Abstract： Objective To explore the feasibility of gene therapy targeting on WT1 gene in leukemia.siRNA inhibiting WT1 gene expression was effectively screened out and its affection on proliferation of K562 cell was observed.Methods Three siRNA for WT1 were designed and transfected into HEK293 cells.WT1 mRNA expression was detected by FQ-RT-PCR.WT1 protein expression was detected by Western blotting.The affection of cell proliferation was detected by MTT method. Results The inhibitory effects of siRNA designed different locations were different for wt1 gene.si-wt1-1 gene was the most significant(P＜0.05),but si-wt1-2 and si-wt1-3 had no inhibitory effect on WT1 mRNA expression(P＞0.05).WT1 mRNA expression was reduced to(42.5±1.0)%and(25.3±1.5)%of the controls at 24 h and 48 h transfected with 100 nmol/L si-wt1-1 respectively(P＜0.05),but restored to normal level at 72 h.There was no dose-dependent inhibitory effect for si-wt1-1 by the statistics analysis.The inhibitory effect of si-wt1-1 was obvious and the effect is best at 96h especially(P＜0.05).But si-wt1-2 and si-wt1-3 had no effect on WT1 protein expression by Western blotting analysis(P＞0.05).si-wt1-1 had inhibitory effect for K562 cell proliferation.there was obvious differenee between si-wt1-1 and negative control (P＜0.05).conclusion siRNA can effectively inhibit WT1 gene expression on HEK293 cells and the inhibitory effect on mRNA level is most significant on protein level.si-wt1-1 can effectively inhibit K562 cell proliferation.[Subjeet words]RNA interference;RNA,small interfering;Genes,Wilms tumor