HTS for inhibitors of IDH1m & synthetic-lethal in tumor cells producing 2HG

描述(由申请人提供)：该项目的目标是识别和优化异柠檬酸脱氢酶1(IDH1)的特异性抑制剂。对22个胶质瘤基因组进行的无偏基因组测序发现，染色体2q33上的IDH1重复突变-编码IIDH1胞浆亚型的基因，与三羧酸循环(TCA)相关，催化异柠檬酸氧化脱羧基生成1-酮戊二酸和二氧化碳，通过NADP+到NADPH的转化。随后的研究证实，高达70%的继发性胶质瘤和10%的AML病例中存在复发的IDH突变。我们已经发现，与癌症相关的IDH1的体细胞突变是一种点突变，导致精氨酸132(IDH1 R132)的各种氨基酸取代基-精氨酸132(IDH1 R132)是酶活性部位的一个关键残基，当突变时会导致丧失代谢异柠檬酸的功能，但提供产生肿瘤性代谢物2-羟基戊二酸(2HG)的功能获得。这实际上将IDH1定义为癌基因，并提供了一个非同寻常的机会来发现针对突变IDH1的化学探针，这可能会转化为胶质瘤和AML患者亟需的新疗法。该建议有两个具体目标：(1)使用IDH1 R132H的HTS验证方法发现针对突变IDH1的新化学探针；(2)使用配对细胞系(亲本U87 MG胶质母细胞瘤和组成表达IDH1R132H突变的U87 MG稳定细胞系)对产生2HG的肿瘤细胞特异性的化学探针进行合成致死筛选。 公共卫生相关性：这项提案的目的是筛选对异柠檬酸脱氢酶1(IDH1)突变形式特异的化学抑制物。最近，70%的II-IV级胶质瘤被发现存在复发的IDH突变。IDH1相关胶质瘤的体细胞点突变导致精氨酸132(IDH1 R132)的各种替换，精氨酸132是IDH1活性部位中的一种残基，当突变时提供功能增益，导致肿瘤代谢物2-羟基戊二酸(2HG)的新构型产生。这项建议中描述的分析方法提供了一个独特的机会来识别化学探针，目的是研究突变的IDH1和2HG在胶质瘤中的作用。

DESCRIPTION (provided by applicant): The goal of this project is to identify and optimize inhibitors that are specific for the isocitrate dehydrogenase 1 (IDH1). Unbiased genomic sequencing for 22 glioma genomes found recurrent mutation of IDH1 on chromosome 2q33-a gene encoding the cytosolic isoform of IIDH1 associated with the tricarboxylic acid cycle (TCA) that catalyzes the oxidative decarboxylation of isocitrate yielding 1-ketoglutarate and CO2 via NADP+ to NADPH conversion. Subsequent studies confirmed the recurrent IDH mutations in up to 70% of secondary gliomas and in 10% of AML cases. We have found that the somatic mutation of cancer-associated IDH1 is a point mutation resulting in various amino-acid substituent's at Arginine132 (IDH1 R132)-a key residue found in the enzyme's active site that when mutated results in the loss-of-function in metabolizing isocitrate but confers a gain-of-function to produce the oncometabolite 2-hydroxyglutarate (2HG). This in effect defines IDH1 as an oncogene and provides an extraordinary opportunity to discover chemical probes against mutant IDH1 that may translate into much needed new therapies for glioma and AML patients. The proposal has two specific aims: (1) Discovery of novel chemical probes against mutant IDH1 using a validated HTS assay for IDH1 R132H; (2) Performing a synthetic-lethal screen for chemical probes specific for 2HG-producing tumor cells using matched pair cell lines (parental U87MG glioblastoma, and a U87MG stable cell-line that constitutively expresses IDH1R132H mutant). PUBLIC HEALTH RELEVANCE: The aim of this proposal is to screen for chemical inhibitors that are specific for the mutant form of isocitrate dehydrogenase 1 (IDH1). Recently, 70% of grade II-IV gliomas were found to harbor recurrent IDH mutations. Somatic point mutations of IDH1-associated gliomas resulted in various substitution at Arginine 132 (IDH1 R132)-a residue found in the IDH1 active site that confers a gain-of-function when mutated, resulting in the neomorphic production of the oncometabolite 2- hydroxyglutarate (2HG). The assays described in this proposal provide a unique opportunity to identify chemical probes aimed at study the role of mutant IDH1 and 2HG in gliomas.