Modulation of the blood-tumor barrier through targeted suppression of claudin 5

描述（由申请人提供）：目前对恶性弥漫性胶质瘤的放化疗联合治疗是有限的，通常导致疾病的持续和复发率高，生存率低。血脑屏障（BBB）传递不足已被确定为导致恶性脑肿瘤全身化疗失败的重要因素。因此，血脑屏障保护大脑免受有害物质侵害的特性与防止药物治疗疾病的特性是一样的。这项工作的主要目标是操纵血脑屏障的分子结构，以增强药物进入脑肿瘤的输送。最近有研究表明，在注射靶向claudin 5的siRNA后，靶向抑制血脑屏障上内皮细胞特异性紧密连接蛋白claudin 5，可导致血脑屏障细胞旁通透性的短暂性和大小选择性增加（Campbell等人，J Gene Med, 2008）。许多测试分子疗法和化学疗法的临床前研究依赖于异种移植肿瘤模型来预测肿瘤反应和生存。PI实验室的初步工作表明，与邻近的正常微血管相比，肿瘤微血管对靶向claudin5的siRNA具有优先的易感性。工作假设是，这种靶向体内claudin 5的新策略将优先靶向脑肿瘤微血管，并导致血脑屏障（也称为血肿瘤屏障）的短暂性肿瘤选择性开放。为了更好地表征这种方法的分子和功能变化，我们建议进行以下测试：1)表征血脑屏障通透性调节的时间过程；2)利用活体颅窗显微镜测定肿瘤微血管的分子孔径阈值及不同大小示踪剂进入血管周围间隙的程度；3)测试这种方法来增加已知抗肿瘤药物的递送。利用这种新颖的分子方法，这些重要的研究将为未来的转化研究奠定基础，从而更好地将化疗药物输送到恶性脑肿瘤及其周围的微环境中。PHS 398/2590(09/04修订版，4/2006修订版

DESCRIPTION (provided by applicant): The current treatment of malignant diffuse gliomas with combined radiation and chemotherapy is limited and often results in high rates of persistent and recurrent disease with poor survival. Inadequate delivery across the blood-brain barrier (BBB) has been identified as a significant factor contributing to the failure of systemic chemotherapy for malignant brain tumors. The properties of the BBB that shield the brain from deleterious agents are thus the same that prevent drugs from treating disease. The primary goal of this work is to manipulate the molecular structure of the BBB to enhance drug delivery into a brain tumor. It was recently shown that targeted suppression of claudin 5, an endothelial cell specific tight junction protein on the BBB, following injection of siRNA targeting claudin 5, caused both a transient and size-selective increase in paracellular permeability of the BBB (Campbell et al, J Gene Med, 2008). Many preclinical studies testing molecular therapeutics and chemotherapeutics rely on xenograft tumor models to predict tumor response and survival. Preliminary work in the PI's laboratory demonstrated a preferential tumor microvessel vulnerability to the siRNA targeting claudin 5 compared to adjacent normal microvessels. The working hypothesis is that this novel strategy of targeting claudin 5 in vivo will preferentially target brain tumor microvessels and result in a transient tumor selective opening of the BBB, also referred to as the blood-tumor barrier. To better characterize the molecular and functional changes with this approach, we propose to test the following: 1) characterize the temporal course of modulation of BBB permeability; 2) determine the molecular pore size threshold in the tumor microvessels and extent of various sized tracers into the perivascular space using intravital cranial window microscopy; and 3) test this approach to augment the delivery of known antitumor agents. Using this novel molecular approach, these important studies will lay the foundation for future translational studies to better deliver chemotherapeutics into malignant brain tumors and the surrounding microenvironment. PHS 398/2590 (Rev. 09/04, Reissued 4/2006) Page Continuation Format Pag1e