Neural Stem Cell-Selective Drug Target for Small Molecule Therapy of Brain Tumors

描述(由申请人提供)尽管目前结合了手术、放疗、化疗和贝伐单抗(一种针对血管内皮生长因子-A的中和抗体)的积极治疗，但诊断出多形性胶质母细胞瘤(GBM)或第四期胶质瘤(最恶性的脑癌形式)的中位生存期约为一年。需要新的治疗方法来控制这种侵袭性的癌症。正在进行的机制和遗传学研究发现，GBM与神经干细胞(NSCs)有许多共同的特性，如在中枢神经系统中迁移，细胞外基质降解，以及分化为多个谱系，提示NSC的增殖机制可以为GBM的治疗提供线索。在这里，我们建议鉴定和表征孤儿受体的第一个功能配体，该受体是神经干细胞增殖所必需的，并选择性地表达在神经干细胞所在的脑室下区和齿状回。受体的过度表达会导致小鼠胶质瘤的形成，而在人类患者中，胶质瘤中的高表达与较差的存活率高度相关。与许多参与干细胞功能的转录因子不同，这种受体在发现靶向GBM的药物方面具有双重优势。首先，它是 它主要在神经干细胞中表达，似乎在控制增殖和分化的结点上发挥作用；第二，它有可能受到小分子配体的调控。因此，该受体的配体具有阻止GBM增殖和抑制肿瘤生长的潜力。在目标1中，我们计划利用一个包含120,000个化合物的多样化小分子文库进行高通量筛选，使用一种新的、严格的特异性方案，该方案排除了大多数假阳性配体，并已在Orphagen得到验证。更有效的配体(EC50；lt；1.0 mM)将从商业上可用的类似物中鉴定出来，在目标2中，我们开发了一种生化分析来检测配体诱导的受体与关键功能相互作用蛋白相互作用的变化，以便通过补充受体筛选技术确认命中。在目标3中，将测试化合物对正常NSC基因表达和增殖的调节。活性化合物将在临床来源的人类GBM细胞培养中进一步检测，以确定它们是否以受体特异性的方式阻止肿瘤细胞的生长。如果成功， SBIR第二阶段资助的一个项目将提议在免疫受损的小鼠中发现和测试抑制人GBM异种移植生长的配体。我们的首要目标是将一种治疗GBM的新型非细胞毒性药物商业化。 与公共卫生相关：胶质母细胞瘤(GBM)是成人最常见的原发脑癌，占美国2010年预计确诊的22,000例恶性脑瘤病例的一半以上。治疗可以延缓癌症的进展，但总体中位生存期仍约为一年，尽管在过去30年里努力引入了改进的治疗方法。我们建议确定调控神经干细胞(NSC)增殖的转录因子的第一个配体。该因子的高水平表达与脑胶质瘤患者预后不良密切相关。我们的目标是开发一种口服生物可用小分子药物，使该转录因子失活，并抑制GBM的侵袭性临床行为。

DESCRIPTION (provided by applicant) Median survival from time of diagnosis of glioblastoma multiforme (GBM) or stage IV glioma, the most malignant form of brain cancer, is about one year, despite the current aggressive treatment that combines surgery, radiotherapy, chemotherapy, and bevacizumab (Avastin), a neutralizing antibody targeting VEGF-A. Novel therapies are needed for controlling this aggressive cancer. Ongoing mechanistic and genetic studies of GBM find many properties in common with neural stem cells (NSCs), such as migration through the CNS, extracellular matrix degradation, and differentiation into multiple lineages, suggesting that mechanisms of NSC proliferation can provide clues for treatment of GBM. We propose here to identify and characterize the first functional ligands to an orphan receptor that is required for neural stem cell proliferation and is selectively expressed in the subventricular zone and the dentate gyrus, where NSCs are found. Receptor overexpression drives glioma formation in mice and, in human patients, elevated expression in glioma is highly correlated with poor survival. Unlike many of the transcription factors involved in stem cell function, this receptor has a dual advantage for the discovery of drugs to target GBM. First, it is primarily expressed in NSCs and appears to act at a nodal point for control of proliferation and differentiation; and second, it has the potential to be regulated by small molecule ligands. Ligands to this receptor thus have the potential to block GBM proliferation and suppress tumor growth. In Aim 1, we plan high throughput screening with a diverse small molecule library of 120,000 compounds utilizing a novel, rigorous specificity protocol that excludes the majority of false positive ligands and has been validated at Orphagen. More potent ligands (EC50 < 1.0 mM) will be identified from commercially available analogues and, in Aim 2, we develop a biochemical assay to detect ligand-induced changes in receptor interaction with a key functional interacting protein in order to confirm hits by a complementary receptor screen technology. In Aim 3, compounds will be tested for regulation of normal NSC gene expression and proliferation. Active compounds will be further examined in clinically-derived human GBM cell cultures to determine if they block tumor cell growth in a receptor-specific manner. If successful, an SBIR Phase 2-funded project would propose to discover and test ligands that suppress human GBM xenotransplant growth in immunocompromised mice. Our overarching goal is to commercialize a novel class of non-cytotoxic drug for treatment of GBM. PUBLIC HEALTH RELEVANCE: Glioblastoma (GBM) is the most common primary brain cancer in adults, accounting for more than half of the 22,000 malignant brain tumor cases expected to be diagnosed in the US in 2010. Treatment can delay cancer progression, but overall median survival remains roughly one year, despite efforts to introduce improved therapies over the past 30 years. We propose to identify the first ligands to a transcription facto that regulates neural stem cell (NSC) proliferation. High level expression of this factor is closel linked to poor prognosis in glioma patients. Our goal is to develop an orally bioavailable small molecule drug that inactivates this transcription factor and inhibits the aggressive clinical behavior of GBM.