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

Figure 3 Quercetin suppresses tumor necrosis factor-α-induced matrix metallopeptidase-9 expression in normal human gastric mucosa epithelial cells. A and B: Effects of quercetin on the viability of normal human gastric mucosa epithelial cells (GES-1). GES-1 cells were treated with different concentrations of quercetin (0, 0.01, 0.1, 1, 10, or 100 mM) for 24 h (A) or 48 h (B), and cell viability was measured using the cell counting Kit-8 assay; C: Cells were either untreated or treated with quercetin (0, 0.1, 0.3, or 1 mM) for 1 h before the addition of tumor necrosis factor-α (TNF-α) (30 ng/mL) and then incubated for 0, 16, or 24 h as described in the Materials and Methods section. Matrix metallopeptidase-9 zymogen activity was analyzed by gelatin zymography. One-way ANOVA was used for comparisons among different treatment time points (^aP < 0.05, ^bP < 0.01 vs control cells in 0 h). One-way ANOVA was used for comparisons among different treatments (^cP < 0.05, ^dP < 0.01 vs TNF-α-stimulated cells). Data are expressed as the mean ± SEM of three independent experiments. CCK-8: Cell Counting Kit-8; GAPDH: Glyceraldehyde-3-phosphate dehydrogenase; GES-1: Normal human gastric mucosa epithelial cell line; MMP-9: Matrix metallopeptidase-9; TNF-α: Tumor necrosis factor-α.