OBJECTIVETo construct eukaryotic expression vector of siRNA specific for BCR/ABL and to investigate the effect of recombinant plasmid on BCR/ABL and P210 protein expression in K562 cells.

METHODSsiRNA(small interfering RNA)was designed according to the Tuschl's principle of Ai-based medicine, and was converted into cDNA coding expression of shRNA(small hairpin RNAs)of siRNA for BCR/ABL fusion gene. The cDNA was synthesized and inserted into plasmid pTER. The pTER117 and pTER363 of recombinant plasmid being eukaryotic expression vector was controlled by the H1 promoter of RNA polymerase III, and identified by the restriction map and the sequence analysis. The recombinant plasmid did not only have the screening resisting antibiotics, its expression but also are induced by tetracycline (tet). After steadily transfection into K562 cells by Lipofectamine, their positive mono-cell clones being resistant to Zeocin were isolated. TaqMan real-time quantitative RT-PCR (RQ-PCR) and Western blot respectively detected expression of BCR/ABL mRNA and P210 protein. Trypaum blue dying was used to analyze the proliferation of K562 cells. Cell apoptosis was observed by flow cytometer.

RESULTSthe recombinant plasmid was steadily transfected into K562 cells by Lipofectamine 2000, Their positive mono-cell clones being resistant to Zeocin were isolated. The proliferation of K562 cells were remarkably inhibited by the recombinant plasmid induced gene expression by tetracycline. Tetracycline induced its expression for 48 h and 72 h. pTER117, pTER363 decreased the mRNA level of BCR/ABL 90%, 82% and 91.5%, 84%, respectively, P210 protein were almost measured in K562 cells. FCM analysis showed that the recombinant plasmid induced apoptosis in K562 cells, the apoptosis rate were respectively 34.4%, 58.1% in K562 cells treated by pTER117 for 48 h and 72 h, apoptosis rate were 31.8%, 54.6% by pTER363, but the control groups did not show these effects on K562 cells.

CONCLUSIONThe siRNA eukaryotic expression vector against BCR/ABL mRNA has been successfully conctructed,and effectively inhibits the expression of BCR/ABL in K562 cells, inhibite cell growth and induce cell apoptosis.