Identification of retinoic acid as an inhibitor of transcription factor Nrf2 through activation of retinoic acid receptor alpha

Proc Natl Acad Sci U S A. 2007 Dec 4;104(49):19589-94. doi: 10.1073/pnas.0709483104. Epub 2007 Nov 28.

Abstract

Isothiocyanates and phenolic antioxidants can prevent cancer through activation of Nrf2 (NF-E2 p45-related factor 2), a transcription factor that controls expression of cytoprotective genes through the antioxidant response element (ARE) enhancer. Using a human mammary MCF7-derived AREc32 reporter cell line, we now report that all-trans retinoic acid (ATRA), and other retinoic acid receptor alpha (RARalpha) agonists, markedly reduces the ability of Nrf2 to mediate induction of ARE-driven genes by cancer chemopreventive agents including the metabolite of butylated hydroxyanisole, tert-butylhydroquinone (tBHQ). The basal and tBHQ-inducible expression of aldo-keto reductase (AKR) AKR1C1 and AKR1C2 genes, which are regulated by Nrf2, was also repressed by ATRA in AREc32 cells. Antagonists of RARalpha augmented induction of ARE-driven gene expression by tBHQ, as did knockdown of RARalpha by using RNAi. The expression of the ARE-gene battery was increased in the small intestine of mice fed on a vitamin A-deficient diet, and this increase was repressed by administration of ATRA. By contrast, in the small intestine of Nrf2 null mice, the expression of ARE-driven genes was not affected by vitamin A status. In MCF7 cells, ATRA did not block the nuclear accumulation of Nrf2 but reduced the binding of Nrf2 to the ARE enhancer as a consequence of forming a complex with RARalpha. These data suggest that cross-talk between Nrf2 and RARalpha could markedly influence the sensitivity of cells to electrophiles and oxidative stressors and, as a consequence, to carcinogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 20-Hydroxysteroid Dehydrogenases / genetics
  • 20-Hydroxysteroid Dehydrogenases / metabolism
  • Animals
  • Antineoplastic Agents / pharmacology*
  • Antineoplastic Agents / therapeutic use
  • Antioxidants / pharmacology
  • Cell Line, Tumor
  • Cell Nucleus / chemistry
  • Cell Nucleus / metabolism
  • Chemoprevention
  • Enhancer Elements, Genetic
  • Gene Expression / drug effects
  • Humans
  • Hydroquinones / pharmacology
  • Hydroxysteroid Dehydrogenases / genetics
  • Hydroxysteroid Dehydrogenases / metabolism
  • Luciferases / analysis
  • Luciferases / genetics
  • Mice
  • Mice, Mutant Strains
  • NF-E2 Transcription Factor, p45 Subunit / antagonists & inhibitors*
  • NF-E2 Transcription Factor, p45 Subunit / genetics
  • NF-E2 Transcription Factor, p45 Subunit / metabolism
  • Neoplasms / prevention & control*
  • Receptors, Retinoic Acid / agonists*
  • Response Elements
  • Retinoic Acid Receptor alpha
  • Tretinoin / pharmacology*
  • Tretinoin / therapeutic use

Substances

  • Antineoplastic Agents
  • Antioxidants
  • Hydroquinones
  • NF-E2 Transcription Factor, p45 Subunit
  • RARA protein, human
  • Rara protein, mouse
  • Receptors, Retinoic Acid
  • Retinoic Acid Receptor alpha
  • Tretinoin
  • 2-tert-butylhydroquinone
  • Hydroxysteroid Dehydrogenases
  • 20-Hydroxysteroid Dehydrogenases
  • 3 alpha-beta, 20 beta-hydroxysteroid dehydrogenase
  • AKR1C2 protein, human
  • Luciferases