Urokinase-type plasminogen activator (uPA) in pathogenesis of lymphangioleiomyomatosis (LAM)

摘要 淋巴管肌瘤病(LAM)是一种进行性肺部肿瘤性疾病，与 结节性硬化症复合体1/2基因失活与mTOR上调 发信号。LAM的特点是增生性肺结节破坏周围 实质和异常淋巴管生成导致乳糜性积液。LAM皮损表达 高水平的尿激酶型纤溶酶原激活物(UPA)，这是一种与增殖有关的酶 和癌症扩散，但不是其主要抑制物(PAI-1)。我们证明了基因 TSC2消融直接导致uPA表达上调，而不是PAI-1表达上调。UPA的删除会减弱 抑制TSC2缺失型肺癌的生长并抑制体内异常淋巴管的生成。 令人惊讶的是，目前用于治疗LAM的雷帕霉素对mTORC1的抑制作用进一步增强- 在TSC2中调节uPA并显著上调其受体(UPAR)，但不上调PAI-1。 受损的细胞，与其未能根除疾病的情况一致。在本提案中，我们将 探讨TSC缺失导致uPA表达上调的机制 尿激酶型纤溶酶原激活剂上调对LAM细胞增殖的影响 淋巴管在体外和体内的发育。在目标1中，我们将勾画出 TSC的缺失诱导uPA，并研究mTORC1的抑制如何放大这一过程。在目标2中， 我们将研究TSC2缺失的LAM细胞分泌的uPA和VEGF-D如何促进uPA LAM肺过度表达与随后的生长、迁移、淋巴管生成和生长 损伤。我们将描述特定的uPA结构域对组织的调节作用 蛋白分解、细胞内信号转导和核转位/基因转录。在《目标3》中，威尔 确定阻断uPA上调是否与抑制mTORC1协同作用 控制小鼠LAM模型中TSC2缺失肿瘤的生长和异常淋巴管生成。 这一研究结果将为LAM的发病机制提供新的见解，促进我们的 了解uPA促进肿瘤形成的机制，并可能确定一种 诊断和治疗LAM的新生物标志物和辅助治疗靶点。

SUMMARY Lymphangioleiomyomatosis (LAM) is a progressive neoplastic lung disease associated with inactivation of tuberous sclerosis complex 1/2 (TSC1/2) genes and upregulation of mTOR signaling. LAM is characterized by proliferative lung nodules that destroy surrounding parenchyma and aberrant lymphangiogenesis causing chylous effusions. LAM lesions express high levels of urokinase plasminogen activator (uPA), an enzyme implicated in the proliferation and spread of cancers, but not its primary inhibitor (PAI-1). We demonstrate that genetic ablation of TSC2 leads directly to upregulation of uPA but not PAI-1. Deletion of uPA attenuates the growth of TSC2-null lung tumors and inhibits aberrant lymphangiogenesis in vivo. Surprisingly, inhibition of mTORC1 by rapamycin, currently used to treat LAM, further up- regulates uPA and dramatically upregulates its receptor (uPAR), but not PAI-1, in TSC2- compromised cells, consistent with its failure to eradicate the disease. In this proposal we will examine the mechanism by which loss of TSC leads to upregulation of uPA expression and activity and the consequences of uPA upregulation on the proliferation of LAM cells and the development of lymphatics in vitro and in vivo. In Aim 1, we will delineate the pathway by which loss of TSC induces uPA and examine how this is amplified by inhibition of mTORC1. In Aim 2, we will examine how uPA and VEGF-D secreted by TSC2-null LAM cells promotes uPA overexpression and subsequent growth, migration, lymphangiongesis and growth of LAM lung lesions. We will delineate the contribution of specific uPA domains that mediate tissue proteolysis, intracellular signaling and nuclear translocation/gene transcription. In Aim 3, will determine whether blocking upregulation of uPA will act in concert with inhibition of mTORC1 to control the growth TSC2-null tumors and aberrant lymphangiongesis in a murine model of LAM. The results of this study will provide new insights into the pathogenesis of LAM, advance our understanding of the mechanism by which uPA promotes neoplasia, and potentially identify a novel biomarker and auxiliary therapeutic target for the diagnosis and management of LAM.