MMP-14 Chimeric Ligands for Targeted Imaging of Metastatic Tumors

 描述(由申请人提供)：建议的工作旨在开发一种选择性的基质金属蛋白酶-14探针，用于检测以基质金属蛋白酶-14过度表达为特征的转移和促肿瘤癌细胞。这将通过优化同时靶向于基质金属蛋白酶-14的两个不同结构域的嵌合异二价平台来实现。催化结构域和血凝素结构域的活性部位的配体将通过模块连接单元连接，该连接单元的长度可以变化，以匹配两个结构域之间的距离。在连接体的溶剂暴露区域，将安装近红外染料，以允许异二价平台选择性地标记MMP-14阳性细胞，以便通过共聚焦显微镜和体内光学成像进行检测。这一成果非常重要，因为它将确保将这项技术推广到PET成像应用的可行性。很有可能，这一通用策略可以应用于选择性靶向作为疾病生物标志物的其他MMP。我们的中心假设是，通过优化基质金属蛋白酶催化结构域抑制剂和血凝蛋白结构域配体之间的连接物长度，可以开发出高亲和力的基质金属蛋白酶-14特异性异二价平台。当配备荧光染料时，这个嵌合平台将选择性地标记MMP-14阳性细胞，分别用于共聚焦显微镜和光学成像的体外和体内检测。开展这项拟议研究的基本原理是，针对基质金属蛋白酶-14的特定成像平台将作为开发临床相关成像模式的基础，用于诊断和治疗后评估以基质金属蛋白酶-14过度表达为特征的乳腺和其他肿瘤。该方法的创新之处在于，它的目标是通过一个异二价平台选择性地针对膜结合的基质金属蛋白酶-14，该平台根据基质金属蛋白酶-14的两个S靶向结构域之间的距离量身定做，而不是优化针对单个结合位点的支架的亲和力。在目标#1中，我们将测试工作假设，即优化基质金属蛋白酶催化结构域抑制剂和血凝蛋白结构域配体之间的连接子长度将比单价配体或抑制剂对基质金属蛋白酶-14产生更大的和选择性的亲和力。我们期望这两个结构域之间的距离将为所提议的嵌合异二价平台提供一个独特的额外的特异性元件，该平台可以为单个MMP量身定做，包括基质金属蛋白酶-14。目的2致力于证明这一概念，即增强与基质金属蛋白酶-14的结合可以通过异二价平台完成，并且用近红外荧光染料荧光标记该平台将使在体光学成像基质金属蛋白酶-14阳性的肿瘤成为可能。在这些研究的结论中，我们期望针对基质金属蛋白酶-14阳性肿瘤的工作探针将可用于随后的放射性标记和开发临床相关的有利于转移的肿瘤的PET显像剂。

 DESCRIPTION (provided by applicant): The proposed work is aimed at developing a selective MMP-14 probe for detecting metastatic and pro-tumorigenic cancer cells characterized by the over-expression of MMP-14. This will be achieved by optimizing a chimeric heterobivalent platform targeted simultaneously to two separate domains of MMP-14. Ligands to both the active site of the catalytic domain and the hemopexin domain will be tethered through a modular linker unit that can be varied in length to match the distance between the two domains. In a solvent exposed region of the linker, a near-IR dye will be installed to allow the heterobivalent platform to selectively label MMP-14- positive cells for detection by confocal microscopy and in vivo optical imaging. This achievement is important because it will ensure the feasibility of advancing this technology to PET imaging applications. In all likelihood, this general strategy can be applied to the selective targeting of other MMPs that serve as disease biomarkers. Our central hypothesis is that a high-affinity MMP-14-specific heterobivalent platform can be developed by optimizing the linker length between a MMP catalytic domain inhibitor and hemopexin domain ligand. When outfitted with a fluorescent dye, this chimeric platform will selectively label MMP-14-positive cells for in vitro and in vivo detection by confocal microscopy and optical imaging, respectively. The rationale for undertaking the proposed research is that the MMP-14-specific imaging platform will serve as the foundation for developing a clinically-relevant imaging modality for the diagnosis and post-treatment assessment of breast and other tumors characterized by over-expression of MMP-14. The approach is innovative in that it aims to selectively target the membrane-bound MMP-14 with a heterobivalent platform tailored to the distance between two of MMP-14's targetable domains rather than optimizing the affinity of scaffolds targeted to a single binding site. In Aim #1, we will test the working hypothesis that optimizing the linker length between a MMP catalytic domain inhibitor and hemopexin domain ligand will result in greater and selective affinity for MMP-14 than monovalent ligands or inhibitors. It is our expectation that the distance between the two domains will provide a unique and additional specificity element to the proposed chimeric heterobivalent platform, which can be tailored to individual MMPs, including MMP-14. Aim 2 is focused on proving-the-concept that enhanced binding to MMP-14 can be accomplished with heterobivalent platform and that fluorescently-labeling this platform with a near-IR fluorescent dye will enable optical in vivo imaging of MMP-14-positive tumors. At the conclusion of these studies, it is our expectation that a working probe for targeting MMP-14-positive tumors will be available for subsequent radiolabeling and the development of a clinically-relevant PET imaging agent for pro-metastatic tumors.