Chemoprevention of Gliomas using Nitrones with Anti-c-Met Activity

描述（由申请人提供）： 该项目的重点是建立α-苯基-叔丁基硝酮（PBN）的机制，在其抑制胶质瘤形成的实验啮齿动物模型，在不同的肿瘤等级的能力。我们有很有希望的初步数据，清楚地表明PBN可能是一种有效的体内抗肿瘤药物，在肿瘤植入之前，或一旦肿瘤形成。我们的假设是，c-Met，肝细胞生长因子（散射因子）的酪氨酸激酶受体在恶性胶质瘤的形成中起着不可或缺的作用，PBN治疗的c-Met水平改变抑制胶质瘤的形成。恶性胶质瘤的重要特征包括其侵袭行为和血管生成。c-Met被认为是恶性脑肿瘤进展的许多过程中的介质，包括细胞增殖、细胞侵袭、细胞凋亡和血管生成。美国每年约有15，000名患者死于胶质母细胞瘤。由于神经胶质瘤的浸润性，手术很少有效。尽管有现代诊断和治疗，胶质母细胞瘤患者的中位生存时间不超过15个月。一种潜在的化学预防剂，可以抑制神经胶质瘤的生长，甚至完全根除神经胶质瘤将是巨大的好处，病人发展恶性肿瘤。体内磁共振（MR）方法理想地适合于跟踪肿瘤生长、血管生成的变化以及可用作预测神经胶质瘤预后的标志物的c-Met水平的评估。我们目前使用非侵入性体内MR成像（MRI）方法来检测肿瘤形态，肿瘤血管或血管生成（使用MR血管造影术（MRA）），并有c-Met表达的初步数据（使用分子靶向MRI）。此外，我们使用分子生物学方法（蛋白质印迹，免疫荧光组织学）和组织学肿瘤分级，与MR成像，血管造影和分子靶向数据相关联。该项目将评估PBN预防恶性胶质瘤形成和发展的能力，使用c-Met敲低胶质瘤细胞克隆，并将新的体内分子靶向MRI技术用于在不同肿瘤级别的颅内大鼠胶质瘤中检测c-Met。将在Fisher 344大鼠中使用脑内植入大鼠C6（形成II级或III级肿瘤）或RG 2（形成更具侵袭性的III级或IV级肿瘤）胶质瘤细胞作为胶质瘤模型。具体目标1是评估2种胶质瘤模型中的c-Met水平具体目标2将是建立PBN作为c-Met抑制剂在预防胶质瘤生长和形成中的有效性，并使用c-Met敲低胶质瘤模型来进一步阐明c-Met在胶质瘤形成中的作用;具体目标3是开发和验证用于体内检测c-Met表达的改进的MRI方法。目前适用于恶性神经胶质瘤干预的现有药物非常少。除了c-Met抑制之外，PBN的其他有希望的特征是它是口服生物可利用的，并且它能够穿过血脑屏障（BBB）。PBN似乎是一个有前途的候选人，在其能力是一个有效的药物对神经胶质瘤的形成，并可能是有用的化学预防剂对多形性胶质母细胞瘤在人类。我们有初步的数据，PBN（α-苯基-叔丁基硝酮）似乎是一个有前途的候选人，在其能力是一个有效的药物对神经胶质瘤的形成，并可能是有用的化学预防剂对多形性胶质母细胞瘤在人类。我们的假设是c-Met，酪氨酸激酶受体，在恶性胶质瘤的形成中起着不可或缺的作用，PBN能够降低c-Met水平，从而抑制胶质瘤的形成。该项目将评估PBN预防恶性胶质瘤形成和发展的能力，使用c-Met敲低胶质瘤细胞克隆来阐明c-Met的作用，并将新的体内分子靶向MRI（磁共振成像）技术用于在不同肿瘤级别的颅内大鼠胶质瘤中体内检测c-Met。

DESCRIPTION (provided by applicant): This project is focused on establishing the mechanism of alpha-phenyl-tert-butyl nitrone (PBN), in its ability to inhibit glioma formation in experimental rodent models that vary in tumor grade. We have promising preliminary data that clearly demonstrates that PBN can potentially be an effective anti-tumor agent in vivo, prior to tumor implantation, or once a tumor has formed. Our hypothesis is that c-Met, a tyrosine kinase receptor for the hepatocyte growth factor (scatter factor) plays an integral role in the formation of malignant gliomas, and that altered c-Met levels from PBN treatment suppresses glioma formation. Important hallmarks of malignant gliomas include their invasive behavior and angiogenesis. c-Met is thought to be a mediator in many of the processes of malignant brain tumor progression, including cell proliferation, cell invasion, apoptosis and angiogenesis. Approximately 15,000 patients in the U.S.A. die with glioblastomas per year. Due to the infiltrative nature of gliomas, surgery is rarely effective. Despite modern diagnostics and treatments the median survival time for patients with glioblastomas does not exceed 15 months. A potential chemo-preventative agent that can suppress glioma growth or even eradicate gliomas entirely would be of tremendous benefit to patients that develop malignant tumors. In vivo magnetic resonance (MR) methods are ideally suited to follow changes in tumor growth, angiogenesis, as well as the assessment of c- Met levels which can be used as a marker for predicting the prognosis of gliomas. We currently use non-invasive in vivo MR imaging (MRI) methods to detect tumor morphology, tumor vasculature or angiogenesis (using MR angiography (MRA)), and have preliminary data on c-Met expression (using molecular-targeted MRI). In addition we use molecular biology methods (Western blots, immunofluorescence histology) and histological tumor grading, to correlate with MR imaging, angiography and molecular targeted data. This project will assess PBN in its ability to prevent malignant glioma formation and development, use c-Met knockdown glioma cell clones, and incorporate novel in vivo molecular-targeted MRI techniques for in vivo detection of c-Met in intracranial rat gliomas varying in tumor grades. Intracerebral implantation of rat C6 (forming grade II or III tumors) or RG2 (forming more aggressive grade III or IV tumors) glioma cells will be used in Fisher 344 rats as the glioma models. Specific aim 1 will be to assess the levels of c-Met in the 2 glioma models (C6 and RG2); specific aim 2 will be to establish the effectiveness of PBN as a c-Met suppressor in preventing glioma growth and formation, and to use c-Met knockdown glioma models to further elucidate the role of c-Met in glioma formation; and specific aim 3 will be to develop and validate improved MRI methods for in vivo detection of c-Met expression. There are very few existing agents that are currently applicable for the intervention of malignant gliomas. Other promising characteristics of PBN, in addition to c-Met suppression, are that it is orally bio-available, and it is able to cross the blood-brain-barrier (BBB). PBN seems to be a promising candidate in its ability to be an effective agent against glioma formation, and may be useful as a chemo-preventative agent against glioblastoma multiforme in humans. We have preliminary data that PBN (alpha-phenyl-tert-butyl nitrone) seems to be a promising candidate in its ability to be an effective agent against glioma formation, and may be useful as a chemo-preventative agent against glioblastoma multiforme in humans. Our hypothesis is that c-Met, a tyrosine kinase receptor, plays an integral role in the formation of malignant gliomas, and that PBN is able to decrease c-Met levels, resulting in the suppression of glioma formation. This project will assess PBN in its ability to prevent malignant glioma formation and development, use c-Met knockdown glioma cell clones to elucidate the role of c-Met, and incorporate novel in vivo moleculartargeted MRI (magnetic resonance imaging) techniques for in vivo detection of c-Met in intracranial rat gliomas varying in tumor grades.