Modulation of gene expression by cancer chemopreventive dithiolethiones through the Keap1-Nrf2 pathway. Identification of novel gene clusters for cell survival

J Biol Chem. 2003 Mar 7;278(10):8135-45. doi: 10.1074/jbc.M211898200. Epub 2002 Dec 27.

Abstract

Enzyme inducers such as 3H-1,2-dithiole-3-thione (D3T) enhance the detoxication of environmental carcinogens and protect against neoplasia. The putative molecular sensor for inducers is Keap1, a sulfhydryl-rich protein that sequesters the transcription factor Nrf2 in the cytoplasm. Expression of these detoxication enzymes is blunted in nrf2-deficient mice; moreover, these mice are more sensitive to carcinogenesis, and the protective actions of dithiolethiones are lost with nrf2 disruption. Hepatic gene expression profiles were examined by oligonucleotide microarray analysis in vehicle- or D3T-treated wild-type mice as well as in nrf2 single and keap1-nrf2 double knockout mice to identify those genes regulated by the Keap1-Nrf2 pathway. Transcript levels of 292 genes were elevated in wild-type mice 24 h after treatment with D3T; 79% of these genes were induced in wild-type, but not nrf2-deficient mice. These nrf2-dependent, D3T-inducible genes included known detoxication and antioxidative enzymes. Unexpected clusters included genes for chaperones, protein trafficking, ubiquitin/26 S proteasome subunits, and signaling molecules. Gene expression patterns in keap1-nrf2 double knockout mice were similar to those in nrf2-single knockout mice. D3T also led to nrf2-dependent repression of 31 genes at 24 h; principally genes related to cholesterol/lipid biosynthesis. Collectively, D3T increases the expression of genes through the Keap1-Nrf2 signaling pathway that directly detoxify toxins and generate essential cofactors such as glutathione and reducing equivalents. Induction of nrf2-dependent genes involved in the recognition and repair/removal of damaged proteins expands the role of this pathway beyond primary control of electrophilic and oxidative stresses into secondary protective actions that enhance cell survival.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptor Proteins, Signal Transducing*
  • Animals
  • Anticarcinogenic Agents / pharmacology*
  • Base Sequence
  • Carrier Proteins / metabolism*
  • Cell Survival / genetics*
  • Cytoskeletal Proteins*
  • DNA Primers
  • DNA-Binding Proteins / metabolism*
  • Gene Expression Profiling
  • Gene Expression Regulation / drug effects*
  • Kelch-Like ECH-Associated Protein 1
  • Mice
  • Mice, Knockout
  • Multigene Family*
  • NF-E2-Related Factor 2
  • Oligonucleotide Array Sequence Analysis
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sulfhydryl Compounds / pharmacology*
  • Trans-Activators / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • Anticarcinogenic Agents
  • Carrier Proteins
  • Cytoskeletal Proteins
  • DNA Primers
  • DNA-Binding Proteins
  • Keap1 protein, mouse
  • Kelch-Like ECH-Associated Protein 1
  • NF-E2-Related Factor 2
  • Nfe2l2 protein, mouse
  • Sulfhydryl Compounds
  • Trans-Activators