The multifunctional role of the immunohistochemical expression of MMP-7 in invasive breast cancer.

The secretion of matrix metalloproteinases (MMPs) is crucial in the metastasis of cancer cells, since MMPs are responsible for the degradation of extracellular matrix (ECM). Among them, matrix metalloproteinase-7 (MMP-7) or matrilysin 1 is a stromelysin which degrades type-IV collagen, fibronectin and laminin. Immunohistochemistry was performed to detect MMP-7 protein in infiltrative breast carcinomas. MMP-7 was studied along with clinicopathological parameters, disease-free and overall survival, and p53, c-erbB-2, topoIIa, MMP-2, uPAR and beta-catenin. MMP-7 immunoreactivity was detected in the cytoplasm of cancer cells in 54.2% (96/177) and tumor stromal cells in 47.5% (84/177), as well as in normal epithelium adjacent to malignant epithelium. MMP-7 reactivity in cancer cells displayed an inverse association with nuclear grade (p=0.049) and topoIIa (p=0.03). A parallel association was observed between the expression of MMP-7 in both malignant and stromal cells with uPAR in cancer cells (p=0.033 and p=0.027, respectively). MMP-7 of tumor stromal cells depicted a parallel correlation with MMP-2 of the same cell type (p=0.044), while abnormal beta-catenin expression was inversely associated with MMP-7 of cancer cells (p=0.047). Our results show the multifunctional role of MMP-7 in the mammary gland, since it seems to be associated with a less aggressive phenotype, while, at the same time, being involved in invasion, through its collaboration with indicators of invasion.