Project 3: MRI Imaging of Redox Active Fe Predicts GBM Responses to Pharmacological Ascorbate

项目摘要/摘要-项目3： 多形性胶质母细胞瘤(GBM)是美国最常见的恶性脑瘤，尽管 积极治疗的GBM预后较差，中位总生存期约15个月。调查人员 在项目3中发现了药理抗坏血酸(P-Asch-)，是一种很有前途的化学辐射佐剂 利用氧化代谢的根本差异对基底膜进行治疗。初步数据显示， 相对于正常人星形胶质细胞(NHA)，P-Asch-对GBM细胞的选择性毒性是通过H_2O_2诱导的 氧化还原活性铁离子介导的氧化应激。此外，在临床前的GBM模型中以及在 1期临床试验(NCT01752491)，他们发现P-Asch-(达到~20 mm[血浆])+辐射和 替莫唑胺治疗耐受性良好，不良反应最少，同时显示出令人鼓舞的治疗效果。 回应。最后，初步数据也支持磁共振(MR)成像可能 能够检测Fe的氧化还原状态(即Fe+2/Fe+3)以预测对P-Asch-In组合的响应 通过评价T2*弛豫度的变化进行放化疗。 目前，对引起基底膜与基底膜不同易感性的机制尚无明确的认识。 正常脑细胞转P-Asch-in活体。项目3将测试P-Asch选择性增加的假设 与正常星形胶质细胞相比，人GBM细胞中不稳定的氧化还原活性铁与H_2O_2的形成有关。 导致氧化DNA损伤增加并增加GBM细胞对辐射和 替莫唑胺可通过T2*弛豫定量磁共振成像进行体内评估 磁化率标测。目标1将确定P-Asch是否诱导细胞内[H_2O_2]中介增加 患者神经、神经、经典和间质GBM细胞的放化疗增敏作用 增强的DNA双链断裂和差异导致的正常人脑星形胶质细胞亚型 在GBM细胞的过氧化氢代谢中。目标2将确定增加的活性铁库(LIP)是否介导了 GBM与NHA对P-Asch化疗放射增敏的敏感性比较。目标3将在正位确定 P-Asch诱导氧化还原活性LIP的调节和选择性增敏的GBM异种移植模型 可以使用T2*MRI成像和定量易感性映射来预测放射和化疗 以及标准的生化分析。这些目标的完成将定义生化机制 P-Asch介导的GBM细胞体外和体内原位选择性放化疗增敏作用 模型，以及研究高度创新的磁共振成像方法，以预测反应。项目3是 也很好地融入了PO1的总体主题，为开发基本知识提供了新的范式 应用P-Asch-改善癌症患者氧化还原代谢的差异以提高疗效。

Project Summary/Abstract - Project 3: Glioblastoma multiforme (GBM) is the most common malignant brain tumor in the United States but despite the aggressive treatment GBM has a dismal prognosis with a median overall survival of ~15 months. Investigators in Project 3 have found that pharmacological ascorbate (P-AscH-), is a promising adjuvant to chemo-radiation therapy in GBM exploiting fundamental differences in oxidative metabolism. Preliminary data demonstrate the selective toxicity of P-AscH- to GBM cells, relative to normal human astrocytes (NHA), occurs via H2O2-induced oxidative stress mediated by redox active Fe ions. Furthermore, in a pre-clinical GBM model as well as in a phase 1 clinical trial (NCT01752491), they found that P-AscH- (achieving ~20 mM [plasma]) + radiation and temozolomide therapy was well-tolerated with minimal adverse events while showing encouraging therapeutic responses. Finally, preliminary data also support the idea that magnetic resonance (MR) imaging may be capable of detecting the redox state of Fe (i.e., Fe+2/Fe+3) for predicting responses to P-AscH- in combination with chemo-radiation therapy via assessing changes of T2* relaxometry. Currently, there is no clear understanding of mechanisms causing the differential susceptibility of GBM vs. normal brain cells to P-AscH- in vivo. Project 3 will test the hypothesis that P-AscH- selectively increases labile redox active Fe associated H2O2 formation in human GBM cells, relative to normal astrocytes, leading to increased oxidative DNA damage and increased sensitivity of GBM cells to radiation and temozolomide that can be assessed in vivo using MR imaging with T2* relaxometry and quantitative susceptibility mapping. Aim 1 will determine if P-AscH--induced increases in intracellular [H2O2] mediate chemo-radiosensitization in patient derived GBM cells of Proneural, Neural, Classical and Meschymal subtypes relative to normal human astrocytes (NHA) via enhanced DNA double strand breaks and differences in H2O2 metabolism in GBM cells. Aim 2 will determine if increased labile iron pools (LIP) mediate the sensitivity of GBM vs. NHA to P-AscH--induced chemo-radiosensitization. Aim 3 will determine in orthotopic GBM xenograft models if P-AscH- induced regulation of the redox-active LIP and selective sensitization to radiation and chemotherapy can be predicted using T2* MRI imaging and quantitative susceptibility mapping as well as standard biochemical assays. Completion of the aims will define biochemical mechanisms underlying P-AscH--mediated selective chemo-radiosensitization of GBM cells in vitro and in vivo orthotopic models as well as investigating highly innovative MR imaging approaches to predict responses. Project 3 is also well-integrated into the overall theme of the PO1 to provide a new paradigm for exploiting fundamental differences in redox metabolism to improve treatment efficacy in cancer patients using P-AscH-.