TARGETING TOXIN POLYPEPTIDES TO TUMOR VASCULATURE

对于直径超过2 - 3 mm的持续生长，固体 肿瘤依赖于新的血液供应的建立。 肿瘤 细胞分泌许多血管生成生长因子， 血管从预先存在的宿主脉管系统发芽 （新血管形成）。 最近的研究表明，血管内皮 血管内皮生长因子（VEGF）/血管通透性因子（VPF）是一种重要的 肿瘤新生血管形成和间质发育的介质。 VEGF结合 受体酪氨酸激酶（flt-1和KDR/flk-1）， 在肿瘤血管内皮细胞上差异过表达 与周围正常组织的血管相比。 由于每个 微血管是大量肿瘤细胞的生命线， 肿瘤脉管系统将对肿瘤生长具有深远的影响。 上 在这些研究的基础上，我们通过化学方法制备了一种细胞毒性缀合物， 连接VEGF的剪接变体和白喉毒素的截短形式。 VEGF-毒素偶联物选择性地抑制了 体外内皮细胞系和体内实验性血管生成。 受体阴性细胞系，如肿瘤细胞，不受 结合治疗 在这些研究之后，我们调查了 VEGF-毒素偶联物对两种实体瘤生长的影响 动物模型 VEGF-毒素缀合物7的腹膜内施用 肿瘤细胞移植后30天延迟肿瘤出现， 随后的增长。 初步组织病理学检查显示VEGF- 毒素选择性地影响肿瘤脉管系统并诱导坏死。 从同一动物身上获得的正常组织显示没有血管 肝、肾或肺损伤/出血或坏死。 这些数据 支持VEGF-毒素可以安全施用。 差动 VEGF-毒素结合物的作用与肿瘤细胞增殖状态相关， 内皮细胞 静止的正常内皮细胞对VEGF毒素有抵抗力 共轭 在目前的提案中，我们将批判性地评估和 通过优化VEGF-毒素偶联物的抗肿瘤活性， 剂量、给药途径以及通过改善药物组合物 基因工程毒素分子的构建体。 另外我们 将通过广泛的毒理学研究来确定这种方法的局限性。 研究和制定解决问题的战略。 最后，VEGF- 将制备融合毒素以促进进一步的临床前 发展

For a sustained growth beyond the size of 2 - 3 mm in diameter, solid tumors are dependent on the establishment of new blood supply. Tumor cells secrete a number of angiogenic growth factors to induce localized vascular sprouting from pre-existing host vasculature (neovascularization). Recent studies have shown that Vascular endothelial growth factor (VEGF)/Vascular permeability factor (VPF) is an important mediator of tumor neovascularization and stroma development. VEGF binds to receptor tyrosine kinases (flt-1 and KDR/flk-1) which are differentially overexpressed on the endothelial cells of tumor vasculature when compared to blood vessels of surrounding normal tissues. Since each microvessel is a life line for a large number of tumor cells, targeting the tumor vasculature will have a profound effect on tumor growth. On the basis of these studies, we prepared a cytotoxic conjugate by chemically linking a splice variant of VEGF and a truncated form of diphtheria toxin. VEGF-toxin conjugate selectively inhibited the proliferation of endothelial cell lines in vitro and experimental angiogenesis in vivo. Receptor negative cell lines such as tumor cells were not affected by the conjugate treatment. Following these studies, we investigated the effect of VEGF-toxin conjugate on the growth of two solid tumors in experimental animal models. Intraperitoneal administration of VEGF-toxin conjugate 7 days after tumor cell transplantation delayed tumor appearance and subsequent growth. Preliminary histopathological examination showed VEGF- toxin selectively affected the tumor vasculature and induced necrosis. Normal tissues obtained from the same animals showed no vascular damage/hemorrhage or necrosis in liver, kidney or lung. These data support that VEGF-toxin can be safely administered. The differential effect of VEGF-toxin conjugate correlated with the proliferative status of endothelium. Quiescent normal endothelium is resistant to VEGF-toxin conjugate. In the current proposal we will critically evaluate and improve the anti-tumor activity of VEGF-toxin conjugate by optimizing the dose, route of administration and by improving the composition of the construct with genetically engineered toxin molecules. In addition, we will identify the limitations of this approach by extensive toxicological studies and develop strategies to overcome the problems. Finally, VEGF- fusion toxins will be prepared to facilitate further preclinical development.