Molecular evidence for an involvement of organic anion transporters (OATs) in aristolochic acid nephropathy

• Published in: Toxicology (Amsterdam) Vol. 264; no. 1; pp. 74 - 79
• Main Authors: Bakhiya, Nadiya, Arlt, Volker M, Bahn, Andrew, Burckhardt, Gerhard, Phillips, David H, Glatt, Hansruedi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ireland Ltd 01.10.2009; Elsevier
• Subjects: Animals; Aristolochia; Aristolochic acid; Aristolochic Acids - metabolism; Aristolochic Acids - toxicity; Biological and medical sciences; Cells, Cultured; DNA adducts; DNA Adducts - drug effects; DNA Adducts - metabolism; Emergency; Extracellular Space - drug effects; Extracellular Space - metabolism; Female; Humans; Kidney - metabolism; Kidney - pathology; Kidney Diseases - chemically induced; Kidney Diseases - metabolism; Kidney Diseases - pathology; Kidney proximal tubule; Medical sciences; Oocytes - metabolism; Organic anion transporters; Organic Anion Transporters - antagonists & inhibitors; Organic Anion Transporters - metabolism; p-Aminohippuric Acid - metabolism; Plant poisons toxicology; Probenecid - pharmacology; Renal Agents - pharmacology; Toxicology; Urothelial cancer; Xenopus laevis; AA; 7-(deoxyadenosin- N 6-yl)aristolactam I; human organic anion transporter; Urothelial cancer; Organic anion transporters; AAI; hOAT; Aristolochic acid; relative adduct labelling; Kidney proximal tubule; aristolochic acid I; aristolochic acid II; dA-AAI; aristolochic acid (plant extract); DNA adducts; RAL; dG-AAI; 7-(deoxyguanosin- N 2-yl)aristolactam I; AAII; Kidney disease; Proximal; Urinary system disease; Kidney; Organic anion; Renal tubule; Nephropathy; Urinary system; DNA; Plant origin; Mechanism of action; Molecular adduct
• ISSN: 0300-483X; 1879-3185
• DOI: 10.1016/j.tox.2009.07.014

Abstract Aristolochic acid (AA), present in Aristolochia species, is the major causative agent in the development of severe renal failure and urothelial cancers in patients with AA nephropathy. It may also be a cause of Balkan endemic nephropathy. Epithelial cells of the proximal tubule are the primary cellular target of AA. To study whether organic anion transporters (OATs) expressed in proximal tubule cells are involved in uptake of AA, we used human epithelial kidney (HEK293) cells stably expressing human (h) OAT1, OAT3 or OAT4. AA potently inhibited the uptake of characteristic substrates, p -aminohippurate for hOAT1 and estrone sulfate for hOAT3 and hOAT4. Aristolochic acid I (AAI), the more cytotoxic and genotoxic AA congener, exhibited high affinity for hOAT1 ( Ki = 0.6 μM) as well as hOAT3 ( Ki = 0.5 μM), and lower affinity for hOAT4 ( Ki = 20.6 μM). Subsequently, AAI-DNA adduct formation (investigated by32 P-postlabelling) was used as a measure of AAI uptake. Significantly higher levels of adducts occurred in hOAT-expressing cells than in control cells: this effect was abolished in the presence of the OAT inhibitor probenecid. In Xenopus laevis oocytes hOAT-mediated efflux of p -aminohippurate was trans -stimulated by extracellular AA, providing further molecular evidence for AA translocation by hOATs. Our study indicates that OATs can mediate the uptake of AA into proximal tubule cells and thereby participate in kidney cell damage by this toxin.