Effect of antisense human telomerase RNA on malignant phenotypes of gastric carcinoma

Aim : The study was designed to explore the effects of antisense human telomerase RNA (ahTR) on the malignant phenotype of gastric carcinoma cell line SGC-7901, and its potential role in gene therapy for tumors. Methods : An ahTR eukaryotic expression vector, including the sequence of template region of telomere repeats, was constructed by recombinant technology of molecules and then transfected into gastric carcinoma cell line SGC-7901 by liposome DOTAP. Subsequently, the expression of hTR RNA and ahTR RNA by reverse transcription–polymerase chain reaction, telomerase activity by telomeric repeat amplification protocol-ELISA (TRAP-ELISA), telomere length by Southern blotting, cell morphology under light microscope, cellular proliferation capacity by 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide assay, cell-cycle distribution by flow cytometry, efficiency of clone formation in soft agar, and tumorigenecity in nude mice were examined and evaluated in ahTR-transfected cells, control plasmid pCI-neo transfected cells and their parental cells. Results : An ahTR eukaryotic expression vector was constructed and successfully transfected into SGC-7901 cells. The telomerase activity in ahTR-transfected SGC-7901 cells decreased from 100% to ap-proximately 25%, and telomere length in the cells shortened to 3.35 from 4.08 Kb at 60 population doublings. Compared with the parental cells and pCI-neo transfected cells, ahTR-transfected cells displayed some morphological changes, such as decreased atypia, and recovery of contact inhibition and density inhibition under light microscope. Furthermore, ahTR-transfected cells displayed decreased invasive capacity in Borden's chamber invasive model, increased G0/G1 phase rate and apoptotic rate. Surprisingly, ahTR-transfected SGC-7901 cells lost their capacity for clone formation in soft agar and tumorigencity in nude mice. Conclusion : Antisense-hTR transfection can inhibit the growth of SGC-7901 cells and partially reverse the malignant phenotypes. This study provides an exciting approach for cancer therapy by inhibiting telomerase activity using an antisense gene. © 2002 Blackwell Publishing Asia Pty Ltd