Figure 2.

Inhibition of MMP-9 and -2 activities by metformin. (A) 80% Confluent HT-1080 cells were treated with various concentrations of metformin or AICAR in serum-free medium. The conditioned media were collected after 24 h, and gelatin zymography was performed. Each blot is representative of at least three others. (B) HT-1080 cells were incubated with metformin or AICAR for 24 h. MMP-9 and -2 expression in the media were analysed by Western blotting. β-Actin in the cell lysate is shown as a control. Each blot is representative of at least three others. (C) HT-1080 cells were incubated with varying concentrations of metformin in the presence of PMA (30 nM) for 24 h. MMP activity in the medium was analysed by gelatin zymography. Each blot is representative of at least three others. (D) HT-1080 cells were incubated with metformin and/or PMA (30 nM) for 24 h. MMP-9 and -2 expressions in the medium were analysed by Western blotting. β-Actin in the cell lysate is shown as a control. Each blot is representative of at least three others. (E and F) HT-1080 cells were incubated with metformin and/or PMA (30 nM) for 24 h. The mRNA expression of MMP-9, -2, TIMP-1 and TIMP-2 in the cells was analysed by semi-quantitative RT–PCR (E). GAPDH expression was included as an internal control. Each blot is representative of at least three others. MMP-9 and -2 mRNA expressions were analysed by real-time PCR (F). MMP-9 and -2 mRNA expressions were compared between treated and untreated cells at each time-point. *Significantly different from PMA treatment only (P < 0.01).