MDR1及MDR3基因沉默逆转卵巢上皮性癌细胞对紫杉醇耐药的实验研究

目的 研究多药耐药基因——MDR1及MDR3基因沉默逆转卵巢上皮性癌（卵巢癌）细胞A2780／taxol对紫杉醇耐药的作用。方法 用真核质粒介导的针对MDR 1及MDR3基因的短发夹状RNA（shRNA）转染A2780／taxol细胞（分别为MDR1组、MDR3组）,空质粒转染作为对照（空载体组）。流式细胞仪分别检测细胞早期凋亡、罗丹明123（Rh123）积聚情况,末端脱氧核苷酸转移酶介导的脱氧尿苷三磷酸标记法（TUNEL）检测细胞晚期凋亡情况,四甲基偶氮唑蓝（MTT）比色法检测细胞对紫杉醇的半数抑制浓度（IC50）,RT-PCR技术检测MDR1及MDR3mRNA的表达,蛋白印迹法（western blot）检测半胱氨酸天冬氨酸蛋白酶3（caspase-3）蛋白的表达。结果转染后,MDR1组及MDR3组A2780／taxol细胞的早期凋亡率分别达（20．21±0．56）％和（10．87±1．24）％。MDR1、MDR3组A2780／taxol细胞内的Rh123平均荧光强度分别为116．6±8．1、98．4±3．8,显著高于空载体组的40．2±1．6,差异有统计学意义（P〈0．05）。TUNEL检测显示细胞发生了晚期凋亡。MDR1、MDR3组A2780／taxol细胞对紫杉醇的IC50明显下降,分别与空载体组比较,差异均有统计学意义（P〈0．05）。转染48h后,A2780／taxol细胞中MDR1和MDR3mRNA的表达水平分别下降了（73．3±0．8）％和（51．6±0．4）％;MDR1、MDR3组细胞caspase-3的表达量分别为（80．8±2．6）％、（72．0±4．7）％,均较空载体组增加。结论 MDR1及MDR3基因沉默能恢复A2780／taxol细胞对紫杉醇的敏感性并诱导细胞凋亡,从而逆转A2780／taxol细胞对紫杉醇的耐药性。

Reversal effect of MDR1 and MDR3 gene silencing on resistance of A2780/taxol cells to paclitaxel

OBJECTIVE: To investigate the reversal effect of MDR1 and MDR3 gene silencing on resistance of A2780/taxol cells to paclitaxel. METHODS: shRNA plasmid vector specifically targeting MDR1 and MDR3 genes was transfected into A2780/taxol cells. The early stage cell apoptosis and the effect of intracellular rhodamine 123 (Rh123) accumulation were detected by flow cytometry (FCM). The late stage cell apoptosis rate was detected by terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL). The 50% inhibition concentration (IC(50)) of paclitaxel on A2780/taxol cells was determined by methyl thiazolyl tetrazolium (MTT) assay. MDR1 and MDR3 mRNA were assessed by RT-PCR, and caspase-3 protein was detected by western blot. RESULTS: After treatment with MDR1 and MDR3 shRNA plasmid vector, early apoptosis rate of A2780/taxol cells was (20.21 +/- 0.56)% and (10.87 +/- 1.24)%, respectively. MDR1 and MDR3 shRNA could increase cellular Rh123 accumulation (116.6 +/- 8.1 and 98.4 +/- 3.8, respectively). The late stage apoptosis rates detected by TUNEL displayed the same tendency as FCM results did. The IC(50) for paclitaxel of A2780/taxol cells was decreased significantly. The mRNA levels of MDR1 and MDR3 in A2780/taxol cells were decreased by (73.3 +/- 0.8)% and (51.6 +/- 0.4)% of control, and the reduction of MDR1 and MDR3 mRNA was in a time-dependent manner. The expression of caspase-3 protein of MDR1 and MDR3 shRNA vector transfected group in A2780/taxol cells was significantly increased (80.8 +/- 2.6)% and (72.0 +/- 4.7)%, respectively]. CONCLUSION: MDR1 and MDR3 gene silencing could recover sensitivity of A2780/taxol cells to paclitaxel and induce cell apoptosis, thus reversing cell resistance to paclitaxel.