Epidermal growth factor and interleukin-1beta utilize divergent signaling pathways to synergistically upregulate cyclooxygenase-2 gene expression in human amnion-derived WISH cells.
In human parturition, uterotonic prostaglandins (PGs) arise predominantly via increased expression of cyclooxygenase-2 (COX-2 [also known as prostaglandin synthase 2]) within intrauterine tissues. Interleukin-1 (IL-1) and epidermal growth factor (EGF), both inducers of COX-2 transcription, are among numerous factors that accumulate within amniotic fluid with advancing gestation. It was previously demonstrated that EGF could potentiate IL-1beta-driven PGE(2) production in amnion and amnion-derived (WISH) cells. To define the mechanism for this observation, we hypothesized that EGF and IL-1beta might exhibit synergism in regulating COX-2 gene expression. In WISH cells, combined treatment with EGF and IL-1beta resulted in a greater-than-additive increase in COX-2 mRNA relative to challenge with either agent independently. Augmentation of IL-1beta-induced transactivation by EGF was not observed in cells harboring reporter plasmids bearing nuclear factor-kappa B (NFkappaB) regulatory elements alone, but was evident when a fragment (-891/ +9) of the COX-2 gene 5'-promoter was present. Both agents transiently activated intermediates of multiple signaling pathways potentially involved in the regulation of COX-2 gene expression. The 26 S proteasome inhibitor, MG-132, selectively abrogated IL-1beta-driven NFkappaB activation and COX-2 mRNA expression. Only pharmacologic blockade of the p38 mitogen-activated protein kinase eliminated COX-2 expression following EGF stimulation. We conclude that EGF and IL-1beta appear to signal through different signaling cascades leading to COX-2 gene expression. IL-1beta employs the NFkappaB pathway predominantly, while the spectrum of EGF signaling is broader and includes p38 kinase. The synergism observed between IL-1beta and EGF does not rely on augmented NFkappaB function, but rather, occurs through differential use of independent response elements within the COX-2 promoter.
Ackerman
William E
WE
Department of Obstetrics and Gynecology (Division of Maternal-Fetal Medicine and Laboratory of Perinatal Research), The Ohio State University, College of Medicine and Public Health, Columbus, Ohio 43210 , USA.
Rovin
Brad H
BH
Kniss
Douglas A
DA
D000650:Amnion / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D002460:Cell Line; D051546:Cyclooxygenase 2; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D015870:Gene Expression; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism* / Q000494:pharmacology; D007976:Leupeptins / Q000494:pharmacology; D008565:Membrane Proteins; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D013997:Time Factors; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors
D004791:Enzyme Inhibitors; D007375:Interleukin-1; D007976:Leupeptins; D008565:Membrane Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D048051:p38 Mitogen-Activated Protein Kinases; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde