The Role of p21-Activated Kinases in Malignant Mesothelioma

描述（由申请人提供）：恶性间皮瘤（Malignant Mesothelioma， MM）是一种相对常见、进展迅速且治疗耐药的恶性肿瘤，与接触石棉有关。MM的人类患者和小鼠模型均表现出II型神经纤维瘤病（NF2）基因的频繁缺失，NF2 -/- MM细胞中NF2 cDNA的重新表达减缓了它们的增殖并抑制了它们的运动，这表明NF2在MM中起着因果作用。NF2基因的蛋白产物Merlin结合并抑制p21活化蛋白激酶（Paks），这些酶积极调节细胞周期进展、存活和运动。我们实验室最近的证据强烈表明，Pak是缺乏NF2基因的细胞转化所必需的。我们假设Pak功能的丧失也会导致nf2缺陷MM细胞中关键Merlin效应通路的激活减少，从而使MM患者受益。我们提出了两个目标：1)通过药理学和遗传学手段使Pak功能失效，我们将在MM细胞中建立受Pak影响的信号通路，并确定这些细胞中Paks影响细胞存活的关键底物；2)穿过Nf2f/f；Ink4a/Arff/f小鼠在胸膜内注射Adeno-Cre后发生MM，转基因小鼠有条件地表达特定的Pak抑制剂。该实验将使我们能够确定Pak功能的丧失是否会影响MM的发生和/或进展，并建立介导这种影响的体内信号通路。这些建议的研究不仅将增加我们对主要信号通路的理解，而且可以确定Paks作为治疗干预这种其他无法治疗的疾病的合适靶点。

DESCRIPTION (provided by applicant): Malignant Mesothelioma (MM) is a relatively common, rapidly progressive and treatment-resistant malignancy that is associated with exposure to asbestos. Both human patients and mouse models of MM show frequent loss of the neurofibromatosis type II (NF2) gene, and re-expression of NF2 cDNA in Nf2-/- MM cells slows their proliferation and restrains their motility, implying that NF2 plays a causal role in MM. The protein product of the NF2 gene, Merlin, binds to and inhibits p21-activated protein kinases (Paks), enzymes that positively regulate cell cycle progression, survival, and motility. Recent evidence from our laboratories strongly suggests that Pak is required for transformation in cells lacking the NF2 gene. We postulate that loss of Pak function will lead to diminished activation of key Merlin effector pathways in NF2-deficient MM cells as well, and thus could benefit patients with MM. We propose two aims: 1) Using pharmacologic and genetic means to disable Pak function, we will establish the signaling pathways affected by Pak in MM cells, and also identify the key substrates of Paks in these cells that affect cell survival; 2) We will cross Nf2f/f; Ink4a/Arff/f mice, which develop MM upon intrapleural injection of Adeno-Cre, with a transgenic mouse that conditionally expresses a specific Pak inhibitor. This experiment will allow us to determine if loss of Pak function affects MM incidence and/or progression, as well as establish the in vivo signaling pathways that mediate this effect. The proposed studies will not only increase our understanding of cardinal signaling pathways, but could establish Paks as suitable targets for therapeutic intervention in this otherwise untreatable disease.