REST negatively and ISGF3 positively regulate the human STAT1 gene in melanoma

Mol Cancer Ther. 2013 Jul;12(7):1288-98. doi: 10.1158/1535-7163.MCT-12-0923. Epub 2013 Apr 18.

Abstract

STAT1 plays a pivotal role in signal transduction and transcriptional activation in response to type I and II IFNs. Regulation of STAT1 expression has significant consequences in human cancer cells, where STAT1 deficiencies have been associated with cellular resistance to type I IFN. Distinct promoter, enhancer, and repressor regions have previously been described in the regulatory part of the human STAT1 gene extending as far as the second intron. A putative IFN-stimulated response element sequence in the STAT1 promoter is inducible by type I IFN and binds the IFN-α/β-induced complex, ISGF3. Together with the previously characterized IRF-E/GAS/IRF-E (IGI) motif, these positive regulatory elements provide a means for intracellular amplification of STAT1 expression, which is necessary for increasing cell responsiveness to the IFNs. In contrast, the transcriptional repressor REST binds to an RE-1 element in the STAT1 repressor region and in doing so represses transcription from the STAT1 gene regulatory region in melanoma cells lines. Repression significantly decreased in a REST-null cell line. Altering REST function from a transcriptional repressor into an activator as REST-VP16 increased expression from RE-1-targeted reporters. RNA expression of 65 melanoma cell lines by microarray and selected lines with known IFN responsiveness showed significant inverse correlations between STAT1/REST that were related to cellular responses to IFN. Thus REST, through the intronic RE-1 element, provides a means for downregulating STAT1 expression, affecting melanoma responsiveness to IFN. Intracellular levels of REST may be a useful marker to test for IFN resistance and as a novel therapeutic target in IFN-resistant melanomas.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromatin Immunoprecipitation
  • Gene Expression
  • Humans
  • Interferon-Stimulated Gene Factor 3, gamma Subunit / genetics
  • Interferon-Stimulated Gene Factor 3, gamma Subunit / metabolism*
  • Melanoma / genetics*
  • Melanoma / metabolism
  • Promoter Regions, Genetic
  • Rats
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • STAT1 Transcription Factor / genetics*
  • STAT1 Transcription Factor / metabolism
  • Signal Transduction
  • Transcriptional Activation
  • Transfection

Substances

  • IRF9 protein, human
  • Interferon-Stimulated Gene Factor 3, gamma Subunit
  • RE1-silencing transcription factor
  • Repressor Proteins
  • STAT1 Transcription Factor
  • STAT1 protein, human