Avaliação da sinalização de c-MET e seus efeitos em linhagens celulares de carcinoma mucoepidermóide

Abstract

Introduction: Malignant salivary gland tumors (MSGTs) account for approximately 2% to 6% of all head and neck neoplasms, with mucoepidermoid carcinoma (MEC) being the most frequent. MSGTs have a terrible prognosis, respond unexpectedly to the available therapies and present high rates of recurrence, leading to patients with these lesions to present a poor survival rate. The pathogenesis of MEC is still unknown, which limits the existence of molecular markers of prognosis that provides a better therapeutic approach, so tools such as cell culture are essential in the process of studying cell behavior. Immunohistochemical studies show that the Hepatocyte Growth Factor (HGF, the sole c-MET ligand) and c-MET (Tyrosine Protein Kinase MET) are present in human MSGT samples. Although these markers are present in these malignant tumors, their contribution to the pathobiology of MSGTs is unknown. Objective: To understand and investigate the role of the HGF/c-MET signaling pathway and its effects on MEC cell lines. Materials and Methods: The used MEC cell lines (UM-HMC-1, UM-HMC-3A and UM-HMC-3B) were established at the University of Michigan. Immunofluorescence and flow cytometry evaluated the presence and quantification, respectively, of the c-MET receptor in the cell lines studied. Pathway activation and signaling was tested using HGF and western blot for MET via PI3K/AKT via MAPK and histone 3. The biological impact of the activation of the HGF/c-MET pathway was assessed using cell migration assay, invasion assay and evaluation of the generation of cancer stem cells through ALDH / CD44 cell labeling. Results: The presence and activation of c-MET were detected in all MEC cell lines. The activation of c-MET, induced by HGF, promoted more invasiveness and cell migration, besides increasing the amount of cancer stem cells in the cell lines UM-HMC-1 and UM-HMC-3A. This activation also produced global changes in chromatin (histone acetylation 3). Conclusions: Our findings provide evidence that the HGF / c-MET signaling pathway is active in MEC and contributes mainly to its invasion, migration and generation of cancer stem cells.