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

描述（由申请人提供）：目前采用放疗和化疗联合治疗恶性弥漫性胶质瘤的方法有限，通常导致高持续性和复发性疾病，生存率低。通过血脑屏障（BBB）的输送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影响的特性与阻止药物治疗疾病的特性相同。这项工作的主要目标是操纵血脑屏障的分子结构，以提高药物输送到脑肿瘤。最近显示，在注射靶向封闭蛋白5的siRNA后，封闭蛋白5（BBB上的内皮细胞特异性紧密连接蛋白）的靶向抑制引起BBB的细胞旁通透性的瞬时和大小选择性增加（坎贝尔等人，J Gene Med，2008）。许多测试分子治疗剂和化学治疗剂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存活。PI实验室的初步工作表明，与邻近的正常微血管相比，优先肿瘤微血管对靶向claudin 5的siRNA的脆弱性。工作假设是，这种在体内靶向密蛋白5的新策略将优先靶向脑肿瘤微血管，并导致BBB（也称为血液肿瘤屏障）的瞬时肿瘤选择性开放。为了更好地表征这种方法的分子和功能变化，我们建议测试以下内容：1）表征BBB渗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各种尺寸示踪剂进入血管周围空间的程度; 3）测试这种方法以增加已知抗肿瘤剂的递送。使用这种新的分子方法，这些重要的研究将为未来的转化研究奠定基础，以更好地将化疗药物递送到恶性脑肿瘤和周围的微环境中。PHS 398/2590（2004年9月修订，2006年4月重新发布）

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