Cysteine S-conjugates activate transcription factor NF-kappa B in cultured renal epithelial cells

Activation of NF-kappa B by the nephrotoxic and cytotoxic cysteine S-conjugate S-(1,2-dichlorovinyl)-L-cysteine (DCVC) was investigated in porcine kidney-derived LLC-PK1 cells. DCVC induced binding of nuclear proteins to an NF-kappa B consensus oligonucleotide from the immunoglobulin kappa-light chain enhancer region, as determined by electrophoretic mobility shift assays, and the activated proteins were identified as the p50/RelA heterodimeric complex of NF-kappa B. Transient transfection experiments with a kappa B-controlled luciferase reporter construct showed that the NF-kappa B complex activated by DCVC was transcriptionally active. NF-kappa B transactivation was blocked by inhibition of DCVC bioactivation with the cysteine conjugate beta-lyase inhibitor (aminooxy)acetic acid, by the antioxidants N,N'-diphenyl-p-phenylenediamine and N-acetyl-L-cysteine, and by the protein kinase inhibitor staurosporine. The cysteine S-conjugates S-(2-bromo-2-chloro-1,1-difluoroethyl)-L-cysteine and S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine also activated NF-kappa B in LLC-PK1 cells. These results demonstrate that the NF-kappa B pathway is present in LLC-PK1 cells and is induced by cysteine S-conjugates. Inhibition of DCVC-induced transactivation of NF-kappa B by staurosporine and by antioxidants indicate roles for protein kinases and oxidative stress in the NF-kappa B pathway.