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

描述(申请人提供)：目前恶性弥漫性胶质瘤的放化疗联合治疗是有限的，往往会导致较高的持续性和复发率，存活率较低。血脑屏障(BBB)转运不足已被认为是导致恶性脑肿瘤全身化疗失败的一个重要因素。因此，保护大脑免受有害物质伤害的血脑屏障的特性与防止药物治疗疾病的特性是相同的。这项工作的主要目标是操纵血脑屏障的分子结构，以增强药物对脑瘤的输送。最近有研究表明，在注射针对claudin 5的siRNA后，靶向抑制BBB上的一种内皮细胞特异性紧密连接蛋白claudin 5，可导致BBB细胞旁通透性的一过性和大小选择性增加(Campbell等，J gene Med，2008)。许多测试分子疗法和化疗药物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，靶向claudin 5的siRNA具有更好的肿瘤微血管脆弱性。工作假设是，这种在体内靶向claudin 5的新策略将优先靶向脑肿瘤微血管，并导致一过性肿瘤选择性开放血脑屏障，也称为血-肿瘤屏障。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)使用活体颅窗显微镜确定肿瘤微血管中的分子孔径阈值和不同大小的示踪剂进入血管周围空间的范围；以及3)测试这种方法以增加已知抗肿瘤药物的输送。使用这种新的分子方法，这些重要的研究将为未来的翻译研究奠定基础，以便更好地将化疗药物输送到恶性脑瘤及其周围的微环境中。PHS 398/2590(09/04版，2006年4月4日重新发布)页面延续格式Pag1e

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