SOX7 Suppresses Wnt Signaling by Disrupting ß-Catenin/BCL9 Interaction.

The Wnt signaling is involved in angiogenesis and tumor development. ß-catenin is the core component of the Wnt pathway, which mediates oncogenic transcription and regulated by a series of proteins. Sex-determining region Y-box 7 (SOX7) is a member of high-mobility-group transcription factor family, which inhibits oncogenic Wnt signaling in lots of tumor cells with unknown mechanism. By coimmunoprecipitation (co-IP) and super Topflash reporter assay, SOX7 can bind ß-catenin and inhibit ß-catenin/T cell factor (TCF)-mediated transcription. Meanwhile, B cell lymphoma 9 (BCL9) drives Wnt signaling path through direct binding-mediated ß-catenin. Finally, we found that SOX7 inhibits oncogenic ß-catenin-mediated transcription by disrupting the ß-catenin/BCL9 interaction. Mechanistically, SOX7 compete with BCL9 to bind ß-catenin. Our results show SOX7 inhibited Wnt signaling as suppressor and could be an important target for anticancer therapy.