t(8;21)急性髓性白血病中白血病干细胞的鉴定及对预后影响的机制研究

Acute myeloid leukemia (AML) is derived from leukemic stem cell (LSC), which results in relapse after remission. LSC has high heterogeneity. Although CD34+CD38- is widely accepted as the phenotypic characteristic of LSC, CD34-LSC has begun to be concerned recently. The fully phenotypic and molecular characteristic of LSC in t(8;21) AML has not been reported to date. We put forward the hypothesis according to several preliminary works: both CD34- and CD34+ LSC population exist in t(8;21) AML, and the former has more stem cell potential and its frequency in bone marrow is prognostic. Therefore, NOD/SCID mouse xero-transplantation model and colony-forming assay will be used to identify LSC function. Immunophenotyping, G0 phase cell percentage, aldehyde dehydrogenase (ALDH) activity and mRNA levels of WT1 and others of sorted cells will be detected to analyze phenotypic, molecular and biological characteristics of LSC. The sorted cells will be used to analyze the mechanism of adverse prognosis of c-KIT mutation/low WT1 expression at diagnosis in t(8;21) AML at stem cell level. The candidate LSC population will be followed up during treatment to evaluate their value for monitoring minimal residual disease (MRD) and prognosis. The results of this project will promote fully and deeply understanding of LSC and the mechanism of its prognostic impact and discovering new MRD and prognostic marker of t(8;21) AML, and is helpful for treatment improvement and development of new LSC target medicine.

急性髓性白血病（AML）起源于白血病干细胞（LSC），LSC是AML缓解后再复发的根源。LSC异质性很强，尽管CD34+CD38-被广泛认为是其表型特征，CD34-LSC开始引起重视。有关t(8;21)AML LSC全面的表型和分子特征以及预后意义未见报道。本项目根据多项前期工作提出假说：t(8;21)AML中同时存在CD34-和CD34+LSC，前者比后者更原始并与预后相关。为此拟通过异种鼠移植及集落形成鉴定LSC功能，免疫标记、G0期细胞和乙醛脱氢酶（ALDH）活性检测及分选细胞WT1等mRNA定量检测研究LSC表型、分子及生物学特征，利用分选细胞研究c-KIT突变/初诊WT1低表达等不良预后因素在LSC层面的作用机制，随访患者候选LSC细胞群评估其微小残留病监测和预后价值。本项目将深化对t(8;21)AML LSC的了解及预后机制和预后标记的研究，有助于提高疗效及开发LSC靶向药物。

白血病是一种严重危害人类健康的恶性血液病。急性髓性白血病（AML）是最常见的白血病类型之一。AML起源于白血病干细胞（LSC），LSC是AML缓解后再复发的根源，是生存的重要影响因素。t(8;21)AML是AML的重要亚型之一，约40%的患者复发，并且复发后再缓解率很低，因而其中LSC的作用有待研究。本项目以t(8;21)AML为研究对象，对其LSC表型及分子特征展开研究。取得以下研究成果：1）依据一系列免疫标记结果提出可能同时存在CD34+和CD34-的LSC, 并且后者比前者更原始；2）评估了LSC相关的标志（包括乙醛脱氢酶（ALDH）、膜表面抗原CD34、CD38、CD123、CD96和TIM-3）在初诊患者的表达特征，依据患者随访资料及生存分析找出各自最适分组阈值并证实这些LSC标志的表现具有强烈的复发预测意义；3）通过Ki67检测证实患者初诊时的增殖潜能与复发有关；4）在前期发现c-KIT突变具有预后意义基础上进一步证实突变各亚型的预后意义不同，D816和D820突变是预示不良预后的突变类型而外显子8和N822突变不具有预后不良的意义；5）评估了治疗后特定时间点检测患者骨髓ALDH的表达用于微小残留病（MRD）监测的意义；6）初步探索了t(8;21)AML骨髓原代细胞NOD/SCID鼠移植模型的构建；7）分选了患者各候选LSC细胞群，初步证实不同患者34+38-与34-“LSC”之间的关系可能不同。以上研究成果不仅加深了我们对t(8;21)AML白血病细胞及LSC生物学特征的认识，而且具有重要的临床应用价值。其应用将促进t(8;21)AML更加精细的预后分层，有助于总体疗效和生存的提高。

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