Oncogenic pathways and therapeutic targets in T cell acute lymphoblastic leukemia

摘要 T细胞急性淋巴细胞白血病(T-ALL)是一种侵袭性的胸腺细胞恶性肿瘤，影响数千人 美国每年儿童和成人的数量。尽管初发T-T患者的预后有所改善 总之，治愈率的提高在很大程度上要归因于高毒性的化疗，包括短期和长期化疗。 长期不良影响。此外，化疗对复发的T-ALL往往无效，它具有令人沮丧的 儿童和成人的5年生存率分别为30%和10%。因此，确定新的可操作的药物靶点 在T-ALL是一项重大的研究和临床势在必行。这项工作的总体目标是定义 蛋白酪氨酸磷酸酶，PRL-3，与T-ALL生长和自我更新有关。PrL3是通过基因扩增的 MYC癌蛋白在12%的人类T-ALL中高表达，在45%的原发T-ALL中高表达。中环 假设致癌基因PRL3通过增加复发驱动白血病的自我更新来促进T-ALL的生长 抑制细胞增殖(LPCS)和抑制细胞凋亡，其阻断可杀死T-ALL细胞。其基本原理是 建议的研究是，通过了解PRL3如何促进T-ALL的生长和进展，药物 靶向这种磷酸酶或其直接下游靶点可被开发用于治疗T-ALL。 目标1将确定PRL3调节T-ALL生长、维持和自我更新的细胞功能。 在这些研究中，一种创新的斑马鱼转基因模型MYC诱导的T-ALL将被用于评估 PRL3在改变T-ALL启动、异质性、自我更新和凋亡中的作用这项工作将得到延长 对于人类患者来源的异种移植模型，建立PRL3作为人类T-ALL的真正药物靶点。这个 目标1背后的工作假说是PRL3促进LPC自我更新并抑制细胞凋亡。它是 还预计PRL3将是白血病在体内持续生长所必需的。《目标2》将揭开 PRL3调控人T-ALL生长的分子机制(S)。我们将用一本小说 磷酸蛋白质组学方法、CRISPR/Cas9筛选和磷酸酶底物TRAP法鉴定 调节诱导细胞凋亡的过程的候选底物。详细的分子分析将确定 PRL3底物改变人T-ALL活性和生长的确切机制。在工作中 对目标2的假设是，PRL3的直接底物抑制了人T细胞的下游凋亡通路。 全。这项工作的成功完成将1)确定PRL3下游的可操作药物靶点 2)发现PRL3的下游底物，可能提供新的生物标志物 用于评估对T-ALL的药物效应和治疗T-ALL的额外药物靶点。我们的工作是 意义重大，并可能产生积极的翻译影响，因为它提供了对 PRL3如何在T-ALL中发挥作用，并将这种磷酸酶确立为T-ALL真正的治疗靶点。这个 PRL3在多种癌症中的癌基因状态表明，我们的研究将有积极的翻译 对PRL3癌基因表达上瘾的T-ALL以外的肿瘤的影响。

ABSTRACT T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of thymocytes that affects thousands of children and adults annually in the United States. Despite improved outcomes for patients with primary T- ALL, the elevated cure rates are largely attributable to highly toxic chemotherapy with both short- and long- term adverse effects. Moreover, chemotherapy is often ineffective against relapsed T-ALL, which has a dismal 5-year survival rate of 30% in children and <10% in adults. Thus, identification of new actionable drug targets in T-ALL is a major research and clinical imperative. The overall objective of this work is to define the role of a protein tyrosine phosphatase, PRL-3, in T-ALL growth and self-renewal. PRL3 is genomically amplified with the MYC oncoprotein in 12% of human T-ALL and is highly expressed in 45% of primary T-ALL. The central hypothesis is that oncogenic PRL3 drives T-ALL growth by increasing self-renewal of relapse-driving leukemia propagating cells (LPCs) and suppressing apoptosis, and that its blockade kills T-ALL cells. The rationale for the proposed research is that by understanding how PRL3 promotes T-ALL growth and progression, drugs targeting this phosphatase or its immediate downstream targets could be developed for the treatment of T-ALL. Aim 1 will identify the cellular function by which PRL3 modulates T-ALL growth, maintenance and self-renewal. For these studies, an innovative zebrafish transgenic model of MYC-induced T-ALL will be used to assess a role for PRL3 in altering T-ALL initiation, heterogeneity, self-renewal and apoptosis. This work will be extended to human patient-derived xenograft models, establishing PRL3 as a bona fide drug target in human T-ALL. The working hypothesis underlying Aim 1 is that PRL3 enhances LPC self-renewal and suppresses apoptosis. It is also expected that PRL3 will be required for continued leukemia growth in vivo. Aim 2 will uncover the molecular mechanism(s) by which PRL3 regulates the growth of human T-ALL. We will use a novel phosphoproteomic approach, a CRISPR/Cas9 screen and phosphatase substrate trap assay to identify candidate substrates that regulate processes that induce apoptosis. Detailed molecular analysis will identify the precise mechanism by which PRL3 substrates alter the viability and growth of human T-ALL. The working hypothesis for Aim 2 is that direct substrates of PRL3 suppress downstream apoptotic pathways in human T- ALL. Successful completion of this work will 1) identify actionable drug targets downstream of the PRL3 pathway in human T-ALL, and 2) discover the downstream substrates of PRL3, likely providing new biomarkers for assessing drug effects on T-ALL and additional drug targets for the treatment of T-ALL. Our work is significant and will likely have a positive translational impact because it provides novel mechanistic insights into how PRL3 functions in T-ALL and establishes this phosphatase as a bona fide therapeutic target in T-ALL. The oncogene status of PRL3 in a wide range of cancers suggests that our studies will have a positive translational impact on tumors other than T-ALL that are addicted to PRL3 oncogene expression.