【Abstract】ObjectiveTo study the effect of transfection with antisense DNMT3b gene eukaryotic expression vector on the expression of DNMT3b gene in human cholangiocarcinoma cell line QBC-939. MethodsThe constructed antisense DNMT3b gene eukaryotic expression vector was transfected into the human cholangiocarcinoma cell line QBC-939 by using lipofectamine transfection reagents, and positive cell clones were obtained by using G418 selection after transfection. Whether the constructed recombinant vector was transfected into QBC-939 cells successfully was confirmed by amplifying the exogenous neoR gene with PCR method. The expression of DNMT3b gene mRNA and protein were detected by semi-quantitative RT-PCR and FCM methods respectively. ResultsFollowing the transfection of antisense DNMT3b gene eukaryotic expression vector, the mRNA level of DNMT3b gene in QBC-939 cells of human cholangiocarcinoma decreased from 0.956±0.053 to 0.209±0.023, and the protein level of DNMT3b gene also decreased from (75.38±3.22)% to (29.87±3.46)%. There were very significant differences on the expression levels of DNMT3b gene between non-tranfections group and the antisense DNMT3b gene eukaryotic expression vector transfection group (P＜0.01). ConclusionTransfection with antisense DNMT3b gene eukaryotic expression vector significantly reduces the expression level of DNMT3b gene in human cholangiocarcinoma cell line QBC-939, and this study may provide a valid tool and method to investigate the function of DNMT3b gene and its role in cholangiocarcinoma.