Tumor Sensitization to Purine Analogs by E. coli PNP

描述（由申请人提供）：本实验室项目描述了在体外和体内使用大肠杆菌PNP基因破坏人类癌细胞。这将包括临床批准的介导旁观者死亡的前药（F-araAMP）的特性，以及在动物模型中的安全性和有效性研究。我们计划开发PNP传递的载体策略，并提高我们对酶化学致敏的理解。这些信息，以及新的分子工具（针对大肠杆菌PNP的单克隆和多克隆抗体；纯化的PNP蛋白）构成了本申请的三个特异性目标的基础，如下所述：特异性目标1：提高大肠杆菌PNP前药的治疗有效性，并检查作用机制。我们将探讨旁观者死亡的阈值，克服毒性的方法，以及该策略在体内赋予的活性谱。具体目标二：开发临床有用的载体系统，将大肠杆菌PNP输送到体内肿瘤。我们将：i)改进gamma1 34.5缺失疱疹病毒载体，专门用于大肠杆菌PNP； ii)通过增强活性和肿瘤内分布，改进最近的数据，表明编码大肠杆菌PNP的腺病毒具有抗肿瘤活性。具体目标III：验证大肠杆菌PNP策略在体内的有效性，并在小鼠胶质瘤、结肠和头颈部肿瘤模型中测试其活性谱和安全性。这些实验旨在利用一种有效的旁观者杀伤机制来证明肿瘤在体内的消退和治愈，为该策略建立广泛的活性谱，并为在人体受试者中测试相同的方法提供基础。

DESCRIPTION (provided by applicant): This Laboratory Program describes use of the E. coli PNP gene for destroying human cancer cells in vitro and in vivo. This will include characterization of a clinically approved prodrug (F-araAMP) that mediates bystander killing, and studies of both safety and efficacy in animal models. We plan to develop vectoring strategies for delivery of PNP, and improve our understanding of enzymatic chemosensitization. This information, together with new molecular tools (monoclonal and polyclonal antibodies against E. coli PNP; purified PNP protein) form the foundation of the three Specific Aims in this application, as described below: Specific Aim I: Improve the therapeutic usefulness of E. coli PNP prodrugs and examine mechanism of action. We will explore thresholds for bystander killing, ways to overcome toxicity, and spectrum of activity conferred by the strategy in vivo. Specific Aim II: Develop clinically useful vector systems for delivering E. coli PNP to tumors in vivo. We will: i) refine gamma1 34.5 deleted herpes viral vectors specifically for use with E. coli PNP and ii) improve upon recent data indicating anti-tumor activity with adenovirus encoding E. coli PNP by augmenting activity and intra-tumoral distribution. Specific Aim III: Validate the E. coli PNP strategy in vivo and test spectrum of activity and safety in murine models of glioma, colon, and head/neck tumors. These experiments are intended to demonstrate tumor regressions and cures in vivo using a potent bystander killing mechanism, establish broad spectrum of activity for the strategy, and provide a foundation for testing the same approach in human subjects in vivo.