title: Ifosfamide metabolites CAA, 4-OH-Ifo and Ifo-mustard reduce apical phosphate transport by changing NaPi-IIa in OK cells.
abstract: Renal Fanconi syndrome occurs in about 1-5% of all children treated with Ifosfamide (Ifo) and impairment of renal phosphate reabsorption in about 20-30% of them. Pathophysiological mechanisms of Ifo-induced nephropathy are ill defined. The aim has been to investigate whether Ifo metabolites affect the type IIa sodium-dependent phosphate transporter (NaPi-IIa) in viable opossum kidney cells. Ifo did not influence viability of cells or NaPi-IIa-mediated transport up to 1 mM/24 h. Incubation of confluent cells with chloroacetaldehyde (CAA) and 4-hydroperoxyIfosfamide (4-OH-Ifo) led to cell death by necrosis in a concentration-dependent manner. At low concentrations (50-100 microM/24 h), cell viability was normal but apical phosphate transport, NaPi-IIa protein, and -mRNA expression were significantly reduced. Coincubation with sodium-2-mercaptoethanesulfonate (MESNA) prevented the inhibitory action of CAA but not of 4-OH-Ifo; DiMESNA had no effect. Incubation with Ifosfamide-mustard (Ifo-mustard) did alter cell viability at concentrations above 500 microM/24 h. At lower concentrations (50-100 microM/24 h), it led to significant reduction in phosphate transport, NaPi-IIa protein, and mRNA expression. MESNA did not block these effects. The effect of Ifo-mustard was due to internalization of NaPi-IIa. Cyclophosphamide-mustard (CyP-mustard) did not have any influence on cell survival up to 1000 microM, but the inhibitory effect on phosphate transport and on NaPi-IIa protein was the same as found after Ifo-mustard. In conclusion, CAA, 4-OH-Ifo, and Ifo- and CyP-mustard are able to inhibit sodium-dependent phosphate cotransport in viable opossum kidney cells. The Ifo-mustard effect took place via internalization and reduction of de novo synthesis of NaPi-IIa. Therefore, it is possible that Ifo-mustard plays an important role in pathogenesis of Ifo-induced nephropathy.
authors.affiliation: Department of Pediatrics, Friedrich-Schiller-University, Jena, Germany. l.patzer@krankenhaus-halle-saale.de
authors.forename: L
authors.initials: L
authors.lastname: Patzer
authors.forename: N
authors.initials: N
authors.lastname: Hernando
authors.forename: U
authors.initials: U
authors.lastname: Ziegler
authors.forename: B
authors.initials: B
authors.lastname: Beck-Schimmer
authors.forename: J
authors.initials: J
authors.lastname: Biber
authors.forename: H
authors.initials: H
authors.lastname: Murer
mesh_terms: D000079:Acetaldehyde / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D018906:Antineoplastic Agents, Alkylating; D001692:Biological Transport / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D007069:Ifosfamide / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015080:Mesna / Q000494:pharmacology; D009893:Opossums; D010710:Phosphates / Q000378:metabolism*; D010752:Phosphoramide Mustards / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*
chemical_list: D018906:Antineoplastic Agents, Alkylating; D010710:Phosphates; D010752:Phosphoramide Mustards; D012333:RNA, Messenger; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa; C012353:hydroperoxyisophosphamide; C027061:isophosphamide mustard; C006446:aldophosphamide; C004656:chloroacetaldehyde; D000079:Acetaldehyde; D015080:Mesna; D007069:Ifosfamide