title: Cisplatin nephrotoxicity is mediated by gamma glutamyltranspeptidase, not via a C-S lyase governed biotransformation pathway.
abstract: Cisplatin exhibits dose-limiting nephrotoxicity in rodents and man. This study investigates the mechanism of cisplatin nephrotoxicity in vivo and in an in vitro model system. Nephrotoxicity was induced in rats (6 mg/kg cisplatin i.p.) and mice (10 mg/kg cisplatin i.p.). Cisplatin administration significantly elevated blood urea nitrogen (BUN) and serum creatinine in male Sprague Dawley rats day 5 post-treatment (BUN Delta+28+/-5 micromol/ml; serum creatinine Delta+108+/-4 nmol/ml, P<0.05) and in male C57BL6 mice day 4 post-treatment (BUN Delta+21+/-4 micromol/ml; serum creatinine Delta+81+/-5 nmol/ml, P<0.05). Nephrotoxicity was confirmed by histological analysis that revealed significant damage to the proximal tubules of cisplatin- versus saline vehicle-treated animals. Inhibition of gamma glutamyltranspeptidase prevented cisplatin nephrotoxicity in Sprague Dawley rats (day 5 BUN Delta+1+/-2 micromol/ml; serum creatinine Delta+8+/-4 nmol/ml) and C57BL6 mice (day 4 BUN Delta+1+/-0.8 micromol/ml; serum creatinine Delta-1+/-2 nmol/ml), but not cellular toxicity in rat proximal tubular (RPT) or human proximal tubular (HPT) cultures. Inhibition of aminopeptidase N (AP-N) or renal dipeptidase (RDP) in male Sprague Dawley rats, or in RPT and HPT cell cultures, did not reduce cisplatin toxicity. In contrast to published findings inhibition of C-S lyase did not prevent the nephrotoxicity of cisplatin in vivo or cellular toxicity in vitro. These data demonstrate that the biotransformation enzymes AP-N, RDP and C-S lyase are not implicated in the metabolism of cisplatin to a nephrotoxic metabolite as has been previously hypothesised. Instead, our data demonstrate that gamma glutamyltranspeptidase is a key enzyme involved in mediating cisplatin nephrotoxicity, which potentially acts to cleave cisplatin-GSH conjugates to a toxic metabolite.
authors.affiliation: Department of Medicine and Therapeutics and School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, UK. rwainf@lsuhsc.edu
authors.forename: Richard D
authors.initials: RD
authors.lastname: Wainford
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Weaver
authors.forename: Keith N
authors.initials: KN
authors.lastname: Stewart
authors.forename: Paul
authors.initials: P
authors.lastname: Brown
authors.forename: Gabrielle M
authors.initials: GM
authors.lastname: Hawksworth
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000633:toxicity*; D001711:Biotransformation; D001835:Body Weight / Q000187:drug effects; D002469:Cell Separation; D002945:Cisplatin / Q000378:metabolism / Q000633:toxicity*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007674:Kidney Diseases / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology; D007677:Kidney Function Tests; D007683:Kidney Tubular Necrosis, Acute / Q000139:chemically induced / Q000473:pathology; D008190:Lyases / Q000037:antagonists & inhibitors / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D005723:gamma-Glutamyltransferase / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D005723:gamma-Glutamyltransferase; D008190:Lyases; C033511:carbon-sulfur lyase; D002945:Cisplatin