EFFECTIVENESS OF 3 RIBOZYMES FOR CLEAVAGE OF AN RNA TRANSCRIPT FROM HUMAN PAPILLOMAVIRUS TYPE-18

We tested three hammerhead ribozymes for their ability to bind and cle ave RNA transcripts derived from the E6 and E7 genes of human papillom avirus (HPV) type-18. Targets were located at nucleotides (nt) 123, 30 9, and 671 of the viral transcript. In vitro each ribozyme hybridized to its target site when the ribozyme:target ratio was 20:1 or greater and achieved maximal hybridization within 1 hour. HPV RNA from the HeL a cervical cancer cell line was cleaved effectively by each ribozyme. When HPV RNA and a ribozyme were expressed simultaneously in Escherich ia coil, each ribozyme produced a significant reduction in the intrace llular concentration of HPV RNA. In each assay the ribozyme directed t o nt 309 was the most effective. A noncatalytic antisense molecule was used as a control and did not digest HPV RNA or reduce its concentrat ion. The data imply that three different ribozymes each have potential for use in gene therapy of human tumors that express HPV-18 but that the ribozyme targeted to nt 309 is likely to be most effective.