Quercetin exerts anti-inflammatory effects via inhibiting tumor necrosis factor-α-induced matrix metalloproteinase-9 expression in normal human gastric epithelial cells

BACKGROUND Gastric injury is the most common digestive system disease worldwide and involves inflammation,which can lead to gastric ulcer or gastric cancer(GC).Matrix metallopeptidase-9[MMP-9(gelatinase-B)]plays an important role in inflammation and GC progression.Quercetin and quercetin-rich diets represent potential food supplements and a source of medications for treating gastric injury given their anti-inflammatory activities.However,the effects and mechanisms of action of quercetin on human chronic gastritis and whether quercetin can relieve symptoms remain unclear.AIM To assess whether tumor necrosis factor-α(TNF-α)-induced MMP-9 expression mediates the anti-inflammatory effects of quercetin in normal human gastric mucosal epithelial cells.METHODS The normal human gastric mucosa epithelial cell line GES-1 was used to establish a normal human gastric epithelial cell model of TNF-α-induced MMP-9 protein overexpression to evaluate the antiinflammatory effects of quercetin.The cell counting Kit-8 assay was used to evaluate the effects of varying quercetin doses on cell viability in the normal GES-1 cell line.Cell migration was measured using Transwell assay.The expression of proto-oncogene tyrosine-protein kinase Src(cSrc),phospho(p)-c-Src,extracellular-signal-regulated kinase 2(ERK2),p-ERK1/2,c-Fos,p-c-Fos,nuclear factor kappa B(NF-κB/p65),and p-p65 and the effects of their inhibitors were examined using Western blot analysis and measurement of luciferase activity.p65 expression was detected by immunofluorescence.MMP-9 m RNA and protein levels were measured by quantitative reverse transcription polymerase chain reaction(q RT–PCR)and gelatin zymography,respectively.RESULTS q RT-PCR and gelatin zymography showed that TNF-αinduced MMP-9 m RNA and protein expression in a dose-and time-dependent manner.These effects were reduced by the pretreatment of GES-1 cells with quercetin or a TNF-αantagonist(TNFR inhibitor)in a dose-and timedependent manner.Quercetin and TNF-αantagonists decreased the TNF-α-induced phosphorylation of c-Src,ERK1/2,c-Fos,and p65 in a dose-and time-dependent manner.Quercetin,TNF-αantagonist,PP1,U0126,and tanshinone IIA(TSIIA)reduced TNF-α-induced c-Fos phosphorylation and AP-1–Luciferase(Luc)activity in a dose-and time-dependent manner.Pretreatment with quercetin,TNF-αantagonist,PP1,U0126,or Bay 11-7082 reduced TNF-α-induced p65 phosphorylation and translocation and p65–Luc activity in a dose-and timedependent manner.TNF-αsignificantly increased GES-1 cell migration,and these results were reduced by pretreatment with quercetin or a TNF-αantagonist.CONCLUSION Quercetin significantly downregulates TNF-α-induced MMP-9 expression in GES-1 cells via the TNFR-c-Src–ERK1/2 and c-Fos or NF-κB pathways.