The Expression And The Significance Of P53, P73α And C-erbB-2 In The Salivary Gland Myoepithelioma And Myoepithelial Carcinoma

Objective: Salivary gland Myoepithelial tumors account for less than 1.5% of all salivary gland tumors. It was recognized as a new entity in the WHO classification for the salivary gland tumors until in 1991. There have been few reports about this tumor until recently. By analyzing the variety of cell morphologies and complex architecture patterns, we are aimed to know it more clearly and improve our ability in diagnosis. In this study we also investigated the expression of p53,p73 and c-erbB-2 in benign myoepithelial tumors (BME) and malignant myoepithelial tumors (MME) in order to learn the role of the these genes in the carcinogenesis of myoepithelial tumors.Materials and methods: 30 myoepithelial tumors (15 benign myoepithelial tumors,15 malignant myoepithelial tumors) and 4 normal salivary glands were retrieved from our department. We analyzed the microscopic characteristics of the tumor structure and tumor cell morphous by light microscope. In addition, Immunohistochemical stain was applied to explore the expression of mutant p53 protein,c-erbB-2 protein and p73αprotein in BME and MME.Results: There are four types of modified myoepithelial cells: epithelial,clear,hyaline or plasmatic,and spindle cells. We classified the 30 tumors according to Dardick's classification standard. From the cell type point, there are 13 epithelial cell type,1 plasmacytoid cell type,6 clear cell type,2 spindle cell type and 8 mixed cell type; From the architecture point, there are 19 solid type,3 myxoid type,6 reticular type and 2 mixed type. In addition, Immunohistochemistry analysis for p53,p73 and c-erbB-2 were performed in 15 BME and 15 MME. p53 positive stain was found in 80% of the 15 MMEs while all negative in 15 BMEs (P<0.05). The expression of p53 differs from weak to strong stain in tumor cells and the stain become stronger in those tumor cells near the normal tissue. p73αnegative expression were found in both the BMEs and the MMEs. c-erbB-2 protein was detected in 2 cases (13.3%) BME and 6 cases (30%) MME (P>0.05).Conclusion: Salivary gland myoepithelial tumors are a tumor type with variety of cell morphologies and complex architecture patterns. p53 mutation might play an important role in the development of the myoepithelial carcinoma. However, the function of p73 might be different from p53'. p73 might be not involved in the carcinogenesis of myoepithelial carcinoma. c-erbB-2 might play a role in the development of myoepithelial tumors.