目的

探讨针对多药耐药基因（MDR-1）的小分子干扰RNA（siRNAs）和反义脱氧寡核苷酸（asODNs）联合应用逆转人乳腺癌细胞MCF-7/ADR的作用效果。

方法

设计并合成针对MDR-1基因同一序列的siRNAs和asODNs及阴性对照siRNAs，采用转染试剂lipofectamine^TM2000分别转染人乳腺癌耐药细胞MCF-7/ADR；利用RT-PCR检测MDR-1mRNA和Western blot检测MDR-1蛋白质的表达；采用罗丹明123外排实验检测P-gp的转运功能，MTT法检测MCF-7/ADR细胞对阿霉素的耐药逆转效果。

结果

siRNAs、asODNs、asODNs和siRNAs联合应用均能降低MDR-1 mRNA及其蛋白质表达，提高P-gp的转运功能，使细胞对阿霉素的敏感性明显恢复；asODNs和siRNAs联合应用效果明显提高；低浓度siRNAs（200 nmol/L）比高浓度asODNs（5μmol/L）的效果强。

结论

siRNAs、asODNs能有效逆转人乳腺癌细胞MCF-7/ADR的多药耐药，asODNs和siRNAs联合应用效果明显加强。

Objective

To study the effect of small interfering RNAs（siRNAs）combined with antisense oligodeoxyribonucleotides（asODNs），which targeted MDR1 gene，on reversing multidrug resistance of human breast cancer cell line MCF-7/ADR.

Methods

The siRNAs and asODNs which targeted the same sequences of MDR1 gene were designed and synthesized.Human breast cancer MCF-7/ADR cells were cultured and tranfected with asODNs，siRNAs＋asODNs，siRNAs，and negative siRNAs using lipofectamine^TM 2000，respectively.MDR-1mRNA was assayed by RT-PCR and the protein expression was detected by Western blotting.The function of P-glycoprotein（P-gp）was detected by rhodamine 123 retention and the resistant efficiency of MCF-7/ADR to ADM was determined by MTT method.

Results

The expressions of MDR-1mRNA and protein decreased significantly after transfection of asODNs，siRNAs＋asODNs，and siRNAs respectively.The transporting function of P-gp increased and the resistance of MCF-7/ADR to ADM reversed significantly.The reversing effect increased significantly by siRNAs combined with asODNs.The inhibition effect of the siRNAs with lower concentration（200 nmol/L）was greater than that of asODNs with higher concentration（5μmol/L）.

Conclusion

siRNAs and asODNs could reverse multidrug resistance of human breast cancer cell line MCF-7/ADR.The inhibition effect is increased significantly by siRNAs combined with asODNs.