急性早幼粒细胞白血病功能性cAMP/PKA/CBP/p300调控网络对白血病干细胞分化调节机制的研究

To overcome the problems of drug-resistance and disease relapse in the treatment of patients with acute promyelocytic leukemia, it is imperative to further improve the efficacy of differentiation induction therapy by targeting leukemia stem cells (LSC). Our previous works have successfully identified the cell population with stem cell properties in a novel murine transgenic leukemia model. We also proved the activation of cyclic AMP/Protein Kinase A (cAMP/PKA) signaling pathway could significantly enhance cellular differentiation of leukemic cells and eradicate LSC in vivo. Taking account of the functional importance of CREB-binding protein (CBP) and p300 in the transcriptional activation of cAMP/PKA pathway, and their significance in the maintenance of self-renewal and differentiation capacity of hematopoietic stem cells, we propose a research project based on our novel cellular and animal disease models, taking advantage of functional genomic techniques, to reveal the differences between CBP and p300 regulatory transcription networks downstream of cAMP/PKA pathway by making comparison between acute promyelocytic leukemia models with different fusion genes, also leukemic cells before and post drug-induced cellular differentiation. We will also investigate the cellular effects of these identified key modulators or networks in hematopoietic and leukemic stem cells, respectively, especially on the cellular survival, self-renewal and lineage-commitment differentiation capacity of these stem cells. These investigations will shed light on the regulatory mechanisms of cAMP/PKA pathway on cellular biology of stem cells, and hopefully identify potential drug-targets for differentiation induction therapy of patients with AML.

诱导分化治疗在急性早幼粒细胞白血病研究领域仍有广阔探索空间，靶向白血病干细胞（LSC）的治疗策略是克服白血病细胞耐药及疾病复发的关键。我们前期工作已经鉴定了这一疾病的LSC亚群，并发现激活cAMP/PKA通路可诱导耐药的白血病细胞分化并清除LSC。考虑到CBP及p300蛋白在调控造血干细胞自我更新和分化中的关键作用及其在cAMP/PKA通路下游的重要调节机能，我们将充分利用一系列新建立的早幼粒细胞白血病生物模型，借助功能基因组学研究手段，通过敏感与耐药细胞的横向比较及药物诱导分化前后的纵向比较，深入挖掘cAMP/PKA通路下游CBP及p300蛋白调控网络的差异性；在白血病干细胞及造血干细胞层面验证关键性调控基因对干细胞生存、自我更新、分化的生物学影响；进一步明确cAMP/PKA通路在维持干细胞功能、调节髓系分化中的作用机制，为急性白血病诱导分化治疗提供新的治疗靶点。

背景：急性早幼粒细胞白血病是严重影响人民健康的急性髓细胞白血病的一种特殊亚型。对其分子病理机制的深入探索不仅丰富对白血病分子病理的认识，有望在其基础上衍生出新的治疗策略。.主要研究内容：利用基因芯片及下一代测序等现代基因组学手段及免疫共沉淀等技术探索影响、决定早幼粒白血病细胞对分化诱导治疗耐药的基因转录调控机制；在此基础上探索可能的干扰及治疗策略。运用前向基因学技术及模式生物体，筛查参与造血调控及造血干祖细胞功能维持的关键基因。.重要结果、关键数据：通过对差异性DNA甲基化修饰区域的比较性分析，发现在对维甲酸敏感及耐药的早幼粒白血病细胞中在基因组水平上存在CREB结合序列的差异性DNA甲基化修饰；运用差异性甲基化区段；.通过斑马鱼突变家系结合高通量测序技术，我们已经筛查到了若干调控斑马鱼造血干细胞自我更新、迁移、增殖、分化过程中的功能基因，分别有RECQL4, HEG以及TARS等，进一步的功能研究正由梯队研究生进行中。.科学意义：对表观遗传学转录调控机制的干预可提供一个除信号通路的激动剂的直接作用之外的另一种全新的治疗机制。由于其表观遗传学治疗机制与我们以往研究提出的运用cAMP途径激动剂治疗相比存在本质上的差异，两者具有互补性而没有交叉耐药。为进一步探索联合治疗，提高清除和根治白血病的可能提供了直接的基础试验依据。通过识别斑马鱼造血干细胞发育和自我更新的关键基因和信号路径，以帮助理解人类造血干细胞和白血病干血病自我更新的遗传学机制，为肿瘤干细胞的靶向治疗搜寻分子靶点。