Tumor Endothelium Marker 8 mediated adhesion in tumor associated vasculature

描述（由申请人提供）：肿瘤内皮是递送用于癌症治疗的抗血管生成和抗血管靶向疗法的主要关注焦点。然而，这些治疗策略的发展受到了阻碍，相当缺乏对肿瘤环境中内皮细胞功能的了解。肿瘤内皮标志物8（tumor endothelial marker 8，TEM 8）是一种在肿瘤相关血管系统中选择性诱导的细胞表面受体。由于这种受限制的表达模式，TEM8已被提议作为抗血管治疗的靶向候选物。有趣的是，这种分子也介导炭疽毒素进入细胞。 这个建议的核心是我们发现TEM8具有粘附分子的特征。本研究旨在探讨TEM 8的粘附功能及其在肿瘤相关血管中的作用。所提出的具体目标集中在将TEM 8定义为粘附分子的特征上：1）通过进行细胞结合和扩散测定来确定胶原蛋白I是否是该受体的粘附配体。 2)通过构建缺失突变体并在下拉试验中使用胞质结构域分离相互作用蛋白，鉴定介导细胞铺展和与肌动蛋白细胞骨架连接所必需的胞质结构域决定簇。 3)我们将探讨TEM8在正常或肿瘤血管系统中的作用，使用鸡绒毛尿囊膜作为模型血管系统，通过静脉内递送重组腺病毒进行遗传操作。此外，TEM8表达对正常发育相关的血管发生、生长因子诱导的血管生成和肿瘤移植物的血管形成的影响将在该模型中进行检查。 鉴于靶向肿瘤相关血管的疗法的发展构成了改善癌症治疗的有希望的新方法，进一步了解候选靶分子如TEM 8如何在脉管系统中发挥作用，将为优化这些治疗干预提供重要而及时的见解。

DESCRIPTION (provided by applicant): The tumor endothelium is a focus of major interest to deliver anti-angiogenic and anti-vascular targeted therapies for cancer treatment. However, the development of these therapeutic strategies has been hampered by the considerable lack of understanding of endothelial cell function in the tumor environment. Tumor endothelium marker 8 (TEM8) is a cell surface receptor selectively induced in tumor-associated vasculature. Because of this restricted expression pattern, TEM8 has been proposed as a targeting candidate for anti-vascular therapies. Interestingly, this molecule also mediates anthrax toxin delivery into cells. Central to this proposal is our finding that TEM8 holds signature features of an adhesion molecule. The purpose of this study is to evaluate the adhesive function of TEM8 and its role in tumor associated vasculature. The proposed specific aims are focused on the features that define TEM8 as an adhesion molecule: 1) to determine whether collagen I is an adhesive ligand for this receptor by performing cell binding and spreading assays. 2) To identify the cytosolic domain determinants necessary to mediate cell spreading and linkage to the actin cytoskeleton by constructing deletion mutants and isolating interacting proteins using the cytosolic domain in pull-down assays. 3) We will explore the role of TEM8 in normal or tumoral vasculature using the chicken chorioallantoic membrane as a model vascular system accessible to genetic manipulation through intravenous delivery of recombinant adenoviruses. In addition, TEM8 expression effects on normal development associated vasculogenesis, growth factor induced angiogenesis and vascularization of tumor grafts will be examined in this model. Given that the development of therapies to target the tumor-associated blood vessels constitutes a promising and novel approach to improve cancer treatment, gaining further understanding of how candidate target molecules, such as TEM8, function in the vasculature, will provide significant and timely insights to optimize these therapeutic interventions.