Relationship between expression level of P-glycoprotein and daunorubicin transport in LLC-PK1 cells transfected with human MDR1 gene.
P-Glycoprotein-mediated transcellular transport and intracellular accumulation of [3H]daunorubicin were examined in cell monolayers with different levels of P-glycoprotein. The porcine kidney epithelial cell line LLC-PK1 was transfected with MDR1 cDNA, and four sublines, LLC-GA5, LLC-GA5-VLB4, LLC-GA5-COL10, and LLC-GA5-COL150, were obtained by culturing the cells in the absence or in the presence of 4 ng/mL vinblastine, 10 ng/mL colchicine, and 150 ng/mL colchicine, respectively. Western blot analysis showed a large difference in P-glycoprotein expression within these sublines. The degree of drug resistance was dependent on the expression level of P-glycoprotein. The amount of the unidirectional transport of [3H]daunorubicin by P-glycoprotein corresponded to the expression level of P-glycoprotein, which was followed by the decrease in intracellular accumulation of the agent. The concentration of cyclosporin A required for the inhibition of P-glycoprotein-mediated transport of [3H]daunorubicin was higher in cells with a high expression of P-glycoprotein. These findings suggest that the transport of daunorubicin by P-glycoprotein and its inhibition by cyclosporin A correspond to the expression level of P-glycoprotein.
Tanaka
K
K
Department of Pharmacy, Faculty of Medicine, Kyoto University Hospital, Japan.
Hirai
M
M
Tanigawara
Y
Y
Ueda
K
K
Takano
M
M
Hori
R
R
Inui
K
K
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000502:physiology*; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000493:pharmacokinetics*; D001692:Biological Transport; D016572:Cyclosporine / Q000493:pharmacokinetics / Q000494:pharmacology; D003630:Daunorubicin / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D018374:LLC-PK1 Cells; D013552:Swine; D014162:Transfection
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D016572:Cyclosporine; D003630:Daunorubicin