UICC World Cancer Congress 2006

Objective:Telomerase activity is mainly regulated by human telomerase reverse transcriptase (hTERT). Here we investigate the effect of short hairpin RNA (shRNA) directed hTERT on telomerase activity in laryngeal cancer cells (Hep-2), nasopharyngeal carcinoma cells (NEC) and bone marrow mesenchyme stem cells (MSCs).

Methods: The primary structures of hTERT cDNA were found in GenBank. Then the structure analyses were done according to the strategy of RNAi, which determined the specific base sequences to design shRNA plasmid. Special plasmids and control plasmids involved in fluorescein gene were synthesised based on the specific base sequences. Cells were treated daily with different plasmids or normal medium only. The expression of hTERT was determined by RT-PCR and Western blotting. The activity of telomerase was measured by telomeric repeat amplification-ELISA (TRAP-ELISA). The cell viability was examined using the MTT and TUNEL assay.

Results: It was found that special short hairpin RNA expression vectors treatment induced significantly decrease in hTERT mRNA expression, the level of hTERT protein, telomerase activity, and cell viability in Hep-2 and NEC cells. In contrast, it did not observed such effect in control groups. None of this effect appeared in MSC cells.

Conclusion: Our results suggest that shRNA against hTERT inhibits telomerase activity and cell viability through suppressing the hTERT expression in cancer cells. And this treatment has no side effect on stem cells. RNA interfering technology may be a promising strategy for the treatment of cancers.

Key words: hTERT; RNA interference; cancer; stem cell; gene therapy