Small-molecule Inhibition of the Interactions of the Urokinase Receptor: A Targe

描述（申请人提供）：尿激酶受体（uPAR）是一种GPI锚定蛋白，作为丝氨酸蛋白酶尿激酶（uPA）的受体。在与其受体对接后，uPA被激活，这是导致细胞周围蛋白水解和细胞外基质降解的事件，细胞外基质是肿瘤和脉管系统之间的主要屏障。但现在广泛认识到，虽然uPAR不能进行信号传导，但uPAR/uPA复合物相互作用并激活许多细胞表面受体，如整联蛋白、受体酪氨酸激酶和GPCR。uPAR/uPA相互作用几乎涉及肿瘤侵袭和转移的每一步，因此是开发抗癌疗法的高度合适的靶标。以前的努力集中在用小分子抑制uPA的丝氨酸蛋白酶活性。但这种策略忽略了uPAR/uPA复合物与细胞信号蛋白的相互作用，这些蛋白不依赖于uPA的蛋白水解活性。在本申请中，我们遵循一种独特的方法，该方法寻求使用小分子靶向uPAR/uPA蛋白质-蛋白质相互作用，期望这些分子将表现出阻断蛋白质水解和信号传导的双重作用。我们最初的努力是非常有益的。初步的基于结构的计算筛选导致了8个活性化合物。基于细胞培养的研究表明，许多这些化合物阻断MDA-MB-231肿瘤细胞粘附、迁移和侵袭。还发现化合物抑制肺H1299肿瘤细胞增殖。生物化学分析表明，这些化合物也阻断整合素与uPAR/uPA复合物的结合。我们在这项资助申请中的目标是优化这些化合物中的三种的药代动力学特性和效力，以阻断体内肿瘤侵袭和转移。为此，将遵循涉及计算生物学，合成化学，生物物理化学，结构生物学和细胞生物学的多学科研究计划。第一个目标将包括基于我们的先导分子创建化合物的虚拟组合库，基于预测的效力对这些化合物进行排名，并预测最有效化合物的药代动力学特性。第二个目标将涉及最有希望的化合物的化学合成，然后使用荧光偏振测定法评估其活性。最有效的化合物进一步用等温滴定量热法表征。然后，我们解决了这些化合物的三维结构与尿激酶受体的复杂使用X-射线衍射。最后，第三个目标将包括评估MDA-MB-231和其他肿瘤细胞系中最具选择性和最有效的抑制剂的细胞功效，并进行初步的体内剂量研究，为小鼠异种移植物的未来研究奠定基础。公共卫生相关性：尿激酶受体是一种细胞表面受体，可结合并激活多种蛋白质。这些相互作用尤其导致原发性肿瘤和脉管系统之间的保护层的降解，以及细胞的粘附和迁移。这些过程是癌症转移的标志。具有药物样性质的小分子可以阻止尿激酶受体与其结合伴侣相互作用，这可能导致高度有效的治疗方法来预防肿瘤转移。

DESCRIPTION (provided by applicant): The urokinase receptor (uPAR) is a GPI-anchored protein that serves as a receptor to the serine protease urokinase (uPA). Upon docking to its receptor, uPA is activated, an event that leads to pericellular proteolysis and degradation of the extracellular matrix, a primary barrier between tumor and vasculature. But it is now widely recognized that while uPAR is not capable of signaling, the uPAR/uPA complex interacts and activates a number of cell surface receptors such as integrins, receptor tyrosine kinases, and GPCRs. The uPAR/uPA interaction has been implicated with nearly every step of tumor invasion and metastasis and is therefore a highly suitable target for the development of anti-cancer therapeutics. Previous efforts have concentrated on inhibiting the serine protease activity of uPA with small molecules. But this strategy neglects interactions of the uPAR/uPA complex with cell signaling proteins that are independent of the proteolytic activity of uPA. In this application, we follow a unique approach that seeks to target the uPAR/uPA protein-protein interaction using small molecules with the expectation that these molecules will exhibit the dual effect of blocking proteolysis and signaling. Our initial efforts have been highly rewarding. A preliminary structure-based computational screen has led to 8 active compounds. Cell culture-based studies reveal that a number of these compounds block MDA-MB-231 tumor cell adhesion, migration, and invasion. Compounds were also found to inhibit lung H1299 tumor cell proliferation. Biochemical analyses reveal that that these compounds also block integrin binding to the uPAR/uPA complex. Our objective in this grant application is to optimize the pharmacokinetic properties and potency of three of these compounds to block tumor invasion and metastasis in vivo. To that end, a multidisciplinary research program involving computational biology, synthetic chemistry, biophysical chemistry, structural biology, and cell biology will be followed. The first aim will consist of creating a virtual combinatorial library of compounds based on our lead molecules, ranking these compounds based on predicted potency, and predicting pharmacokinetic properties of the most potent compounds. The second aim will involve the chemical synthesis of the most promising compounds, followed by an assessment of their activity using a fluorescence polarization assay. The most potent compounds are further characterized with isothermal titration calorimetry. We then solve the three-dimensional structure of these compounds in complex with the urokinase receptor using x-ray diffraction. Finally, the third aim will consist of assessing the cellular efficacy of the most selective and potent inhibitors in MDA-MB-231 and other tumor cell lines, and to perform preliminary in vivo dosage studies to set the stage for future studies in mice xenografts. PUBLIC HEALTH RELEVANCE: The urokinase receptor is a cell surface receptor that binds and activates various proteins. These interactions lead, among other things, to the degradation of a protective layer between a primary tumor and the vasculature, as well as the adhesion and migration of cells. These processes are hallmarks of cancer metastasis. Small molecules with drug-like properties that prevent the urokinase receptor from interacting with its binding partners could lead to highly effective therapeutics to prevent tumor metastasis.