TY - JOUR T1 - Interindividual Regulation of the Breast Cancer Resistance Protein/<em>ABCG2</em> Transporter in Term Human Placentas JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 619 LP - 627 DO - 10.1124/dmd.117.079228 VL - 46 IS - 5 AU - Kristin M. Bircsak AU - Jamie E. Moscovitz AU - Xia Wen AU - Faith Archer AU - Poi Yu Sofia Yuen AU - Moiz Mohammed AU - Naureen Memon AU - Barry I. Weinberger AU - Laura M. Saba AU - Anna M. Vetrano AU - Lauren M. Aleksunes Y1 - 2018/05/01 UR - http://dmd.aspetjournals.org/content/46/5/619.abstract N2 - The breast cancer resistance protein (BCRP/ABCG2) is a maternally-facing efflux transporter that regulates the placental disposition of chemicals. Transcription factors and gene variants are important regulatory factors that influence transporter expression. In this study, we sought to identify the genetic and transcriptional mechanisms underlying the interindividual expression of BCRP mRNA and protein across 137 term placentas from uncomplicated pregnancies. Placental expression of BCRP and regulatory transcription factor mRNAs was measured using multiplex-branched DNA analysis. BCRP expression and ABCG2 genotypes were determined using Western blot and Fluidigm Biomark genetic analysis, respectively. Placentas were obtained from a racially and ethnically diverse population, including Caucasian (33%), African American (14%), Asian (14%), Hispanic (15%), and mixed (16%) backgrounds, as well as unknown origins (7%). Between placentas, BCRP mRNA and protein varied up to 47-fold and 14-fold, respectively. In particular, BCRP mRNA correlated significantly with known transcription factor mRNAs, including nuclear factor erythroid 2-related factor 2 and aryl hydrocarbon receptor. Somewhat surprisingly, single-nucleotide polymorphisms (SNPs) in the ABCG2 noncoding regions were not associated with variation in placental BCRP mRNA or protein. Instead, the coding region polymorphism (C421A/Q141K) corresponded with 40%–50% lower BCRP protein in 421C/A and 421A/A placentas compared with wild types (421C/C). Although BCRP protein and mRNA expression weakly correlated (r = 0.25, P = 0.040), this relationship was absent in individuals expressing the C421A variant allele. Study results contribute to our understanding of the interindividual regulation of BCRP expression in term placentas and may help to identify infants at risk for increased fetal exposure to chemicals due to low expression of this efflux protein. ER -