Induction of matric metalloprotease-7 is common in mucinous ovarian tumors including early stage disease

Matrix metalloproteases are known to play an important role in tumor invasion by mediating degradation of the extracellular matrix. In this study, we have investigated the immunohistochemical expression of matrix metalloprotease-7 (MMP-7) in 44 mucinous ovarian tumors (9 adenomas, 13 low malignant potential tumors, 22 adenocarcinomas) and 6 normal ovaries. Positive staining of MMP-7 is observed in all mucinous ovarian tumors, whereas little or no staining was observed in surface epithelium as well as the epithelial cells of germinal inclusion cyst of the normal ovary. Positive immunostaining of MMP-7 is also observed in the secreted mucin in the tumor glands, which suggests the secretion of the MMP-7 protein from tumor cells. mRNA expression of MMP-7 was confirmed using RT-PCR. The MMP-7 gene was amplified in parallel with an internal control gene β-tubulin using a thermal cycler. mRNA expression levels of MMP-7 were significantly elevated in mucinous tumor samples compared with that in normal ovaries. Our results suggest that MMP-7 is frequently overexpressed in mucinous ovarian tumors and secreted with the mucin which is produced from the tumor cells. MMP-7 may therefore contribute to mucinous ovarian tumor development or enhanced growth capacity of mucinous ovarian tumors. MMP-7 may also serve as a target for therapeutic intervention in the down regulation of tumor progression.