Abstract
S-(1,2-Dichlorovinyl)-l-cysteine (DCVC) is the penultimate nephrotoxic metabolite of the environmental contaminant trichloroethylene. Although metabolism of DCVC by the cysteine conjugate β-lyase is the most studied bioactivation pathway, DCVC may also be metabolized by the flavin-containing monooxygenase (FMO) to yield DCVC sulfoxide (DCVCS). Renal cellular injury induced by DCVCS was investigated in primary cultures of human proximal tubular (hPT) cells by assessment of time- and concentration-dependent effects on cellular morphology, acute cellular necrosis, apoptosis, mitochondrial function, and cellular glutathione (GSH) status. Confluent hPT cells incubated with as little as 10 μM DCVCS for 24 h exhibited morphological changes, although at least 100 μM DCVCS was required to produce marked changes. Acute cellular necrosis did not occur until 48 h with at least 200 μM DCVCS, indicating that this is a high-dose, late response. The extent of necrosis was similar to that with DCVC. In contrast, apoptosis occurred as early as 1 h with as little as 10 μM DCVCS and the extent of apoptosis was much less than that with DCVC. Mitochondrial function was maintained with DCVCS concentrations up to 100 μM, consistent with hPT cells only being competent to undergo apoptosis at early time points and relatively low concentrations. Marked depletion (>50%) of cellular GSH content was only observed with 500 μM DCVCS. These results, combined with previous studies showing protection from DCVC-induced necrosis and apoptosis by the FMO inhibitor methimazole, suggest that formation of DCVCS plays a significant role in trichloroethylene-induced renal cellular injury in hPT cells.
Footnotes
-
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
-
DOI: 10.1124/jpet.102.046185.
-
This work was funded by National Institute of Environmental Health Sciences Grant R01-ES08828 (to L.H.L.) and National Institute of Diabetes and Digestive and Kidney Diseases Grant R01-DK44295 (to A.A.E.). Core facilities funded by the National Institute of Environmental Health Sciences Center for Molecular Toxicology with Human Applications (Grant P30-ES06639) at Wayne State University were used for some of this study.
-
ABBREVIATIONS: TRI, trichloroethylene; GSH, reduced glutathione; DCVC, S-(1,2-dichlorovinyl)-l-cysteine; FMO, flavin-containing monooxygenase; DCVCS, S-(1,2-dichlorovinyl)-l-cysteine sulfoxide; rPT, rat proximal tubular; hPT, human proximal tubular; TMPD, N,N,N′,N′-tetramethyl-p-phenylenediamine; FITC, fluorescein isothiocyanate; HPLC, high-pressure liquid chromatography; PBS, phosphate-buffered saline; DMEM/F-12, Dulbecco's modified Eagle's medium/Ham's F-12; FACS, flow activated cell sorter; LDH, lactate dehydrogenase; ΔΨ, mitochondrial membrane potential.
- Received October 25, 2002.
- Accepted February 21, 2003.
- The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|