Transcription factor Nrf2 mediates an adaptive response to sulforaphane that protects fibroblasts in vitro against the cytotoxic effects of electrophiles, peroxides and redox-cycling agents
Higgins, L. G., Kelleher, M. O., Eggleston, I. M., Itoh, K., Yamamoto, M. and Hayes, J. D., 2009. Transcription factor Nrf2 mediates an adaptive response to sulforaphane that protects fibroblasts in vitro against the cytotoxic effects of electrophiles, peroxides and redox-cycling agents. Toxicology and Applied Pharmacology, 237 (3), pp. 267-280.
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Sulforphane can Stimulate cellular adaptation to redox stressors through transcription factor Nrf2. Using mouse embryonic fibroblasts (MEFs) as a model, we show herein that the normal homeostatic level of glutathione in Nif2(-/-) MEFs was only 20% of that in their wild-type counterparts. Furthermore, the rate of glutathione synthesis following its acute depletion upon treatment with 3 mu mol/l sulforaphane was very substantially lower in Nrf2(-/-) MEFs than in wild-type cells, and the rebound leading to a similar to 1.9-fold increase in glutathione that Occurred 12-24 h after Nrf2(+/+) MEFs were treated with sulforaphane was not observed in Nrf2(-/-) fibroblasts. Wild-type MEFs that had been pre-treated for 24 h with 3 mu mol/l sulforaphane exhibited between 1.4- and 3.2-fold resistance against thiol-reactive electrophiles, including isothiocyanates, alpha,beta-unsaturated carbonyl compounds (e.g. acrolein), aryl halides and alkene epoxides. Pretreatment of Nrf2(+/+) MEFs With sulforaphane also protected against hydroperoxides (e.g. cumene hydroperoxide, CuOOH), free radical-generating Compounds (e.g. menadione), and genotoxic electrophiles (e.g. chlorambucil). By contrast, Nrf2(-/-) MEFs were typically similar to 50% less tolerant of these agents than wildtype fibroblasts, and sulforaphane pre-treatment did not protect the mutant cells against xenobiotics. To test whether Nrf2-mediated up-regulation of glutathione represents the major cytoprotective mechanism Stimulated by sulforaphane, 5 mu mol/l buthionine sulfoximine (BSO) was used to inhibit glutathione synthesis. In Nrf2(+/+) MEFs pre-treated with sulforaphane, BSO diminished intrinsic resistance and abolished inducible resistance to acrolein, CuOOH and chlorambucil, but not menadione. Thus Nrf2-dependent up-regulation of GSH is the principal mechanism by which sulforaphane pre-treatment induced resistance to acrolein, CuOOH and chlorambucil, but not menadione.
|Creators||Higgins, L. G., Kelleher, M. O., Eggleston, I. M., Itoh, K., Yamamoto, M. and Hayes, J. D.|
|Uncontrolled Keywords||glutathione s-transferases,acrolein,glutathione,chlorambucil,cancer chemoprevention,menadione|
|Departments||Faculty of Science > Pharmacy & Pharmacology|
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