Inhibitory effect of statins on tumor cell metastasis, migration, and invasion. (A, B) Determination of the statin concentrations suitable for administration to B16BL6 cells. The cells were incubated in 96-well plates for 24 h and then treated with 0.01-0.5 μM fluvastatin, or 0.1-5 μM simvastatin. After 1, 3, or 5 d, cell viability was quantified by WST-8 assays. The results are representative of 5 independent experiments. (C) B16BL6 cells, which had been pretreated with 0.05 μM fluvastatin or 0.1 μM simvastatin for 3 d, were injected into the tail veins of syngeneic C57BL/6J mice. After 14 d, visible nodules that had metastasized to the lungs were counted. The results are expressed as the mean ± SD of 9 mice. (D, E) B16BL6 cells were pretreated with 0.05 μM fluvastatin or 0.1 μM simvastatin for 3 d, after which cells were seeded into the upper compartments of chambers. (D) Migration was analyzed by Boyden chamber assays using Falcon cell culture inserts. (E) Invasive properties were analyzed using Falcon cell culture inserts covered with 50 μg of Matrigel per filter. For both assays, the lower chambers contained conditioned media from NIH/3T3 cells cultured for 24 h, which was used as a chemoattractant. After incubation for 24 h, the cells invading the lower surface were counted microscopically. The results are representative of 5 independent experiments.