米非司酮对卵巢上皮性癌耐药细胞DNA修复基因表达和顺铂敏感性的影响

Influence of mifepristone on DNA repair genes and cisplatin sensitivity in human ovarian cancer drug.resistance cells

目的研究米非司酮对卵巢上皮性癌（卵巢癌）耐药细胞DNA修复基因表达的调控，及对顺铂的增敏作用。方法应用四甲基偶氮唑蓝比色法检测2．5、5．0、10．0μmol／L米非司酮作用后卵巢癌顺铂耐药细胞株COC1／DDP的顺铂半数抑制浓度（IC50）；用RT-PCR技术、流式细胞仪检测米非司酮联合顺铂作用后COC1／DDP细胞ERCC1、BRCA1、hMLH1 mRNA的表达水平及细胞周期和凋亡率的变化；建立COC1／DDP细胞裸鼠皮下移植瘤模型，分为顺铂组、米非司酮组、联合组和对照组，观察米非司酮在裸鼠体内对顺铂的增敏作用。结果2．5、5．0、10．0μmol／L米非司酮分别使COC1／DDP细胞对顺铂的IC50下降为（3．18±0．46）、（1．95±0．14）和（0．64±0．18）μg／ml，2．5μmol／L米非司酮联合顺铂作用后的IC50与单用顺铂者[（3．71±0．38）μg／ml]比较，差异无统计学意义（P=0．076），其他浓度之间两两比较，差异均有统计学意义（P〈0．01）。米非司酮下调ERCC1、BRCA1、hMLH1 mRNA表达水平，3种基因mRNA的相对表达量随米非司酮浓度的升高均呈下降趋势。2．5、5．0、10．0μmol／L米非司酮联合顺铂对COC1／DDP细胞作用后，G0／G1期细胞比例升高（分别为51．68％、53．74％、55．08％）。2．5、5．0、10．0μmol／L米非司酮与10μg／ml顺铂联合作用使细胞凋亡率分别增加为5．11％、9．13％和12．24％。米非司酮联合顺铂治疗裸鼠皮下移植瘤的生长抑制率为70．1％，与顺铂组、米非司酮组（分别为22．5％、6．5％）比较，差异均有统计学意义（P〈0．05）。结论米非司酮通过下调ERCC1、BRCA1、hMLH1基因的表达及阻滞G0／G1期细胞、增加细胞凋亡率来增强顺铂对卵巢癌细胞的抗肿瘤敏感性。

Objective To study the changes of DNA repair genes and enhanced anti-tumor effect of cisplatin induced by mifepristone in human ovarian cancer drug resistance cells. Methods The alterations of cisplatin concentration producing 50% inhibition （ IC50 ） in the COC1/DDP cell lines were examined by methyl thiazolyl tetrazolium （MTY） assay. RT-PCR and flow cytometry were used to analyze the changes of the mRNA of ERCC1, BRCA1, hMLH1 genes and cell cycle and apoptosis. Subcutaneous implantation of COC1/DDP was established in nude mice and the enhanced anti-tumor effect of cisplatin by mifepristone was observed in vivo. Results Cisplatin IC50 values of COC1/DDP cell were decreased from （3.71 ± 0. 38 ） μg/ml to （3. 18 ±0. 46）, （1.95 ±0. 14）, （0. 64 ±0. 18） μg/ml respectively when treated with 2. 5, 5.0, 10. 0 μmol/L mifepristone. Mifepristone could down-regulate the mRNA levels of ERCC1, BRCA1, hMLH1 genes and enhance G0/G1 phase block effect of cisplatin, and 2.5, 5.0, 10. 0 μmol/L mifepristone combined with cisplatin increased rate of cell apeptosis from 0.08% to 5.11%, 9.13% and 12.24% respectively. The percentage of inhibition of xenograft tumor volume in combined treatment group was 70. 1%, which was significantly different （P 〈 0. 05 ）. Conclusion By down-regulating ERCC1, BRCA1, hMLH1 genes, blocking G0/G1 phase, and increasing apeptosis rate, mifepristone could enhance anti-tumor effect of cisplatin.