RT Journal Article
SR Electronic
T1 Co-expression of ABCB1 and ABCG2 in a Cell Line Model Reveals Both Independent and Additive Transporter Function
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP dmd.118.086181
DO 10.1124/dmd.118.086181
A1 Andrea N. Robinson
A1 Bethelihem G. Tebase
A1 Sonia C. Francone
A1 Lyn M. Huff
A1 Hanna Kozlowski
A1 Dominique Cossari
A1 Jung-Min Lee
A1 Dominic Esposito
A1 Robert W. Robey
A1 Michael M. Gottesman
YR 2019
UL http://dmd.aspetjournals.org/content/early/2019/05/02/dmd.118.086181.abstract
AB Although overexpression of multiple ATP-binding cassette transporters has been reported in clinical samples, few studies have examined how co-expression of multiple transporters affected resistance to chemotherapeutic drugs. We therefore examined how co-expression of ABCB1 (P-glycoprotein) and ABCG2 contribute to drug resistance in a cell line model. HEK-293 cells were transfected with vector encoding full-length ABCB1, ABCG2, or a bicistronic vector containing both genes, each under the control of a separate promoter. Cells transfected with both transporters (B1/G2 cells) demonstrated high levels of both transporters and uptake of both the ABCB1-specific substrate rhodamine 123 and the ABCG2-specific substrate pheophorbide a was reduced when examined by flow cytometry. B1/G2 cells were also cross-resistant to the ABCB1 substrate doxorubicin, the ABCG2 substrate topotecan, as well as mitoxantrone and the cell cycle checkpoint kinase 1 inhibitor prexasertib, both of which were found to be substrates of both ABCB1 and ABCG2. When B1/G2 cells were incubated with both rhodamine 123 and pheophorbide a, transport of both compounds was observed, suggesting that ABCB1 and ABCG2, when co-expressed, can function independently to transport substrates. ABCB1 and ABCG2 also functioned additively to transport the common fluorescent substrates mitoxantrone and BODIPY®-prazosin, as it was necessary to inhibit both transporters to prevent efflux from B1/G2 cells. ABCG2 expression was also found to decrease the efficacy of the ABCB1 inhibitor tariquidar in B1/G2 cells. Thus, ABCB1 and ABCG2 can independently and additively confer resistance to substrates, underscoring the need to inhibit multiple transporters when they are co-expressed.SIGNIFICANCE STATEMENT N/A