Newly Gene Therapy Targetting Inhibition of the Tumor Angiogenesis Using Decoy System

The development of newly capillary networks from the normal microvasculature of the surrounding tissue has thought to play a.critical role for the growth of the solid tumors.Tumor cells influence the angiogenesis by stimulation of endothelial cells with producing several angiogenic factors.Among them，vascular endothelial growth factor(VEGF)is one of the most potent angiogenic factors，and endothelial cell specific mitogen.Several previous studies suggested that inhibition of VEGF using antisense oligodeoxynucleotides or neutralizing antibodies against VEGF suppressed tumor growth in various in vivo and in vitro models.VEGF is well known to be hypoxia-inducible.And has been recently reported to be synthesized by stimulation with tumor necrosis factor a(TNFα)via binding of transcription factor Spl to the VEGF promoter.We hypothesized that transfection into the tumor cells nucleus of the synthetic double stranded DNA including consensus sequence of binding site of the Spl as cis-trans element me decoy mould block the binding of Spl to the VEGF promoter gene.Transfection of wild type Spl decoy，but mutant type decoy，revealed prominent inhibitory effects of VEGF synthesis of cultured human carcinoma cells stimulated by TNFα.This Spl decoy introduction into tumor cells may be a novel and useful therapeutic tool for induction of tumor domancy by its inhibitory effect on VEGF synthesis.In addition，the transfer of the Spl decoy would be more effective for regulating tumor growth and invasion than that of antisense oligonucleotide。Since not all angiogenic factors but also growth and invasion related factors expression modulated by Spl could be simultaneously suppressed。

The development of newly capillary networks from the normal microvasculature of the surrounding tissue has thought to play a. critical role For the growth of the solid tumors. Tumor cells influence the angiogenesis by stimulation of endothelial cells with producing several angiogenic factors. Among them, vascular endothelial growth factor(VEGF) is one of the most potent angiogenic factors, and endothelial cell specific mitogen. Several previous studies suggested that inhibition of VEGF using antisense oligodeoxynucleotides or neutralizing antibodies against VEGF suppressed tumor growth in various in vivo and in vitro models. VEGF is well known to be hypoxia-inducible. and has been recently reported to be synthesized by stimulation with tumor necrosis factor a(TNFα) via binding of transcription factor Spl to the VEGF promoter. We hypothesized that transfection into the tumor cells nucleus of the synthetic double stranded DNA including consensus sequence of binding site of the Spl as cis-trans element メdecoyモ could block the binding of Spl to the VEGF promoter gene. Transfection of wild type Spl decoy, but mutant type decoy, revealed prominent inhibitory effects of VEGF synthesis of cultured human carcinoma cells stimulated by TNFα. This Spl decoy introduction into tumor cells may be a novel and useful therapeutic tool for induction of tumor domancy by its inhibitory effect on VEGF synthesis. In addition, the transfer of the Spl decoy would be more effective for regulating tumor growth and invasion than that of antisense oligonucleotide. since not all angiogenic factors but also growth and invasion related factors expression modulated by Spl could be simultaneously suppressed.