title: Prostaglandins promote colon cancer cell invasion; signaling by cross-talk between two distinct growth factor receptors.
abstract: Colorectal cancer is the second most frequent cancer in the Western world, often lethal when invasion and/or metastasis occur. In addition to hepatocyte growth factor (HGF), colon cancer invasion may be driven by prostaglandins, especially the E2 series (PGE2), generated by the cyclooxygenase-2 (Cox-2) enzyme. While concentration of PGE2 as well as expression of Cox-2, HGF receptor (c-Met-R), epidermal growth factor receptor (EGFR), and beta-catenin are all dramatically increased in colon cancers and implicated in their growth and invasion, the precise role of PGE2 in the latter process remains unclear. Here we provide evidence that PGE2 transactivates c-Met-R (contingent upon functional EGFR), increases tyrosine phosphorylation and nuclear accumulation of beta-catenin, and induces urokinase-type plasminogen activator receptor (uPAR) mRNA expression. This is accompanied by increased beta-catenin association with c-Met-R and enhanced colon cancer cell invasiveness. Inactivation of EGFR and c-Met-R significantly reduced PGE2-induced cancer cell invasiveness. Clinical relevance of these findings is confirmed by our immunohistochemical studies demonstrating that cancer cells in the invasive front overexpress Cox-2, c-Met-R, and beta-catenin. Our findings explain a functional relationship between prostaglandins, EGFR, and c-Met-R in colon cancer growth and invasion.
authors.affiliation: Medical Service, Department of Veterans Affairs Medical Center, Long Beach, California 90822, USA. rpai@uci.edu.com
authors.forename: Rama
authors.initials: R
authors.lastname: Pai
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Nakamura
authors.forename: Woo S
authors.initials: WS
authors.lastname: Moon
authors.forename: Andrzej S
authors.initials: AS
authors.lastname: Tarnawski
mesh_terms: D018938:Caco-2 Cells; D002465:Cell Movement; D002467:Cell Nucleus / Q000378:metabolism; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D051546:Cyclooxygenase 2; D003598:Cytoskeletal Proteins / Q000378:metabolism; D015232:Dinoprostone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008565:Membrane Proteins; D009361:Neoplasm Invasiveness; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D020239:Receptor Cross-Talk; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000235:genetics; D055293:Receptors, Urokinase Plasminogen Activator; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; C524898:PLAUR protein, human; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D015534:Trans-Activators; D051176:beta Catenin; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D066246:ErbB Receptors; D019859:Proto-Oncogene Proteins c-met; D015232:Dinoprostone