title: TNF-α potentiates lysophosphatidic acid-induced COX-2 expression via PKD in human colonic myofibroblasts.
abstract: The myofibroblast (MFB) has recently been identified as an important mediator of tumor necrosis factor-α (TNF-α)-associated colitis and cancer, but the mechanism(s) involved remains incompletely understood. Here, we show that treatment of 18Co cells, a model of human colonic MFBs, with TNF-α and lysophosphatidic acid (LPA) induced striking synergistic cyclooxygenase-2 (COX-2) protein expression and production of PGE(2). This effect was prevented by the LPA(1) receptor antagonist Ki16425, the G(iα)-specific inhibitor pertussis toxin, and by the preferential protein kinase (PK) C inhibitors GF109203X and Go6983. As a known downstream target of LPA and PKC, we tested whether PKD, recently implicated in the regulation of COX-2 expression in MFB, was involved in this response. TNF-α, while having no detectable effect on the activation of PKD when added alone, augmented PKD activation stimulated by LPA, as measured by PKD autophosphorylation at Ser(910). LPA-induced PKD activation was also inhibited by Ki16425, pertussis toxin, GF109203X, and Go6983. Transfection of 18Co cells with short interfering RNA targeting PKD completely inhibited the synergistic increase in COX-2 protein, demonstrating a critical role of PKD in this response. Our results imply that cross talk between TNF-α and LPA results in the amplification of COX-2 protein expression via a conserved PKD-dependent signaling pathway that appears to involve the LPA(1) receptor and the G protein G(iα). PKD plays a critical role in the expression of COX-2 in human colonic MFBs and may contribute to an inflammatory microenvironment that promotes tumor growth.
authors.affiliation: Departments of Surgery and Medicine, David Geffen School of Medicine, CURE: Digestive Diseases Research Center and Molecular Biology Institute, University of California, Los Angeles, 90095, USA.
authors.forename: Citlali Ekaterina
authors.initials: CE
authors.lastname: Rodriguez Perez
authors.forename: Wenxian
authors.initials: W
authors.lastname: Nie
authors.forename: James
authors.initials: J
authors.lastname: Sinnett-Smith
authors.forename: Enrique
authors.initials: E
authors.lastname: Rozengurt
authors.forename: James
authors.initials: J
authors.lastname: Yoo
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D015232:Dinoprostone / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology; D008246:Lysophospholipids / Q000378:metabolism / Q000494:pharmacology*; D058628:Myofibroblasts / Q000187:drug effects / Q000378:metabolism*; D037342:Pertussis Toxin / Q000494:pharmacology; D011422:Propionates / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
chemical_list: C477898:3-(4-(4-((1-(2-chlorophenyl)ethoxy)carbonyl amino)-3-methyl-5-isoxazolyl) benzylsulfanyl) propanoic acid; D007555:Isoxazoles; D008246:Lysophospholipids; D011422:Propionates; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D051546:Cyclooxygenase 2; D037342:Pertussis Toxin; C089212:protein kinase D; D011493:Protein Kinase C; D015232:Dinoprostone; C032881:lysophosphatidic acid