Artur Cunha Vasconcelos1, Vivian Petersen Wagner1, Luise Meurer2, Pablo Agustin Vargas3, Lélia Batista de Souza4, Felipe Paiva Fonseca3, Cristiane Helena Squarize5, Rogerio Moraes Castilho5, Manoela Domingues Martins6. 1. Department of Oral Pathology, School of Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil. 2. Department of Pathology, Hospital de Clínicas de Porto Alegre (HCPA/UFRGS), Porto Alegre, Rio Grande do Sul, RS, Brazil. 3. Department of Oral Diagnosis, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil. 4. Department of Oral Pathology, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil. 5. Laboratory of Epithelial Biology, Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA. 6. Department of Oral Pathology, School of Dentistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil. Electronic address: manomartins@gmail.com.
Abstract
OBJECTIVE: The aim of this study was to analyze the expression pattern of proteins in the HGF/c-MET/PI3K signaling pathway in salivary gland tumors (SGTs) and to correlate the findings with the proliferative index and clinical parameters. STUDY DESIGN: We assembled tissue microarrays (TMAs) of 108 cases of SGTs, including 69 cases of pleomorphic adenoma (PA), 24 cases of adenoid cystic carcinoma (AdCC), and 15 cases of mucoepidermoid carcinoma (MEC). An immunohistochemical analysis of hepatocyte growth factor (HGF), MET phosphorylation (p-MET), protein kinase B (AKT) phosphorylation (p-AKT), and Ki-67 proteins was performed. RESULTS: Benign and malignant SGTs presented similar scores of HGF-positive cells (P = .36), whereas, malignant SGTs exhibited higher levels of p-MET (P = .001) and p-AKT (P = .001) than benign SGTs. No correlation of HGF, p-MET, or p-AKT expression was observed with clinical parameters. PA had a lower proliferative index than either AdCC (P = .001) or MEC (P = .001). CONCLUSIONS: The salivary gland carcinomas exhibited increased activation of the HGF pathway, as evidenced by the phosphorylation of the MET receptor, and increased activation of the PI3K pathway, as indicated by p-AKT. These data suggest that the HGF/c-MET/PI3K signaling pathway is active in SGTs, especially in malignant neoplasms.
OBJECTIVE: The aim of this study was to analyze the expression pattern of proteins in the HGF/c-MET/PI3K signaling pathway in salivary gland tumors (SGTs) and to correlate the findings with the proliferative index and clinical parameters. STUDY DESIGN: We assembled tissue microarrays (TMAs) of 108 cases of SGTs, including 69 cases of pleomorphic adenoma (PA), 24 cases of adenoid cystic carcinoma (AdCC), and 15 cases of mucoepidermoid carcinoma (MEC). An immunohistochemical analysis of hepatocyte growth factor (HGF), MET phosphorylation (p-MET), protein kinase B (AKT) phosphorylation (p-AKT), and Ki-67 proteins was performed. RESULTS: Benign and malignant SGTs presented similar scores of HGF-positive cells (P = .36), whereas, malignant SGTs exhibited higher levels of p-MET (P = .001) and p-AKT (P = .001) than benign SGTs. No correlation of HGF, p-MET, or p-AKT expression was observed with clinical parameters. PA had a lower proliferative index than either AdCC (P = .001) or MEC (P = .001). CONCLUSIONS: The salivary gland carcinomas exhibited increased activation of the HGF pathway, as evidenced by the phosphorylation of the MET receptor, and increased activation of the PI3K pathway, as indicated by p-AKT. These data suggest that the HGF/c-MET/PI3K signaling pathway is active in SGTs, especially in malignant neoplasms.