The Function of CDK5 in Metastasis

本申请集中于细胞周期蛋白依赖性激酶5（CDK 5）。本提案的总体目标是 测试抑制CDK 5激酶是否可能代表治疗 转移性黑素瘤在我们的研究中，我们将利用人类癌细胞系以及小鼠癌症模型。 我们的工作可能会为癌症患者带来一种以CDK 5抑制为中心的新治疗方法。尽管 CDK 5不受细胞周期蛋白调控。CDK 5在其单体形式下是无活性的，并且其激酶活性是 由与称为p35和p39的非细胞周期蛋白相互作用触发。在正常发育过程中，CDK 5-p35 而CDK 5-p39激酶在神经系统中具有活性。CDK 5-p35/p39激酶被证明可以调节一个细胞周期。 广泛的神经元功能，包括终末分化，突触形成和可塑性，轴突 引导，轴突生长，膜运输和神经元迁移，通过磷酸化的各种 神经元基质越来越多的证据表明CDK 5在肿瘤发生中起重要作用。几 研究证明，人癌细胞表达CDK 5和p35/p39，并含有催化活性的 CDK 5-p35/p39复合物。CDK 5在肿瘤中的高表达显示出总体预后不良。 CDK 5在肿瘤细胞中的确切分子功能尚未完全了解。据推测，CDK 5 影响细胞增殖，或调节肿瘤细胞迁移或存活，不同的研究将其归因于激活 或抑制CDK 5在这些过程中的作用。在我们的研究中，我们决定把重点放在黑色素瘤上， 型表达特别高的CDK 5水平。我们获得的初步证据表明，CDK 5发挥了重要作用， 在肿瘤细胞侵袭和转移中的作用。我们获得了关于分子作用的初步结果 CDK 5在肿瘤细胞转移扩散中的作用。我们还开发了一种新的小鼠品系， 我们在体内关闭CDK 5活性。在本申请中提出的工作中，我们将扩展这些发现。在 具体目标1，我们将利用我们的小鼠品系，其允许CDK 5的急性关闭，沿着良好的- 建立小鼠黑色素瘤模型，进一步研究CDK 5在黑色素瘤体内转移中的作用。在 目标2，我们将跟进我们的初步结果，我们将确定确切的分子功能发挥 CDK 5在黑色素瘤转移中的作用。最后，在目标3中，我们将进行临床前研究， 是否抑制CDK 5激酶将阻断人黑色素瘤的转移扩散，使用大的 人患者来源的异种移植物（PDX）的收集。该提案的预期总体影响是， 将阐明CDK 5在黑素瘤细胞中的分子功能，并将导致新的靶向治疗 以CDK 5抑制为中心的策略。

This application focuses on the cyclin-dependent kinase 5 (CDK5). The overarching goal of this proposal is to test whether inhibition of CDK5 kinase might represent an effective therapeutic strategy in treatment of metastatic melanomas. In our study, we will utilize human cancer cell lines as well as mouse cancer models. Our work may lead to a novel therapeutic approach for cancer patients centered on CDK5 inhibition. Despite its name, CDK5 is not regulated by cyclins. CDK5 is inactive in its monomeric form, and its kinase activity is triggered by interaction with non-cyclin proteins termed p35 and p39. During normal development, CDK5-p35 and CDK5-p39 kinases are active in the nervous system. CDK5-p35/p39 kinases were shown to regulate a wide range of neuronal functions, including terminal differentiation, synapse formation and plasticity, axon guidance, neurite outgrowth, membrane transport and neuronal migration, through phosphorylation of various neuronal substrates. Growing evidence indicates that CDK5 plays an important role in tumorigenesis. Several studies documented that human cancer cells express CDK5 and p35/p39, and contain catalytically active CDK5-p35/p39 complexes. High expression of CDK5 in tumors was shown to confer overall poor prognosis. The exact molecular function of CDK5 in tumor cells is not fully understood. It has been postulated that CDK5 affects cell proliferation, or regulates tumor cell migration, or survival, with different studies ascribing activating or inhibitory roles for CDK5 in these processes. In our study, we decided to focus on melanoma, as this tumor type expressed particularly high CDK5 levels. We obtained preliminary evidence that CDK5 plays an important role in tumor cell invasiveness and metastasis. We obtained preliminary results about the molecular role played by CDK5 in the metastatic spread of tumor cells. We also developed a novel mouse strain that allows us to switch off CDK5 activity in vivo. In the work proposed in this application, we will extend these findings. In Specific Aim 1, we will utilize our strain of mice that allows an acute shutdown of CDK5, along with a well- established mouse model of melanoma, to further study the role of CDK5 in melanoma metastasis in vivo. In Aim 2, we will follow up on our preliminary results, and we will determine the exact molecular function played by CDK5 in melanoma metastasis. Lastly, in a translational Aim 3, we will perform a pre-clinical study to test whether inhibition of CDK5 kinase would block the metastatic spread of human melanomas, using a large collection of human patient-derived xenografts (PDX). The expected overall impact of this proposal is that it will elucidate the molecular function of CDK5 in melanoma cells, and will lead to novel targeted therapeutic strategies centered on CDK5 inhibition.