LPA Receptor Signaling in Colonic Epithelia

描述（由申请方提供）：生长因子信号通路的异常导致异常生长和分化，进而导致恶性转化。溶血磷脂酸（LPA）是最简单的磷脂之一，介导生长因子样作用，能够调节肠上皮细胞的命运和先天性免疫。LPA通过激活一个G蛋白偶联受体家族LPA 1R~LPA 5R介导多种生物学效应。LPA和结肠癌之间的病理学联系已经通过发现LPA 2受体（LPA 2R）的表达水平在人结肠癌组织和细胞系中升高而被提出。LPA在体外调节结肠癌细胞的增殖、存活和侵袭，但来自我们的研究的直接体内证据表明，LPA 2R的缺乏导致结肠癌啮齿动物模型中肿瘤负荷降低。我们的研究表明，LPA2R介导的信号传导靶向几种癌基因和促炎蛋白，包括c-Myc，细胞周期蛋白D，缺氧诱导因子（HIF）-1？，HIF-2？，环氧合酶-2和巨噬细胞移动抑制因子（MIF）。然而，LPA如何调节这些致癌靶点的表达以及这些基因和基因产物在何种程度上有助于LPA介导的发病机制尚未阐明。我们的目标是确定HIF-1？的调节机制，HIF-2？，通过LPA2R介导的信号传导抑制HIF和MIF的表达，并检验LPA2R通过激活HIF和MIF刺激肿瘤生长、糖酵解和促炎细胞因子分泌的假设（特异性目的1）。LPA2R信号传导部分通过激活？我们将确定LPA诱导的β-连环蛋白激活的潜在机制。连环蛋白。我们将确定Kruppel样因子5（KLF5）和？catenin和确定KLF5的重要性？体内连环蛋白核转位。我们将确定选择的Wnt途径基因在？LPA对连环蛋白的调节（特异性目的2）。有证据表明，LPA2R的缺乏减弱了结肠癌的发病机制。然而，LPA2R单独过表达是否足以在肠道中发展成癌症尚不清楚。我们将产生LPA2R转基因小鼠，以确定LPA2R过表达对肠道肿瘤发展的影响。此外，我们将使用NHERF2缺陷小鼠确定NHERF2（与LPA2R相互作用以增强其细胞信号传导）的缺失是否是LPA诱导的结肠癌体内进展所必需的（特异性目的3）。该提议的意义在于更好地理解LPA 2R介导的信号传导途径和机制，以及靶向LPA/LPA受体的可能性，将为治疗肠道病症（例如癌症和炎症相关疾病）提供更好的治疗模式。 公共卫生相关性：生长因子信号通路的异常导致细胞的异常生长和分化，从而导致恶性转化。溶血磷脂酸（LPA）作用于受体家族，介导生长因子样生长因子，在多种疾病的发病机制中起主要作用。LPA和癌症之间的病理联系已被广泛的癌症中异常的LPA和LPA受体表达所暗示，但对LPA在肠癌进展中的作用的理解最近才开始出现。因此，进一步了解LPA和LPA2受体介导的作用将最终为肠道疾病（包括结肠癌）患者提供新的治疗策略。本研究的目的是了解LPA2受体介导的结肠癌进展机制。

DESCRIPTION (provided by applicant): Aberration in the growth factor signaling pathways leads to abnormal growth and differentiation that contribute to malignant transformation. Lysophosphatidic acid (LPA), one of the simplest phospholipids, mediates growth factor-like effects that are capable of regulating the fate of intestinal epithelial cells and the innate immunity. LPA mediates diverse biological effects by activating a family of G protein-coupled receptors: LPA1R~LPA5R. The pathological link between LPA and colon cancer has been suggested by the finding that the expression level of LPA2 receptor (LPA2R) is elevated in human colon cancer tissues and cell lines. LPA regulates proliferation, survival, and invasion of colon cancer cells in vitro, but direct in vivo evidence came from our studies that the absence of LPA2R results in decreased tumor burden in rodent models of colon cancer. Our studies have shown that LPA2R-mediated signaling targets several oncogenes and pro-inflammatory proteins, including c-Myc, cyclin D, hypoxia-inducible factor (HIF)-1?, HIF-2?, cyclooxygenase-2, and macrophage migration inhibitory factor (MIF). However, how LPA regulates the expression of these oncogenic targets and to what extend these genes and gene products contribute to the pathogenesis mediated by LPA has not been elucidated. We aim to determine the mechanisms of the regulation of HIF-1?, HIF-2?, and MIF by LPA2R- mediated signaling and to test the hypothesis that LPA2R stimulates tumor growth, glycolysis, and secretion of pro-inflammatory cytokines through the activation of HIF and MIF (Specific Aim 1). LPA2R-signaling facilitates cell proliferation in part by activation of ?-catenin and we will determine the underlyng mechanism of LPA- induced activation of ?-catenin. We will determine the interaction between Kruppel-like factor 5 (KLF5) and ?- catenin and determine the importance of KLF5 in ?-catenin nuclear translocation in vivo. We will determine the importance of selected Wnt pathway genes in ?-catenin regulation by LPA (Specific Aim 2). Evidence shows the absence of LPA2R attenuates the pathogenesis of colon cancer. However, whether overexpression of LPA2R alone is sufficient for the development of cancer in the intestine is not known. We will generate LPA2R transgenic mice to determine the effects of LPA2R overexpression on tumor development in the intestine. In addition, we will determine whether the absence of NHERF2, which interacts with LPA2R to enhance its cellular signaling, is necessary for LPA-induced colon cancer progression in vivo using mice deficient in NHERF2 (Specific Aim 3). The significance of this proposal is that a better understanding of the LPA2R- mediated signaling pathways and mechanisms, together with the possibility of targeting LPA/LPA receptors, will provide better therapeutic modality for treatment of intestinal disorder, such as cancer and inflammation- associated diseases. PUBLIC HEALTH RELEVANCE: Aberration in the growth factor signaling pathways results in abnormal growth and differentiation of cells that contribute to malignant transformation. Lysophosphatidic acid (LPA) acting on a family of receptors mediates growth factor-like that plays a major role in the pathogenesis of various diseases. The pathological link between LPA and cancer has been suggested by the aberrant LPA and LPA receptor expression in a broad range of cancer, but the understanding of the role of LPA on intestinal cancer progression has only begun to emerge recently. Hence, further understanding of the effects mediated by LPA and LPA2 receptor will ultimately shed lights on novel treatment strategies to patients with intestinal disorders including colon cancer. The goal of this proposal is to understand the mechanisms of colon cancer progression mediated by LPA2 receptor.