TSC signaling and pulmonary LAM

描述(申请人提供)：肺部LAM是一种罕见的肺部疾病，主要影响育龄妇女，与结节性硬化症复合体(TSC)肿瘤抑制基因的突变有关。LAM表现为肺囊性破坏、自发性气胸和肿瘤性LAM细胞生长。虽然LAM细胞的生长与mTORC1活性的上调有关，但最重要的问题仍然是：1)LAM细胞肿瘤转化的机制是什么；2)这些变化是如何导致LAM特有的肺囊肿形成的。我们已经建立了一种新的实验性TSC缺失的小鼠LAM模型，在该模型中，TSC缺失的细胞渗透到肺中，这些细胞引起与人类LAM非常相似的囊性形态变化。重要的是，分别用雷帕霉素和辛伐他汀抑制mTORC1和mTORC2信号，可以抑制TSC阴性肿瘤的生长和腔隙扩大。我们发表的和新的数据也表明，TSC缺失促进LAM细胞的侵袭性，激活mTORC2，增加MMP-9的表达，通过上调rac1 GTPase活性下调E-cadherin的膜定位，并诱导细胞转化。这些数据支持我们的中心假设：TSC的缺失通过依赖mTORC2的rac1激活来诱导细胞转化，从而下调E-cadherin的膜定位，上调MMP-9的表达。这进而导致细胞外基质(ECM)的蛋白水解性破坏、肺泡细胞凋亡、炎性细胞浸润导致肺实质破坏、肺泡腔扩大和肺功能丧失。这些观察结果还导致了一种翻译假说，即mTORC2和mTORC1信号的药理学靶向将在肺LAM中提供联合治疗。这些研究将在LAM中建立TSC丢失和肺泡破坏之间的机制联系，并将为潜在的新的分子靶点和潜在的联合治疗LAM提供见解。 公共卫生相关性：肺淋巴管肌瘤病(LAM)是一种罕见的肺部疾病，主要影响育龄妇女，与结节硬化症(TSC)肿瘤抑制基因的突变有关。LAM细胞中TSC的缺失如何导致肺囊肿形成，以及LAM中的囊性肺破坏是否可以得到改善，目前还知之甚少。在这项使用我们新开发的TSC缺失的雌性小鼠LAM模型的提案中，我们将确定LAM囊性肺破坏的细胞机制，提供关于新分子靶点的见解，并将为LAM的潜在治疗提供临床前证据。

DESCRIPTION (provided by applicant): Pulmonary LAM, a rare lung disease affecting predominantly women of childbearing age, is associated with mutations of the Tuberous Sclerosis Complex (TSC) tumor suppressor genes. LAM manifests by cystic lung destruction, spontaneous pneumothoraces and neoplastic LAM cell growth. Although LAM cell growth has been linked to upregulation of the mTORC1 activity that is amenable to rapamycin treatment, key questions remain, among the most important: 1) what is the mechanism of LAM cell neoplastic transformation and 2) how do these changes lead to lung cyst formation characteristic of LAM. We have developed a novel experimental TSC-null murine LAM model in which there is infiltration of TSC-null cells into the lung and these cells induce cystic morphological changes highly similar to those seen in human LAM. Importantly, inhibition of both mTORC1 and mTORC2 signaling with rapamycin and with simvastatin, respectively, inhibits TSC-null tumor growth and airspace enlargement. Our published and new data also show that TSC loss promotes LAM cell invasiveness, activates mTORC2, increases MMP-9 expression, downregulates membrane localization of E-cadherin through upregulation of Rac1 GTPase activity, and induces cell transformation. These data supports our central hypothesis that: loss of TSC induces cell transformation by mTORC2-dependent Rac1 activation that downregulates membrane localization of E-cadherin and upregulates MMP-9 expression. This, in turn, induces proteolytic destruction of extracellular matrix (ECM), alveolar cell apoptosis, an inflammatory cell infiltration leading to destruction of lung parenchyma, alveolar space enlargements and the loss of pulmonary function. These observations also lead to the translational hypothesis that pharmacological targeting of both mTORC2 and mTORC1 signaling will provide combinational therapy in pulmonary LAM. These studies will establish a mechanistic link between loss of TSC and alveolar destruction in LAM, and will provide insights about potential novel molecular targets and potential combinational therapy to treat LAM. PUBLIC HEALTH RELEVANCE: Pulmonary lymphangioleiomyomatosis (LAM), a rare lung disease affecting predominantly women of childbearing age, is associated with mutations of the Tuberous Sclerosis Complex (TSC) tumor suppressor genes. Little is known about how TSC loss in LAM cells induces lung cyst formation and whether cystic lung destruction in LAM can be ameliorated. In this proposal using our newly developed TSC-null female mouse LAM model, we will identify the cellular mechanisms of cystic lung destruction in LAM, provide insights about novel molecular targets, and will generate pre-clinical evidence for potential treatments of LAM.