ESTABLISHMENT AND APPLIANCE OF NEWLY GENE THERAPY FOR INHIBITION OF MULTIDRUG RESISTANCE

从周围组织的正常微血管系统发展而来的新的毛细血管网络被认为对实体肿瘤的生长起着关键作用。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)是最强的血管生成因子之一，也是内皮细胞特异性的丝裂原。先前的一些研究表明，在体内和体外模型中，使用反义寡核苷酸或中和抗体抑制血管内皮生长因子可抑制肿瘤生长。众所周知，血管内皮生长因子是低氧诱导的，最近有报道称，通过转录因子Sp1与血管内皮生长因子启动子结合，在肿瘤坏死因子α刺激下合成血管内皮生长因子α。我们推测，将合成的含有Sp1结合位点共同序列的双链DNA作为顺反向元件“诱饵”导入肿瘤细胞核，可以阻断Sp1与血管内皮生长因子促进基因的结合。野生型Sp1诱骗和突变型诱骗对肿瘤坏死因子α刺激的培养的人癌细胞血管内皮生长因子合成有显著的抑制作用。这种Sp1诱骗基因导入肿瘤细胞可能是一种新的有效的治疗工具，它通过抑制血管内皮生长因子的合成而诱导肿瘤转移。此外，转移Sp1诱饵比转移反义寡核苷酸更有效地调控肿瘤的生长和侵袭，因为并不是所有的血管生成因子都能被同时抑制，而且Sp1调控的生长和侵袭相关因子的表达也可以同时被抑制。

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 prompter 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 TNF α. This Sp1 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 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.