Involvement of cyclooxygenase-2--prostaglandin E2 pathway in interleukin-8 production in gastric cancer cells.
Prostaglandin E(2) (PGE(2)) is thought to play an important role in both inflammatory and anti-inflammatory effects. The effect of PGE(2) on the proinflammatory chemokine interleukin-8 (IL-8) in the gastric epithelial cells has not been defined yet. A gastric cancer cell line (MKN45) and primary gastric fibroblasts were cocultured with Helicobacter pylori standard strain (NCTC11637). The expressions of IL-8 and cyclooxygenase 2 (COX-2) mRNA were examined by reverse transcription polymerase chain reaction (RT-PCR) amplification. The amount of IL-8 antigen secreted by the MKN45 cells and gastric fibroblasts was measured by enzyme-linked immunosorbent assay (ELISA). We examined the effects of H pylori stimulation on IL-8 and COX-2 expression levels and the effects of COX-2 inhibitor on H pylori-induced IL-8 production in the MKN45 cells and gastric fibroblasts. Furthermore, we examined the expressions of subtypes of PGE(2) receptors, the effects of arachidonic acid and PGE(2) on IL-8 production, and the effects of PGE(2) on the total cellular cyclic adenosine monophosphate (cAMP) in MKN45 cells. MKN45 cells and gastric fibroblasts expressed IL-8 and COX-2 mRNA under stimulation with H pylori. The MKN45 cells produced IL-8 and PGE(2) antigen into the culture medium with H pylori stimulation, and the production level of IL-8 and PGE(2) antigen decreased significantly with COX-2 inhibitor pretreatment (concentration: 50 muM). On the other hand, the gastric fibroblasts strongly produced IL-8 antigen even in the unstimulated condition, and the amount of IL-8 antigen was not affected by H pylori stimulation and/or COX-2 inhibitor pretreatment. The MKN45 cells expressed IL-8 mRNA and released IL-8 antigen slightly, and the expression level of IL-8 mRNA and the amount of IL-8 antigen increased significantly with PGE(2) treatment in a dose-dependent manner. PGE(2)-induced IL-8 production was inhibited by pretreatment with EP2 and EP4 antagonists. The MKN45 cells expressed EP2 and EP4 subtypes of PGE(2) receptors, and these expression levels were not affected by H pylori stimulation or PGE(2) treatment. The amount of IL-8 antigen increased slightly, but not significantly, with arachidonic acid treatment. PGE(2) treatment for 15 minutes increased the total cellular cAMP in the MKN45 cells. These results suggest that the COX-2-PGE(2) pathway may be involved in IL-8 production in gastric epithelial cells.
Takehara
Hisashi
H
Fifth Department of Internal Medicine, Tokyo Medical University, Chuo 3-20-1, Ami, Inashiki, Ibaraki, 300-0395, Japan. priss2199@yahoo.co.jp
Iwamoto
Junichi
J
Iwamoto
Jun-Ichi
J
Mizokami
Yuji
Y
Takahashi
Kimiko
K
Ootubo
Toshiya
T
Miura
Syuuhei
S
Narasaka
Toshiaki
T
Takeyama
Hiroki
H
Omata
Takayuki
T
Shimokobe
Koichi
K
Ito
Masanori
M
Matsuoka
Takeshi
T
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016718:Arachidonic Acid / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000235:genetics / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D016480:Helicobacter pylori; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D009578:Nitrobenzenes / Q000494:pharmacology; D011448:Prostaglandin Antagonists / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018078:Receptors, Prostaglandin E / Q000235:genetics / Q000378:metabolism; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D013449:Sulfonamides / Q000494:pharmacology; D044004:Xanthones / Q000494:pharmacology
D001713:Biphenyl Compounds; D052246:Cyclooxygenase 2 Inhibitors; D016209:Interleukin-8; D009578:Nitrobenzenes; D011448:Prostaglandin Antagonists; D012333:RNA, Messenger; D018078:Receptors, Prostaglandin E; D013449:Sulfonamides; D044004:Xanthones; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D016718:Arachidonic Acid; C053876:6-isopropoxy-9-oxoxanthene-2-carboxylic acid; C046926:AH 23848; D000242:Cyclic AMP; D051546:Cyclooxygenase 2; D015232:Dinoprostone