Induced microsomal PGE synthase-1 is involved in cyclooxygenase-2-dependent PGE2 production in gastric fibroblasts.
We have previously shown that the cyclooxygenase (COX)-2/PGE2 pathway plays a key role in VEGF production in gastric fibroblasts. Recent studies have identified three PGE synthase (PGES) isozymes: cytosolic PGES (cPGES) and microsomal PGES (mPGES)-1 and -2, but little is known regarding the expression and roles of these enzymes in gastric fibroblasts. Thus we examined IL-1beta-stimulated mPGES-1 and cPGES mRNA and protein expression in gastric fibroblasts by quantitative PCR and Western blot analysis, respectively, and studied both their relationship to COX-1 and -2 and their roles in PGE2 and VEGF production in vitro. IL-1beta stimulated increases in both COX-2 and mPGES-1 mRNA and protein expression levels. However, COX-2 mRNA and protein expression were more rapidly induced than mPGES-1 mRNA and protein expression. Furthermore, MK-886, a nonselective mPGES-1 inhibitor, failed to inhibit IL-1beta-induced PGE2 release at the 8-h time point, while totally inhibiting PGE2 at the later stage. However, MK-886 did inhibit IL-1beta-stimulated PGES activity in vitro by 86.8%. N-(2-cyclohexyloxy-4-nitrophenyl)-methanesulfonamide (NS-398), a selective COX-2 inhibitor, totally inhibited PGE2 production at both the 8-h and 24-h time points, suggesting that COX-2-dependent PGE2 generation does not depend on mPGES-1 activity at the early stage. In contrast, NS-398 did not inhibit VEGF production at 8 h, and only partially at 24 h, whereas MK-886 totally inhibited VEGF production at each time point. These results suggest that IL-1beta-induced mPGES-1 protein expression preferentially coupled with COX-2 protein at late stages of PGE2 production and that IL-1beta-stimulated VEGF production was totally dependent on membrane-associated proteins involved in eicosanoid and glutathione metabolism (MAPEG) superfamily proteins, which includes mPGES-1, but was partially dependent on the COX-2/PGE2 pathway.
Pathophysiological Management, Medical Oncology Third Department of Internal Medicine, Graduate School of Medicine, Nippon Medical School, Bunkyo-ku, Tokyo, Japan.
Yoko
Y
Shinji
Taku
T
Tsukui
Atsushi
A
Tatsuguchi
Kei
K
Shinoki
Masafumi
M
Kusunoki
Kenji
K
Suzuki
Tetsuro
T
Hiratsuka
Ken
K
Wada
Seiji
S
Futagami
Kazumasa
K
Miyake
Katya
K
Gudis
Choitsu
C
Sakamoto
D002460:Cell Line; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D015232:Dinoprostone / Q000096:biosynthesis*; D005347:Fibroblasts / Q000201:enzymology*; D015870:Gene Expression; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D008565:Membrane Proteins; D008861:Microsomes / Q000201:enzymology*; D009578:Nitrobenzenes / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011720:Pyrazoles / Q000494:pharmacology; D013270:Stomach / Q000166:cytology / Q000502:physiology; D013449:Sulfonamides / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D002722:Chlorobenzenes
D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D015232:Dinoprostone; D007211:Indoles; D007375:Interleukin-1; D008565:Membrane Proteins; D009578:Nitrobenzenes; D011451:Prostaglandin-Endoperoxide Synthases; D011720:Pyrazoles; D013449:Sulfonamides; D042461:Vascular Endothelial Growth Factor A; C115461:SC 560; C467484:VEGFA protein, human; C060893:MK-886; D002722:Chlorobenzenes; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human