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

周围组织的正常微血管形成新的毛细血管网络被认为对实体瘤的生长起关键作用。肿瘤细胞通过刺激内皮细胞产生多种血管生成因子来影响血管生成。其中，血管内皮生长因子（VEGF）是最有效的血管生成因子之一，是内皮细胞特异性的有丝分裂原。先前的一些研究表明，在各种体内和体外模型中，使用反义寡脱氧核苷酸或中和抗体抑制VEGF可抑制肿瘤生长。众所周知，VEGF是缺氧诱导的，最近有报道称，它是通过肿瘤坏死因子α (TNFα)的刺激，通过转录因子Sp1与VEGF启动子的结合而合成的。我们假设将合成的双链DNA（包括Sp1结合位点的一致序列）作为顺式反式元件诱饵转染到肿瘤细胞核中可以阻断Sp1与VEGF启动子基因的结合。转染野生型Sp1诱饵，而非突变型诱饵，在TNFα刺激下对培养的人癌细胞的VEGF合成有明显的抑制作用。将Sp1诱骗物引入肿瘤细胞可能是一种新的有用的治疗工具，通过其对VEGF合成的抑制作用诱导肿瘤休眠。此外，Sp1诱饵的转移比反义寡核苷酸更有效地调节肿瘤的生长和侵袭，因为Sp1介导的血管生成因子和生长及侵袭相关因子的表达并不能同时被抑制。

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 α (TNFα) via binding of transcription factor Sp1 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 Sp1 as cis-trans element decoy could block the binding of Sp1 to the VEGF promoter gene. Transfection of wild type Sp1 decoy, but mutant type decoy, revealed prominent inhibitory effects of VEGF synthesis of cultured human carcinoma cells stimulated by TNFα. This Sp1 decoy introduction into tumor cells may be a novel and useful therapeutic tool for induction of tumor dormancy by its inhibitory effect on VEGF synthesis. In addition, the transfer of the Sp1 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 Sp1 could be simultaneously suppressed.