RESUMO
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.
Assuntos
Adenocarcinoma/metabolismo , Ciclo-Oxigenase 2/metabolismo , Dinoprostona/metabolismo , Interleucina-8/metabolismo , Neoplasias Gástricas/metabolismo , Adenocarcinoma/genética , Adenocarcinoma/patologia , Ácido Araquidônico/farmacologia , Compostos de Bifenilo/farmacologia , Linhagem Celular Tumoral , AMP Cíclico/genética , AMP Cíclico/metabolismo , Ciclo-Oxigenase 2/genética , Inibidores de Ciclo-Oxigenase 2/farmacologia , Dinoprostona/genética , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Regulação Neoplásica da Expressão Gênica , Helicobacter pylori , Humanos , Interleucina-8/genética , Nitrobenzenos/farmacologia , Antagonistas de Prostaglandina/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Prostaglandina E/genética , Receptores de Prostaglandina E/metabolismo , Neoplasias Gástricas/genética , Neoplasias Gástricas/patologia , Sulfonamidas/farmacologia , Xantonas/farmacologiaRESUMO
OBJECTIVE: Destruction of the extracellular matrix is essential for tumor invasion and metastasis. The relationship between Helicobacter pylori (H. pylori) infection and destruction of the extracellular matrix is not yet clear. Urokinase-type plasminogen activator (uPA) plays an important role in the destruction of the extracellular matrix and basement membrane. Urokinase-type plasminogen activator receptor (uPAR) and plasminogen activator inhibitor-1(PAI-1) appear to be associated with these processes. To clarify the role of H. pylori infection in the processes of destruction of the extracellular matrix and basement membrane in cancerous tissue, the effect of H. pylori on the expressions of uPA, uPAR and PAI-1 in cancer cells was investigated. MATERIALS AND METHODS: Gastric cancer cell lines (MKN45, KATO-III) were co-cultured with H. pylori standard strain (NCTC11637), cagA-negative strain and clinical isolated strain. The specific inductions of uPA, uPAR and PAI-1 mRNA were examined by reverse transcription-polymerase chain reaction (RT-PCR) amplification. The secreted uPA antigen was measured by enzyme-linked immunosorbent assay (ELISA). To evaluate the role of transcription factor NF-kappaB in uPA and uPAR gene transcription with H. pylori stimulation, the effect of NF-kappaB inhibitor MG132 on H. pylori-induced uPA and uPAR mRNA expression was examined. RESULTS: The expressions of both uPA and uPAR mRNAs in the gastric cancer cell lines (MKN45 and KATO- III) were increased markedly (uPA mRNA; MKN45: 12-fold, KATO-III: 5-fold) (uPAR mRNA; MKN45: 3-fold, KATO-III: 3-fold) with H. pylori NCTC11637 strain stimulation, whereas the expression levels of uPA and uPAR mRNA did not increase with cagA-negative strain stimulation. These cancer cell lines slightly secreted uPA antigen into the culture medium, and the amount of uPA antigen increased dramatically by stimulation with H. pylori NCTC11637 and cagA-positive clinical isolated strains. These gastric cancer cell lines also slightly secreted PAI-1 antigen into the culture medium, and the amount of PAI-1 antigen was not affected by H. pylori NCTC11637 stimulation. H. pylori-induced uPA and uPAR mRNA expressions were strongly down-regulated by pretreatment with MG132 in both cell lines. CONCLUSIONS: The results of this study indicated the possibility that cagA-positive H. pylori may play an important role not only in tissue remodeling, angiogenesis and wound healing but also in the process of degradation of the extracellular matrix breakdown, tumor invasion and metastasis by inducing uPA and uPAR complex in the gastric cancer cells.
