Abstract
DAX1 is well known for its fundamental role in several types of cancer, while its biological role in cervical cancer remains largely unexplored. The expression of DAX1 in cervical carcinoma tissue was examined using immunohistochemistry and western blot. The effects of DAX1 silencing on the cell growth, tumor formation, and CSC (cancer stem cell) characteristics were also investigated. DAX1 expressed a gradual increase from normal cervix to high-grade squamous intraepithelial lesions, and consequently to cervical cancer. Silence of DAX1 significantly inhibited the cell growth, tumorigenicity, and tumorsphere formation. Furthermore, the TOP/FOP-Flash reporter assay revealed that Wnt/β-catenin pathway was significantly inactivated in DAX1-silenced cervical cancer cells with the downregulation of Wnt/β-catenin targeting genes, including cyclinD1 and c-myc. Moreover, dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assay confirmed that DAX1 transcriptionally repressed glycogen synthase kinase 3β (GSK3β), an inhibitor of the Wnt/β-catenin pathway, by physically interacting with -666~-444 motif on the GSK3β promoter. Additionally, the blockage of GSK3β by CHIR-99021 resulted in a significant increase of CSC characteristics induced by the silence of DAX1. Our data demonstrated that DAX1 is overexpressed in cervical cancer, and that it promotes cell growth and tumorigenicity through activating Wnt/β-catenin pathway mediated by GSK3β.