title: YC-1 increases cyclo-oxygenase-2 expression through protein kinase G- and p44/42 mitogen-activated protein kinase-dependent pathways in A549 cells.
abstract: YC-1, an activator of soluble guanylate cyclase (sGC), has been shown to increase the intracellular cGMP concentration. This study was designed to investigate the signaling pathway involved in the YC-1-induced COX-2 expression in A549 cells. YC-1 caused a concentration- and time-dependent increase in COX activity and COX-2 expression in A549 cells. Pretreatment of the cells with the sGC inhibitor (ODQ), the protein kinase G (PKG) inhibitor (KT-5823), and the PKC inhibitors (Go 6976 and GF10923X), attenuated the YC-1-induced increase in COX activity and COX-2 expression. Exposure of A549 cells to YC-1 caused an increase in PKC activity; this effect was inhibited by ODQ, KT-5823 or Go 6976. Western blot analyses showed that PKC-alpha, -iota, -lambda, -zeta and -mu isoforms were detected in A549 cells. Treatment of A549 cells with YC-1 or PMA caused a translocation of PKC-alpha, but not other isoforms, from the cytosol to the membrane fraction. Long-term (24 h) treatment of A549 cells with PMA down-regulated the PKC-alpha. The MEK inhibitor, PD 98059 (10 - 50 microM), concentration-dependently attenuated the YC-1-induced increases in COX activity and COX-2 expression. Treatment of A549 cells with YC-1 caused an activation of p44/42 MAPK; this effect was inhibited by KT-5823, Go 6976, long-term (24 h) PMA treatment or PD98059, but not the p38 MAPK inhibitor, SB 203580. These results indicate that in human pulmonary epithelial cells, YC-1 might activate PKG through an upstream sGC/cGMP pathway to elicit PKC-alpha activation, which in turn, initiates p44/42 MAPK activation, and finally induces COX-2 expression.
authors.affiliation: Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Ming-Shyan
authors.initials: MS
authors.lastname: Chang
authors.forename: Wen-Sen
authors.initials: WS
authors.lastname: Lee
authors.forename: Che-Ming
authors.initials: CM
authors.lastname: Teng
authors.forename: Horng-Mo
authors.initials: HM
authors.lastname: Lee
authors.forename: Joen-Rong
authors.initials: JR
authors.lastname: Sheu
authors.forename: George
authors.initials: G
authors.lastname: Hsiao
authors.forename: Chien-Huang
authors.initials: CH
authors.lastname: Lin
mesh_terms: D000704:Analysis of Variance; D015153:Blotting, Western; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D051546:Cyclooxygenase 2; D020536:Enzyme Activators / Q000494:pharmacology*; D004790:Enzyme Induction; D006801:Humans; D007191:Indazoles / Q000494:pharmacology*; D007527:Isoenzymes / Q000096:biosynthesis*; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D020536:Enzyme Activators; D007191:Indazoles; D007527:Isoenzymes; D008565:Membrane Proteins; C090937:3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole; D009569:Nitric Oxide; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D017869:Cyclic GMP-Dependent Protein Kinases; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases