OBJECTIVETo study selective killing effect of herpes simplex virus-thymidine kinase/ganciclovir (Hsv-tk/GCV) driven by human telomerase catalytic subunit (hTERT) promoter on lung cancer cell line A549 in vitro.

METHODS(1) Expression plasmids of Hsv-tk gene driven by hTERT promoter and sv40 promoter respectively (pGL3-hTp-tk and pGL3-sv40-tk) were transfected into telomerase-positive human lung adenocarcinoma cell line A549 and telomerase-negative fetal lung fibroblast cell line MRC-5. Reverse transcription-PCR was performed to detect expression of tk gene in above transfected cell lines; (2) Inhibition effect on proliferation of above transfected cell lines treated with GCV was investigated with MTT method; (3) Influence of GCV on apoptosis and cell cycle of above transfected cell lines was investigated with flow cytometry.

RESULTS(1) tk mRNA expression was detected in both A549 and MRC-5 transfected with pGL3-sv40-tk, also in A549 transfected with pGL3-hTp-tk, but not in pGL3-hTp-tk transfected MRC-5; (2) GCV showed significant inhibition effects on proliferation of pGL3-sv40-tk transfected A549 and MRC-5 in vitro, also on that of pGL3-hTp-tk transfected A549, but not on that of pGL3-hTp-tk transfected MRC-5; (3) Treated with GCV, apoptosis index (AI) of pGL3-sv40-tk transfected A549 and MRC-5 as well as pGL3-hTp-tk transfected A549 (21.58%, 9.35% and 23.19% respectively) increased significantly, compared with A549, MRC-5 transfected with pGL3-hTp (0.78% and 0.55% respectively) and A549, MRC-5 without plasmid transfection as blank control (2.17% and 0.60% respectively); GCV had no influence on AI of pGL3-hTp-tk transfected MRC-5 (0.88%).

CONCLUSIONtk gene driven by hTERT promoter could express selectively in lung cancer cell A549. Hsv-tk/GCV driven by hTERT promoter could selectively inhibit proliferation of lung cancer cell.