OBJECTIVE:To explore the killing effect of enhanced TK vector regulated by hTERT promoter and CMV enhancer, pGL3basicEGFPTKhTRETpCMV enhancer, in nasopharyngeal carcinoma cells. METHODS:pGL3basic as a basic vector template, a targetenhanced TK vector, pGL3basicEGFPTKhTRETpCMV enhancer, was cut, linked, and constructed by restriction enzymes (regulated by hTERT promoter and CMV enhancer). Monopromoter vector, pGL3basic EGFP TK -hTRETp, was chosen as control group; the vectors were transfected into telomerase (+) 58F cells of human nasopharyngeal carcinoma and telomerase (+) human MCF7 cells of breast cancer (positve control) and telomerase (-) human vascular endothelial ECV cells (negative control) respectively. The expression of TK gene green fluorescent protein was observed under fluorescence microscope, the difference of quantitative expression of TK gene mRNA was detected with realtime fluorescent quantitative PCR; telomerase activity was determined with Stretch PCR in maligment tumour cells, and the killing effects of the vectors to the 58F cells and MCF7 cells were analyzed with MTT. The abovementioned indexes were chosen to evaluate the killing effects of enhanced TK vector. RESULTS:① Strong expression of TK gene green fluorescent protein and TK mRNA was displayed in enhancedvector transfected 58F cell line and MCF7 cell line, while that in the monopromoter transfected cell lines and ECV cells transfected by enhanced TK vector was weak. Realtime fluorescent quantative PCR also showed that the Avalue of enhanced TK vector group was higher than that of the control group. Stretch PCR showed that the telomerase activity in the 58F cell line transfected by enhanced TK vector was inhibited. ② After adding GCV, obvious cell growth inhibition was observed in pGL3basicEGFPTKhTRETp CMV enhancer transfected 58F cell line and MCF7 cell line, which was more obvious than those of pGL3basicEGFPTKhTRETp, pGL3basicEGFPTKhTRETp CMV without GCV group, pGL3basicEGFP group and the blank control. CONCLUSION:Targetenhanced TK vector regulated by hTERT promoter and CMV enhancer can effectively kill 58F cells of human nasopharyngeal carcinoma with good specificity, which indicates this targetenhanced TK gene vector may be useful in the strategy of target gene therapy of malignant tumours including nasopharyngeal carcinoma.