Modulation of Ten-Eleven-Translocation Enzymes as Treatment Option for IDH-mutated Cancer

异柠檬酸脱氢酶1、2和3 （IDH1/2/3）是柠檬酸循环的关键酶，它们催化异柠檬酸氧化转化为α-酮戊二酸（αKG）。它作为α kg依赖性双加氧酶的共底物，如10 - 11易位（TET）酶，在退役基因的表观遗传再激活中起着至关重要的作用。它们催化5-甲基胞嘧啶的顺序氧化并促进位点特异性DNA去甲基化。TET和IDH酶在某些肿瘤疾病的进展中具有重要的相关性。IDH1和IDH2基因突变在胶质母细胞瘤和骨髓增生异常综合征（如急性髓性白血病（AML））中尤为常见。这些突变导致新形态酶活性和肿瘤代谢物2-羟戊二酸（2HG）的大量过量产生，后者与αKG竞争并抑制TET酶。到目前为止，只有维生素C被描述为对TET酶有激活作用。然而，分子机制尚不清楚，讨论了对TETs活性中心铁离子的还原作用。而其他还原剂则无效果。这种矛盾可能与维生素C的代谢有关。事实上，TET酶的必需辅助因子αKG与维生素C的代谢物2,3-二酮gulonic acid （DKA）在结构上具有显著的相似性。在硅上的初步工作已经表明，DKA与αKG类似，可以进入TET酶的活性口袋，并且能够在功能上结合。这已经通过无细胞TET酶测定和基于细胞的测试得到证实。到目前为止，这一发现还没有得到完全的描述。因此，计划的研究项目的目的是表征维生素C及其代谢物DKA的确切作用机制。此外，将开发治疗方案，以逆转2hg诱导的α kg依赖性双加氧酶失活。药效学和药代动力学的问题也将得到回答。为此，DNA甲基化、DNA羟甲基化和进一步氧化状态的全基因组和基因特异性变化被用作细胞TET活性的证据。此外，研究DKA在小鼠模型中可能的肿瘤抑制作用，并测试其治疗急性髓系白血病细胞的可能性也是非常有意义的。随着DKA的作用模式的阐明，发现新的DKA类似分子结构将是该项目的进一步目标。用于治疗AML的IDH抑制剂已经可用或正在进行临床试验。这些抑制剂与新的基于dka的类似物的组合将代表一种新的分子策略，用于治疗肿瘤疾病，如胶质母细胞瘤和AML。

Isocitrate dehydrogenases 1, 2 and 3 (IDH1/2/3) are key enzymes of the citrate cycle as they catalyze the oxidative conversion of isocitrate to α-ketoglutarate (αKG). This serves as a co-substrate for αKG-dependent dioxygenases such as the Ten-Eleven-Translocation (TET) enzymes, which play a crucial role in the epigenetic reactivation of decommissioned genes. They catalyze the sequential oxidation of 5-methylcytosine and promote locus-specific DNA demethylation. There is an important correlation between TET and IDH enzymes in the progression of certain tumor diseases. Mutations in IDH1 and IDH2 genes are particularly common in glioblastomas and myelodysplastic syndromes such as acute myeloid leukemia (AML). These mutations lead to neomorphic enzyme activity and massive overproduction of the oncometabolite 2-hydroxyglutarate (2HG), which competes with αKG and inhibits TET enzymes. So far only vitamin C has been described as having an activating effect on TET enzymes. However, the molecular mechanism is not known, a reducing effect on iron ions in the active center of the TETs is discussed. However, other reducing agents have no effect. A possible explanation for this contradiction could be the metabolism of vitamin C. In fact, there is a remarkable structural similarity between αKG, the essential co-factor of TET enzymes, and the vitamin C metabolite 2,3-diketogulonic acid (DKA). Initial preliminary work in silico has already shown that DKA, similar to αKG, fits into the active pocket of TET enzymes and is able to bind functionally. This has already been confirmed with the aid of a cell-free TET enzyme assay and a cell-based test. This finding has so far been completely undescribed. Therefore, the aim of the planned research project is to characterize the exact mechanism of action of vitamin C and its metabolite DKA. Furthermore, therapy options will be developed that can reverse the 2HG-induced inactivation of αKG-dependent dioxygenases. Pharmacodynamic and pharmacokinetic questions will also be answered. For this purpose, genome-wide and gene-specific changes in DNA methylation, DNA hydroxymethylation and further oxidation states are used as evidence of cellular TET activity. In addition, it is of great interest to investigate the possible tumor-inhibiting effect of DKA in the mouse model and to test the possibility of treating acute myeloid leukaemia cells. With the elucidation of the mode of action of DKA, the discovery of new DKA-analog molecule structures will be a further goal of the project. IDH inhibitors for the therapy of AML are already available or are clinically tested. The combination of such inhibitors with new DKA-based analogs would represent a new molecular strategy for the treatment of tumor diseases such as glioblastomas and AML.