Targeting dormant leukemia-initiating cells in T-cell acute lymphoblastic leukemia

项目摘要/摘要 治疗耐药是儿童T细胞急性淋巴细胞白血病长期缓解的主要障碍。 全部)。复发或难治性疾病的儿童预后很差。白血病起始细胞(L-IC) 移植到小鼠体内可再生疾病。他们还概括了猪细小病毒免疫表型的复杂性 支持这一点的亲代白血病，就像在正常的造血系统中一样，在白血病之间有一个细胞等级 细胞。我们的实验室先前已经证明L-IC是一个致力于胸腺细胞的祖细胞，并居住在 然而，在白血病DN3人群中，只有一小部分DN3细胞可以引起疾病。L-IC依赖于 NOTCH1诱导的MYC生存信号。最近的研究发现，在这两种疾病中都存在潜伏的、治疗耐药的L-IC 小鼠模型和T-ALL患者样本。细胞周期限制在L-IC潜伏期中的作用尚不完全 明白了。为了揭示控制L-IC功能的通路，我们进行了单细胞核糖核酸- 使用我们的转基因Tal1/Lmo2模型对T细胞白血病发生不同阶段的胸腺细胞进行测序。 这种方法发现了一个休眠的DN3簇，其标志是Ki67的低表达，这在其他 小鼠T-ALL样本。处于休眠状态的DN3细胞表现出Notch1的高表达，而Myc的低表达。转录本 这些细胞的特征表明，先前与白血病启动或白血病干细胞有关的基因丰富 细胞功能。休眠的DN3细胞表现出非规范的Wnt受体Ryk的丰富，据报道 通过限制增殖和促进静止来维持造血干细胞的自我更新。Ryk是 与健康胸腺相比，儿童T-ALL和TAL1/Lmo2诱导的小鼠T-ALL中高表达。 这表明RYK可能不局限于这个稀有的亚群，而且可能存在一个 RYK抑制复发性T-ALL的治疗窗。这一提议的中心假设是，休眠 DN3细胞是静止的L细胞，保持增殖和分化能力，这使得他们的治疗成为可能 在复发期间的耐受性和随后的扩张。这项提议将识别休眠的DN3的基因签名 通过评估这些细胞的L-IC功能，揭示这些细胞在T-ALL复发中的潜在作用 化疗耐药(目标1)。目标2将在T-ALL和UNCOVER中定义非规范的WNT/RYK信令网络 通过检测RYK抑制是否减少这些通路在休眠DN3细胞中的作用和L-IC的功能 小鼠和患者T-ALL细胞的L IC频率。总而言之，这些研究将为T- 这将为L-IC靶向治疗复发性疾病的发展奠定基础。

PROJECT SUMMARY/ABSTRACT Therapy resistance is a major barrier to long term remission in pediatric T-cell acute lymphoblastic leukemia (T- ALL). The prognosis for children with relapsed or refractory disease is dismal. Leukemia-initiating cells (L-ICs) regenerate disease upon transplantation into mice. They also recapitulate the immunophenotypic complexity of the parent leukemia supporting that, as in normal hematopoiesis, there is a cellular hierarchy among leukemic cells. Our laboratory has previously demonstrated that the L-IC is a committed thymocyte progenitor and resides in the leukemic DN3 population, however, only a fraction of DN3 cells can give rise to disease. L-ICs rely on NOTCH1-induced MYC signaling for survival. Recent studies identified dormant, therapy resistant L-ICs in both murine models and T-ALL patient samples. The role of cell cycle restriction in L-IC latency is incompletely understood. In an effort to uncover pathways that govern L-IC function, we performed single cell RNA- sequencing on thymocytes at varying stages of T-cell leukemogenesis using our transgenic Tal1/Lmo2 model. This approach identified a dormant DN3 cluster, marked by low Ki67 expression, which is observed in other murine T-ALL samples. Dormant DN3 cells exhibit high Notch1, but low Myc expression. The transcriptional signature of these cells shows enrichment of genes previously implicated in leukemia initiation or leukemia stem cell function. Dormant DN3 cells show enrichment of the non-canonical Wnt receptor Ryk, which is reported to maintain hematopoietic stem cell self-renewal by limiting proliferation and promoting quiescence. RYK is overexpressed in primary pediatric T-ALL and in Tal1/Lmo2-induced murine T-ALL compared to healthy thymus. This indicates that RYK may not be restricted to this rare subpopulation and moreover, there may be a therapeutic window for RYK inhibition in relapsed T-ALL. The central hypothesis of this proposal is that dormant DN3 cells are quiescent L-ICs that retain proliferative and differentiative capacity, which permits their therapy tolerance and subsequent expansion during relapse. This proposal will identify a gene signature of dormant DN3 cells and uncover the potential role of these cells in T-ALL relapse by evaluating their L-IC function and chemoresistance (Aim 1). Aim 2 will define the non-canonical WNT/RYK signaling network in T-ALL and uncover the role of these pathways in dormant DN3 cells and L-IC function by testing whether inhibition of RYK reduces the L-IC frequency of murine and patient T-ALL cells. Collectively, these studies will provide critical insight to T- ALL heterogeneity and will lay the foundation for development of L-IC targeted therapy for relapsed disease.