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

Toxicol Appl Pharmacol. 2009 Jun 15;237(3):267-80. doi: 10.1016/j.taap.2009.03.005. Epub 2009 Mar 20.


Sulforaphane 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 Nrf2(-/-) 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 micromol/l sulforaphane was very substantially lower in Nrf2(-/-) MEFs than in wild-type cells, and the rebound leading to a approximately 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 micromol/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. Pre-treatment 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 approximately 50% less tolerant of these agents than wild-type 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 micromol/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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / drug effects*
  • Adaptation, Physiological / physiology*
  • Animals
  • Cells, Cultured
  • Fibroblasts / drug effects
  • Fibroblasts / pathology
  • Fibroblasts / physiology*
  • Free Radicals / toxicity
  • Glutathione / metabolism
  • Isothiocyanates / toxicity
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • NF-E2-Related Factor 2 / deficiency
  • NF-E2-Related Factor 2 / genetics
  • NF-E2-Related Factor 2 / physiology*
  • Oxidation-Reduction / drug effects
  • Peroxides / toxicity*
  • Sulfoxides
  • Thiocyanates / toxicity*
  • Xenobiotics / toxicity


  • Free Radicals
  • Isothiocyanates
  • NF-E2-Related Factor 2
  • Peroxides
  • Sulfoxides
  • Thiocyanates
  • Xenobiotics
  • sulforaphane
  • Glutathione