Human P-glycoprotein transports cyclosporin A and FK506.
Cyclosporin A, a cyclic undecapeptide, and FK506 are efficient immunosuppressive agents. They also attract attention as effective P-glycoprotein modulators that inhibit P-glycoprotein from binding to anticancer drugs and overcome multidrug resistance. Cyclosporin A itself interacts with a common binding site of P-glycoprotein to which Vinca alkaloids and verapamil bind. We were interested to determine whether cyclosporin A and FK506 are substrates for P-glycoprotein to transport, and we studied their transcellular transport. In LLC-PK1 cells, derived from porcine kidney proximal tubule and forming a highly polarized epithelium, cyclosporin A was transported in a saturable manner. LLC-GA5-COL300, a transformant cell line derived by transfecting LLC-PK1 with human MDR1 cDNA isolated from normal adrenal gland, expresses P-glycoprotein specifically on the apical surface and shows a typical multidrug-resistant phenotype. LLC-GA5-COL300 cells showed increased transport of cyclosporin A from the basal to the apical side. Kinetic analysis showed that this transport was a typical saturable transport with the calculated apparent Michaelis constant (Kappm) and the maximum flux (Vmax) as 8.4 microM and 2.4 nmol/mg protein/h, respectively. LLC-GA5-COL300 also showed increased transport of FK506 from the basal to the apical side. These results indicate that P-glycoprotein transports the immunosuppressive agents cyclosporin A and FK506.
Saeki
T
T
Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto University Hospital, Japan.
Ueda
K
K
Tanigawara
Y
Y
Hori
R
R
Komano
T
T
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002461:Cell Line, Transformed; D016572:Cyclosporine / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000378:metabolism*; D013552:Swine; D016559:Tacrolimus / Q000378:metabolism*; D014162:Transfection
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D016572:Cyclosporine; D016559:Tacrolimus