Experimental Study Of Dual Promoter Baculovirus-mediated Radioiodine Tumor Targeted Therapy Combined Withanti-tumorangiogenesis

Objective: Multi-modal individualized cancer therapy is a research trend. Anti-tumorangiogenesis therapy with plasminogen kringle5(K5) gene and radioiodine therapymediated by sodium iodide symporter (NIS) gene are twe hot spots of cancer gene therapy.However, the issues of gene targeted delivery and expression regulation need still to beresolved. This study intends to construct a recombinant baculovirus vector containing K5and NIS gene for the purpose of exploring the enhanced anti-tumor effect of these twotherapies.Methods: The recombinant baculovirus encoding K5gene directed by early growthresponse1(Egr1) promoter and NIS gene directed by human telomerase reversetranscriptase (hTERT) promoter (Bac-hTERT-NIS-Egr1-K5) was constructed according tothe manual of the Bac-to-Bac baculovirus expression system. After cervical cancer cellsHeLa, lung adenocarcinoma cell A549and fetal lung fibroblasts MRC5were infected bythe recombinant baculovirus and exposed to131I, the targeted expression of NIS gene andthe expression of K5gene induced by131I irradiation were respectively detected byrealtime PCR and western blot analysis. To validate the function of NIS protein in tumorcells, iodine uptake test was performed. The anti-tumor effect was determined by CCK-8cell proliferation assay. Furthermore, HeLa tumor-bearing mice were estabilshed.131Iscintigraphy and therapy after infection with the recombinant baculovirus in mice wereperformed. Immunohistology test were performed to verify the effect of anti-angiogenesis.Results: We successfully constructed the recombinant baculovirus Bac-hTERT-NIS -Egr1-K5. Realtime PCR and Western blot analysis showed that NIS gene expressionmediated by hTERT promoter was observed only in HeLa and A549cells, but not inMRC5cell.131I irradiation induced the expression of K5gene in HeLa and A549cells. A7.8-fold increase of iodine uptake and an inhibition effect of proliferaiton were observedin HeLa cells infected by Bac-hTERT-NIS-Egr1-K5compared with non-infected cells.However, the effect of anti-angiogenesis with K5could not be determined in Hela cells.Furthermore, an increased131I uptake and expression of K5protein as well as a decreasedexpression of VEGF protein were observed in HeLa tumor-bearing mice infected byBac-hTERT-NIS-Egr1-K5. The combination therapy of anti-angiogenesis and131Iirradiation showed an enhanced anti-tumor effect with48.95%tumor inhibition rate.Conclusion: The recombinant baculovirus Bac-hTERT-NIS-Egr1-K5can induce atargeted expression of NIS gene, which mediate131I to regulate K5gene expression intumor. Our results indicate an enhanced anti-tumor effec of the combination therapy withanti-angiogenesis and131I irradiation.