Identification of Food-Derived Isoflavone Sulfates as Inhibition Markers for Intestinal Breast Cancer Resistance Proteins.

Abstract

Potential inhibition of the breast cancer resistance protein (BCRP), a drug efflux transporter, is a key issue during drug development, and the use of its physiologic substrates as biomarkers can be advantageous to assess inhibition. In this study, we aimed to identify BCRP substrates by an untargeted metabolomic approach. Mice were orally administered lapatinib to inhibit BCRP in vivo, and plasma samples were assessed by liquid chromatography/time of flight/mass spectrometry with all-ion fragmentation acquisition and quantified by liquid chromatography with tandem mass spectrometry. A differential metabolomic analysis was also performed for plasma from Bcrp -/- and wild-type mice. Plasma peaks of food-derived isoflavone metabolites, daidzein sulfate (DS), and genistein sulfate (GS) increased after lapatinib administration and in Bcrp -/- mice. Administration of lapatinib and another BCRP inhibitor febuxostat increased the area under the plasma concentration-time curve (AUC) of DS, GS, and equol sulfate (ES) by 3.6- and 1.8-, 5.6- and 4.1-, and 1.6- and 4.8-fold, respectively. BCRP inhibitors also increased the AUC and maximum plasma concentration of DS and ES after coadministration with each parent compound. After adding parent compounds to the apical side of induced pluripotent stem cell-derived small intestinal epithelial-like cells, DS, GS, and ES in the basal compartment significantly increased in the presence of lapatinib and febuxostat, suggesting the inhibition of intestinal BCRP. ATP-dependent uptake of DS and ES in BCRP-expressing membrane vesicles was reduced by both inhibitors, indicating inhibition of BCRP-mediated DS and ES transport. Thus, we propose the first evidence of surrogate markers for BCRP inhibition. SIGNIFICANCE STATEMENT: This study performed untargeted metabolomics to identify substrates of BCRP/ABCG2 to assess changes in its transport activity in vivo by BCRP/ABCG2 inhibitors. Food-derived isoflavone sulfates were identified as useful markers for evaluating changes in BCRP-mediated transport in the small intestine by its inhibitors.