Role of Dok-1 in oncogenic tyrosine kinase signaling

描述（由申请方提供）：本研究的长期目的是确定Dok-1抑制p210 Bcr-Abl诱导的导致肿瘤转化的信号传导事件的分子机制。p210 Bcr-Abl是一种组成型活性酪氨酸激酶，是慢性髓细胞性白血病（CML）的病原体，CML是一种造血细胞疾病，每年发生率约为1/100，000人。酪氨酸激酶活性对p210 Bcr-Abl的转化能力至关重要，事实上，用特异性Abl激酶抑制剂（如甲磺酸伊马替尼）抑制p210 Bcr-Abl激酶可导致疾病缓解，使CML的治疗成为靶向癌症治疗的成功范例。然而，大多数接受这些药物的患者保留了残留的白血病细胞，有些患者由于Abl激酶结构域的突变而产生耐药性，最终导致CML复发。因此，需要开发新的治疗策略来治疗对Abl激酶抑制剂耐药的CML病例。在这种情况下，它是至关重要的，以阐明关键的信号通路和组件，温和的p210 Bcr-Abl驱动的白血病。我们已经发现Dok-1是CML患者慢性期祖细胞中被p210 Bcr-Abl组成性酪氨酸磷酸化的衔接蛋白，其抑制促有丝分裂信号并对抗p210 Bcr-Abl引发的致癌转化。Dok-1在小鼠中的失活加速了p210 Bcr-Abl诱导的CML样疾病的发病，而Dok-1的表达降低了表达p210 Bcr-Abl的细胞的增殖活性。这些发现提供了一个独特的框架，收购新的见解p210 Bcr-Abl介导的致癌信号的分子基础和机制，抵消it. This应用程序的目的是描绘的分子机制（S）Dok-1干扰p210 Bcr-Abl介导的信号和肿瘤发生。为了实现这些目标，第一个具体目标将定义Dok-1中的决定因素，这些决定因素对于其对p210 Bcr-Abl驱动的转化和白血病发生的抑制作用至关重要。具体目标2将描述和表征Dok-1作用于抑制p210 Bcr-Abl诱导的致癌转化的信号通路。分子、生物化学和细胞生物学方法以及小鼠模型将用于实现这些目标。第三个具体目标是通过使用生化纯化技术结合多维蛋白质鉴定技术来鉴定Dok-1相互作用蛋白，该蛋白在p210 Bcr-Abl介导的致癌信号传导中具有重要功能。从这些研究中获得的信息不仅将为Dok-1的功能和作用模式提供新的见解，而且还将有助于更好地理解p210 Bcr-Abl信号级联中驱动CML祖细胞异常扩增的关键下游事件。了解Dok-1如何抑制p210 Bcr-Abl致癌信号可能会导致改善控制CML和其他肿瘤性疾病的策略的概念。 公共卫生相关性：Dok-1衔接蛋白已成为致癌酪氨酸激酶（包括酪氨酸激酶融合蛋白p210 Bcr-Abl）驱动的肿瘤转化的关键调节因子，而p210 Bcr-Abl是慢性粒细胞白血病（CML）的致病事件。这些研究旨在了解Dok-1抑制p210 Bcr-Abl诱导的信号传导事件和致癌转化的分子机制，并可能为开发更有效的策略和药物来控制CML以及可能的其他肿瘤性疾病提供基础。

DESCRIPTION (provided by applicant): The long-term objective of this study is to define the molecular mechanisms by which Dok-1 inhibits p210Bcr-Abl-induced signaling events that lead to neoplastic transformation. p210Bcr-Abl, a constitutively active tyrosine kinase, is the causative agent of chronic myelogenous leukemia (CML), a disorder of hematopoietic cells that occurs with a frequency of about 1 in 100,000 people a year. It is well established that the tyrosine kinase activity is crucial to the transforming capacity of p210Bcr-Abl. Indeed, inhibition of the p210Bcr-Abl kinase with specific Abl kinase inhibitors, such as imatinib mesylate, leads to disease remission - making treatment of CML a successful paradigm of targeted cancer therapy. However, most patients receiving these drugs retain residual leukemic cells, and some develop drug resistance due to the acquisition of mutations in the Abl kinase domain, which eventually leads to relapse of CML. Therefore, new therapeutic strategies need to be developed to treat CML cases resistant to Abl kinase inhibitors. In this context, it is of utmost importance to elucidate the critical signaling pathways and components that moderate p210Bcr-Abl-driven leukemogenesis. We have found that Dok-1, an adaptor protein constitutively tyrosine phosphorylated by p210Bcr-Abl in chronic phase progenitor cells of CML patients, inhibits mitogenic signaling and opposes oncogenic transformation triggered by p210Bcr- Abl. Inactivation of Dok-1 in mice accelerates the onset of the CML-like disease induced by p210Bcr-Abl, whereas expression of Dok-1 diminishes the proliferative activity of p210Bcr-Abl expressing cells. These findings provide a unique framework for the acquisition of novel insights into the molecular underpinnings of p210Bcr-Abl- mediated oncogenic signaling and mechanisms that counteract it. This application aims to delineate the molecular mechanism(s) by which Dok-1 interferes with p210Bcr-Abl-mediated signaling and oncogenesis. Towards these goals, the first specific aim will define the determinants in Dok-1 that are critical for its inhibitory effect on p210Bcr-Abl-driven transformation and leukemogenesis. Specific aim 2 will delineate and characterize signaling pathways Dok-1 acts upon to inhibit p210Bcr-Abl-induced oncogenic transformation. Molecular, biochemical, and cell biological approaches, as well as mouse models, will be used to achieve these objectives. The third specific aim will identify Dok-1 interacting proteins important for its function in p210Bcr-Abl- mediated oncogenic signaling, by using biochemical purification techniques combined with Multidimensional Protein Identification Technology. Information gained from these studies will not only provide novel insights into Dok-1's function and mode of action, but will also contribute to a better understanding of the critical downstream events in the p210Bcr-Abl signaling cascades that drive aberrant expansion of CML progenitor cells. Understanding how Dok-1 inhibits p210Bcr-Abl oncogenic signaling could lead to the conception of improved strategies to control CML and possibly other neoplastic diseases as well. PUBLIC HEALTH RELEVANCE: The Dok-1 adaptor protein has emerged as a critical regulator of neoplastic transformation driven by oncogenic tyrosine kinases, including the tyrosine kinase fusion protein p210Bcr-Abl, which is the causative event of chronic myelogenous leukemia (CML). The proposed studies are aimed at understanding the molecular mechanisms by which Dok-1 inhibits p210Bcr-Abl- induced signaling events and oncogenic transformation, and may provide the basis for developing more effective strategies and drugs to control CML and possibly other neoplastic diseases as well.