Investigation of the role of cancer stem cells and microenvironment on epithelial-to-mesenchymal transition, invasion and metastasis in oral squamous cell carcinoma

Abstract

Recent evidences has shown that there is a link between cancer stem cells (CSC) and the process of epithelial-to-mesenchymal transition (EMT), so that the CSCs are more migratory and have higher metastasizing potential compared to other cancer cells. It is also known that EMT is increased by hypoxia and by inflammatory cytokines, environmental influences common within the tumors. In view of that, the purpose of this study is to determine the factors influencing the behaviour of EMT-CSCs and investigate whether their molecular signature can be used for identification of biomarkers that can be used as prognostic factors or for the choice of treatment. For this purpose, different putative CSC (CD44, P75NGFR, BMI-1 and ALDH-1), EMT (vimentin, Snail, Axl, E/N-cadherin and Twist1), macrophages (CD68, CD163 and F4/80) and TGFB1 signaling markers will be evaluated by immunohistochemistry on primary OSCC and associated metastatic lymph nodes. CD44 and ESA expression levels will also be analyzed by flow cytometry on fresh tissue samples, and the data will be collectively associated with clinical and pathological parameters. Additionally, circulating tumor cells on peripheral blood of advanced OSCC patients will be isolated, quantified and characterized regarding their CSC and EMT phenotype. Lastly, the functional relationship between tumor-associated macrophages (TAM), CSC and EMT will be further investigated regarding the invasive capacity of different CSC subpopulations (EMT-CSC or non-EMT-CSC) isolated by cell sorting, by means of indirect co-culture and invasion assays. The role of cytokines released from TAM, as well as TGFB1, will be specifically evaluated by gene silencing or over expression studies. (AU)