Transport of dietary phenethyl isothiocyanate is mediated by multidrug resistance protein 2 but not P-glycoprotein.
We demonstrated recently that phenethyl isothiocyanate (PEITC), a potent anticarcinogen present in cruciferous vegetables, inhibited P-glycoprotein (P-gp) and multidrug resistance protein 1 (MRP1) and that MRP1 can transport PEITC and/or its metabolites. In this study, we have examined whether PEITC is transported by P-gp and MRP2, two transporters with high expression in human intestine, liver and kidney. Using (14)C-PEITC, no significant difference was observed for the intracellular accumulation of PEITC in human breast cancer MCF-7/sensitive (control) and MCF-7/ADR (P-gp overexpressing) cells at PEITC concentrations of 1, 10 and 50 microM. Moreover, the presence of verapamil or PSC833, two P-gp inhibitors, had no significant effect on the intracellular accumulation of PEITC in P-gp overexpressing MCF-7/ADR and MDA435/LCC6MDR1 cells, indicating that PEITC may not be a substrate for P-gp. In contrast, (14)C-PEITC intracellular accumulation in the kidney epithelial MDCK II/MRP2 cells (transfected with human MRP2) was significantly lower than in the wild-type MDCK II/wt cells at PEITC concentrations of 1, 5, 10 and 50 microM. The presence of MK571, an MRP inhibitor, significantly enhanced (14)C-PEITC accumulation in MDCK II/MRP2 but not MDCK II/wt cells. Furthermore, depletion of intracellular glutathione (GSH) following treatment with buthionine sulphoximine, an inhibitor of GSH biosynthesis, significantly increased (14)C-PEITC intracellular accumulation in a concentration-dependent manner. Transcellular transport studies also demonstrated that depletion of intracellular GSH reduced the mean ratio of basal-to-apical transport to apical-to-basal transport of PEITC in MDCK II/MRP2, but not MDCK II/wt cell monolayers. These results indicate that GSH plays an important role in the MRP2-mediated transport of PEITC. The findings provide new information concerning the interactions between PEITC and membrane transporters and suggest the possibility of PEITC interactions with xenobiotics that are MRP2 substrates.
Ji
Yan
Y
Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, The State University of New York at Buffalo, Amherst, NY 14260, USA.
Morris
Marilyn E
ME
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000502:physiology*; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000502:physiology*; D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D045744:Cell Line, Tumor; D004032:Diet; D004285:Dogs; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D017879:Isothiocyanates / Q000378:metabolism*; D000089762:Multidrug Resistance-Associated Protein 2; D000097202:ATP-Binding Cassette Sub-Family B Member 4
D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D005978:Glutathione; D017879:Isothiocyanates; D000089762:Multidrug Resistance-Associated Protein 2; D000097202:ATP-Binding Cassette Sub-Family B Member 4; C000715087:ABCC2 protein, human; C058305:phenethyl isothiocyanate