Expanding the Efflux In Vitro Assay Toolbox: A CRISPR-Cas9 Edited MDCK Cell Line with Human BCRP and Completely Lacking Canine MDR1

Abstract The Breast Cancer Resistance Protein (BCRP) is a key transporter in drug efflux and drug-drug interactions. However, endogenous expression of Multidrug 1 (MDR1) confounds the interpretation BCRP-mediated transport in vitro models. Here we used CRISPR-Cas9 edited Madin-Darby canine kidney (MDCK) II cell line (MDCKcMDR1-KO) for stable human BCRP (hBCRP) with no MDR1 (cMDR1) (MDCK-hBCRPcMDR1-KO). Targeted quantitative proteomics verified hBCRP, global analysis entire proteome corroborated or very low background other proteins metabolizing enzymes. This new line, had similar like MDCKcMDR1-KO previously established, corresponding overexpressing (hMDR1), MDCK-hMDR1cMDR1-KO. Functional studies MDCK-hBCRPcMDR1-KO confirmed high hBCRP activity. together MDCK-hMDR1cMDR1-KO easily accurately identified shared specific substrates hMDR1 transporters. These lines offer new, improved tools assessment interactions development.