Enhancement of Drug Accumulation by Andrastin A Produced by Penicillium sp. FO-3929 in Vincristine-resistant KB Cells

Abstract

In the course of our screening for compounds that reverse multidrug resistance, we found that the cytotoxicity of vincristine was enhanced 1.5∼20-fold depending on the concentration of andrastin A in vincristine-resistant KB cells (VJ-300). Andrastin A alone had no effect on the growth of drug sensitive KB cells and VJ-300 cells. On the other hand, andrastin A (25 and 50 μg/ml) significantly enhanced accumulation of [³H]vincristine in VJ-300 cells. Andrastin A (50 μg/ml) completely inhibited the binding of [³H]azidopine to the P-glycoprotein in VJ-300 cells. The result suggests that andrastin A directly interacts with P-glycoprotein and inhibits the efflux of antitumor agents in drug resistant cells.