Like other ribozymes, HDV ribozyme has this property. So it may have a potential application in gene therapy in which an engineered ribozyme is directed to inhibit gene expression by targeting a specific PLX 4720 mRNA molecule. As hepatocellular carcinoma is often associated with the infection of HBV and HDV, The

facts that HDV ribozyme derived from HDV and that pathogen naturally infects and replicates in hepatocytes suggest that it can be used to control gene expression in human cells. The HDV ribozyme is active in vitro in the absence of any proteins, it is the only known example of a catalytic RNA associated with an animal virus. there are no known homologues of HDV ribozymes, and sequence variation of the HDV ribozymes in clinical isolates is minimal. FDA-approved Drug Library cell line Then we imagine whether HDV ribozyme can be used to inhibit hepatocellular carcinoma. In the present study we designed a HDV ribozyme against RNA component of human telomerase in hepatocellular carcinoma cell lines,

as well as in normal hepatocytes and other cancers, then examined the function of the HDV ribozyme and the effects of developing the HDV ribozyme as a tool of cancer gene therapy Methods The bel7402, HCT116 cells were given by Department of molecular Biology, Shandong University, DNA of HDV ribozyme was BMS345541 chemical structure synthesized by Shanghai Biosun Sci&Tech. Co. LTD. Recombinant plasmid pBBS212 containing hTR gene was provided by Geron Company. Design and synthesis of HDV ribozyme It was demonstrated that antigenomic ribozyme of HDV (g.RZ 1/84) is composed of 84 nucleotides[9]. It composed four stems (P1-P4), two loops and three junctions. As seen in Figure 1. Figure 1 Structure of antigenomic ribozyme of HDV (g.RZ Erythromycin 1/84). gRZ.1/84 can cleave 8-13 nt substrate by inter-molecular cleavage [10], the substrate must integrate with P1 stem of HDV ribozyme through base-pairing before cleavage, only 7 nt base pairing are needed, then the cleavage can occur. In P1 stem

G.U wobbling pair is essential for the activity of gRZ.1/84 and cannot be changed. The other 6 nucleotides can be changed, but the change must keep Waston-Crick pairing to substrate [11–13]. P4 stem isnot essential and can be deleted for easier access of ribozyme to substrate [14]. The activities of modified ribozyme do not decrease, but sometimes increase [15, 16]. We chose 12-84 nt of g.RZ 1/84, deleted 16 nt from P4 stem, and changed 6 nt of P1 stem from CCGACC to GGUUGA, only keeping G.U wobbling pair, to meet the need of cleavage of telomerase. We called the new ribozyme g. RZ57. The double-sranded DNA of g. RZ57 was synthesized with ApaΙ and HindIII protruding ends. Their sequences are as follows: 5′ AGCTT GGGAC CACCA CCACG CGGAC GCAAG AAGGG CAAGC GGCAA CGCAA GGCAA AGGGACCC CCC 3′ and 5′ A CCCTG GTGGT GGTGC GCCTG GCTGG TCCCG TTCGC CGTTG CGTTC CGTTT CCCTG GG GGG 3′. The predicted secondary structure of g. RZ57 are seen in Figure 2.