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

总结 淋巴管平滑肌瘤病（LAM）是一种进行性肿瘤性肺病， 结节性硬化症复合体1/2（TSC 1/2）基因的失活和mTOR的上调 信号LAM的特征是增生性肺结节， 实质和异常淋巴管生成引起乳糜渗出。LAM病变表达 高水平的尿激酶纤溶酶原激活物（uPA），一种与增殖有关的酶， 和癌症的扩散，但不是其主要抑制剂（派-1）。我们证明了基因 切除TSC 2直接导致uPA而不是派-1的上调。uPA的缺失减弱了 TSC 2-null肺肿瘤的生长并抑制体内异常淋巴管生成。 令人惊讶的是，目前用于治疗LAM的雷帕霉素对mTORC 1的抑制作用进一步升高。 调节uPA并显著上调其受体（uPAR），但不上调派-1，在TSC 2- 受损的细胞，这与它未能根除疾病相一致。在本提案中，我们将 研究TSC的丧失导致uPA表达上调的机制， 活性和uPA上调对LAM细胞增殖的影响， 在体外和体内的药物开发。在目标1中，我们将描述 TSC的丧失诱导uPA，并检查其如何通过抑制mTORC 1而放大。在目标2中， 我们将研究TSC 2缺失的LAM细胞分泌的uPA和VEGF-D如何促进uPA 过度表达和随后的生长、迁移、淋巴管增生和LAM肺的生长 病变我们将描绘特定的uPA结构域的贡献，介导组织 蛋白水解、细胞内信号传导和核转位/基因转录。在目标3中，将 确定阻断uPA的上调是否与mTORC 1的抑制一致， 在LAM的鼠模型中控制无TSC 2肿瘤的生长和异常淋巴管增生。 本研究结果将为LAM的发病机制提供新的认识， 了解uPA促进肿瘤形成的机制，并可能确定一种 新的生物标志物和辅助治疗靶点，用于LAM的诊断和管理。

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.