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

标题：p21激活的激酶作为1型神经纤维瘤病的新治疗靶点。 项目总结： 神经纤维瘤病1型(NF1)是一种由生殖系引起的相对常见的遗传性疾病综合征 NF1基因突变。大约三分之一的NF1患者发展为弥漫性丛状神经纤维瘤 这可能会转化为恶性周围神经鞘瘤--一种经常致命的癌症。 值得注意的是，在人类肿瘤和NF1小鼠模型中，神经纤维瘤几乎总是含有 NF1缺失的雪旺细胞和NF1杂合子的肥大细胞。将这种有NF1倾向的小鼠移植到野生- 类型的骨髓防止肿瘤的发生，这意味着骨髓来源的细胞，如肥大细胞 是致病过程中的必需成分，并且以雪旺细胞或雪旺细胞中的信号通路为靶点 或者肥大细胞可能对治疗有好处。NF1基因编码一个带有GTP酶的大蛋白 激活蛋白(GAP)对RAS的活性。NF1基因的完全或半合子丢失导致 雪旺细胞和肥大细胞中RAS活性增加，并伴随下游激活 促进细胞增殖、改变细胞形状和运动的效应器。最近，我们展示了 P21激活的激酶在激活ERK介导的增殖和p38- NF1基因缺陷的肥大细胞中RAS下游介导的运动通路。我们假设帕克的损失 功能还会减少NF1缺陷的雪旺细胞中关键的RAS效应通路的激活，以及 因此，NF1患者可能会受益。我们提出了三个目标：1)我们将确定关键的底物 A组肥大细胞中影响细胞运动的PAK；2)使用药物和遗传手段使 在来自NF1缺陷小鼠的雪旺细胞中，我们将确定PAK功能的丧失是否逆转 MAPK的激活和体外细胞骨架的改变；以及3)我们将与Krox20-cre/Nf1flx/-小鼠杂交， 患上恶性周围神经鞘瘤的小鼠，或移植此类肿瘤的小鼠 NF1小鼠，用Pak1-/-骨髓细胞，以确定Pak1基因的丢失，是整体还是在骨髓中 细胞，影响疾病的进展。拟议的研究不仅将增加我们对 红衣主教癌症相关的信号通路，但可以建立PAK作为合适的靶点 对这种无法治愈的疾病的治疗干预。

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.