title: KLF4 and SOX9 transcription factors antagonize β-catenin and inhibit TCF-activity in cancer cells.
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.
authors: Department of Physiology, University of South Alabama, Mobile, AL 36688, USA. hsellak@usouthal.edu
authors: Hassan
authors: H
authors: Sellak
authors: Songwei
authors: S
authors: Wu
authors: Thomas M
authors: TM
authors: Lincoln
mesh_terms: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000378:metabolism*; D001667:Binding, Competitive / Q000187:drug effects; D045744:Cell Line, Tumor; D057809:HEK293 Cells; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D009841:Oligonucleotides / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D055758:SOX9 Transcription Factor / Q000378:metabolism*; D000073940:Transcription Factor 4; D014157:Transcription Factors / Q000378:metabolism*; D051176:beta Catenin / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C495270:CTNNB1 protein, human; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D009841:Oligonucleotides; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; C532096:TCF4 protein, human; D000073940:Transcription Factor 4; D014157:Transcription Factors; D051176:beta Catenin; D008156:Luciferases