目的 通过RNA干扰沉默MDR1基因,探讨后者在乳腺癌多细胞球阿霉素耐药中的作用.方法 用liquid overlay技术培养获得多细胞球(multicellular spheroids, MCS),用脂质体转染法把特异针对MDR1基因的双链小RNA干扰片段导入MCF-7细胞中,采用台盼蓝拒染法检测阿霉素对MCF-7的细胞抑制率,MDR1 mRNA水平及蛋白水平分别用RT-PCR和免疫印迹法检测,用荧光光度计法检测阿霉素在细胞内的蓄积情况.结果 多细胞球形成后,阿霉素对MCF-7细胞的抑制率明显减少,MDR1 mRNA及蛋白水平明显升高,阿霉素在细胞内的蓄积量减少;RNA干扰法能明显抑制MDR1基因表达,增加阿霉素在MCS细胞中的蓄积,提高阿霉素对MCS的细胞抑制率.结论 多细胞球的形成可以增强MCF-7细胞的阿霉素耐药性,RNA干扰沉默MDR1基因可以部分逆转MCF-7多细胞球的阿霉素耐药.%Objective To investigate the role of MDRI gene expression in drug resistance of multicellular spheroids of breast carcinoma to Adriamycin( ADM) by RNA interfering technique. Methods MCF - 7 multicellular spheroids were obtained from liquid overlay technique culture. MDR1 - targeted small interfering double - stranded RNAs ( SiRNA) were introduced into MCF - 7 cells by lipofectamine. Adriamycin resistance was detected with trypan blue exclusion testing. MDR1 mRNA and MRD1 protein levels were determined by reverse transcroption - polymerase chain reaction( RT - PCR) and Westernblot, and Adriamycin accumulation in MCF - 7 cells was tested by fluorescence spectrophotometry. Results Compared with monolayer cells, MCS showed lower cell inhibitory rate and ADM accumulation in cells after ADM expoaure for 24h, and both mRNA and protein level of MDRI were elevated in MCS obviously. RNA inter ference markedly inhibited the expressiong of MDRI mRNA and protein, and enhanced the intracellular accumulation of andpartially restored sensitivity to ADM in MCF -7 MCS. Conclusion Breast carcinoma MCF - 7 multicellular spheroids induced resistance to ADM.RNA interference to target MDRI gene can partially restore sensitivity to ADM in MCS.
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