title: Beta-lyase-dependent attenuation of cisplatin-mediated toxicity by selenocysteine Se-conjugates in renal tubular cell lines.
abstract: Cisplatin [cis-diamminedichloroplatinum(II)] is a widely used antitumor drug with dose-limiting nephrotoxic side effects due to selective toxicity to the proximal tubule. In the present study, the chemoprotective potential of three selenocysteine Se-conjugates, Se-methyl-L-selenocysteine, Se-(2-methoxyphenyl)-L-selenocysteine, and Se-(2-chlorobenzyl)-L-selenocysteine, belonging to three structural classes, against the nephrotoxic effects of cisplatin was investigated. Selenocysteine Se-conjugates have previously been proposed as kidney-selective prodrugs of pharmacologically active selenols because of their active uptake and bioactivation by cysteine conjugate beta-lyases in the kidney. To elucidate whether chemoprotection is beta-lyase-dependent wild-type LLC-PK(1) cells, possessing a very low beta-lyase activity, and LLC-PK(1) cells stably transfected with full-length cDNA coding for rat kidney cysteine conjugate beta-lyase/glutamine transaminase K (R1J) were used. The results indicate that all three selenocysteine Se-conjugates were able to attenuate the cisplatin-induced loss of viability in R1J cells but not in the parental LLC-PK(1) cells, as determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and neutral red uptake. In addition, cisplatin-induced reactive oxygen species (ROS) production was determined using 2',7'-dichlorodihydrofluorescein diacetate. The selenocysteine Se-conjugates were able to decrease ROS levels after cisplatin exposure in both cell types. However, this ROS-protective effect was more profound in R1J cells. Se-Methyl-L-selenocysteine provided the strongest protection. The protective activity against cisplatin-induced cytotoxicity and ROS generation was blocked by aminooxyacetic acid, a selective inhibitor of pyridoxal 5'-phosphate-dependent cysteine conjugate beta-lyases, further supporting the role of beta-lyase in the observed chemoprotection. The precise molecular mechanism by which selenols, generated by beta-lyase, provide protection against cisplatin-induced cytotoxicity, however, remains to be established.
authors.affiliation: Leiden/Amsterdam Center for Drug Research, Division of Molecular Toxicology, Department of Pharmacochemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: Rooseboom
authors.forename: Gerben
authors.initials: G
authors.lastname: Schaaf
authors.forename: Jan N M
authors.initials: JN
authors.lastname: Commandeur
authors.forename: Nico P E
authors.initials: NP
authors.lastname: Vermeulen
authors.forename: Johanna
authors.initials: J
authors.lastname: Fink-Gremmels
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002945:Cisplatin / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D018374:LLC-PK1 Cells; D008190:Lyases / Q000378:metabolism* / Q000494:pharmacology / Q000633:toxicity; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D012643:Selenium / Q000378:metabolism / Q000494:pharmacology / Q000633:toxicity; D017279:Selenocysteine / Q000378:metabolism* / Q000494:pharmacology / Q000633:toxicity; D013552:Swine
chemical_list: D000970:Antineoplastic Agents; D017382:Reactive Oxygen Species; D017279:Selenocysteine; D008190:Lyases; C034278:selenocysteine lyase; D012643:Selenium; D002945:Cisplatin