p21-Activated Kinases as New Therapeutic Targets in Neurofibromatosis Type 1

p21激活激酶作为1型神经纤维瘤病的新治疗靶点。 项目摘要： 1型神经纤维瘤病（NF 1）是一种较为常见的遗传性疾病综合征， NF 1基因突变。大约三分之一的NF 1患者发展为弥漫性丛状神经纤维瘤 它可以转化为恶性外周神经鞘瘤--一种经常致命的癌症。 值得注意的是，在人类肿瘤和NF 1小鼠模型中，神经纤维瘤几乎总是含有 Nf 1缺失的雪旺细胞和Nf 1杂合肥大细胞。将这种NF 1易感小鼠移植到野生型 型骨髓可防止肿瘤发生，这意味着骨髓来源的细胞如肥大细胞 是发病机制中必需的组成部分，并且靶向雪旺细胞中的信号通路 或肥大细胞可能有治疗效果。NF 1基因编码一个大的蛋白质， 活化蛋白（GAP）对Ras的活性。NF 1基因的完全或半合子缺失导致 在雪旺细胞和肥大细胞中Ras活性增加，伴随着下游 促进细胞增殖和改变细胞形状和运动的效应物。最近，我们发现 p21激活的激酶在激活ERK介导的增殖和p38- 在Nf 1缺陷型肥大细胞中Ras下游介导的运动途径。我们假设失去帕克 功能也会减少Nf 1缺陷型雪旺细胞中关键Ras效应通路的激活， 因此可以使NF 1患者受益。我们提出了三个目标：1）我们将确定的关键基板 A组肥大细胞中的Paks影响细胞运动; 2）使用药理学和遗传学手段使 Paks的雪旺细胞来源于Nf 1缺陷小鼠，我们将确定Pak功能的丧失是否逆转 MAPK的激活和细胞骨架的体外改变; 3）我们将Krox 20-cre/Nf 1flox/-小鼠杂交， 其发展为恶性外周神经鞘瘤，用Pak 1敲除小鼠，或移植这种 用Pak 1-/-骨髓细胞的NF 1小鼠，以确定Pak 1的丢失是否是整体或骨髓来源的 细胞，影响疾病进展。建议的研究不仅会增加我们对 主要的癌症相关的信号通路，但可以建立Paks作为合适的目标， 对这种无法治愈的疾病进行治疗干预。

Title: p21-activated kinases as new therapeutic targets in neurofibromatosis type 1. Project Summary: Neurofibromatosis type 1 (NF1) is a relatively common inherited disease syndrome caused by germline mutations in the NF1 gene. About one third of NF1 patients develop diffuse, plexiform neurofibromas that can transform to a malignant peripheral nerve sheath tumor - a cancer that is frequently fatal. Remarkably, in human tumors and in mouse models of NF1, neurofibromas almost invariably contain Nf1-null Schwann cells and Nf1 heterozygous mast cells. Transplanting such NF1-prone mice with wild- type bone marrow prevents tumorigenesis, implying that bone marrow derived cells such as mast cells are a required component in pathogenesis, and that targeting signaling pathways in either Schwann cells or mast cells might be of therapeutic benefit. The NF1 gene encodes a large protein with GTPase Activating Protein (GAP) activity towards Ras. Complete or hemizygous loss of the NF1 gene leads to increased Ras activity in both Schwann cells and mast cells, with concomitant activation of downstream effectors that promote proliferation and changes in cell shape and movement. Recently, we have shown that p21-activated kinases play an important role in activating an Erk-mediated proliferation and a p38- mediated motility pathway downstream of Ras in Nf1-deficient mast cells. We postulate that loss of Pak function will diminish activation of key Ras effector pathways in Nf1-deficient Schwann cells as well, and thus could benefit patients with NF1. We propose three aims: 1) We will identify the key substrates of group A Paks in mast cells that affect cell motility; 2) Using pharmacologic and genetic means to disable Paks in Schwann cells derived from Nf1-deficient mice, we will determine if loss of Pak function reverses the activation of MAPK and cytoskeletal alterations in vitro; and 3) We will cross Krox20-cre/Nf1flox/- mice, which develop malignant peripheral nerve sheath tumors, with Pak1 knock out mice, or transplant such NF1 mice with Pak1-/- bone marrow cells, to determine if loss of Pak1, globally or in bone marrow derived cells, affects disease progression. The proposed studies will not only increase our understanding of cardinal cancer-relevant signaling pathways, but could establish the Paks as suitable targets for therapeutic intervention in this otherwise untreatable disease.