Targeting Choline Phospholipid Metabolism in Lymphangioleiomyomatosis

 描述(申请人提供)：淋巴管肌瘤病(LAM)是一种罕见的女性多系统疾病。肺LAM包括平滑肌肌动蛋白阳性细胞的弥漫性增殖和淋巴管密度的增加。LAM细胞存在TSC1或TSC2肿瘤抑制基因的失活突变，导致哺乳动物TOR(雷帕霉素靶标)复合体1(MTORC1)的结构性激活。MTORC1整合生长因子和营养信号，刺激细胞生长和代谢。LAM尚未满足的关键需求是开发和优化有效的治疗策略，以及可获得敏感和特定的疾病进展和治疗反应生物标记物，这可以简化早期临床试验的设计、持续时间和成本。我们的长期目标是确定LAM细胞的mTORC1依赖或独立的代谢易损性，这些易损性可以作为LAM的治疗靶点。在脂质组学研究中，我们发现与对照细胞相比，LAM患者细胞模型中胆碱磷脂代谢增强，与健康女性相比，LAM患者血浆中磷脂酰胆碱(PC)和溶血磷脂酰胆碱(LPC)的种类增加。我们的中心假设是脂代谢异常参与了LAM的分子发病机制，并代表了LAM疾病进展的治疗靶点和代谢成像生物标志物的来源。这一假设将在三个目标上得到检验。目的1.明确LAM胆碱磷脂合成失调的分子机制。我们的工作假设是，在TSC2基因缺陷的细胞中，PC的从头合成和PC重塑通路通过mTOR依赖和独立的机制异常激活。目的2.探讨脂代谢异常对LAM细胞增殖和LAM相关淋巴管生成的影响。我们的工作假设是，胆碱激酶或PLA2下游的脂质和信号修饰参与了LAM细胞的增殖，并触发了淋巴管微血管内皮细胞的迁移和增殖。目的3.确定靶向治疗对LAM体内胆碱磷脂代谢的影响。我们的工作假设是LAM中异常的脂代谢可以被靶向治疗和用于诊断。我们将使用LAM小鼠模型、[11C]胆碱微型PET(正电子发射断层扫描)检测体内TSC2缺陷细胞胆碱摄取的变化，以及LAM细胞相关淋巴管生成的小鼠耳模型，进行胆碱磷脂代谢抑制剂的临床前试验。拟议的研究具有临床意义，因为它们将探讨胆碱磷脂途径的关键酶作为LAM疗法靶点的潜力，以及[11C]胆碱作为LAM患者疾病进展和/或治疗反应的代谢成像生物标记物的潜力。

 DESCRIPTION (provided by applicant): Lymphangioleiomyomatosis (LAM) is a rare, multisystem disease of women. Pulmonary LAM consists of a diffuse proliferation of smooth muscle actin-positive cells and increased lymphatic vessel density. LAM cells harbor inactivating mutations in either the TSC1 or TSC2 tumor suppressor gene, resulting in constitutive activation of mammalian TOR (target of rapamycin) complex 1 (mTORC1). mTORC1 integrates growth factor and nutrient signaling to stimulate cell growth and metabolism. Critical unmet needs in LAM are the development and optimization of effective therapeutic strategies and the availability of sensitive and specific biomarkers of disease progression and response to therapy, which could streamline the design, duration, and cost of early phase clinical trials. Our long-term goal is to identify mTORC1-dependent or independent metabolic vulnerabilities of LAM cells that can be targeted therapeutically in LAM. In lipidomic studies, we identified enhanced choline phospholipid metabolism in cellular models of LAM compared to control cells, and elevated phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) species in LAM patient plasma compared to healthy women. Our central hypothesis is that abnormal lipid metabolism contributes to the molecular pathogenesis of LAM and represents a source for therapeutic targets and metabolic imaging biomarkers of disease progression in LAM. This hypothesis will be tested in three Aims. Aim 1. To identify the molecular mechanisms underlying dysregulation of choline phospholipid synthesis in LAM. Our working hypothesis is that the de novo PC synthesis and PC remodeling pathways are aberrantly activated via mTOR-dependent and independent mechanisms in TSC2-deficient cells. Aim 2. To determine the impact of aberrant lipid metabolism on LAM cell proliferation and LAM-associated lymphangiogenesis. Our working hypothesis is that lipid and signaling modifications downstream of choline kinase or PLA2 participate in the proliferation of LAM cells and trigger lymphatic microvascular endothelial cell migration and proliferation. Aim 3. To determine the impact of therapeutic targeting of choline phospholipid metabolism in LAM in vivo. Our working hypothesis is that aberrant lipid metabolism in LAM can be targeted therapeutically and used diagnostically. We will conduct preclinical trials of inhibitors of choline phospholipid metabolism using mouse models of LAM, [11C]choline Micro-PET (positron emission tomography) to detect in vivo changes in choline uptake of TSC2-deficient cells, and a mouse-ear model of LAM cell-associated lymphangiogenesis. The proposed studies have clinical significance because they will address the potential for key enzymes of the choline phospholipid pathway as targets in LAM therapeutics, and for [11C]choline as a metabolic imaging biomarker of disease progression and/or response to treatment in LAM patients.