Role of Glypican-1 in Pancreatic Cancer

描述(申请人提供)：胰腺导管腺癌(PDAC)过度表达多种酪氨酸激酶受体，如I型成纤维细胞生长因子受体(FGFR-1)及其配体。其中许多配体是肝素结合生长因子(HBGFs)，其促有丝分裂作用往往依赖于与硫酸乙酰肝素蛋白多糖(HSPGs)的相互作用，从而促进配体与高亲和力受体的结合。我们已经确定，PDAC过度表达Glypcan-1，但不表达Glypcan家族其他5个成员的高水平，这增加了Glypcan-1在PDAC中可能具有独特而重要的作用的可能性。然而，Glypcian-1在PDAC中的确切作用及其作用机制尚不清楚。因此，我们将使用4种互补的方法来检验这一假设，即Glypcan-1在PDAC中起着至关重要的作用，它通过促进有丝分裂、侵袭和/或转移而发挥作用。我们将首先检查GLYPICON-1的表达是否与肿瘤分级和分期或患者生存相关。其次，我们将建立过表达GLYPICON-1的胰腺癌细胞系以及GLYPICON-1反义构建体抑制GLYPICON-1表达的细胞系，以期在合适的体外和体内模型系统中评估GLIPICON-1在癌细胞生长、侵袭和转移中的作用。第三，我们将确定GLYPICAN-1的任何致瘤作用是否被I型成纤维细胞生长因子受体(FGFR-1)的存在所增强，因为该受体在PDAC中过表达，并被多个HBGFs激活。为此，我们将在不存在或存在两种主要的FGFR-1亚型的情况下，将编码GLYPICAN-1的cDNA导入培养的人胰腺导管细胞。第四，我们将通过检测Glypcan-1的糖基化状态及其与FGFR复合体的相互作用，以及通过设计各种Glypcan-1嵌合蛋白并将它们的作用与野生型Glypcan-1的作用进行比较，来探索Glypcan-1赋予培养的胰腺癌细胞生长优势的机制。综上所述，这些研究将有助于阐明Glypcan-1在PDAC中的作用。

DESCRIPTION (provided by applicant): Pancreatic ductal adenocarcinomas (PDACs) overexpress multiple tyrosine kinase receptors such as the type I FGF receptor (FGFR-1), and their ligands. Many of these ligands are heparin-binding growth factors (HBGFs), whose mitogenic actions are often dependent on interactions with heparan sulfate proteoglycans (HSPGs) that facilitate ligand binding to high affinity receptors. We have determined that PDACs overexpress glypican-1 but de not express high levels of other 5 members of the glypican family, raising the possibility that glypican-1 may have a unique and important role in PDAC. However, the exact role of glypcian-1 in PDAC and its mechanisms of action are not well understood. Therefore, we will use 4 complementary approaches to test the hypothesis that glypican-1 is of paramount importance in PDAC and that it acts by promoting mitogenesis, invasion and/or metastasis. We will first examine whether glypican-1 expression correlates with tumor grade and stage, or patient survival. Second, we will establish pancreatic cancer cell lines that overexpress glypican-1, as well as cell lines whose glypican-1 expression is suppressed by a glypican-1 antisense construct, in order to assess the role of glypican-1 in cancer cell growth, invasion, and metastasis in appropriate in vitro and in vivo model systems. Third, we will determine whether any tumorigenic effects of glypican-1 are enhanced by the presence of the type I fibroblast growth factor receptor (FGFR-1), since this receptor is overexpressed in PDAC and is activated by multiple HBGFs. To this end, we will transfect cultured human pancreatic ductal cells with cDNAs encoding glypican-1 in the absence or presence of the two major FGFR-1 isoforms. Fourth, we will explore the mechanisms whereby glypican-1 confers a growth advantage to cultured pancreatic cancer cells by examining its glycanation status and its interactions with FGFR complexes, and by engineering various glypican-1 chimeric proteins and comparing their actions with the actions of wild type glypican-1. Together, these studies will help to elucidate the role of glypican-1 in PDAC.