Renal Cysteine Conjugate Beta-Lyase-Mediated Toxicity Studied With Primary Cultures of Human Proximal Tubular Cells

Toxicol Appl Pharmacol. 1990 May;103(3):463-73. doi: 10.1016/0041-008x(90)90319-p.

Abstract

The beta-lyase pathway has been shown to mediate the nephrotoxicity of S-cysteine conjugates of a variety of haloalkenes in a number of animal models in vitro and in vivo. However, there is no information available concerning this mechanism of bioactivation in human tissues. In this investigation a well-characterized model of human proximal tubule epithelial cells, the presumed target cell, was used to investigate the toxicity of a series of glutathione and cysteine conjugates of nephrotoxic haloalkenes. Both S-(1,2-dichlorovinyl)-glutathione (DCVG) and S-(1,2-dichlorovinyl)-L-cysteine (DCVC) caused dose-dependent toxicity over a range of 25 to 500 microM. DCVC was consistently found to be more toxic than DCVG, but the inclusion of gamma-glutamyltransferase (0.5 U/ml) increased the toxicity of DCVG to that observed with an equimolar concentration of DCVC, indicating that metabolism to the cysteine conjugate is an important rate-limiting step in this in vitro model. S-(1,2,3,4,4-Pentachlorobutadienyl)-L-cysteine, S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine, and S-(1,1,2,2-tetrafluoroethyl)-L-cysteine were also found to be toxic to human proximal tubular cells. Incubation with [35S]DCVC resulted in covalent binding of 35S-label, which increased linearly to a final level of 1.05 nmol/mg protein at 6 hr. Aminooxyacetic acid (250 microM), an inhibitor of pyridoxal phosphate-dependent enzymes such as beta-lyase, protected the cells from the toxicity of all of the cysteine conjugates and inhibited the covalent binding of 35S-label from [35S]DCVC to cellular macromolecules. The results of the present study provide the first evidence that human proximal tubular cells are sensitive to the toxicity of glutathione and/or cysteine conjugates of a variety of chloro- and fluoroalkenes which are activated via the beta-lyase pathway. The implications for human health are discussed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aminooxyacetic Acid / metabolism
  • Butadienes / toxicity
  • Carbon-Sulfur Lyases*
  • Cells, Cultured
  • Child
  • Cysteine / analogs & derivatives
  • Cysteine / toxicity
  • Dose-Response Relationship, Drug
  • Epithelial Cells
  • Female
  • Glutathione / analogs & derivatives
  • Glutathione / toxicity
  • Humans
  • Hydrocarbons, Fluorinated / toxicity
  • Kidney Tubules, Proximal / cytology
  • Kidney Tubules, Proximal / enzymology*
  • Lyases / metabolism*
  • Male
  • Middle Aged
  • Structure-Activity Relationship

Substances

  • Butadienes
  • Hydrocarbons, Fluorinated
  • Aminooxyacetic Acid
  • S-(1,2-dichlorovinyl)cysteine
  • S-pentachlorobuta-1,3-dien-yl-cysteine
  • S-(1,1,2,2-tetrafluoroethyl)cysteine
  • S-(2-chloro-1,1,2-trifluoroethyl)cysteine
  • S-(1,2-dichlorovinyl)glutathione
  • Lyases
  • Carbon-Sulfur Lyases
  • S-alkylcysteine lyase
  • Glutathione
  • Cysteine