Labeling Small Interference RNA Targeting To Human Vascular Endothelial Growth Factor With Radioactive Iodine Atom

Objective: To explore a method labelling small interfering RNA with radioactive iodine for in vivo tumor imaging and future gene therapy in combination with radiation.Methods: Small interference RNA targeting human vascular endothelial growth factor (hVEGF) was designed.PCR and Western blotting were performed to prove its efficacy.hVEGF siRNA was indirectly radioiodine labelled by Bolton-Hunter method. The radiolabelled products were verified through film exposure of 3% agarose gel and incubated at 37℃in 50% fetal bovine serum to observe their serum stability through polyacrylamide gel electrophoresis . TLC(thin-layer chromatography) was performed in methanol and 5% ammonium acetate (1:1) mixture and acetone and saline (1:1) mixture ,respectively.And then the radiochemical purity of products was detected by radioactive TLC scanner.The biological activity of radioiodine labelled hVEGF siRNA was studied through real-time PCR.Results: VEGF siRNA was radioiodine labeled successfully by Bolton-Hunter method, and the products had satisfying radiochemical purity(>80%)and good stability in 50% fetal bovine serum at 37℃. The radioiodine labeled hVEGF siRNAs demonstrated strong degradation effects on hVEGF mRNA, along with the original VEGF siRNA. In addition, Lipofectamin2000 could reduce hVEGF mRNA expression in HepG2 cells at some extent.Conclusion: The radioiodine labeling of hVEGF siRNA laid the foundation for targeting delivery of siRNA and future gene therapy in combination with radiation.