ABSTRACT
Objective To construct a recombinant baculovirus dual expression vector containing NIS gene under the control of human telomerase reverse transcriptase (hTERT) promoter and plasminogen kringle 5 (K5) gene driven by early growth response 1 (Egr1) promoter,and to explore the feasibility of targeting both tumor and tumor vessel with combination of radioiodide and antiangiogenic therapy.Methods The hTERT-NIS gene and Egr1-K5 gene fragments were subcloned into baculovirus vector,then packaged and amplified in the sf9 cells to obtain recombinant baculovirus Bac-hTERT-NIS-Egr1-K5.Bac-CMV-NISEgr1-K5,Bac-hTERT-0-Egr1-K5 and Bac-hTERT-NIS-Egr1-0 were constructed as controls.The expression of NIS and K5 genes in human cervix cancers cells (HeLa) was examined by Western blot and quantitative real-time PCR.Functional NIS activity was confirmed by the uptake of 125I,the inhibition of NaClO4 and the cytotoxicity of 131I.The apoptotic effect of 131I-inducedK5 on human umbilical veins endothelial cells (HUVEC)was analyzed by an apoptosis assay using flow cytometry.Statistical analysis was performed using the analysis of variance.Results The recombinant baculovirus Bac-hTERT-NIS-Egr1-K5 was successfully constructed.The NIS gene under the control of hTERT promoter was specifically expressed in HeLa cells.The baculovirusinfected HeLa cells showed a significant increase of 125I uptake,which was significantly inhibited by NaClO4(F199.296,P＜0.05).Furthermore,a notable decreased cell survival rate (38.3％) was found after 131I treatment.The expression of K5 gene induced by 131I was elevated in a dose or time dependent manner and resulted in obvious inhibition with cell survival rate of 30.8％ in baculovirus-infected HUVEC cells,which was significantly higher than that in the control groups (11.2％ and 10.9％ respectively,F=19.926,45.409;both P＜0.05).Conclusions A recombinant baculovirus dual expression vector containing the NIS and K5 genes has been successfully constructed.This study suggests the feasibility of a synergistic strategy of NISbased raidoiodide therapy and K5-based antiangiogenic therapy in vitro,and make it possible to perform in vivo study in the near future.