摘要 应用计算机对mdr1 mRNA二级结构进行模拟，设计针对mdr1 mRNA 1 959位GUC的锤头状(hammerhead)核酶(RZ1)基因，定点克隆于质粒pGEMEX-1的BamH Ⅰ和EcoR Ⅰ位点上；将mdr1 cDNA 864bp的片段亚克隆于pGEMEX-1的Hind Ⅲ和EcoR Ⅰ位点上，在T₃ 启动子作用下体外转录成RZ1和864nt的mdr1 mRNA，RZ1在体外将864nt的mdr1 mRNA切割成两个片段，说明所设计的核酶可用于肿瘤细胞多药耐药性的逆转，改善肿瘤的化疗疗效。

    Ribozyme-mediated cleavage of mdr1 mRNA He Bin, Jing Xiyu, Yang Tangjun, et al. Department of Urology, The Second Affiliated Hospital, The Third Military Medical University, Chongqing 400037

    Abstract A hammerhead ribozyme has been designed to cleave the GUC sequence at codon 1 959 of mdr1 mRNA after analysis of the secondary structure of mdr1 cDNA by computer. The hammerhead ribozyme 1 gene was synthesized and cloned into the BamH Ⅰ/EcoR Ⅰ sites of pGEMEX-1 as pEX-RZ1. The 864bp fragment of mdr1 cDNA was subcloned into the Hind Ⅲ/EcoR Ⅰ sites of pGEMEX-1 as pMDR-864. The pEX-RZ1 and pMDR-864 were lineralized with Hind Ⅲ and transcribed with T₃ promotor in vitro. The ribozyme 1 showed strong cleavage activity after mixed the 2 transcripts for 2 hours at temperature 42℃ and 52℃. The results imply that the designed ribozyme could be used as a reverting tool for multidrug resistance of cancer cells.

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