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)是柠檬酸循环中的关键酶，它们催化异柠檬酸氧化转化为α-酮戊二酸(αKG)。这是αKG依赖的双加氧酶的共同底物，如10-11易位(TET)酶，它们在表观遗传重新激活去功能化的基因中发挥关键作用。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。在某些肿瘤疾病的进展中，Tet和IDH酶有重要的相关性。IDH1和IDH2基因突变在胶质母细胞瘤和骨髓增生异常综合征(如急性髓系白血病(AML))中尤其常见。这些突变导致新形酶活性和与αKG竞争并抑制Tet酶的肿瘤性代谢产物2-羟基戊二酸(2HG)的大量过度生产。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，本文讨论了TETS对活性中心铁离子的还原作用。然而，其他还原剂没有任何效果。这一矛盾的一个可能的解释是维生素C的代谢。事实上，αKG是Tet酶的重要辅助因子，与维生素C代谢产物2，3-二酮丙二酸在结构上有显著的相似之处。在计算机上的初步研究已经表明，DKA类似于αKG，适合Tet酶的活性口袋，并能够在功能上结合。这一点已经通过无细胞Tet酶检测和基于细胞的检测得到了证实。到目前为止，这一发现完全没有得到描述。因此，计划中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，还将开发可逆转2HG诱导的αKG依赖的双加氧酶失活的治疗方案。药效学和药代动力学问题也将得到解答。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，在小鼠模型中研究DKA可能的肿瘤抑制作用以及测试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抑制剂已经可用或已进行临床测试。这种抑制剂与新的基于DKA的类似物的结合将代表着治疗胶质母细胞瘤和急性髓细胞白血病等肿瘤疾病的新分子策略。

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.