To search for the biochemical properties of esophageal carcinoma relevant to its aggressive behavior, we studied metalloproteinases released from surgical specimens of the carcinoma. In an assay with [H-3]-labeled gelatin, esophageal carcinoma tissues showed gelatinolytic activities clearly higher than those of paired normal mucosae. EDTA and TIMP-1 could strongly suppress these activities, suggesting that the activities belong to metalloproteinases. In addition, levels of TIMP-1 expression did not show good correlation with these activities, suggesting that tumor-specific elevation of gelatinolytic activity depended on metalloproteinase per se rather than the suppression of TIMP-1-secretion. By zymographic analysis, two gelatinase bands of 82- and 62-kDa were found specifically in carcinoma tissues, in addition to the other 6 bands detected both in normal and carcinoma tissues. Immunoprecipitation and immunoblotting of gelatinases with anti-MMP-9 or anti-MMP-2 monoclonal antibody, and treatment of the enzymes with APMA showed that these 82- and 62-kDa gelatinases were cleaved products of MMP-9 and MMP-2, respectively. These results imply that enhanced secretion and proteolytic activation of MMP-2 and MMP-9 take place specifically in the esophageal carcinoma tissues. Moreover, the levels of gelatinolytic activity expressed good correlation with the organ metastasis rate of the carcinoma, suggesting that MMPs play an important role in tumor metastasis.

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