The most important biologic characters of malignant tumor are invasion and metastasis, and extracellular matrix is first barrier in metastatic process. Therefore, proteases are linked to the malignant phenotype of different solid tumor.

In this study, the expression of the matrix metalloproteinase (MMP)-2 and MMP-9 and of the serine protease urokinase-type plasminogen activator (uPA) and its inhibitor plasminogen activator inhibitor type 1 (PAI-1) in the ovarian epithelial tumors was investigated. Immunohistochemical expression of MMP-2, MMP-9, uPA, and PAI-1 were analyzed in formalin fixed tumor tissues of 20 benign cystadenomas, 20 low malignant potential (LMP) tumors, and 20 malignant ovarian cancer, including 10 FIGO stage I cancer and 10 stage III cancer. In the same tissue extracts, DNA levels of MMP-2, MMP-9, uPA, and PAI-1 were determined by PCR.

The immunohistochemical expression and DNA level of MMP-2, MMP-9, uPA, and PAI-1 were low in benign ovarian tumors but significantly increased LMP tumors and malignant ovarian cancers. The highest values of all of the proteolytic enzymes were detected in stage III ovarian cancers with omentum metastases. There are significant correlations between expression of uPA and MMP.

These results suggest that high expression of MMP-2, MMP-9, and uPA is associated with activity of tumor invasion and metastasis, and expressions of MMP-2 and MMP-9 are correlated with uPA activity.