Clarification of the active gelatinolytic sites in human ovarian neoplasms using in situ zymography

Tissues from 26 human ovarian common epithelial tumors were examined to determine where and how gelatinolytic activity was present, in relation to tumor-stromal interaction and histologic types. For this purpose, we used in situ zymography, a newly developed technique using gelatin-coated film. Gelatinolytic activity was evident in ovarian carcinomas and in borderline tumors. Benign tumors had no or only weak activity. Four tissue localization patterns of gelatinolysis were identified: pattern A, tumor cytoplasm; pattern B, tumor-stromal junction; pattern C, stroma; and pattern D, cystic fluid. Mucinous cystadenocarcinomas showed A and/or D patterns. One mucinous and one serous adenocarcinoma and one mucinous borderline tumor had a B pattern. Most serous and all clear cell adenocarcinomas showed strong gelatinolysis of C pattern, especially in the desmoplastic stroma, an area where the tumor cells were dispersed. Immunohistochemically in 12 adenocarcinomas and 3 borderline tumors, the tumor cytoplasm was positive for matrix metalloproteinases (MMP-2) (5 cases), MMP-7 (9 cases), and MMP-9 (6 cases). Stromal components were positive for MMP-2 in 5 cases and for MMP-9 in 3 cases, but they were not positive for MMP-7. MMP antigens were mostly distributed in an almost identical pattern consistent with that seen with in situ zymography. In situ zymography clarified the cellular localization of active gelatinolysis in human ovarian neoplasms, a finding which supports the view that interaction between tumor and stroma is critical for tumor growth. This newly developed method contributes to a better understanding of biologic features of ovarian malignancies.