Abstract
Overexpression of the cyclooxygenase-2 (COX-2) gene is observed in several neoplastic diseases. However, molecular mechanisms involved in the regulation of expression of COX-2 are not well understood. In this report, we describe a unique post-transcriptional regulatory mechanism of COX-2 mRNA stabilization in MDA-MB-231 cells, a highly metastatic cell line derived from a human mammary tumor. High levels of COX-2 mRNA, protein, and enzyme activity were induced by serum withdrawal, which were potently inhibited by the addition of serum or >100-kDa serum factor. Nuclear run-on analysis and actinomycin D chase experiments indicate that regulation is primarily at the level of post-transcriptional mRNA stability. Interestingly, SB203580, an inhibitor of the p38 stress-activated protein kinase (SAPK), and overexpression of the dominant-negative p38alpha construct potently inhibited the serum withdrawal-induced COX-2 mRNA levels. Indeed, the half-life of COX-2 mRNA decreased from 9 to 4.5 h after SB203580 treatment, suggesting that signal transduction by the p38 SAPK pathway is required for COX-2 mRNA stability.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Apoptosis
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Blotting, Northern
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Blotting, Western
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Breast Neoplasms / metabolism*
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Bromodeoxyuridine / metabolism
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Cell Cycle
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Cell Nucleus / metabolism
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Culture Media, Serum-Free / metabolism
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Cyclooxygenase 2
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Dactinomycin / pharmacology
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Dinoprostone / metabolism
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Dose-Response Relationship, Drug
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Enzyme Inhibitors / pharmacology
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Gene Expression Regulation, Enzymologic
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Genes, Dominant
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Humans
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Imidazoles / pharmacology
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Isoenzymes / metabolism*
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Membrane Proteins
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Microscopy, Fluorescence
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Mitogen-Activated Protein Kinases / metabolism
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Mitogen-Activated Protein Kinases / physiology*
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Nucleic Acid Synthesis Inhibitors / pharmacology
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Prostaglandin-Endoperoxide Synthases / metabolism*
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Pyridines / pharmacology
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RNA Processing, Post-Transcriptional*
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RNA, Messenger / metabolism*
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Signal Transduction
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Time Factors
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Transfection
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Tumor Cells, Cultured
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p38 Mitogen-Activated Protein Kinases
Substances
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Culture Media, Serum-Free
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Enzyme Inhibitors
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Imidazoles
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Isoenzymes
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Membrane Proteins
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Nucleic Acid Synthesis Inhibitors
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Pyridines
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RNA, Messenger
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Dactinomycin
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Cyclooxygenase 2
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PTGS2 protein, human
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Prostaglandin-Endoperoxide Synthases
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases
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Bromodeoxyuridine
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Dinoprostone
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SB 203580