Imaging and therapy of tumors using biotinylated cell surface docking sites

描述（由申请人提供）：报告基因的无创、实时成像已成为生物医学应用的重要工具，包括肿瘤检测、细胞跟踪和基因治疗。在这里，我们将通过表达一个单一的报告蛋白（22 kDa）来评估一种多功能的、有效的技术，用于肿瘤细胞的靶向、成像和治疗，该报告蛋白可以通过多种方式成像。首先，细胞表面受体将被设计成有效地介导代谢生物素化。其次，目标分子将包括成像剂磁共振，光学和正电子发射断层扫描使用标记链亲和素部分。第三，探索含链霉亲和素的白喉毒素的催化结构域，选择性地杀死表达生物素化表面受体的肿瘤细胞。最后，肿瘤的生长和治疗将通过生物发光来监测，利用肿瘤细胞稳定表达一种新型荧光素酶，这种荧光素酶比目前使用的荧光素酶敏感得多。重要的是，这些融合结构可以很容易地转化为人类，因为它们与AAV载体和生物素-链亲和素系统以及磁性纳米颗粒和放射性核素兼容，正在临床试验中使用。

DESCRIPTION (provided by applicant): Non-invasive, real time imaging of reporter genes has become an important tool in biomedical applications, including detection of tumors, cell tracking and gene therapy. Here, a versatile, potent technique for targeting, imaging and therapy of tumor cells in culture and in vivo will be evaluated by expressing a single reporter protein (22 kDa) which can be imaged with multiple modalities. First, cell surface receptors will be engineered to efficiently mediate metabolic biotinylation. Second, targeting molecules will include imaging agents for magnetic resonance, optical and positron emission tomography using labeled streptavidin moieties. Third, catalytic domain of diphtheria toxin incorporating streptavidin will be explored to selectively kill tumor cells expressing biotinylated surface receptors. Finally, tumor growth and therapy will be monitored by bioluminescence using tumor cells stably expressing a novel luciferase that is far more sensitive than the ones currently in use. Importantly, these fusion constructs can be easily translated into humans since they are compatible with AAV vectors and the biotin-streptavidin system as well as magnetic nanoparticles and radionuclides are being used in clinical trials. In this project, a new method to target, image, and treat tumors will be explored. First, a virus will be genetically modified to carry a specific DNA sequence (transgene) that once it infects tumor cells in culture and in living mice, it will trigger these cells to produce a specific protein that would make them a selective, easy target for diphtheria toxin, a killing agent, as well as imaging agent for magnetic resonance (MR) and positron emission tomography (PET) therefore only tumors will be imaged and killed.