Expressão de metalotioneína e sua influência no comportamento biológico in vitro do carcinoma mucoepidermoide

Abstract

The Mucoepidermoid Carcinoma (MEC) is the most common tumor of salivary glands, presenting considerable rates of recurrence and distant metastasis due to high invasive capacity of tumor cells, probably favored by metallothionein (MT) actuation, an zinc storage protein that supply this element to protease activity and synthesis of proteins and nucleic acids. So, the aim of this paper was to characterize a cell line from MEC and to correlate expression of MT with the Transforming Growth Factor-α (TGF-α), Tumor Necrosis Factor-α (TNF-α) and Matrix Metalloproteinases (MMPs). Indirect Immunofluorescence assay was realized to detect expression to epithelial and mesenchymal markers. Besides, it was realized cytogenetic analysis to verify cellular chromosomal alterations. The metallothionein2A (MT2A) gene silencing was obtained by small-interference RNA (siRNA) assay, and then, western blot technique was performed to correlate the expression of growth factors and MMPs studied with MT-2A silencing. Indirect immunofluorescence revealed expression to cytokeratines 19 and AE1/AE3, fibronectin, vimentin andα-smooth muscle actin. Cytogenetic evaluation demonstrated several structural and numerical alterations, among which the translocation t(11;19) (q21;p13), characteristic of MEC. After siRNA assay, a decreased expression of TGF-α and MMP-9 was visualized, while TNF-α became more expressed and MMP-2 kept its expression unaltered. Our findings suggest that MT presents important role in tumor invasion mechanism in MEC, because it interferes with expression of proteins directly involved in this process.