Melittin Inhibits Cell Migration and Invasion

Cell invasion and migration assays were performed as described previously (25 (link)). In brief, A549 and H358 cells were treated with melittin (2 μg/mL) for 24 h and non-treated cells were used as control. Migration and invasion of A549 and H358 cells was conducted in a 6-well culture plate with chamber inserts (BD Biosciences, USA). For migration assays, 1×10⁴/well concentration of the A549 and H358 cells were placed into the upper chamber with the non-coated membrane for 48 h at 37°C. For invasion assays, cells (1×10⁴/well) were placed into the upper chamber with the Matrigel-coated membrane for 48 h at 37°C. Cells were fixed in 4% paraformaldehyde at 25°C for 15 min and stained with 0.1% crystal violet dye (Sigma-Aldrich) at 25°C for 15 min. Migration and invasion of A549 and H358 cells were counted in at least three random fields of every membrane in a microscope (magnification ×50; Olympus, Japan). The percentage of migrated cells was qualified as follows: (control - melittin) / control × 100%.