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Sox9 and KLF4 transcription factors antagonize β‐catenin and inhibit TCF‐activity in cancer cells
Author(s) -
Sellak Hassan,
Lincoln Thomas M.,
Wu Songwei
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.115.10
Subject(s) - wnt signaling pathway , transcription factor , catenin , luciferase , beta catenin , cancer research , chromatin immunoprecipitation , chemistry , sox9 , activator (genetics) , tcf4 , klf4 , microbiology and biotechnology , biology , signal transduction , promoter , enhancer , gene , gene expression , transfection , biochemistry , sox2
The transcriptional activator β‐catenin is the key mediator of the canonical Wnt signaling pathway. However, β‐catenin does not itself bind to DNA, rather, it functions via interaction with T‐cell factor (TCF)/lymphoid‐enhancing factor (LEF). Thus, in the case of active Wnt signaling, β‐catenin induces, in cooperation with TCF/LEF family, 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 by assessing the protein‐DNA binding using elecrophoretic mobility shift assay and TCF‐luciferase activity assessment. Using TCF4 as a probe in a competition assay, we screened consensus sequences known to bind specific transcription factors that might dislodge or antagonize β‐catenin binding to TCF complex. We found that Sox9 and KLF4 consensus sequences antagonized β‐catenin binding to TCF in most analyzed cancer cells, e.g. lung (A549), colon (SW480), and breast (T47D). The inhibition of β‐catenin binding to TCF was concentration dependant and correlated to TCF‐luciferase activity decrease. Overexpression of Sox9 or KLF4 in cancer cells showed a concentration dependent reduction of β‐catenin binding to TCF4 concomitant to TCF4‐luciferase activity decrease. Further, immunoprecipitation assay revealed that both Sox9 and KLF4 interact with β‐catenin. Taken together, these results demonstrate that Sox9 and KLF4 compete with β‐catenin and prevent its binding to TCF. Supported by HL66164 & HL66299.