siRNA对K562和K562/ADM细胞耐药和凋亡的调节

目的 研究联合转染以MRP和bcl-2基因为靶标的siRNA,对白血病细胞株K562和耐药的K562/ADM细胞药物敏感性和凋亡的影响.方法 体外化学合成以多药耐药相关蛋白(MRP)和bcl-2为靶标的siRNA,分别或联合用脂质体转染人阿霉素处理的K562和K562/ADM以单纯化疗处理组和未处理组为对照.转染后24、48、72 h,MTT法检测各组细胞生长抑制率,计算IC50值.转染24 h后RT-PCR检测各组细胞相应靶基因mRNA表达水平,48 h后流式细胞仪检测细胞MRP和bcl-2蛋白表达率和细胞凋亡率.结果 K562/ADM细胞ADM的IC50为12.81 μg/ml,ADM MRP-siRNA组降为3.74 μg/ml,ADM bcl2-siRNA组降为6.82 μg/ml ADM MRP-siRNA bcl2-siRNA组降至2.51 μg/ml;K562细胞ADM的IC50为6.75 μg/dml,ADM MRP-siRNA组降为3.22 μg/ml,ADM bcl2-siRNA组降为3.56 μg/ml,ADM MRP-siRNA bcl2-siRNA降至1.84 μg/ml,有统计学意义(P<0.01).转染以MRP和bcl-2为靶标的siRNA后,细胞相应靶基因的mRNA及蛋白的表达明显减低,细胞凋亡率显著升高,联合转染两种siRNA,细胞的IC50进一步下降,细胞凋亡率进一步升高,与分别转染组相比有统计学差异(P<0.05);结论联合转染以MRP和bcl-2基因为靶标的siRNA,通过降低靶基因蛋白表达,产生协同作用,明显增加耐药和亲本肿瘤细胞药物敏感性和凋亡率.

Effect of small interfering RNA targeting multidrug resistance-related protein and bcl-2 on drug resistance and apoptosis of K562 and K562/ADM cells

OBJECTIVE: To observe the effect of small interfering RNA (siRNA) targeting multidrug resistance-related protein (MRP) and bcl-2 genes in modulating drug resistance and apoptosis of K562 and K562/ADM cells. METHODS: Two siRNA constructs targeting respectively bcl-2 and MRP genes, were synthesized and transfected either alone or in combination into K562 and K562/ADM cells via lipofectamine2000. MTT assay was used to evaluate the viability of the transfected cells at 24, 48 and 72 h Post-fransfection, and RT-PCR was performed to determine the mRNA levels of bcl-2 and MRP. The effects of MRP siRNA and bcl2 siRNA on the apoptosis and the protein expression of Bcl-2 and MRP were evaluated with flow cytometry. RESULTS: In K562/ADM cells, the IC (50) decreased from 12.81 microg/ml (ADM group) to 3.74 microg/ml (ADM+MRP siRNA group), 6.82 microg/ml (ADM+bcl2 siRNA group) and 2.51 microg/ml (ADM+MRP siRNA+bcl2 siRNA). Similarly, in K562 cells, the IC(50) decreased significantly from 6.75 microg/ml (ADM) to 3.22 microg/ml (ADM+MRP siRNA), 3.56 microg/ml (ADM+bcl2 siRNA) and 1.84 microg/ml (ADM+MRP siRNA+bcl2 siRNA) (P<0.05). Flow cytometry demonstrated significantly increased apoptosis of the cells following MRP siRNA and bcl2 siRNA transfection, which also resulted in significantly decreased expressions of MRP and bcl-2 proteins (P<0.05). CONCLUSION: Treatment with both MRP and bcl-2 siRNAs inhibits the target gene expression, and increases the drug sensitivity and apoptosis of K562 and K562/ADM cells.