Phorbol 12-myristate 13-acetate upregulates cyclooxygenase-2 expression in human pulmonary epithelial cells via Ras, Raf-1, ERK, and NF-kappaB, but not p38 MAPK, pathways.
In this study, we investigated the signaling pathway involved in cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) release by phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator, in human pulmonary epithelial cells (A549). PMA-induced COX-2 expression was attenuated by PKC inhibitors (Go 6976 and Ro 31-8220), a Ras inhibitor (manumycin A), a Raf-1 inhibitor (GW 5074), a MEK inhibitor (PD 098059), and an NF-kappaB inhibitor (PDTC), but not by a tyrosine kinase inhibitor (genistein) or a p38 MAPK inhibitor (SB 203580). PMA also caused the activation of Ras, Raf-1, and ERK1/2. PMA-induced activation of Ras and Raf-1 was inhibited by Ro 31-8220 and manumycin A. PMA-mediated activation of ERK1/2 was inhibited by Ro 31-8220, manumycin A, GW 5074, and PD 098059. Stimulation of cells with PMA caused IkappaBalpha phosphorylation, IkappaBalpha degradation, and the formation of a NF-kappaB-specific DNA-protein complex. The PMA-mediated increase in kappaB-luciferase activity was inhibited by Ro 31-8220, manumycin A, GW5074, PD 098059, and PDTC. Taken together, these results indicate that PMA might activate PKC to elicit activation of the Ras/Raf-1/ERK1/2 pathway, which in turn initiates NF-kappaB activation, and finally induces COX-2 expression and PGE2 release in A549 cells.
Chang
Ming-Shyan
MS
Graduate Institute of Biomedical Technology, Taipei Medical University, Taipei, Taiwan.
Chen
Bing-Chang
BC
Yu
Ming-Tze
MT
Sheu
Joen-Rong
JR
Chen
Tseng-Fu
TF
Lin
Chien-Huang
CH
D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D017930:Genes, Reporter; D006801:Humans; D008565:Membrane Proteins; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000502:physiology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000037:antagonists & inhibitors / Q000502:physiology*; D020545:Respiratory Mucosa / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D018631:ras Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*
D008565:Membrane Proteins; D016328:NF-kappa B; C016658:phorbolol myristate acetate; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019908:Proto-Oncogene Proteins c-raf; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D018631:ras Proteins; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate