Calcifying Cystic Odontogenic Tumour: immunohistochemical expression of matrix metalloproteinases, their inhibitors ( TIMP s and RECK ) and inducer ( EMMPRIN )

Background Calcifying cyst odontogenic tumour ( CCOT ) is a rare benign cystic neoplasm of odontogenic origin. MMP s are responsible for extracellular matrix remodelling and, together their inhibitors and inducer, determinate the level of its turnover in pathological processes, leading to an auspicious microenvironment for tumour development. Thus, our goal was to evaluate matrix metalloproteinases ( MMP s‐2, ‐7, ‐9 and ‐14), their inhibitors ( TIMP s‐2, ‐3, ‐4 and RECK ) and its inductor ( EMMPRIN ) expression in CCOT . Materials and Methods We used 18 cases of CCOT submitted to immunolocalization of the target proteins and analysed in both neoplastic odontogenic epithelial and stromal compartments. Results All molecules evaluated were expressed in both compartments in CCOT . In epithelial layer, immunostaining for MMP s, TIMP s, RECK and EMMPRIN was found in basal, suprabasal spindle and stellate cells surrounding ghost cells and ghost cells themselves, except for MMP ‐9 and TIMP ‐2 which were only expressed by ghost cells. In stromal compartment, extracellular matrix, mesenchymal ( MC ) and endothelial cells ( EC ) were positive for MMP ‐2, ‐7, TIMP ‐3 and ‐4, while MMP ‐9, TIMP ‐2 and RECK were positive only in MC and MMP ‐14 only in EC . Statistical significance difference was found between both compartments for MMP ‐9 ( P  < 0.001), RECK ( P  = 0.004) and EMMPRIN ( P  < 0.001), being more expressed in epithelium than in stroma. Positive correlation between both stromal EMMPRIN and RECK expression was found ( R  = 0.661, P  = 0.003). Conclusions We concluded that these proteins/enzymes are differentially expressed in both epithelium and stroma of CCOT , suggesting an imbalance between MMP s and their inducer/inhibitors may contribute on the tumour behaviour.