EXPRESSION OF MATRIX METALLOPROTEINASE MMP-2 AND ITS TISSUE INHIBITOR TIMP-2 IN INTRAORAL PLEOMORPHIC ADENOMA AND ADENOID CYSTIC CARCINOMA

Matrix metalloproteinases (MMPs) are proteolytic enzymes that are capable of degrading different substrates within extracellular matrix (ECM), and are believed to be crucial for tumor invasion and metastasis. Tissue inhibitors of MMP (TIMPs) can inhibit the action of MMPs The aim of this study was to analyze protein expression of MMP-2 and TIMP-2 in intraoral pleomorphic adenoma (PLA) and adenoid cystic carcinoma (ACC). A total of 35 formalin-fixed paraffin-embedded specimens comprising 19 PLA and 16 ACC were utilized in this study. A standard immunohistochemical technique was used to determine the expression levels of MMP-2 and TIMP-2 proteins. Sections were assessed semi quantitatively .Staining was scored as 0 (< 1% positive tumor staining), 1+ (< 25% positive tumor cells), 2+ (20-50% positive tumor cells) and 3+ (> 50% positive tumor cells). For statistical analysis, tumors were divided into two groups, low expressors ( 0-1+) and high expressors (2-3+). PLA showed higher TIMP-2 expression than ACC (p<0.05). No significant difference was observed between PLA and ACC regarding MMP-2 expression. MMP-2 and TIMP-2 expressed mainly in the cytoplasm of epithelial/ myoepithelial components of PLA and neoplastic epithelial cells of ACC. Myoepithelial cells may be the primary source of gelatinases in PLA and the down regulation of TIMP-2 expression in ACC might be responsible for metastasis and recurrence. The ratio value of MMP-2/TIMP-2 is valuable parameter to demonstrate the ECM degradation/ deposition imbalance.