Efflux and uptake of androgen sulfates using transporter-overexpressing HEK293 cells and membrane vesicles

Hydrophilic steroid conjugates require active and facilitated transport mechanisms for their distribution into tissues and excretion from the body. The ATP-binding cassette (ABC) and solute carrier organic anion (SLCO) transporters involved in androgen sulfate (-S) disposition have been poorly characterized. In this study, we investigated the in vitro transport of testosterone-S, epitestosterone-S, dehydroepiandrosterone-S (DHEA-S), androsterone-S, and etiocholanolone-S by the multidrug resistance-associated proteins 2-4 (MRP2-4, ABCC2-4), breast cancer resistance protein (BCRP, ABCG2), and organic anion-transporting polypeptides (OATP) 1B1, 1B3, and 2B1 (SLCO1B1, SLCO1B3, and SLCO2B1) using human transporter-overexpressing HEK293 cells and membrane vesicles. We found testosterone-S, epitestosterone-S, and DHEA-S to be selectively transported by BCRP and/or MRP4, whereas all studied androgen sulfates were substrates of MRP3, OATP1B1, OATP1B3, and OATP2B1. MRP2 did not transport any of the studied compounds. Evaluation of transport kinetics revealed MRP4 to interact with its substrates at high to moderate affinity, whereas the observed affinities towards MRP3, BCRP, and OATPs were mostly moderate. These results help to build a better mechanistic understanding of the disposition of androgen sulfates in the human body. Additionally, this data may be used to assess the feasibility of androgen sulfates as additional biomarkers in doping detection.