The Significance of Isocitrate Dehydrogenase Mutations in Gliomas

描述（由申请人提供）：本研究计划的目标是确定突变异柠檬酸脱氢酶1 （IDH1）导致脑肿瘤侵袭性降低的机制。最常见的脑肿瘤类型是弥漫性浸润性胶质瘤；这些肿瘤不能通过手术完全切除，也很难用放疗和化疗来治疗。因此，浸润性胶质瘤是无法治愈的。在这些胶质瘤中发现IDH1的特定点突变（以及IDH2的不太常见的类似突变）相当常见。当出现时，它是一个强大的有利预后因素，与更长的患者生存密切相关。突变体IDH1最近被证明产生一种新的化合物，2-羟基戊二酸（2-HG）。然而，IDH1和2-HG突变体对胶质瘤细胞的影响尚不清楚。其他研究表明，2-HG在非肿瘤组织模型中引起氧化应激，我们的初步数据表明，2-HG对胶质瘤细胞有毒性，并诱导自噬、ERK激活和活性氧的产生。因此，我们假设，IDH1突变体在弥漫性胶质瘤中的生存率提高是由于2- hg诱导活性氧的产生，导致氧化损伤和细胞死亡。我们还假设细胞死亡主要是由自噬引起的，自噬是一种涉及溶酶体的程序性细胞死亡形式，在许多胶质瘤中表现突出。为了验证这些假设，胶质瘤细胞将用2-HG处理或用突变体IDH1转染，并测量多种描述良好的自噬和活性氧标记物。胶质瘤细胞对自噬和活性氧调节的反应将被评估。对于患者来源的肿瘤活检和人类小鼠异种移植，自噬和氧化应激的免疫组织化学标志物将被量化，并与IDH突变状态相关。该项目的成功将确定突变型IDH1是否会导致胶质瘤中氧化应激和自噬增加，从而产生与IDH1野生型肿瘤相比侵袭性较低的胶质瘤。这些知识可以用来开发治疗胶质瘤的新方法。我很幸运得到了杰出的科学家和医生的指导，因此我渴望追求一种综合我作为科学家和神经病理学家所学到的职业。我在神经科学方面的研究生和博士后工作，以及我在神经肿瘤学方面的工作，给了我在这个项目中使用的各种各样的技术和方法。我目前的职位是肯塔基大学病理学系的助理教授，这为我追求成为一名独立研究者的目标提供了理想的机会。我有9人月（75%）的保证研究保护时间，独立的实验室空间，设备齐全，有一个全职的技术人员来增加产量，有足够的资金来进行未来四年的实验。所有这些都是由我的主席保罗·巴赫纳博士实施的，而不管我是否成功地获得了外部资金。我也受益于一个合作的环境，博士的优秀指导。Natasha Kyprianou， Arie Perry和Jeremy Rich，以及优秀的技术资源。现在我已经完成了我的临床培训，K08奖提供的资金将使我能够发展成为一名独立的研究者。此外，本提案中描述的项目提供了一个极好的机会来发现为什么IDH1突变体赋予胶质瘤患者更有利的生存，从而有助于确定有效治疗干预的途径和靶点。

DESCRIPTION (provided by applicant): The goal of this research proposal is to determine the mechanism(s) by which mutant isocitrate dehydrogenase 1 (IDH1) causes brain tumors to be less aggressive. The most common type of brain tumor is the diffusely infiltrative glioma; these tumors cannot be completely excised surgically, and are difficult to treat with radiation and chemotherapy. Thus, infiltrative gliomas are incurable. A specific point mutation in IDH1 (and a less common analogous mutation in IDH2) has been found to be quite frequent in these gliomas. When present, it is a powerful favorable prognostic factor, being strongly associated with longer patient survival. Mutant IDH1 has recently been shown to produce a novel compound, 2-hydroxyglutarate (2-HG). However, the effects of mutant IDH1 and 2-HG on glioma cells are unknown. Other work showed that 2-HG causes oxidative stress in nonneoplastic tissue models, and our preliminary data indicate that 2-HG is toxic to glioma cells and induces autophagy, ERK activation, and reactive oxygen species production. We therefore hypothesize that the improved survival imparted by mutant IDH1 in diffuse gliomas is due to 2-HG-induced production of reactive oxygen species, leading to oxidative damage and cell death. We also hypothesize that the cell death is primarily by autophagy, a form of programmed cell death involving lysosomes that has been shown to be prominent in many gliomas. To test these hypotheses, glioma cells will be treated with 2-HG or transfected with mutant IDH1, and multiple well-described markers of autophagy and reactive oxygen species will be measured. Response of glioma cells to autophagy and reactive oxygen species modulation will be assessed. For patient-derived tumor biopsies and human-mouse xenografts, immunohistochemical markers of autophagy and oxidative stress will be quantified and correlated with IDH mutation status. Success in this project would determine whether mutant IDH1 causes increased oxidative stress and autophagy in gliomas, thereby producing a less aggressive glioma compared to tumors that are wild type for IDH1. This knowledge could then be exploited to develop novel ways of treating gliomas. I am fortunate to have been mentored by exceptional scientists and physicians, thus instilling in me a desire to pursue a career that synthesizes what I have learned as a scientist and neuropathologist.My graduate and postdoctoral work in neuroscience and my work in neuro-oncology have given me a diverse array of techniques and approaches that will be used in this project. My current position as an Assistant Professor in the Department of Pathology in the University of Kentucky offers the ideal opportunity to pursue my goal of being an independent investigator. I have nine person-months (75%) of guaranteed protected time for research, separate laboratory space that has been fully equipped, a full-time technician to increase output, and sufficient funds to conduct experiments for the next four years. All this has been put in place by my chairman, Dr. Paul Bachner, independent of my success in securing extramural funding. I also benefit from a collaborative environment, superb mentorship by Drs. Natasha Kyprianou, Arie Perry, and Jeremy Rich, and excellent technical resources. Now that I have completed my clinical training, the funding provided by this K08 award would allow me to develop as an independent investigator. Furthermore, the project described in this proposal provides a superb opportunity to discover why mutant IDH1 imparts a more favorable survival in patients afflicted with gliomas, in turn helping to identify pathways and targets for effective therapeutic interventions. PUBLIC HEALTH RELEVANCE: This research explores why mutant isocitrate dehydrogenase 1, an abnormal enzyme found in many brain tumors, is such a powerful marker of longer patient survival. Discovering why this is so will help find new ways to treat these incurable tumors. The written critiques and criteria scores of individual reviewers are provided in essentially unedited form in the "Critique" section below. Please note that these critiques and criteria scores were prepared prior to the meeting and may not have been revised subsequent to any discussions at the review meeting. The "Resume and Summary of Discussion" section above summarizes the final opinions of the committee.