Targeting TET DNA Dioxygenases as Therapeutic Principle in Myeloid Neoplasms

项目摘要/摘要 11个易位(TET1、TET2和TET3)是α-酮戊二酸(αKG)和Fe2+依赖的DNA- 双加氧酶是表观遗传景观的关键调节因子。这些酶逐渐氧化5- DNA中的甲基胞嘧啶为5-羟甲基胞嘧啶，进而为5-甲酰胞嘧啶和5-羧基胞嘧啶 最终导致DNA去甲基化，这对大规模高效转录至关重要。功能丧失 TET2突变(TET2MT)是MDS及其相关血液病最常见的致病病变之一 人类的恶性肿瘤。TET2MT存在于所有疾病阶段和侵袭性水平。此外，最近 研究表明，体细胞TET2MT在“健康”的老年人中非常常见。.的存在 CHIP中的TET2MT提示它是血液病发生的早期事件。它还支持小鼠 研究结论：TET2MT可引起造血干/祖细胞(HSPC)的扩增。早些时候 缺陷克隆进化中的事件是预防性策略的合理目标，因为在这种情况下克隆 各个阶段很可能取决于这些事件。然而，它们在所有细胞中的存在也可以在 疾病的晚期。例如，小鼠造血细胞中TET1和TE2的联合丢失 仅与TET2损耗相比，型号就能显著延长寿命。此外，还给出了原则性证明 通过对IDH1/2MT患者的观察，这些新形性突变导致产生 弱Tet抑制剂，2-羟基谷氨酸(2-HG)，已知的双加氧酶抑制剂。我们观察到IDH1/2MT 与TET2MT相互排斥，有力地支持了我们的假设，即Tet抑制剂2-HG可以防止 TET2MT克隆的进化这一观察结果在髓系恶性细胞模型中得到了进一步证实。 细胞和支持合成杀伤力可以通过消除剩余的Tet活性必需的 用于在Tet-双加氧酶缺陷的TET2MT克隆中高效转录以促进增殖。 我们的主要假设是，合理设计和合成的小分子TETi76可以被利用 抑制源自TET3和TET1的代偿性TET双加氧酶活性，以导致合成的 TET2MT失活病例的致死性或血统重定向。我们的目标是开发一种新的治疗方法 通过评估TETi76在临床前模型中作为靶向治疗的潜在用途，为TET2MT MDS提供方法。 更具体地说，我们的目标是：i)研究Tet抑制在正常和恶性中的机制后果 体外造血。二)在体外利用人和小鼠细胞建立Teti化合物的作用 模型和III)表征TETI的预防和治疗效果以及临床前的耐受性 小鼠模型。 我们的建议，如果成功，将导致一类治疗TET2MT相关造血的新型药物 疾病，也许还有其他双加氧酶突变。这项研究也可能对癌症产生影响。 组蛋白去甲基酶KDM6A突变，与TET2相似，在膀胱癌中频繁突变。

PROJECT SUMMARY/ABSTRACT Ten Eleven Translocation (TET1, TET2 and TET3) are α-ketoglutarate (αKG) and Fe2+ dependent DNA- dioxygenases that is a key regulator of epigenetic landscape. These enzymes progressively oxidize 5- methylcytosine to 5-hydroxymethylcytosine and further to 5-formylcytosine and 5-carboxylcytosine in DNA culminating into DNA demethylation essential for efficient transcription over large time scales. Loss-of-function TET2 mutations (TET2MT), is one of the most frequent pathogenic lesion in MDS and related hematologic malignancies in humans. TET2MT are found in all disease stages and levels of aggressiveness. In addition, recent studies have demonstrated that somatic TET2MT are very frequently found in “healthy” elderly. The presence of TET2MT in CHIP implies that it is an early event in the creation of hematologic disorders. It also supports murine study conclusions that TET2MT cause expansions of hematopoietic stem and progenitor cells (HSPC). Early events in the evolution of defective clones are rational targets for preventative strategies since clones in such stages are likely to be dependent on these events. Their presence in all cells can, however, also be exploited in late stages of the disease. For example, the combined loss of TET1 and TE2 in hematopoietic cells in murine models extends life substantially relative to TET2 loss alone. In addition, the proof of principle is also derived from observation in patients with IDH1/2MT whereby, these neomorphic mutations lead to the production of a weak TET inhibitor, 2-hydroxyglutyrate (2-HG), known inhibitor of dioxygenases. Our observations that IDH1/2MT are mutually exclusive with TET2MT, strongly supports our hypotheses that the TET inhibitor, 2-HG, prevents evolution of TET2MT clones. This observation was further substantiated in a cellular model of myeloid malignant cells and supports that synthetic lethality can be achieved through elimination of remaining TET-activity essential for efficient transcription for proliferation in TET-dioxygenase deficient TET2MT clones. Our overarching hypothesis is that rationally designed and synthesized small molecules TETi76 can be utilized to impede compensatory TET dioxygenase activity originating from TET3 and TET1, to cause either synthetic lethality or lineage redirection in cases with TET2MT inactivation. Our goal is to develop a novel therapeutic approach for TET2MT MDS by evaluating the potential use of TETi76 as targeted treatments in preclinical models. More specifically, we aim to: i) Study the mechanistic consequences of TET inhibition in normal and malignant hematopoiesis in vitro. ii) Establish the effects of TETi compounds in vitro using human and murine cellular models and iii) Characterize TETi preventative and therapeutic efficacy as well as tolerability in pre-clinical murine models. Our proposal, if successful, will lead to a novel class of therapeutic agents for TET2MT associated hematopoietic disorders, and perhaps also other dioxygenase mutations. This work could also have implications for cancers mutated in histone demethylase KDM6A, which is similar to TET2 and frequently mutated in bladder cancer.