核酶对人肝癌细胞多药耐药性的逆转

目的 利用核酶技术切割肿瘤多药耐药基因(MDR1),逆转肿瘤抗药性。方法按照“锤头结构”模型设计、合成了核酶196MDR1(196 RZ),并定向克隆入包含RNA多聚酶Ⅲ启动子的逆转录病毒载体中。通过脂质体介导,将抗mdrl核酶表达质粒(N2A tRNA1^(met)-iMDRl-Rz)导入人肝癌耐药细胞株HepG2。分别采用RT-PCR、荧光PCR、蛋白质印迹分析(western blot)、流式细胞仪检测术、罗丹明聚集及MTT、方法,观察细胞的．RZ、mdrl mRNA、P糖蛋白(Pgp)表达和对化疗药物敏感性的变化。结果经抗MDR1核酶处理的耐药HepG2细胞,RZ稳定表达,MDRl mRNA、Pgp明显降低,细胞内罗丹明聚集,对阿霉素的敏感性提高200倍。结论针对多药耐药基因mdrl的核酶可明显降解mdrl mRNA,抑制Pgp的表达,具有强大的逆转肝癌耐药细胞HepG2多药耐药的作用。

Overcoming multi-drug resistance using anti-MDR1 ribozymes

Objective To reverse multidrug resistance(MDR) of HepG2 by anti-MDR1 hammerhead ribozyme. Methods We developed an anti-MDR1 hammerhead ribozyme and delivered it to P-gp-overproducing human hepatocarcinoma cell line HepG2 by a retroviral vector containing RNA polymerase III promoter. We detected the expression of MDR1/Pgp and Rz in HepG2, HepG2 multidrug-resistant cell line and HepG2 Rz-tranduced cells by real-time RT-PCR, semi-quantitative RT-PCR and western blot methods. Moreover, MTT assay was tested to detect sensitivity of these ribozyme-tranduced cells, and Rhodamine123 (Rh123) applied to test the function of Pgp. Results The Rz-tranduced HepG2 cells became doxorubicin-sensitive, concomitant with the decreases in MDR1 expression, P-gp amounts and efflux pump function. Conclusions The approaches using either retrovirus or liposome-mediated transfer of anti-MDR1 ribozyme may be selectively applicable to the treatment of MDR cells.