Table 1.
List of primers for real-time quantitative PCR.
Fig 1.
The effect of S-1-propenyl-L-cysteine (S1PC) on the lipopolysaccharide (LPS)-induced gene expression of matrix metalloproteinase (MMP)-1 and -3.
HGF-1 cells were exposed to S1PC (300 μM) in the presence or absence of LPS (3 μg/mL) for 48 h. Bar graphs show the mRNA level of MMP-1 and -3, calculated relative to the level in each vehicle group. Values represent the mean ± S.D. (n = 5). ## p < 0.01.
Fig 2.
The effect of S1PC on the LPS-induced expression and secretion of MMP-1.
(a) HGF-1 cells were exposed to S1PC (300 μM) in the presence or absence of LPS (3 μg/mL) for the indicated times. Bar graphs show the mRNA level of MMP-1, calculated relative to the level in the vehicle group at each time point. Values represent the mean ± S.D. (n = 5). # p < 0.05, ## p < 0.01. (b) HGF-1 cells were exposed to S1PC in the presence or absence of LPS for 48 h at indicated concentrations. The graph shows the mRNA level of MMP-1. Values represent the mean ± S.D. (n = 3). # p < 0.05, ## p < 0.01. (c) HGF-1 cells were exposed to S1PC (300 μM) in the presence or absence of LPS for the indicated times. Photographs show a representative result of Western blotting of MMP-1 with β-actin as an internal control. The graph shows the ratio of the MMP-1 band intensity relative to that of β-actin. Values represent the mean ± S.D. (n = 5). # p < 0.05, ## p < 0.01. (d) HGF-1 cells were exposed to S1PC in the presence or absence of LPS for 72 h. The graph shows the concentration of MMP-1 in media determined by ELISA normalized to the total cell protein amount in each treatment group. Values represent the mean ± S.D. (n = 3). ## p < 0.01.
Fig 3.
The effect of S1PC on the LPS-induced epidermal growth factor receptor (EGFR) transactivation.
(a) HGF-1 cells were exposed to S1PC (300 μM) in the presence or absence of LPS (3 μg/mL) for the indicated times. Photographs show a representative result of Western blotting of phosphorylated EGFR (pEGFR) and EGFR with β-actin as an internal control. Bar graphs show the ratio of the pEGFR band intensity relative to that of EGFR and β-actin, calculated relative to the level at 0 min. Values represent the mean ± S.D. (n = 4). ## p < 0.01. (b) HGF-1 cells were exposed to EGFR tyrosine kinase inhibitor AG-1478 (0.1 nM) in the presence or absence of LPS for 48 h. Photographs show a representative result of Western blotting of MMP-1 with β-actin as an internal control. Bar graphs show the ratio of the MMP-1 band intensity relative to that of β-actin. Values represent the mean ± S.D. (n = 3). ## p < 0.01.
Fig 4.
The effect of S1PC on the LPS-induced tumor necrosis factor-α converting enzyme (TACE/ADAM17) cleavage.
(a) HGF-1 cells were exposed to S1PC (300 μM) in the presence or absence of LPS (3 μg/mL) for the indicated times. Photographs show a representative result of Western blotting of the active form of TACE with β-actin as an internal control. Bar graphs show the ratio of the active form of TACE band intensity relative to that of β-actin, calculated relative to the level at 0 min. Values represent the mean ± S.D. (n = 4). ## p < 0.01. (b) HGF-1 cells were exposed to an TACE inhibitor TAPI-1 (1 μM) in the presence or absence of LPS for 48 h. Photographs show a representative result of Western blotting of MMP-1. Bar graphs show the ratio of the MMP-1 band intensity relative to that of β-actin. Values represent the mean ± S.D. (n = 3). # p < 0.05.
Fig 5.
A proposed mechanism by which S1PC suppressed the LPS-induced MMP-1 expression in human gingival fibroblasts.
The binding of LPS to TLR4 activates TACE and this activation promotes the phosphorylation of EGFR to induce the expression of MMP-1 in HGF-1 cells. Both EGFR tyrosine kinase and TACE inhibitors, AG-1478 and TAPI-1, antagonize the LPS-induced expression of MMP-1. S1PC suppresses the LPS-induced activation of TACE and subsequent phosphorylation of EGFR, thus ultimately suppressing the expression of MMP-1. TACE: tumor necrosis factor-α converting enzyme, EGFR: epidermal growth factor receptor, LPS: lipopolysaccharide, MMP-1: matrix metalloproteinase-1, S1PC: S-1-propenyl-L-cysteine, TLR4: toll-like receptor 4.