Tumor Endothelium Marker 8 mediated adhesion in tumor associated vasculature

描述(申请人提供)：肿瘤内皮细胞是为癌症治疗提供抗血管生成和抗血管靶向治疗的主要兴趣焦点。然而，由于对肿瘤环境中内皮细胞功能的相当缺乏了解，这些治疗策略的发展一直受到阻碍。肿瘤内皮标记物8(TEM8)是肿瘤相关血管系统选择性诱导的细胞表面受体。由于这种限制性表达模式，TEM8已被认为是抗血管治疗的靶向候选基因。有趣的是，这种分子还介导炭疽毒素进入细胞。 这一提议的核心是我们的发现，TEM8具有黏附分子的特征。本研究旨在探讨TEM8的黏附功能及其在肿瘤相关血管形成中的作用。所提出的具体目标集中在将TEM8定义为黏附分子的特征上：1)通过执行细胞结合和铺展试验来确定I型胶原是否是该受体的黏附配体。2)通过构建缺失突变体，并在下拉分析中利用胞浆结构域分离相互作用的蛋白，来鉴定介导细胞扩散和与肌动蛋白细胞骨架连接所必需的胞浆结构域决定因素。3)我们将利用鸡绒毛膜尿囊膜作为模型血管系统，通过静脉注射重组腺病毒来探索TEM8在正常或肿瘤血管系统中的作用。此外，在该模型中还将检测TEM8表达对肿瘤移植物正常发育相关的血管生成、生长因子诱导的血管生成和血管生成的影响。 鉴于针对肿瘤相关血管的治疗方法的发展构成了改善癌症治疗的一种有前途的新方法，进一步了解候选靶分子(如TEM8)在血管系统中的功能将为优化这些治疗干预措施提供重要和及时的见解。

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.