title: Regulation of the expression of renal drug transporters in KEAP1-knockdown human tubular cells.
abstract: The kidney secretes various xenobiotics through a well-established transport system. The transcription factor NF-E2-related factor 2 (NRF2) up-regulates a subset of genes encoding antioxidant and detoxification proteins. Kelch-like ECH-associated protein 1 (KEAP1) down-regulates NRF2 by facilitating continuous degradation of NRF2 protein. Here, we investigated the role of NRF2 in the expression of renal drug transporters by using a stable KEAP1 knockdown renal tubular HK-2 cell line (shKEAP1). KEAP1 knockdown resulted in a significant increase in the expression of four renal transporters, namely, multidrug resistance protein 1 (MDR1; ABCB1), breast cancer resistance protein (BCRP; ABCG2), multidrug resistance-associated protein 2 (MRP2; ABCC2), and MRP3 (ABCC3). In western blot and immunocytochemical analyses, protein levels of these transporters were also significantly higher in the knockdown group. Consequently, shKEAP1 cells released more Hoechst 33342 fluorescent dye and doxorubicin, and they were more resistant to doxorubicin than the control cells. In addition, cisplatin resistance of shKEAP1 decreased upon co-incubation with a transporter inhibitor. Whereas, a short term incubation (24h) with sulforaphane did not show noticeable changes in the expression of transporter. Collectively, these results indicate that NRF2 regulates the expression of MDR1, BCRP, MRP2, and MRP3 in human tubular epithelial cells. Altered expression of these transporters affects drug secretion in these cells, which may result in the renal cellular damage upon exposure to nephrotoxic xenobiotics.
authors.affiliation: College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do 420-743, Republic of Korea.
authors.forename: Hyuk-Sang
authors.initials: HS
authors.lastname: Jeong
authors.affiliation: College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do 420-743, Republic of Korea.
authors.forename: In-geun
authors.initials: IG
authors.lastname: Ryoo
authors.affiliation: College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do 420-743, Republic of Korea. Electronic address: mkwak@catholic.ac.k.
authors.forename: Mi-Kyoung
authors.initials: MK
authors.lastname: Kwak
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D001562:Benzimidazoles / Q000494:pharmacology; D002460:Cell Line; D002945:Cisplatin / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D055785:Gene Knockdown Techniques; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D017879:Isothiocyanates / Q000494:pharmacology; D000072019:Kelch-Like ECH-Associated Protein 1; D000089762:Multidrug Resistance-Associated Protein 2; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D011422:Propionates / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D013454:Sulfoxides
chemical_list: C000715087:ABCC2 protein, human; D018528:ATP-Binding Cassette Transporters; D001562:Benzimidazoles; D047908:Intracellular Signaling Peptides and Proteins; D017879:Isothiocyanates; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D000089762:Multidrug Resistance-Associated Protein 2; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D011422:Propionates; D011804:Quinolines; D013454:Sulfoxides; C059141:verlukast; D004317:Doxorubicin; C016766:sulforaphane; C017807:bisbenzimide ethoxide trihydrochloride; D002945:Cisplatin
keywords: ABC transporters; KEAP1; NRF2; Proximal tubule epithelial cells; SLC transporters; Sulforaphane