目的：研究siRNA下调Mcl-1后奥沙利铂对Y79凋亡率的影响。

方法：使用RPMI1640培养液培养Y79细胞。将培养后的细胞用0.25μmol/L的奥沙利铂进行刺激，分别在6、16和24h后，使用Western blot法对Mcl-1蛋白的表达效果进行检测。收集对数生长期的细胞，制备单细胞悬液，分别转染空质粒和Mcl-1-homo-991、Mcl-1-homo-1114、Mcl-1-homo-1235质粒。6h后使用荧光显微镜拍照，观察转染效率，选出最佳的siRNA序列。将未进行转染操作的RB细胞Y79分为A组，将转染空质粒的为对照组，将行转染下调Mcl-1操作后的细胞分为B组和C组，其中A组和C组均采用0.25μmol/L的奥沙利铂进行刺激诱导处理，B组转染细胞常规培养，24h后采用Annexin V-FITC/PI双染法和流式细胞术进行检测对比4组的细胞凋亡率。

结果： Western blot检测结果表明处理Y79细胞24h后Mcl-1的表达最为显著，转染Mcl-1-homo-991质粒后能够明显抑制Y79细胞中Mcl-1的表达，转染效率最高。采用Annexin V-FITC/PI双染法和流式细胞术进行检测A组凋亡率(11.1%±1.2%)与对照组(6.1%±0.6%)对比，差异无统计学意义(P>0.05)； C组Y79的凋亡率(49.2%±2.7%)显著高于B组(20.8%±1.9%)，同时这两组的凋亡率都显著高于A组和对照组，差异有统计学意义(P<0.05)。

结论：通过siRNA下调Mcl-1后，可以降低Y79的抗药性，从而增强奥沙利铂对Y79的凋亡，降低了Y79的存活。

METHODS: Y79 cells were cultured in RPMI1640. The cultured cells were stimulated with 0.25μmol/L of oxaliplatin. The expression of Mcl-1 protein was detected by Western blot after 6, 16 and 24h respectively. Cells in logarithmic phase were collected and used for single-cell suspension. Then they were transfected with empty plasmid, Mcl-1-homo-991, Mcl-1-homo-1114 and Mcl-1-homo-1235. After 6h, fluorescence microscope was used to observe the transfection efficiency and the optimal one was selected. The cells were divided into Group A and transfected with empty plasmids. The cells transfected with Mcl-1 were divided into Group B and Group C. Group A and Group C were treated with 0.25μmol/L oxaliplatin for stimulating induction, and the apoptotic rate was compared after 24h.

RESULTS: The expression of Mcl-1 in Y79 stimulated by oxaliplatin was the most after 24h of culture. Mcl-1-homo-991 significantly inhibited the expression of Mcl-1 in Y79 after transfection. There was no significant difference in the apoptosis rate in Group A(11.1%±1.2%)and in the control group(6.1%±0.6%)(P>0.05). The apoptotic rate of Group C(49.2%±2.7%)was significantly higher than that of Group B(20.8%±1.9%). At the same time, the apoptotic rates of these two groups were significantly higher than those of Group A and control group, the difference was statistically significant(P<0.05).

CONCLUSION:Downregulation of Mcl-1 by siRNA can reduce the drug resistance of Y79, thereby enhancing the apoptosis of Y79, and reducing the survival rate of Y79.