Abstract: Abstract: Objective To detect the effects of siRNA targeting CDX2 gene expression on of BCR-ABL, caspase and Bax expressions, and the mechanisms thereof. Methods According to the earlier experiments, siRNA specifically targeting CDX2 gene (CDX2-siRNA) and the negative control sequence (CDX2-siRNA-NC) were selected, and then were transfected into K562 cells by Roche X-tremeGENE HP DNA Transfection Reagent. The flow cytometry analysis was used to detect the effects of siRNA on cell apoptosis. The expressions of BCR-ABL, caspase- 9, Bax mRNA and protein were tested by RTPCR and Western blot assay. Results MTT and flow cytometry analysis showed that after the silence of CDX2 gene expression, the proliferation of K562 cells was prohibited and the apoptotic rate of K562 cells was distinctly increased compared with that of normal cell group, but the negative control group had no significant change. According to the RT-PCR and Western blot assay, in comparison with the normal cell group and the negative control group, the expression levels of BCR-ABL mRNA and protein were obviously decreased, and the difference was statistic significance. On the other hand, the expressions of caspase- 9 and Bax mRNA and protein were significantly higher than those of other two groups (P＜0.05). Conclusion CDX2-siRNA can promote apoptosis of K562 cells obviously, and the mechanism is related with the downregulation of BCR-ABL and the up-regulation of caspase-9 and Bax.

Key words: leukemia, RNA interference, gene silencing, apoptosis, fusion proteins, BCR-ABL, CDX2, RNA interference, Caspase-9, Bax