RNA特异性干扰bcr-abl融合基因联合p27基因克隆对K562细胞的影响

Effects of Specific siRNA Targeting at bcr-abl Fusion Gene and Its Combination with p27 Gene Clone on Chronic Myeloid Leukemia Cell Line K562

本研究旨在探讨RNA干扰抑制慢性髓系白血病bcr-abl融合基因表达,以及RNAi和p27基因克隆联合作用对K562细胞的细胞增殖、细胞周期及凋亡等的调控作用。以细胞系K562为研究对象,合成并转染针对K562细胞bcr-abl融合基因融合位点的21nt siRNA,应用Northern blot法检测bcr-abl融合基因的表达,Western blot法检测BCR-ABL蛋白及凋亡相关蛋白BCL-xL的表达;同时应用RT-PCR扩增p27基因,构建P27-pcDNA3.1载体,转染p27基因入缺失p27基因的K562细胞,经筛选得到G418抗性的K562细胞株;经Western blot证实有P27蛋白表达后,联合应用RNA干扰及p27基因克隆,通过MTT法及流式细胞仪等检测联合作用后对K562细胞的细胞增殖、细胞周期及凋亡等的调控作用。结果表明,RNA干扰组K562细胞bcr-abl融合基因的表达水平明显下降,转染24小时时有18.4%的K562细胞发生凋亡,细胞凋亡相关蛋白BCL-xL的表达水平下调,出现明显的G1期阻滞;表达外源性P27蛋白的P27-pcDNA3.1-K562细胞株生长速度明显慢于对照K562细胞株。流式细胞仪检测显示,G0/G1期细胞增多,S期细胞明显减少;RNA干扰与p27基因克隆联合作用于K562细胞后,凋亡细胞比例明显上升(33.4%)。MTT法显示,细胞存活率较单纯p27-K562细胞组及RNA干扰-K562细胞组均明显下降(p<0.01和p<0.05)。结论:特异性siRNA分子可以抑制bcr-abl融合基因的表达,诱导K562细胞分化或凋亡。RNA干扰联合p27基因克隆对抑制K562细胞增殖及促凋亡方面具有协同作用。

This study was purposed to explore the effect of specific small interfering RNA targeting at bcr-abl fusion gene and its combination with p27 gene clone on the proliferation, cell cycle and apoptosis of chronic myeloid leukemia （CML） cell line K562. CML cell line K562 was used as the study object. A 21nt siRNA targeting at the fusion site of b3 ：a2 mRNA in bcr-abl fusion gene was designed, synthesized and transfected into the K562 cells as RNA interference group. Northern blot was used to detect the bcr-abl fusion gene, Western blot was used to detect the expression of P210 protein and apoptosis-related protein BCL-xL after the transfection. Meanwhile, p27 gene was amplified from peripheral blood mononuclear cells by RT-PCR, and was confirmed to be correct by sequencing, then p27-pcDNA3.1 vector was constructed and transfected into K562 cell line by Lipofectine. After being selected with G418, p27-pcDNA3. 1-K562 cell clone stably expressing p27 was isolated. P27 protein was identified by Western blot. Finally, siRNA and p27 gene clone were together applied to K562 cells, the cell survival rate was tested by MTT. The cell cycle and the apoptosis were tested by flow cytometry. The result showed that in contrast with the control group, the expression level of bcr-abl fusion gene was much lower in siRNA group , about 18.4% of K562 cells in siRNA group were apoptotic at 24 hours after siRNA transfection, and the expression of apoptosis-associated protein BCL-xL was greatly down-regulated. The expression of P27 protein could be detected by Western blot in p27-pcDNA3.1-K562 cells. The strong inhibition of cell proliferation was observed in p27-pcDNA3. 1-K562 cells, as compared with control K562 cells. The count of p27- pcDNA3.1-K562 cells in G0/G~ phase increased apparently, but that in S phase declined greatly. Cell cycle was arrested in G0/G1 phase. After the combination of p27-pcDNA3.1-K562 cells with specific siRNA, the percentage of apoptosis obviously increased and cell survival rate significantly declined. It is concluded that the specific siRNA distinctly inhibits the expression of bcr-abl fusion gene, and can induce K562 cell apoptosis. The combination of specific siRNA with P27 gene clone displays a synergy of inhibition and pro-apoptosis effects to K562 cells.