KLF4 and SOX9 transcription factors antagonize β-catenin and inhibit TCF-activity in cancer cells

Biochim Biophys Acta. 2012 Oct;1823(10):1666-75. doi: 10.1016/j.bbamcr.2012.06.027. Epub 2012 Jul 2.

Abstract

The transcriptional activator β-catenin is a key mediator of the canonical Wnt signaling pathway. β-catenin itself does not bind DNA but functions via interaction with T-cell factor (TCF)/lymphoid-enhancing factor (LEF) transcription factors. Thus, in the case of active Wnt signaling, β-catenin, in cooperation with TCF/LEF proteins family, activates the expression of a wide variety of genes. To date, the list of established β-catenin interacting targets is far from complete. In this study, we aimed to establish the interaction between β-catenin and transcription factors that might affect TCF activity. We took advantage of EMSA, using TCF as a probe, to screen oligonucleotides known to bind specific transcription factors that might dislodge or antagonize β-catenin/TCF binding. We found that Sox9 and KLF4 antagonize β-catenin/TCF binding in HEK293, A549, SW480, and T47D cells. This inhibition of TCF binding was concentration-dependent and correlated to the in vitro TCF-luciferase functional assays. Overexpression of Sox9 and KLF4 transcription factors in cancer cells shows a concentration-dependent reduction of TCF-luciferase as well as the TCF-binding activities. In addition, we demonstrated that both Sox9 and KLF4 interact with β-catenin in an immunoprecipitation assay and reduce its binding to TCF4. Together, these results demonstrate that Sox9 and KLF4 transcription factors antagonize β-catenin/TCF in cancer cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism*
  • Binding, Competitive / drug effects
  • Cell Line, Tumor
  • HEK293 Cells
  • Humans
  • Kruppel-Like Transcription Factors / metabolism*
  • Luciferases / metabolism
  • Oligonucleotides / pharmacology
  • Protein Binding / drug effects
  • SOX9 Transcription Factor / metabolism*
  • Transcription Factor 4
  • Transcription Factors / metabolism*
  • beta Catenin / antagonists & inhibitors*
  • beta Catenin / metabolism

Substances

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • CTNNB1 protein, human
  • GKLF protein
  • Kruppel-Like Transcription Factors
  • Oligonucleotides
  • SOX9 Transcription Factor
  • SOX9 protein, human
  • TCF4 protein, human
  • Transcription Factor 4
  • Transcription Factors
  • beta Catenin
  • Luciferases