Abstract: ObjectiveTo construct an expression vector of CD137L under the control of hTERT promoter and to investigate the expression of this gene in human ovarian tumor cell lines and the possibility of the targeted gene therapy of CD137L. MethodsThe CD137L gene was cloned from the K562 cell lines and was inserted into the pcDNA3 vector to form a new plasmid named pcDNA3-hCD137L. The plasmid was digested by Hind Ⅲ and Xba Ⅰ, then the CD137L fragment was inserted into the pBTdel279 plasmid to get a new plasmid pBTdel-279-hCD137L, in which the expression of CD137L was under the control of hTERT promoter. The new plasmid was identified by digestion of restriction enzyme and sequencing. pcDNA3-hCD137L and pBTdel-279-hCD137L plasmids were transfected into human ovarian tumor cell line OVCR3 and human embryonic lung fibroblast cell line HELF. The expression of hCD137L was determined by RT-PCR and flow cytometry. ResultsThe plasmids were properly constructed. Both OVCR3 and HELF cell lines can express hCD137L after transfection with pcDNA3-hCD137L plasmids, but only OVCR3 cell line can expression hCD137L gene after transfection with pBTdel-279-hCD137L plasmids. The results of flow cytometry showed that the transfection efficiency of pBTdel-279-hCD137L was much lower than that of the pcDNA3-hCD137L plasmid. ConclusionsThe expression vector of CD137L under the control of hTERT promoter is successfully constructed and the expression of hCD137L gene can be targeted in tumor cells by the hTERT promoter. But the activity of hTERT promoter is much lower than that of the CMV promoter. How to increase the activities of the hTERT promoter needs further investigation.

Key words: Ovarian neoplasms, CD137L, human telomerase reverse transcriptase, Gene therapyCD137（4-1BB）