Proteolysis in human breast and colorectal cancer

Proteolysis occurs when proteinase activity exceeds inhibitor activity. Pro teolysis is normally tightly regulated and is involved in cancer invasion a nd metastasis. The aim of this study was to compare proteolysis in breast a nd colorectal cancer. Proteinase and inhibitor expression were analysed in paired tumour and normal tissue samples from 43 breast and 24 colorectal ca ncer patients using substrate zymography, Western blotting and quenched flu orescence substrate hydrolysis. The expression of the latent forms of matri x metalloproteinase-2 (MMP-2), MMP-3 and MMP-9, urokinase plasminogen activ ator (uPA), tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2 exp ression were observed in both tumour and normal tissue samples from breast and colorectal tissue; however, expression was greater in the tumour tissue . Expression of active MMP-2 and MMP-9 and the total MMP activity were grea ter in tumour compared to normal samples in both tissues (P < 0.05). The ex pression of all proteinases and total MMP activity was greater in colorecta l tissue than breast tissue samples. Breast and colorectal cancer demonstra ted different proteinase profiles, however proteolysis in both tissues was greater in tumour tissue than normal tissue. (C) 1999 Cancer Research Campa ign.