Methods QBC939 cells were transfected with antisense vector of human COX- 2 gene using LipoVecTM transfecting te-chnique. Transfected cells were selected with G418; COX-2 mRNA was examined using reverse transcription polymerase chain reaction (RT-PCR) and COX-2 protein expression was detected by immunocytochemistry using isozyme selective anti-bodies. The proliferative status of transfected cells was measured by using methabenzthiazuron (MTT) assay; Cell cycle and apoptosis were analyzed by using flow cytometry. Results RT-PCR showed a lower COX-2 mRNA level in antisense vector transfected cells and immunocytochemistry showed a weaker COX -2 protein expression in antisense vector transfected cells. The antisense vector transfected cells proli-ferative index decreased significantly (P <0.05) in antisense vec-tor transfected cells (9.27% ​​± 1.91%) compared with that in QBC939 cells without transfection (16.35% ± 2.87%), and the The percentage of G0 / G1 phase increased significantly (P <0.05) in antisense vector transfected cells (75.16% ± 4.13%) compared with that in QBC939 cells without transfection (57.31% ± 10.16%). Transfection with antisense vector of human COX-2 gene had no significant influence on the apoptosis in QBC939 cells (P> 0.05). Conclusion Transfection with antisense vector of human COX-2 gene could inhibit the proliferation of human cholan-giocarcinoma QBC939 cells.