Inflammation in Oncogenic K-ras-induced Lung Tumorigenesis

描述(申请人提供)：K-ras原癌基因的激活突变发生在大约30%的肺腺癌中，肺腺癌是非小细胞肺癌(NSCLC)最常见的亚型。K-ras是一种膜相关的GTP酶，可激活多个激酶通路，其中几个通路在细胞模型中具有转化活性。这些K-ras下游分子中有哪些参与了肺肿瘤的发生，目前还没有完全阐明。此外，目前尚无治疗K-ras基因突变的NSCLC的有效方法。我们的全球假设是，致癌K-ras诱导的肺肿瘤发生部分是由宿主对转化的肺泡上皮细胞存在的反应驱动的。这些细胞来源于细支气管肺泡干细胞(BASCs)，分泌趋化因子招募宿主炎症细胞和内皮细胞，后者又分泌趋化因子和生长因子促进肺部肿瘤的发生。我们建议通过完成两个具体目标来检验这一假设。第一个特定目的是检查炎症细胞中CXCR2的缺失是否足以抑制致癌K-ras诱导的肺肿瘤形成。我们将通过创建两个新的致癌K-ras驱动的肺癌小鼠模型来实现这一点，一个是趋化因子受体CXCR2在全球范围内被耗尽，以证实我们的发现：用CXCR2中和抗体治疗KrasLA1小鼠可以阻止肺癌的发生，而在另一个模型中，CXCR2在炎症细胞中被特异性地耗尽。我们调查在这些小鼠模型中肺肿瘤的发生是否被取消。第二个具体目标是在体外共培养模型中检测肿瘤/基质细胞相互作用促进肺肿瘤发生的机制。我们将使用明确定义的肿瘤细胞(细胞增殖、迁移和侵袭)、BASCs(增殖和分化)和间质细胞(细胞增殖、迁移和内皮管形成)的终点，研究肺基质细胞(成纤维细胞、内皮细胞和巨噬细胞)是否以双向方式影响肺肿瘤细胞(BASCs和来自KrasLA1小鼠的肺腺癌细胞系)。我们将研究CXCR2在这些双向相互作用中的作用，并将通过对条件培养液样本进行蛋白质组学分析，在体外模型中鉴定新的趋化因子和生长因子。我们希望更好地了解肿瘤/间质细胞相互作用促进肺癌发生的机制，并为测试CXCR2作为肺癌预防和治疗的靶点奠定基础。

DESCRIPTION (provided by applicant): Activating mutations in the K-ras proto-oncogene occur in approximately 30% of lung adenocarcinomas, the most common subtype of non-small cell lung cancer (NSCLC). K-ras is a membrane-associated GTPase that activates multiple kinase pathways, several of which have transforming activity in cellular models. Which of these downstream mediators of K-ras contribute to lung tumorigenesis has not been fully elucidated. Moreover, no effective approaches are available for the treatment of K-ras-mutant NSCLC. Our global hypothesis is that oncogenic K-ras-induced lung tumorigenesis is driven in part by a host response to the presence of transformed alveolar epithelial cells. These cells arise from bronchioalveolar stem cells (BASCs) and secrete chemokines that recruit host inflammatory cells and endothelial cells, which, in turn, secrete chemokines and growth factors that promote lung tumorigenesis. We propose to test this hypothesis by the completion of two Specific Aims. The first Specific Aim is to examine whether CXCR2 loss in inflammatory cells is sufficient to inhibit lung tumorigenesis induced by oncogenic K-ras. We will achieve this by creating two new oncogenic K-ras-driven mouse models of lung cancer, one in which the chemokine receptor CXCR2 is depleted globally to confirm our finding that treatment of KrasLA1 mice with a CXCR2 neutralizing antibody blocks lung tumorigenesis, and the other in which CXCR2 is depleted specifically in inflammatory cells. We investigate whether lung tumorigenesis is abrogated in these mouse models. The second Specific Aim is to examine the mechanisms by which tumor/stromal cell interactions promote lung tumorigenesis in an in vitro co-culture model. We will examine whether lung stromal cells (fibroblasts, endothelial cells, and macrophages) affect lung tumor cells (BASCs and a lung adenocarcinoma cell line derived from KrasLA1 mice) in a bi-directional manner using well-defined endpoints for tumor cells (cell proliferation, migration, and invasion), BASCs (proliferation and differentiation), and stromal cells (cell proliferation, migration, and endothelial tube formation). We will investigate the role of CXCR2 in these bi-directional interactions, and we will identify novel chemokines and growth factors in the in vitro model by performing proteomic analysis on conditioned media samples. We hope to better understand the mechanisms by which tumor/stromal cell interactions promote lung tumorigenesis and to build a rationale to test CXCR2 as a target for lung cancer prevention and therapy.