Specific inhibition of human telomerase activity by transfection reagent, FuGENE6-antisense phosphorothioate oligonucleotide complex in HeLa cells.

Human telomerase might be associated with malignant tumor development and could be a highly selective target for antitumor drug design. Antisense phosphodiester (ODNs) and phosphorothioate (S-ODNs) oligonucleotides were investigated for their abilities to inhibit telomerase activity in the HeLa cell line. The ODNs and S-ODNs were designed to be complementary to nucleotides within the RNA active site of telomerase. As a transfection reagent, FuGENE6 was used to enhance the cellular uptake of oligonucleotides in cell cultures. The results showed that S-ODN-3 (19-mer) encapsulated with FuGENE6 clearly inhibited the telomerase activity in HeLa cells, and the inhibitory efficiency increased with an increase in the S-ODN-3. However, free S-ODN-3 showed no inhibitory activity. On the other hand, ODN-3 encapsulated with FuGENE6 had no detectable inhibitory activity. The encapsulated S-ODNs exhibited higher inhibitory activities than the free S-ODNs, and showed sequence specific inhibition. Thus, the activities of the S-ODNs were effectively enhanced by using the transfection reagent. The transfection reagent, FuGENE6, may thus be a potentially useful delivery vehicle for oligonucleotide-based therapeutics and transgenes, and is appropriate for use in vitro and in vivo.