The Role of HIF1A-DNMT3A axis in AML1/ETO-Driven Acute Myelogenous Leukemia

融合蛋白AML-1/ETO(AE)是由t(8；21)易位产生的一种白血病启动型转录因子，常与急性髓系白血病(AML)相关。尽管被定义为AML的“有利”亚型，但许多AE阳性(AE+)患者的复发和死亡原因大多不明。目前也不清楚AE如何调节疾病可预测的DNA甲基化特征。长期目标是进一步阐明AE+AML的发病机制，发现新的治疗靶点，开发有效的靶向治疗。这项建议的目的是探索AE+AML背后可预测疾病的DNA甲基化信号的分子基础，重点是缺氧非依赖性HIF1α-DNMT3a信号轴激活的影响。这一提议背后的理论基础是，不依赖缺氧的HIF1α信号激活是癌症的一个新标志。与该项目相关的是，HIF1α信号的过度激活可能是AE+AML的促病因子和表观遗传介体。HIF1α与AE形成前馈循环，并反式激活DNMT3a，这是AE+AML的另一个预后标志物。抑制HIF1α可抑制AML细胞的生长。然而，HIF1α信号与AEAML发病机制和疾病复发之间的详细机制和生化联系尚不清楚。中心假说是，HIF1α通过增强AE转录活性和调节AML细胞中由AE支配的DNA甲基化而促进AE的白血病原性；因此，HIF1α可能是AE+AML的一个易受攻击和可用药的靶点。这一假设将通过追求三个具体目标来检验：1)剖析HIF1α如何在AE驱动的白血病发生中起关键作用的机制细节；2)确定HIF1α在AE依赖的DNA甲基化中的作用；3)测试HIF1α作为AE+AML的治疗选择的药理学靶点。为了实现我们的目标，我们将使用生物技术与独特的转基因和患者来源的异种移植(POX)小鼠模型的创新组合，以及在理解和治疗AE+AML方面创新地整合异常HIF1α信号和表观遗传学。这项拟议的研究具有重要意义，因为它将揭示AE白血病致病所必需的新基因/机制途径，识别治疗性生物标志物，并发现治疗AE+AML的新药物。此外，它还将深入研究HIF1α在癌症中的表观遗传学和致癌作用。最接近的预期结果是证明HIF1α-表观遗传学在确定AE启动的转录调控和白血病发病机制方面的串扰，并建立使用HIF1α抑制剂来提高现有治疗方案的治疗指数的可行性。这些结果将产生重要的影响，因为它们将促进我们对AE+AML分子病理学、白血病的异常表观遗传学以及肿瘤中缺氧非依赖性HIF1α信号的致癌功能的理解。这些发现还将为开发更好地针对AE+AML的新策略奠定基础。

The fusion protein AML 1/ETO (AE), resulting from the t(8;21) translocation, is a leukemia-initiating transcription factor that is frequently associated with acute myeloid leukemia (AML). Despite being defined as a "favorable" subtype of AML, many AE positive (AE+) patients relapse and die with largely unknown causes. It is also unclear how AE mediates a disease-predictable DNA methylation signature. The long-term goals are to elucidate further the mechanisms of AE+ AML leukemogenesis, discover new therapeutic targets and develop effective targeted therapies. The objective of this proposal is to explore the molecular basis of a disease-predictable DNA methylation signature underlying AE+ AML with a focus on the impact of hypoxia-independent HIF1alpha-DNMT3a signaling axis activation. The rationale underlying this proposal is that the hypoxia-independent HIF1alpha signaling activation is a new hallmark of cancer. In relation to this project, the hyperactive HIF1alpha signaling may be a disease-promoting factor and an epigenetic mediator in AE+ AML. HIF1alpha forms a feedforward loop with AE and transactivates DNMT3a, another prognostic marker in AE+ AML. HIF1alpha inhibition suppresses AML cell growth. However, the detailed mechanistic and biochemical links between HIF1alpha signaling and AE AML pathogenesis and disease recurrence are poorly defined. The central hypothesis is that HIF1alpha promotes AE leukemogenicity through enhancing AE transcriptional activities and modulating the AE-governed DNA methylation landscape in AML cells; therefore HIF1alpha may be a vulnerable and druggable target in AE+ AML. This hypothesis will be tested by pursuing three specific aims: 1.) Dissect the mechanistic details of how HIF1alpha is critical for AE-driven leukemogenesis; 2) Determine the role of HIF1alpha in AE-dependent DNA methylation; 3) Test pharmacological targeting of HIF1alpha as a therapeutic option for AE+ AML. To pursue our aims, we will use innovative combinations of biological techniques with unique transgenic and patient-derived xenograft (POX) mouse models, as well as innovative integration of aberrant HIF1alpha signaling and epigenetics in understanding and treating AE+ AML. The proposed research is significant, because it will disclose new genes/mechanistic pathways that are necessary for AE leukemogenicity, identify the therapeutic biomarkers, and discover new medicinal agents for AE+ AML. Further, it will thoroughly investigate the epigenetic and oncogenic role of HIF1alpha in cancer. The proximate expected outcomes are to demonstrate HIF1alpha-epigenetics crosstalk in defining AE-initiated transcriptional regulation and leukemia pathogenesis, and to establish the feasibility of using HIF1alpha inhibitors to enhance the therapeutic index of the existing treatment regimens. The results will have an important impact because they will advance our understanding of AE+ AML molecular pathology, aberrant epigenetics in leukemia and the oncogenic functions of hypoxia-independent HIF1alpha signaling in cancers. The findings will also lay the groundwork to develop newer strategies to better target AE+ AML.