[Circumventing multidrug resistance in human cancer by anti-ribozyme]

The demonstration tha RNA can be cleavaged by cis-ribozyme(catalytic RNAs, RNA enzyme) has potentially important therapeutic implications. Ribozymes are effective for modulation of gene expression because of their simple structure, site-specific cleavage activity and catalytic potential. The targets of ribozyme-mediated gene modulation have ranged from cancer cells to foreign genes that cause infectious diseases. Additional target sites for ribozymes are in initial phases of development and design. Ribozymes have been targeted against myriad genes, including oncogenes (ras, BCR-ABL) and drug resistance genes(MDR-1, c-fos, DHFR). These ribozymes have cleaved the target RNAs in culture system(in vitro) and developed in vivo system. We reported that anti-fos ribozyme has altered the expression of c-fos and DNA repair genes in cisplatin-resistance cancer cells, and reversed the sensitivity to ciaplatin. Furthermore, we have developed high efficiency by the transfer system using an electroporation in vivo.