Epithelial to Mesenchymal Transition： A Link between Metastatic and Cancer Stem-like Cells？

More than 40% of patients with squamous cell carcinoma of the head and neck (SCCHN) have lymph node metastases (LNM) at the time of diagnosis. Metastasis is one of the main poor prognostic factors of SCCHN.

More than 40% of patients with squamous cell carcinoma of the head and neck （SCCHN） have lymph node metastases （LNM） at the time of diagnosis. Metastasis is one of the main poor prognostic factors of SCCHN. Understanding metastasis is essential for development of an early detection system and treatment of this disease. Since being first proposed in 2005, accumulating evidence supports a new concept that migrating/metastatic cancer stem- like cells （mCSC） may be responsible for cell progression to metastasis. It is proposed that there are two forms of CSCs in tumor progression - stationary CSC （sCSC） and mobile or migrating CSC （mCSC）. sCSCs are embedded in epithelial tissues or epithelial-based tumors and cannot disseminate. In contrast, mCSCs, which are derived from sCSC by acquiring a transient epithelial to mesenchymal transition （EMT）, are located at the tumor-host interface and mediate tumor cell metastasis. In a colorectal cancer model, it was observed that not only the expression Ievels of the EMT-related biomarkers but also their locations in the tumor nest were significantly associated with metastasis.