AIM:To investigate the killing effects of tumor cells specific vector of suicide gene of CDglyTK driven by hTERT promoter on retinoblastoma Y79 cells in vitro. ·METHODS:At first,the recombinant plasmid was transfered into Y79 cells with electroblot as a delivery system. RT-PCR and Western blot analysis were used to determine the CDTK mRNA and protein expression in Y79 cells which had been transfected by pcDNA3.1-CMV-hTERT-CDTK plasmid vector. The conversion efficiency of 5-FC into 5-FU in CDglyTK-expressing Y79 cells was measured by HPLC. The killing effects of double suicide genes on Y79 cells that treated with 5-FC,GCV of different concentrations were determined by the method of MTT. ·RESULTS:The expression of CDTK gene in Y79 cells was certificated by RT-PCR and Western blot and a 59kD protein was obtaind which was equal to the sequence expection of CDTK gene. In MTT analysis,there was significant difference between transfected and non-transfected survival Y79 cells(P<0.05).The survival Y79 cells treated with 5-FC and GCV was lower than 5-FC or GCV. ·CONCLUSION:The recombinant plasmid vector pcDNA3.1-CMV-hTERT-CDTK can be transcribed and translated into CDTK fusion protein in Y79 cells.The transfer of the CDglyTK fusion gene into Y79 cells followed by the administration of 5-FC or GCV can kill Y79 cells in vitro. The killing effect of two predrugs is stronger than that of one predrug.