title: Mechanistic study of BNP7787-mediated cisplatin nephroprotection: modulation of human aminopeptidase N.
abstract: OBJECTIVE
  Previous studies from our laboratory have identified a role for gamma-glutamyl transpeptidase (GGT) in BNP7787 (disodium 2,2'-dithio-bis ethane sulfonate, dimesna, Tavocept™)-mediated cisplatin nephroprotection. Dekant has proposed that gamma-glutamyl transpeptidase (GGT), aminopeptidase N (APN) and cysteine-conjugate-β-lyase (CCBL) comprise a multi-enzyme pathway that acts on xenobiotic-glutathione conjugates converting them to nephrotoxic metabolites. We report modulation of APN activity within this pathway by BNP7787-derived mesna-disulfide heteroconjugates.
  
  
  METHODS
  A fluorimetric assay was used to determine the effect of BNP7787, BNP7787-derived mesna-disulfide heteroconjugates, and the BNP7787 metabolite, mesna (sodium 2-mercaptoethane sulfonate), on the initial velocity and overall progress curve of the human APN reaction in vitro.
  
  
  RESULTS
  Neither BNP7787 nor mesna-cysteinyl-glutamate inhibited human APN. Select BNP7787-derived mesna-disulfide heteroconjugates (mesna-cysteine, mesna-glutathione, mesna-cysteinyl-glycine) and high concentrations of mesna inhibited APN activity. Allosteric effects on the enzyme progress curve outside of the linear initial velocity region were observed for mesna-cysteinyl-glycine, mesna-glutathione and mesna-cysteinyl-glutamate and appeared to be a function of having both mesna and di- or tri-peptide functionalities in one molecule. In situ-generated mesna-cisplatin conjugates were not a substrate for human APN.
  
  
  CONCLUSIONS
  BNP7787-mediated prevention or mitigation of cisplatin-induced nephrotoxicity may involve APN inhibition by certain BNP7787-derived mesna-disulfide heteroconjugates and appears correlated to the presence of a glycinate moiety and/or an anionic group. Two general mechanisms for BNP7787-mediated nephroprotection of cisplatin-induced nephrotoxicity involving the GGT, APN and CCBL nephrotoxigenic pathway are proposed which acting in a concerted and/or synergistic manner, and thereby prevent or mitigate cisplatin-induced renal toxicity.
authors.affiliation: BioNumerik Pharmaceuticals, Inc., 8122 Datapoint Drive, Suite 400, San Antonio, TX 78229, USA. fred.hausheer@bnpi.com
authors.forename: F H
authors.initials: FH
authors.lastname: Hausheer
authors.forename: A R
authors.initials: AR
authors.lastname: Parker
authors.forename: P N
authors.initials: PN
authors.lastname: Petluru
authors.forename: K W
authors.initials: KW
authors.lastname: Jair
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: Q
authors.initials: Q
authors.lastname: Huang
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: P Y
authors.initials: PY
authors.lastname: Ayala
authors.forename: D
authors.initials: D
authors.lastname: Shanmugarajah
authors.forename: H
authors.initials: H
authors.lastname: Kochat
mesh_terms: D000494:Allosteric Regulation; D055162:Biocatalysis / Q000187:drug effects; D018826:CD13 Antigens / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D002945:Cisplatin / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology / Q000633:toxicity*; D003545:Cysteine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D005978:Glutathione / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007674:Kidney Diseases / Q000139:chemically induced* / Q000517:prevention & control*; D007700:Kinetics; D015080:Mesna / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D008954:Models, Biological; D020011:Protective Agents / Q000378:metabolism / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: D004151:Dipeptides; D020011:Protective Agents; D011994:Recombinant Proteins; C028505:cysteinylglycine; C027032:2,2'-dithiodiethanesulfonic acid; D018826:CD13 Antigens; D005978:Glutathione; D003545:Cysteine; D015080:Mesna; D002945:Cisplatin; D005998:Glycine