Interleukin-1beta induces cyclo-oxygenase-2 expression in gastric cancer cells by the p38 and p44/42 mitogen-activated protein kinase signaling pathways.
OBJECTIVE
Cyclo-oxygenase-2 (COX-2) is the inducible enzyme in the gastric mucosa responsible for prostaglandin production during inflammation and ulcer healing. The regulation of COX-2 gene expression in gastric epithelial cells is not well understood. In this study, we investigated the effect of interleukin (IL)-1beta on COX-2 expression in the human gastric cancer cell, and explored the signaling pathways involved.


METHODS
Gastric cancer cell line AGS was treated with IL-1beta or the inhibitors of mitogen-activated protein-Erk kinase (MEK) and p38 mitogen-activated protein (MAP) kinase prior to the addition of IL-1beta. The COX-2 mRNA or protein levels were measured by using RT-PCR or western blot analysis, respectively. Prostaglandin E2 (PGE2) production/secretion was determined by using the prostaglandin E2 EIA assay. The phosphorylation/activation of p44/42 and p38 MAP kinases were determined by using western blot analysis and using phospho-specific antibodies.


RESULTS
Interleukin-1beta treatment dose- and time-dependently increased COX-2 mRNA and protein expression levels, and enhanced PGE2 production/secretion in AGS cells. In contrast, IL-1beta had no effect on the level of the constitutively expressed COX-1. In parallel to the increase of COX-2, we showed that p44/42 and p38 MAP kinase activities were also upregulated by IL-1beta treatment. To demonstrate the cause-effect relationship, we showed that inhibition of MEK and p38 MAP kinase with specific inhibitors suppressed IL-1beta-mediated increases in COX-2 mRNA and protein levels, and the PGE2 production.


CONCLUSIONS
Our results demonstrated that in human gastric cancer cells, IL-1beta upregulates the COX-2 gene expression through the activation of MEK/p44/42 and p38 MAP kinases pathway.
Fan
X M
XM
Department of Medicine, University of Hong Kong, Hong Kong.
Wong
B C
BC
Lin
M C
MC
Cho
C H
CH
Wang
W P
WP
Kung
H F
HF
Lam
S K
SK
D000230:Adenocarcinoma / Q000378:metabolism; D015153:Blotting, Western; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis* / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013274:Stomach Neoplasms / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D007375:Interleukin-1; D007527:Isoenzymes; D008565:Membrane Proteins; D011725:Pyridines; D012333:RNA, Messenger; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D015232:Dinoprostone; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one