Actin dynamics as a therapeutic target for Bcr-Abl-positive acute lymphoblastic leukemia.

描述(由申请人提供)：肌动蛋白细胞骨架重构的解除调控是导致白血病细胞异常生长和迁移的关键事件。尽管已经确定了许多肌动蛋白细胞骨架重塑的调节分子，但了解这些分子如何协调调节白血病细胞中动态的肌动蛋白细胞骨架重塑仍然是一个重大挑战。这项建议的长期目标是了解肌动蛋白细胞骨架重塑的解除调控如何有助于白血病的发生。拟议的研究重点是肌动蛋白重塑的中央调节因子，波调节复合体(WRC)。活跃的Abl酪氨酸激酶对WRC信号的正向调节已被很好地记录下来。然而，目前尚不清楚该通路在激活后如何失活以实现肌动蛋白的动力学并与细胞周期进程相协调。我们推测，细胞周期蛋白依赖性激酶1(CDK1)介导的磷酸化，随后与NIMA-1相互作用的蛋白(Pin1)的募集，促进了WRC在有丝分裂开始时的酪氨酸去磷酸化和失活。这使得肌动蛋白组装与细胞周期进程相协调。我们认为，这种失活机制与致癌基因bcr-Abl介导的激活机制一起，在调控bcr-Abl阳性白血病细胞的增殖和侵袭中起着重要作用。因此，靶向该通路可能对伊马替尼耐药的bcr-Abl阳性白血病具有治疗潜力。在特定的目标1中，我们将确定Pin1在bcr-Abl阳性白血病细胞肌动蛋白动力学调节中的作用。一个bcr-Abl阳性的小鼠前-B白血病细胞模型，其中WRC被结构性激活，将被用来确定CDK1/Pin1如何去激活WRC介导的肌动蛋白组装。特异性目标2将测试靶向CKD1和Pin1作为治疗bcr-Abl阳性白血病的治疗策略的潜力。建议结合药理学和遗传学的方法来确定抑制CDK1和Pin1在体外和动物模型中对bcr-Abl阳性白血病细胞的生长、迁移和侵袭的影响。这些研究将深入了解白血病细胞中肌动蛋白动力学的调控机制，并确定CDK1/Pin1通路在bcr-Abl诱导的白血病发生中的作用。除了从根本上推进细胞生物学领域的发展外，这项研究有望为人类白血病的治疗提供新的诊断和治疗靶点。

DESCRIPTION (provided by applicant): Deregulation of actin cytoskeleton remodeling is a key event contributes to abnormal growth and migration of leukemic cells. Although numerous regulatory molecules for actin cytoskeleton remodeling have been identified, understanding how these molecules orchestrates to regulate dynamic actin cytoskeleton remodeling in leukemic cells still remains a major challenge. The long-term goal of this proposal is to understand how deregulation of actin cytoskeleton remodeling contributes to leukemia development. The proposed research focuses on a central regulator of actin remodeling, WAVE regulatory complex (WRC). A positive regulation of the WRC signaling by active Abl tyrosine kinases has been well documented. It is not clear, however, how this pathway is deactivated following its activation to achieve actin dynamics and to coordinate with cell cycle progression. We hypothesize that the cyclin dependent kinase 1 (CDK1)-mediated phosphorylation followed by recruitment of the protein interacting with NIMA-1 (Pin1) promotes the tyrosine dephosphorylation and inactivation of WRC at the onset of mitosis. This allows coordination of actin assembly with cell cycle progression. We propose that this deactivation mechanism, together with the activation mechanism mediated by oncogenic Bcr- Abl, plays an important role in regulating Bcr-Abl-positve leukemic cell proliferation and invasion. Therefore, targeting this pathway may have therapeutic potential for imatinib-resistant Bcr-Abl- positive leukemia. In specific aim 1, we will define the role of Pin1 in the regulation of actin dynamics in Bcr-Abl-positive leukemic cells. A Bcr-Abl-positive murine pro-B leukemic cell model, in which WRC is constitutively activated, will be used to determine how CDK1/Pin1 deactivates WRC-mediated actin assembly. Specific aim 2 will test the potential of targeting CKD1 and Pin1 as a therapeutic strategy for treatment of Bcr-Abl-positive leukemia. A combination of pharmacological and genetic approaches is proposed to determine the effect of the inhibition of CDK1 and Pin1 on Bcr-Abl-positive leukemic cell growth, migration, and invasion both in vitro and in animal models. These studies will provide insight into the mechanism by which actin dynamics is regulated in leukemic cells and define the role of the CDK1/Pin1 pathway in Bcr-Abl-induced leukemogenesis. The research is expected to provide new diagnostic and therapeutic targets for treatment of human leukemia in addition to fundamentally advancing the fields of cell biology.