MMP-14 Chimeric Ligands for Targeted Imaging of Metastatic Tumors

 描述（由申请人提供）：所提出的工作旨在开发用于检测以MMP-14过表达为特征的转移性和促肿瘤发生性癌细胞的选择性MMP-14探针。这将通过优化同时靶向MMP-14的两个单独结构域的嵌合异二价平台来实现。与催化结构域的活性位点和血红素结合蛋白结构域两者的配体将通过模块化接头单元拴系，所述模块化接头单元的长度可以变化以匹配两个结构域之间的距离。在接头的溶剂暴露区域中，将安装近IR染料以允许异二价平台选择性地标记MMP-14阳性细胞，用于通过共聚焦显微镜和体内光学成像进行检测。这一成就非常重要，因为它将确保将该技术推进到PET成像应用的可行性。在所有的可能性中，这种一般策略可以应用于作为疾病生物标志物的其他MMPs的选择性靶向。 我们的中心假设是，可以通过优化MMP催化结构域抑制剂和血红素结合蛋白结构域配体之间的接头长度来开发高亲和力MMP-14特异性异二价平台。当配备荧光染料时，这种嵌合平台将选择性地标记MMP-14阳性细胞，分别通过共聚焦显微镜和光学成像进行体外和体内检测。开展拟议研究的基本原理是MMP-14特异性成像平台将作为开发临床相关成像模式的基础，用于乳腺和其他以MMP-14过度表达为特征的肿瘤的诊断和治疗后评估。该方法是创新的，因为它旨在用针对MMP-14的两个可靶向结构域之间的距离定制的异二价平台选择性地靶向膜结合的MMP-14，而不是优化靶向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MMP催化结构域抑制剂和血红素结合蛋白结构域配体之间的接头长度将导致对MMP-14的亲和力比单价配体或抑制剂更大且具有选择性。我们期望两个结构域之间的距离将为所提出的嵌合异二价平台提供独特和额外的特异性元件，其可以针对个体MMP（包括MMP-14）进行定制。目的2集中于证明可以用异二价平台实现与MMP-14的增强结合的概念，并且用近IR荧光染料荧光标记该平台将使得能够对MMP-14阳性肿瘤进行光学体内成像。在这些研究的结论中，我们期望用于靶向MMP-14阳性肿瘤的工作探针将可用于随后的放射性标记和用于促转移肿瘤的临床相关PET成像剂的开发。

 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.