Quantitative immunohistochemical analysis of matrilysin 1 (MMP-7) in various renal cell carcinoma subtypes

The role of matrilysin 1 or matrix metalloproteinase-7 (MMP-7) in cancer is extremely complex and poorly understood. In this study we investigated differential expression of MMP-7 in the epithelium and stroma of 95 paraffin-embedded renal tumor samples by immunohistochemistry and compared tumoral with normal peritumoral renal tissue. We also determined a possible correlation of the immunohistochemical findings with histological subtype, tumor grade and stage of RCC. In all areas examined MMP-7 protein expression was significantly higher in epithelium than in stroma (P less than 0.01). MMP-7 was more less expressed in peritumoral normal areas than in benign epithelial neoplasias (renal papillary and oncocytomas) and RCC carcinomas, reaching the highest immunopositive reaction in chromophobe RCC subtypes, followed by conventional clear-cell and chromophilic-papillary RCC histological subtypes and the lowest levels in more aggressive RCC histotypes (spindle-cell and collecting-duct RCCs). MMP-7 reached their highest levels in high-grade and high-stage RCCs. Our observation suggests an important role of MMP-7 in the development and progression of renal cancer. The differential expression of MMP-7 in the various histological RCC subtypes may reflect the malignant phenotype and more aggressive behavior of RCCs.