Targeting the Microenvironment/Oncogene Cooperation to treat poor prognosis T-ALL

背景资料。尽管最近的治疗取得了显著的成功，急性淋巴母细胞性白血病(ALL)仍然 儿童死亡的第二大原因。治疗的进步和差之间的不协调 结果部分是由挽救复发疾病的困难造成的。虽然结果在 从新治疗开始，在复发的ALL亚型中观察到总体存活率很低(低于25%)。 治疗复发或难治性T-ALL的临床设备必须有新的选择。 战略。虽然大多数T-ALL病例表现出Notch信号的功能增益突变，但针对 Noch并没有实现他们的临床承诺。为了寻找新疗法的替代靶点，我们建议 定义细胞内在致癌事件如何与来自微环境的外部信号相结合。近期 研究指出“间质”信号在白血病生物学中的功能影响。然而，一个显著的差距是 这个知识库就是微环境因素如何成为白血病发生和维持所必需的。 初步结果。根据我们在原代T-ALL细胞中的结果，激活Notch突变未能 饱和Notch信号：当T-All细胞遇到Notch配体时，Notch信号强度增加 微环境--如白介素7(IL-7)。Notch信号强度的增加与 通过直接转录激活IL-7Rα启动子表面表达IL-7Rα，导致T-ALL高表达。 对IL-7的反应性。IL-7还诱导了细胞周期调节因子Skp2，激活了STAT5，并(令人惊讶地) 统计数据3.原代T-ALL细胞显示持续的STAT3激活，我们的结果表明STAT3缺失会损害 T-ALL白血病发生。假设。这些数据支持致癌因素和 微环境。根据我们的假设，微环境信号(IL-7)、Notch 信号、Skp2和STAT3形成了一个相互作用的正反馈环，对T细胞白血病的发生是必不可少的； 这一轴也补偿了标准疗法在复发和难治性疾病中的作用。 接近。为了测试这一点，我们建议：1)确定启动中STAT3缺失的时间要求， 在T-ALL中使用STAT3基因可诱导缺失和联合应用的模型 Notch诱导的T-ALL模型。2)绘制Notch/IL-7/STAT3/Skp2对T-ALL发育的影响 通过使用过度表达和基因沉默方法来定义信号通路的相互调节 Noch、STAT3和Skp2。3)确定抑制Notch/STAT/Skp2电路对复发T-ALL的影响 通过在临床前PDX中测试STAT信号和Skp2抑制剂的临床前和临床前抑制剂 T-ALL的模特。冲击力。这项拟议工作的成功完成将：1)确定 致癌信号和微环境影响复发和难治性T-ALL的治疗；2)建立一个 为验证复发和难治性T-ALL的新分子靶点奠定基础；3)提供原理证明 另一种策略是在治疗方法的开发过程中考虑整个分子回路。

Background. Despite the significant success of recent therapies, Acute Lymphoblastic Leukemia (ALL) remains the second leading cause of childhood death. The discordance between therapeutic improvements and poor outcomes is partially caused by the difficulty of salvaging relapsed disease. While outcomes have improved in de novo treatment, dismal rates of overall survival (less than 25%) were observed in relapsed subtypes of ALL. The clinical armamentarium for treating relapsed or refractory T-ALL must be supported with new options. Strategy. While most of T-ALL cases exhibit gain-of-function mutations in Notch signaling, therapies against Notch have not fulfilled their clinical promise. To identify alternative targets for new therapies, we propose to define how cell-intrinsic oncogenic events integrate with external signals from the microenvironment. Recent studies point to the functional impact of “stromal” signals in leukemia biology. However, one significant gap in this knowledgebase is how microenvironmental factors become essential for leukemogenesis and maintenance. Preliminary results. According to our results in primary T-ALL cells, activating mutations in Notch failed to saturate Notch signaling: Notch signal strength increased when T-ALL cells encounter Notch ligands within the microenvironment – e.g. interleukin 7 (IL-7). The increased strength of Notch signaling correlated with increased surface expression of IL-7Rα by direct transcriptional activation of the IL-7Rα promoter, resulting in T-ALL hyper- responsiveness to IL-7. IL-7 also induced the cell cycle regulator SKP2, activated STAT5, and (surprisingly) STAT3. Primary T-ALL cells showed persistent STAT3 activation and our results suggest STAT3 deletion impairs T-ALL leukemogenesis. Hypothesis. These data support significant interplay between oncogenic factors and the microenvironment. According to our hypothesis, interplay between microenvironmental signals (IL-7), Notch signaling, SKP2, and STAT3 form a reciprocal positive feedback loop that is essential for T-cell leukemogenesis; this axis also compensates for the action of standard therapies in relapsed and refractory disease. Approach. To test this, we propose: 1) To determine the temporal requirement for STAT3 deletion in initiation, progression, and relapse in T-ALL by using a model of inducible genetic deletion of STAT3 in combination with a model of Notch-induced T-ALL. 2) To map how T-ALL development is affected by Notch/IL-7/STAT3/SKP2 signaling circuitry by using overexpression and gene silencing approaches to define the reciprocal regulation of Notch, STAT3, and SKP2. 3) To identify the impact of inhibiting Notch/STAT/SKP2 circuitry in relapsed T-ALL by testing both pre-clinical and clinical inhibitors of STAT signaling and SKP2 inhibitors in pre-clinical PDX models of T-ALL. Impact. Successful completion of this proposed work will: 1) define how cooperation between oncogenic signaling and the microenvironment affects therapy of relapsed and refractory T-ALL; 2) build a foundation for validating new molecular targets in relapsed and refractory T-ALL; 3) provide a proof-of-principle for an alternative strategy in which entire molecular circuits are considered during the development of therapies.