The Role of p21-Activated Kinases in Malignant Mesothelioma

描述（由申请方提供）：恶性间皮瘤（MM）是一种相对常见的、进展迅速的、耐药的恶性肿瘤，与石棉暴露有关。MM的人类患者和小鼠模型都显示出II型神经纤维瘤病（NF 2）基因的频繁丢失，并且NF 2-/- MM细胞中NF 2 cDNA的再表达减缓了它们的增殖并抑制了它们的运动性，这意味着NF 2在MM中起因果作用。NF 2基因的蛋白产物Merlin结合并抑制p21活化蛋白激酶（Paks），积极调节细胞周期进程、存活和运动的酶。我们实验室最近的证据强烈表明，Pak是缺乏NF 2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NF 2缺陷的MM细胞中关键的Merlin效应子通路的激活减弱，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功能失活，我们将在MM细胞中建立Pak影响的信号通路，并确定Pak在这些细胞中影响细胞存活的关键底物; 2）我们将Nf 2f/f; Ink 4a/Arff/f小鼠与条件性表达特异性Pak抑制剂的转基因小鼠杂交，所述小鼠在胸膜内注射Adeno-Cre后发展MM。该实验将使我们能够确定Pak功能的丧失是否影响MM发病率和/或进展，以及建立介导该效应的体内信号传导途径。拟议的研究不仅将增加我们对主要信号通路的理解，而且可以将Paks作为这种无法治愈的疾病的治疗干预的合适靶点。 公共卫生相关性：由于目前没有有效的药物治疗MM，一种与石棉暴露和NF 2基因丢失相关的致命疾病，了解NF 2在细胞增殖，存活，运动和侵袭中的功能是识别可能在这种疾病中提供有用药物靶点的信号通路的关键策略。NF 2蛋白产物Merlin与p21激活激酶（Paks）相互作用并抑制Paks;当Merlin不表达时，Paks变得高度活跃。由于活化的Paks本身是致癌的，并且与Merlin不同，它们易于被小分子抑制，因此我们处于独特的位置来探索Paks在MM中的生物学作用，并确定这些酶是否代表合适的治疗靶点。

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. PUBLIC HEALTH RELEVANCE: As there is currently no effective medical therapy for MM, a deadly disease associated with asbestos exposure and loss of the NF2 gene, understanding how NF2 functions in cell proliferation, survival, motility, and invasion is a key strategy to identify signaling pathways that might provide useful drug targets in this disease. The NF2 protein product, Merlin, interacts with and inhibits p21-activated kinases (Paks); when Merlin is not expressed, Paks become highly active. Because activated Paks are themselves oncogenic, and, unlike Merlin, are amenable to inhibition by small molecules, we are in a unique position to explore the biological role of Paks in MM and to determine if these enzymes represent suitable targets for therapy.