(PQ4A) Metabolic Plasticity of Pre-Malignant Cells During Tumor Progression

 描述（由申请人提供）：小细胞肺癌（SCLC）每年导致全球超过20万例患者死亡。与许多实体瘤一样，导致SCLC预后不佳的一个主要因素是对过去30年来基本保持不变的现有疗法的耐药性。小细胞肺癌复发和进展的细胞起源和分子决定因素是迷人的，但知之甚少的巨大的临床重要性的主题。尽管有证据表明癌前细胞具有相同的肿瘤起始突变和肿瘤进展中的潜在影响，但由于缺乏易处理的模型和定义异常过程的知情方法，这些细胞的表征一直具有挑战性。使用SCLC的基因工程小鼠模型，我们用特异性谱系示踪剂分离癌前细胞，并建立了缺乏已知致癌畸变且在培养和同种异体移植模型中不发生自发转化的细胞系。癌前细胞和SCLC细胞的比较分子谱导致鉴定与肿瘤进展病理相关的“驱动因素”，而不是在比较整个肺和肿瘤的常规方法中鉴定的那些。本研究的目的是利用整合基因表达分析和功能遗传学来确定preSC的分子特性及其恶性进展，并评估preSC作为治疗靶点。假设是胆固醇代谢的可塑性定义了肿瘤进展期间SCLC的癌前体细胞（preSC）。这一假设是基于我们的初步研究结果提出的，这些研究结果指出，恶性进展期间胆固醇代谢增加，癌基因转化细胞对具有抗胆固醇特性的药物的反应是生长减少。我们提出以下具体目标。在目标1中，我们将确定胆固醇代谢及其相关信号通路的基因的作用，在体内和体外使用病毒介导的基因表达方法。在目标2中，我们将测试胆固醇代谢的全身水平的变化是否通过使用高胆固醇饮食或已知调节胆固醇合成和转运的药物调节身体胆固醇水平来影响肿瘤进展。在目标3中，我们将通过分析在胆固醇摄入和合成中起作用的蛋白质来检查人类肺肿瘤的胆固醇代谢失调。为了验证胆固醇代谢在肿瘤进展中的临床意义，我们的目标是建立人癌前细胞，并测试调节胆固醇代谢对癌基因诱导的人癌前细胞转化的影响。该提案概述了了解肿瘤进展过程中关键驱动分子的详细分子机制的第一步，这将为旨在开发新的预防和治疗策略的更令人兴奋的实验铺平道路。最后，这一提议的成功结果可以提供一个确定许多癌症的关键决定因素的范例，因为这些癌症的起源细胞和谱系标志物将在不久的将来被发现。

 DESCRIPTION (provided by applicant): Small cell lung cancer (SCLC) causes over 200,000 patient deaths worldwide each year. A major factor contributing to the dismal outcome of SCLC, as in many solid tumors, is resistance to current therapies that have remained largely the same for the past 30 years. Cell-of-origin and molecular determinants of SCLC recurrence as well as progression are fascinating yet poorly understood subjects of immense clinical importance. Despite evidence of pre-malignant cells possessing the same tumor-initiating mutations and potential implications in tumor progression, characterization of these cells has been challenging due to lack of tractable model and informed ways of defining aberrant processes. Using genetically engineered mouse models of SCLC, we isolated pre-malignant cells with specific lineage-tracer and established lines of the cells that lack known oncogenic aberrations and do not undergo spontaneous transformation in culture and allograft model. Comparative molecular profiling of the pre-malignant cell and SCLC cell resulted in identification of `drivers' pathologically relevant to tumor progression as opposed to ones identified in conventional approaches comparing whole lung and tumor. The objectives of this proposal are to define molecular properties of preSC as well as its malignant progression using integrative gene expression analyses and functional genetics, and to assess preSC as therapeutic target. The hypothesis is that plasticity in cholesterol metabolism defines pre- malignant precursor cells of SCLC (preSC) during tumor progression. This hypothesis has been formulated based on our preliminary findings pointing to increased cholesterol metabolism during malignant progression and the reduced growth of oncogene-transformed cells in response to a drug with anti-cholesterol properties. We propose the following specific aims. In Aim 1, we will determine roles of genes for cholesterol metabolism and its related signaling pathways, using virus-mediated gene expression approaches in vivo and in vitro. In Aim 2, we will test whether changes in systemic level of cholesterol metabolism influences tumor progression by modulating body cholesterol level using high-cholesterol diet or drugs known to regulate cholesterol synthesis and transport. In Aim 3, we will examine human lung tumors for deregulated cholesterol metabolism by analyzing proteins that play role in cholesterol intake and synthesis. To validate clinical significance of cholesterol metabolism in tumor progression, we aim to establish human pre-malignant cells and test effect of modulating cholesterol metabolism on oncogene-induced transformation of human pre-malignant cells. This proposal outlines a first step toward understanding detailed molecular mechanisms of key driver molecules during tumor progression, which will pave the way for even more exciting experiments aimed at developing novel strategies for prevention and treatment. Lastly, successful outcomes of this proposal could provide a paradigm of identifying key determinant of many cancers given that cell-of-origins and lineage markers for those caners will be known in the near future.