Transfection of T-Box Transcription Factor and Synergistically Promote Self-Renewal and Invasive Phenotype in Oral Cancer Cells.

Recent studies suggest that epithelial⁻mesenchymal transition (EMT) correlates with cancer metastasis. In addition, there is growing evidence of the association of EMT with cancer stem cells (CSCs). Recently, we showed that the T-box transcription factor could be a strong regulator of EMT and the CSC phenotype, which were effectively suppressed by a knockdown in an adenoid cystic carcinoma cell line. In this study, we further tested whether is a regulator of cancer stemness by means of forced expression of in oral cancer cell lines. , , or both were stably transfected into oral carcinoma cell lines. We analysed these transfectants with respect to self-renewal phenotypes using a sphere-formation assay, and we assessed the expression levels of EMT markers and stem cell markers using real-time reverse transcription-polymerase chain reaction (RT-PCR). Cell migration and invasiveness in vitro were evaluated using a wound healing assay and a tumour cell dissemination assay, respectively. Forced expression of or slightly increased expression of EMT and stem cell markers and the self-renewal phenotype. The expression levels, however, were much lower compared to those of cancer stem cell-like cells. Forced co-expression of and strongly upregulated EMT and stem cell markers and the self-renewal phenotype. Cell migration and invasiveness in vitro were also remarkably enhanced. These synergistic effects increased expression levels of , , , and . In particular, the effects on and were significant. We found that and synergistically promote cancer stemness in oral cancer cells. This finding points to the importance of gene or protein networks associated with and in the development and maintenance of the CSC phenotype.