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

描述（由申请人提供）：该项目的目标是鉴定和优化针对异柠檬酸脱氢酶1 （IDH1）的特异性抑制剂。22个胶质瘤基因组的无偏性基因组测序发现，编码IIDH1胞质异构体的染色体2q33-a基因上的IDH1反复突变与三羧酸循环（TCA）有关，该循环催化异柠檬酸的氧化脱羧，通过NADP+转化为NADPH产生1-酮戊二酸和二氧化碳。随后的研究证实，高达70%的继发性胶质瘤和10%的AML病例中存在复发性IDH突变。我们发现，与癌症相关的IDH1体细胞突变是一个点突变，导致精氨酸132上的各种氨基酸取代基（IDH1 R132）——一种在酶活性位点发现的关键残基，当突变时导致代谢异柠檬酸盐的功能丧失，但赋予产生肿瘤代谢物2-羟基戊二酸（2HG）的功能获得。这实际上将IDH1定义为一种致癌基因，并为发现针对突变IDH1的化学探针提供了难得的机会，这些探针可能转化为胶质瘤和AML患者急需的新疗法。该提案有两个具体目标：(1)使用经过验证的IDH1 R132H HTS试验发现针对突变IDH1的新型化学探针；(2)利用配对细胞系（亲代U87MG胶质母细胞瘤和组成表达IDH1R132H突变体的U87MG稳定细胞系）对产生2hg的肿瘤细胞特异性化学探针进行合成致死筛选。

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.