Characterization of substrates and inhibitors for the in vitro assessment of Bcrp mediated drug-drug interactions.
OBJECTIVE
In vitro assessment of drug candidates' affinity for multi-drug resistance proteins is of crucial importance for the prediction of in vivo pharmacokinetics and drug-drug interactions. To have well described experimental tools at hand, the objective of the study was to characterize substrates and inhibitors of Breast Cancer Resistance Protein (BCRP) and P-glycoprotein (P-gp).


METHODS
Madin-Darbin canine kidney cells overexpressing mouse Bcrp (MDCKII-Bcrp) were incubated with various Bcrp substrates, or a mixture of substrate and inhibitor to either the apical (A) or basolateral (B) compartment of insert filter plates. Substrate concentrations in both compartments at time points t = 0 h and t = 2 h were determined by LC-MS/MS, and respective permeation coefficients (Papp) and efflux ratios were calculated.


RESULTS
The Bcrp inhibitor Ko143 blocked topotecan and ABZSO transport in a concentration-dependent manner. P-gp inhibitors ivermectin, LY335979, PSC833, and the P-gp/Bcrp inhibitor ritonavir did not influence Bcrp mediated topotecan transport, however, blocked ABZSO transport. Additionally, neither was ABZSO transport influenced by topotecan, nor topotecan transport by ABZSO.


CONCLUSIONS
Data suggest different modes of substrate and inhibitor binding to Bcrp. In order to not overlook potential drug-drug interactions when testing drug candidates for inhibitory potential towards Bcrp, distinct Bcrp probe substrates should be used.
Muenster
Uwe
U
Department of Metabolism and Pharmacokinetics, Bayer HealthCare AG, Aprather Weg, 42096, Wuppertal-Aprath, Germany.
Grieshop
Birgit
B
Ickenroth
Karsten
K
Gnoth
Mark Jean
MJ
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015766:Albendazole / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D002460:Cell Line; D003524:Cyclosporins / Q000494:pharmacology; D003986:Dibenzocycloheptenes / Q000494:pharmacology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007559:Ivermectin / Q000494:pharmacology; D018374:LLC-PK1 Cells; D051379:Mice; D011804:Quinolines / Q000494:pharmacology; D019438:Ritonavir / Q000494:pharmacology; D013552:Swine; D013997:Time Factors; D019772:Topotecan / Q000378:metabolism; D014162:Transfection
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; C501412:Abcg2 protein, mouse; D003524:Cyclosporins; D003986:Dibenzocycloheptenes; D011804:Quinolines; D007559:Ivermectin; D019772:Topotecan; C095179:zosuquidar trihydrochloride; D015766:Albendazole; C027186:albendazole sulfoxide; D019438:Ritonavir; C070272:valspodar