Estudo do efeito da modulação de caveolina-1 em carcinoma epidermóide de boca

Abstract

Introduction: Oral squamous cell carcinoma (OSCC) presents invasive and metastatic capacity as a consequence of phenotypic and genotypic alterations, such as the epithelial-mesenchymal transition (EMT). Changes in cell membranes can affect the structure of caveolae, composed of cholesterol and caveolins (CAV), which are associated with the tumorigenesis process. Cholesterol depletion and altered CAV1 expression can affect tumor cells and interfere with carcinogenesis. Objective: To evaluate the expression of CAV1 in OSCC tumors and the effect of cholesterol depletion and CAV1 silencing (siCAV1) in tongue OSCC cell lines. Material and methods: Microarray hybridization, mRNA expression and immunohistochemistry were performed on OSCC and non-tumor tissue (margin) samples. Tumors were divided into groups: more (T1 / T2 N +, n = 14) and less (T3 / T4 N0, n = 19) aggressive. The effect of cholesterol depletion and siCAV1 were analyzed in SCC-25 cell lines, with a non-metastatic profile, and HSC-3, with a metastatic profile, and cell viability, membrane fluidity, gene and protein expression of CAV1 and of EMT markers (E-cadherin, N-cadherin, β-catenin and Vimentin) were evaluated and their migratory and invasive capacities. Results: CAV1 was 1.77 times more expressed in tumors than in non-tumor tissues and about 2 times more expressed in more aggressive than in less aggressive tumors. qRT-PCR showed no difference in CAV1 expression in any comparison made. The CAV1 protein was located both in the tumor epithelium and in the stroma, in three different patterns. Stromal positivity has been associated with larger tumors. Furthermore, CAV1-positive tumor epithelial cells tended to be associated with low or negative CAV1 in the tumor stroma. Cholesterol depletion reduced cell viability and membrane fluidity in SCC-25 cells, whereas the viability of HSC-3 cells was less affected by depletion and no changes in membrane fluidity was observed. Cholesterol depletion interfered with the expression of CAV1 and of EMT markers in both cells, and decreased their migratory capacity, with SCC-25 being more affected. The invasive capacity of metastatic cells was also reduced, but of non-metastatic cells increased with cholesterol depletion. siCAV-1 increased cell viability only in SCC-25 and gene expression of EMT markers (N-cadherin and β-catenin), but not protein levels, only in HSC-3. Furthermore, siCAV1 stimulated the invasiveness of metastatic cells. Conclusion: The switch of CAV1 expression from tumor epithelial cells to tumor stromal cells may be useful to predict OSCC aggressiveness. Both cholesterol depletion and siCAV1 change the viability of tumor cells and affect the expression of EMT markers, which interferes with migratory and invasive capabilities. Cellular response to cholesterol depletion was different from response to CAV1 silencing, which also varied between non-metastatic and metastatic cells.