Molecular Characterization of Acute Myeloid Leukemia

描述（由申请人提供）：这项竞争性更新提议继续我们的研究，以我们在当前资助期内在小鼠模型和人类白血病中取得的重大发现为基础，研究急性髓性白血病（AML）的特征。1998年，我们发现小鼠AML是一个多阶段的过程，涉及抗程序性细胞死亡的细胞克隆扩增。在2000年，我们发现在AML1-ETO易位的人类AML中，只有多能祖细胞（MPP）期细胞是白血病细胞；更重要的是，在相同的患者中，这种易位存在于正常的自我更新的血液干细胞（HSC）中。我们提出，白血病前期的发展阶段只能发生在自我更新的HSC克隆中，而一些克隆在MPP阶段进展为白血病干细胞（LSC）。这些LSC是唯一真正负责驱动疾病的细胞。MPP，而不是前体HSC或子代胚细胞，将白血病转移到免疫缺陷小鼠。最近的证据表明，癌症干细胞（CSC）对针对其后代增殖细胞的化疗和放疗具有更强的抵抗力。因此，肿瘤对化疗的反应通常是缩小，但由于癌症干细胞的抵抗，几乎普遍复发。癌症干细胞模型的一个关键含义和要求是，只有杀死LSC/CSC的治疗才能治愈患者。因此，为了开发csc靶向治疗，有必要确定LSC特异性分子和对其发病机制至关重要的失调分子和途径。我们在此提出3个目标，旨在增加我们对人类AML LSC的理解，以便治疗它们。首先，根据新的报告和我们自己的发现，我们将对新生AML患者样本中的LSC进行严格的鉴定和量化，并调查这些LSC的正常对应体。其次，我们将研究CD96在人类AML的进展和发病机制中的功能作用，并研究靶向CD96作为治疗策略的潜在方法。在目前的资助期内，CD96在两项独立研究中被确定为候选的lsc特异性标志物。最后，我们将通过检测巨噬细胞和树突状细胞的各种亚群吞噬白血病细胞和向适应性免疫系统呈递抗原的能力，来检查白血病细胞上CD47的表达（“不要吃我”信号）是否使它们对先天（巨噬细胞）和适应性（肿瘤抗原的树突状细胞呈递）免疫系统不可见。我们将测试阻断抗cd47抗体是否可以克服这种影响，使它们易于免疫清除。

DESCRIPTION (provided by applicant): This competitive renewal proposes to continue our efforts characterizing acute myelogenous leukemia (AML) with studies that build on the significant findings that we achieved in the current funding period in both mouse models and human leukemia. In 1998 we showed that mouse AML was a multistage process involving clonal expansion of cells that resist programmed cell death. In 2000 we found that only multipotent progenitor (MPP) stage cells in human AML with AML1-ETO translocations are leukemia cells; more importantly, in the same patients, the translocation is present in normal self-renewing blood stem cells (HSC). We proposed that pre-leukemic stages of development can only occur in self-renewing clones of HSC, and that some clones progress to leukemia stem cells (LSC) at the stage of MPP. These LSC are the only cells truly responsible for driving the disease. The MPP, but not precursor HSC or progeny blast cells, transfer the leukemia to immunodeficient mice. Recent evidence has revealed cancer stem cells (CSC) to be more resistant to chemo- and radiotherapy that target their progeny proliferating cells. Thus, tumors often shrink in response to chemotherapy, but almost universally recur due to resistance of the cancer stem cells. A key implication and requirement of the cancer stem cell model is that only therapies that kill LSC/CSC can cure the patient. Thus, in order to develop CSC-targeted therapies, it is necessary to identify molecules specific to the LSC and dysregulated molecules and pathways that are critical for their pathogenesis. We propose here 3 aims designed to increase our understanding of human AML LSC in order to therapeutically target them. First, in light of new reports and our own findings, we will conduct a rigorous identification and quantification of LSC from patient samples of de novo AML, as well as investigate the normal counterparts to these LSC. Second, we will investigate the functional role of CD96 in the progression and pathogenesis of human AML, and investigate potential methods of targeting CD96 as a therapeutic strategy. During the current funding period, CD96 was identified as a candidate LSC-specific marker in two independent studies. Finally, we will examine whether CD47 expression (a 'don't eat me' signal) on leukemic cells renders them invisible to the innate (macrophage) and adaptive (dendritic cell presentation of tumor antigens) immune systems by examining the ability of various subsets of macrophages and dendritic cells to phagocytose leukemic cells and present antigen to the adaptive immune system. We will test whether a blocking anti-CD47 antibody can overcome this effect and render them susceptible to immune clearance. PUBLIC HEALTH RELEVANCE: Narrative Human acute myeloid leukemia (AML) is an aggressive cancer of the bone marrow with five year overall survival rates between 30-40%. This disease is maintained by a small population of leukemia stem cells (LSC) that must be eliminated for a cure. The goal of this research is identify potential therapeutic targets for AML, by characterizing LSC markers to understand how they help AML develop and persist, including examining a mechanism of immune evasion.