Evaluation of Drug Transport in MDCKII-Wild Type, MDCKII-MDR1, MDCKII-BCRP and Caco-2 Cell Lines

Background: Drug transporters function as gatekeepers and modulate drug access into body and various tissues. Thus, a thorough and precise understanding of transporter liability for compound uptake and efflux is critical during drug development.

Methods: In the present study, we assessed the apparent permeability (Papp) and compared efflux ratio of various compounds in stably transfected Madin-Darby Canine Kidney (MDCKII) cells overexpressing human P-gp (MDCKII-MDR1), human BCRP (MDCKII-BCRP), wild-type (MDCKII-WT), and Caco-2 cell monolayers.

Results: We observed that quinidine, a substrate for MDR1 transporter, showed efflux ratio (Papp B-A/ Papp A-B) of 838 in MDCKII-MDR1 cells which plummeted to 14 in presence of verapamil, a known inhibitor of MDR1. With MDCKII-WT cells, Papp of quinidine dropped from 2 to 1, in the presence of verapamil. Caco-2 cells showed a diminutive decrease in efflux ratio of quinidine from 2.5 to 1.6 by verapamil. Prazosin and dantrolene were evaluated in MDCKII-BCRP cells and were found to have 80-fold higher efflux ratio compared to MDCKII-WT cells. In Caco-2 cells, prazosin and dantrolene showed efflux ratio of 4 and 2, respectively. Rhodamine-123, a fluorogenic probe substrate of MDR1 showed an efflux ratio of 4 in Caco-2 cells and BCRP substrate estrone-3-sulphate showed an efflux ratio of 7. In presence of BCRP inhibitor fumitremorgin-c, the efflux ratio of estrone-3-sulfate dropped to 1 in Caco-2 cells.

Conclusion: The very high efflux ratios of MDR1 and BCRP substrates in transfected MDCKII cells clearly demonstrate the potential usefulness of these models to provide more definitive data to evaluate the transporter involvement compared to Caco-2 or MDCKII-WT cells.