AML造血干细胞移植后复发和白血病干细胞增殖动力学变化的相关性及其机制

Acute leukemia can be cured by allogenetic hematopoietic stem cell transplantation (allo-HSCT), but relapse of the disease remains to be a major cause of treatment failure. It is accepted that leukemia stem cells (LSC) are the key cells in the initiation, progression and recurrence of leukemias, and the origin of relapse post allo-HSCT. Our previous observation suggested that relapse is closely associated with proliferative discrepancies between leukemic cells and hematopoietic stem cells and the level of minimal residual leukemia defined by LSC. In the present project, we propose to investigate the biological characteristics, especially proliferative capacities of LSCs, in comparison with that of normal hematopoietic stem cells, in response to preconditioning intensive chemo- and/or radiotherapy as well as to donor derived immune effector cells and during relapse of the disease, by using murine models of acute myeloid leukemia carrying specific genetic and surface markers. The mechanisms of cell cycle control and kinetics of LSC proliferation before and after transplant and during the process of leukemia relapse will be further studied, with the aim to identify the key genes and signal pathways by means of high-through and bioinformatics techoniques. We believe that these studies will provide key information about, and new insights into, the mechanisms and new strategies for prevention and treatment of post transplantation leukemia relapse.

异基因造血干细胞移植是治愈急性白血病的重要手段，但多年来复发率居高不下，是移植失败的主要原因。多项研究提示白血病干细胞（LSC）是白血病发生、发展和复发的关键细胞，是移植后复发的根源。我们的前期研究表明，化疗后白血病细胞与正常造血干/祖细胞的增殖差异及以"LSC"界定的微小残留白血病水平与疾病复发密切相关。本课题拟应用携带特定遗传和表面标记的白血病移植后复发的动物模型，研究急性髓细胞白血病的LSC在移植前、后和白血病复发过程中生物学特性尤其是细胞增殖调控的变化，并与正常造血干/祖细胞比较，以评价移植预处理和供体免疫效应细胞对LSC细胞周期调控和增殖动力学的影响，阐明移植后白血病复发和LSC增殖动力学等生物学特性改变的相关性，并利用高通量生物信息学技术筛选可干预的关键分子进行干预，为深入理解移植后白血病复发的机制，探索干预策略提供新的思路。

既往研究提示白血病干细胞（LSC）是白血病发生、发展和复发的关键细胞，本课题组前期研究也发现LSC频率越高，患者复发率越高，预后越差，提示残留的LSC可能是移植后复发的主要因素。本项目拟通过对AML异基因移植后复发患者肿瘤细胞遗传学改变的纵向比较分析及建立携带特定遗传和表面标记的白血病移植后复发动物模型，研究移植后白血病复发和LSC增殖动力学等生物学特性改变的相关性并筛选可干预的相关分子靶点。本项目通过对AML移植后复发患者临床特征分析，明确了复发相关临床因素，此外通过对比分析发现，对于CBF-AML患者Flow-FISH方法可以比RT-PCR及流式更早筛选出微小残留病灶阳性高复发风险群体，可用于指导预后分层及个体化治疗。通过对化疗后微小残留白血病模型的研究发现，化疗后正常造血干/祖细胞的增殖早于白血病细胞的复发，在此过程中细胞周期的调控起关键因素，但是由于正常造血干细胞在化疗后的过度增殖诱发了细胞衰老，最终可导致正常造血重建功能的受损。在此基础上又对移植物抗白血病效应（GVL）下的白血病细胞及LSC的动力学及功能变化情况探索发现，GVL效应可以降低小鼠各部位白血病细胞负荷，随着疾病进展LSC比例有上升趋势。研究还发现，在GVL效应下白血病细胞在骨髓和外周血的增殖可能受抑，小鼠生存期延长，但可以浸润中枢神经系统导致髓外复发。