Effect of CD133 overexpression on the epithelial-to-mesenchymal transition in oral cancer cell lines

Oral squamous cell carcinoma (OSCC) is one of the most common cancers in the world. In OSCC, CD133 promotes tumor invasion and metastasis by inducing the epithelial-to-mesenchymal transition (EMT). A small subset of cancer cells known as cancer stem cells (CSCs) are thought to give rise to differentiated tumor cells and to predict tumor recurrence and metastases, i.e., CSCs may be metastatic precursors. In this study, we show that ectopic overexpression of CD133 in OSCC cell lines KB, YD9, and YD10B cells significantly promotes the EMT and acquisition of stemness properties. CSC properties were analyzed by colony-formation assay and measurement of OCT4, SOX2, and NANOG expression, and the EMT was monitored by cell migration, a cell invasion assay, and analysis of E-cadherin, N-cadherin, and vimentin expression. CD133 overexpression led to formation of irregular spheroid colonies consistent with a stem cell phenotype and increased the expression of OCT4, SOX2, NANOG, N-cadherin, and vimentin. Taken together, these findings show that elevated levels of CD133 lead to OSCC invasiveness and metastasis, associated with the upregulation of EMT and stemness markers.