Eicosanoids in Lung Cancer: Progression and Metastasis

描述（由申请人提供）：肺癌是癌症死亡的主要原因，主要是由于在诊断时存在转移。在过去的25年里，对上皮性癌症的研究已经确定了肿瘤细胞本身的遗传变化。然而，癌症的进展和转移需要肿瘤细胞和周围基质之间复杂的相互作用。我们实验室研究了胞质磷脂酶A2-？（cPLA2）在肺癌发展中的作用。cPLA2代表了在癌症进展中具有不同影响的二十烷类蛋白家族生产的限速步骤。我们已经证明cPLA2敲除（KO）小鼠对化学诱导的肺肿瘤发生具有保护作用。然而，这些研究并没有区分cPLA2在肿瘤细胞中的作用与肿瘤周围微环境（TME）的作用。为了解决这个问题，我们开发了一种模型，将小鼠肿瘤细胞直接注射到具有免疫能力的同基因小鼠的肺部。这些细胞形成明确的原发肿瘤，并转移到肺的其他叶、纵隔淋巴结和远处器官，包括肝和脑。重要的是，当将相同的细胞注射到cPLA2-KO小鼠中时，原发肿瘤的生长没有明显改变，但对转移有深刻的抑制。在cPLA2- ko小鼠中生长的肿瘤表现出肿瘤周围巨噬细胞模式的改变，支持cPLA2在巨噬细胞募集/功能中的作用。将cPLA2 KO骨髓移植到野生型小鼠体内，足以抑制肿瘤转移，促进生存。这些数据表明，cPLA2对肿瘤细胞和TME细胞都有不同的作用。因此，我们假设这些影响是通过以细胞特异性和时间依赖性的方式产生的不同的类二十烷介导的。虽然包括我们自己的实验室在内的许多实验室之前的工作都集中在特定类二十烷的影响上，但还没有对cPLA2产生的产物光谱以及这些分子在癌症进展中的作用进行系统的检查。质谱方法的出现使我们能够以一种公正的方式定义这些分子，并确定它们的生物效应。本项目将使用这种方法在体内和体外方法确定cPLA2和类二十烷酸在不同细胞类型中的作用。提出了四个具体目标。目的1将定义肿瘤进展过程中肿瘤、周围基质、未受累肺和远端器官的类二十烷谱。在特定区室中删除cPLA2的影响将与肿瘤进展的变化和TME的改变相关。目的2将使用体外研究来检查cPLA2在癌细胞和巨噬细胞中的作用，以及这些细胞之间的串扰。机制研究将确定特定类二十烷酸及其下游效应物的作用。Aim 3将使用缺乏PGE2或LTC4产生的小鼠来确定这些产物在肿瘤进展中的作用。最后，Aim 4将研究人类肺癌中的类二十烷酸谱，并将其与临床数据和突变状态相关联。

DESCRIPTION (provided by applicant): Lung cancer is the leading cause of cancer deaths, largely due to the presence of metastasis at the time of diagnosis. During the past 25 years, studies in epithelial cancers have defined genetic changes in the tumor cells themselves. However, cancer progression and metastasis requires complex interactions between tumor cells and the surrounding stroma. Our laboratory has studied the role of cytosolic phospholipase A2-? (cPLA2) in the development of lung cancer. cPLA2 represents the rate-limiting step in production of a family of eicosanoids with diverse affects in cancer progression. We have demonstrated that cPLA2 knockout (KO) mice are protected against chemically-induced lung tumorigenesis. However, these studies do not discriminate between the action of cPLA2 in the tumor cells versus the surrounding tumor microenvironment (TME). To address this question, we developed a model in which mouse tumor cells are directly injected into the lungs of syngeneic, immune-competent mice. These cells form well-defined primary tumors which metastasize to other lobes of the lungs, the mediastinal lymph nodes and to distant organs including the liver and brain. Importantly, when identical cells are injected into cPLA2-KO mice, primary tumor growth is not significantly altered, but there is a profound inhibition of metastasis. Tumors growing in cPLA2-KO mice exhibit alterations in the pattern of macrophages surrounding the tumor, supporting a role for cPLA2 in macrophage recruitment/function. Transplantation of cPLA2 KO bone marrow into wild-type mice was sufficient to inhibit tumor metastasis and promote survival. These data demonstrate that cPLA2 has distinct effects both in tumor cells and cells of the TME. We therefore hypothesize these effects are mediated through distinct eicosanoids which are produced in a cell-specific and time dependent fashion. While previous work by many laboratories including our own has focused on the effects of specific eicosanoids, there has not been a systematic examination of the spectrum of products produced through cPLA2 and the role these molecules play in cancer progression. The advent of mass spectrometric approaches allows us to define these molecules in an unbiased way, and determine their biological effects. This project will use this approach to define the role of cPLA2 and eicosanoids in distinct cell types using both in vivo and in vitro approaches. Four Specific Aims are proposed. Aim 1 will define the eicosanoid spectrum during tumor progression in tumors, surrounding stroma, uninvolved lung and distant organs. The effects of deleting cPLA2 in specific compartments will be correlated with changes in tumor progression and alterations in the TME. Aim 2 will use in vitro studies to examine the role of cPLA2 in cancer cells and macrophages, as well as in cross-talk between these cells. Mechanistic studies will define the role of specific eicosanoids and their downstream effectors. Aim 3 will use mice deficient in production of PGE2 or LTC4 to define the role of these products in tumor progression. Finally Aim 4 will examine eicosanoid profiles in human lung cancers and correlate this with clinical data and mutational status.