Up-regulation of gelatinases in the colorectal adenoma-carcinoma sequence

Gelatinase activity has been associated with colorectal cancer (CRC) invasion and metastasis. However, it remains unresolved whether these proteases participate in early colorectal carcinogenesis. The activity of metalloproteinases (MMP) 2 and 9 were measured by zymography in 122 colorectal adenomas, 22 CRC samples, 12 hyperplasic polyps and in 114 matched normal mucosal samples from 114 patients undergoing colonoscopy. There was a progressive and significant increase of pro-MMP-9 activity from adenoma to CRC tissue, whereas the activity of the latent and active forms of MMP-2 was exclusively up-regulated in CRC samples. Among neoplastic polyps, pro-MMP-9 activity was significantly higher in advanced versus non-advanced adenomas and in those harbouring high grade dysplasia. In addition, a positive correlation was observed between MMP-9 activity and the size of the adenomas. The present study demonstrates that MMP-9 is markedly up-regulated in the adenomatous tissue and suggests that this gelatinase might be a marker for early colorectal carcinogenesis.