Genotoxicity of haloalkene and haloalkane glutathione S-conjugates in porcine kidney cells

Abstract

The genotoxicity of the glutathione S-conjugates S-(12-dichlorovinyl)glutathione (DCVG), S-(1,2,2-trichlorovinyl)glutathione (TCVG), S-(1,2,3,4,4-pentachlorobutadienyl)glutathione (PCBG) and S-(2-chloroethyl)glutathione (CEG) was investigated in LLC-PK1, a cultured line of porcine kidney cells that exhibits many properties of proximal tubular cells. DNA damage caused by treatment of the cells with the S-conjugates was estimated by determining the induction of unscheduled DNA synthesis (UDS) after inhibition of replicative DNA synthesis in confluent LLC-PK1 monolayers. DCVG-, TCVG- and PCBG-induced dose-dependent UDS at concentrations not causing cytotoxicity, as determined by the release of lactate dehydrogenase into the medium. Acivicin, which inhibits irreversibly γ-glutamyl-transpeptidase (GGT) and aminooxyacetic acid, an inhibitor of cysteine conjugate β-lyase, blocked DCVG-, TCVG- and PCBG-induced genotoxicity. CEG, however, was genotoxic in subconfluent cells and this was not dependent on GGT and β-lyase activities. The DNA damaging effects in kidney cells of DCVG, TCVG and PCBG, which are metabolites of the nephrocarcinogens trichloroethylene, tetrachloroethylene and hexachlorobutadiene, respectively, suggest that the parent haloalkenes are potentially genotoxic in the rat kidney, the target organ for both acute toxicity and carcinogenicity.