Figure 6.

Pretreatment with piperine inhibits MMP-2 activity and expression in A549 cells treated with TGF-β1. A549 cells were pretreated with non-cytotoxic doses of piperine (20, 40 and 80 μM) for 24 h, followed by treatment with 1 ng/mL TGF-β1 for 48 h. (A) After treatments, gelatin zymography was employed to detect MMP activity. (B) Western blot analysis to investigate the expression of MMP-2 (C) and MMP-9 (D) was performed by using the cell culture medium. The maximum volume of supernatant used to analyze the activity and expression of MMPs was 30 µL. The volume of each experimental point was adjusted based on the amount of protein in the cell lysates. The results are representative of three independent experiments. Quantitative Western blot analyses are shown as mean ± SD. * p ≤ 0.05 vs. untreated cells (CTR), † p ≤ 0.05 vs. TGF-β.