title: Prostaglandin E2 receptor EP1 transactivates EGFR/MET receptor tyrosine kinases and enhances invasiveness in human hepatocellular carcinoma cells.
abstract: Recent evidence indicates that cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) are involved in hepatocarcinogenesis. This study was designed to evaluate the possible interaction between the COX-2 and EGFR signaling pathways in human hepatocellular carcinoma (HCC) cells. Immunohistochemical analysis using serial sections of human HCC tissues revealed positive correlation between COX-2 and EGFR in HCC cells (P < 0.01). Overexpression of COX-2 in cultured HCC cells (Hep3B) or treatment with PGE(2) or the selective EP(1) receptor agonist, ONO-DI-004, increased EGFR phosphorylation and tumor cell invasion. The PGE(2)-induced EGFR phosphorylation and cell invasiveness were blocked by the EP(1) receptor siRNA or antagonist ONO-8711 and by two EGFR tyrosine kinase inhibitors, AG1478 and PD153035. The EP(1)-induced EGFR transactivation and cell invasion involves c-Src, in light of the presence of native binding complex of EP(1)/Src/EGFR and the inhibition of PGE(2)-induced EGFR phosphorylation and cell invasion by the Src siRNA and the Src inhibitor, PP2. Further, overexpression of COX-2 or treatment with PGE(2) also induced phosphorylation of c-Met, another receptor tyrosine kinase critical for HCC cell invasion. Moreover, activation of EGFR by EGF increased COX-2 promoter activity and protein expression in Hep3B and Huh-7 cells, whereas blocking PGE(2) synthesis or EP(1) attenuated EGFR phosphorylation induced by EGF, suggesting that the COX-2/PGE(2)/EP(1) pathway also modulate the activation of EGFR by its cognate ligand. These findings disclose a cross-talk between the COX-2/PGE(2)/EP(1) and EGFR/c-Met signaling pathways that coordinately regulate human HCC cell invasion.
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, Pennsylvania 15213, USA.
authors.forename: Chang
authors.initials: C
authors.lastname: Han
authors.forename: George K
authors.initials: GK
authors.lastname: Michalopoulos
authors.forename: Tong
authors.initials: T
authors.lastname: Wu
mesh_terms: D000527:Alprostadil / Q000031:analogs & derivatives / Q000494:pharmacology; D001643:Bridged Bicyclo Compounds / Q000494:pharmacology; D000081247:CSK Tyrosine-Protein Kinase; D002208:Caproates / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D051546:Cyclooxygenase 2 / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D015232:Dinoprostone / Q000494:pharmacology; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D009361:Neoplasm Invasiveness; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D011982:Receptors, Prostaglandin / Q000235:genetics / Q000378:metabolism; D018078:Receptors, Prostaglandin E / Q000235:genetics / Q000502:physiology*; D058306:Receptors, Prostaglandin E, EP1 Subtype; D014162:Transfection; D019061:src-Family Kinases
chemical_list: D001643:Bridged Bicyclo Compounds; D002208:Caproates; D008565:Membrane Proteins; C122148:ONO 8711; C500045:ONO-DI-004; C545635:PTGER1 protein, human; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D011982:Receptors, Prostaglandin; D018078:Receptors, Prostaglandin E; D058306:Receptors, Prostaglandin E, EP1 Subtype; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D019859:Proto-Oncogene Proteins c-met; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D000527:Alprostadil; D015232:Dinoprostone