Summary Proteolysis occurs when proteinase activity exceeds inhibitor activity. Proteolysis is normally tightly regulated and is involved in cancer invasion and metastasis. The aim of this study was to compare proteolysis in breast and colorectal cancer. Proteinase and inhibitor expression were analysed in paired tumour and normal tissue samples from 43 breast and 24 colorectal cancer patients using substrate zymography, Western blotting and quenched fluorescence substrate hydrolysis. The expression of the latent forms of matrix metalloproteinase-2 (MMP-2), MMP-3 and MMP-9, urokinase plasminogen activator (uPA), tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2 expression 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 greater in tumour compared to normal samples in both tissues (P < 0.05). The expression of all proteinases and total MMP activity was greater in colorectal tissue than breast tissue samples. Breast and colorectal cancer demonstrated different proteinase profiles, however proteolysis in both tissues was greater in tumour tissue than normal tissue.

Background-The process of proteolysis is important at several stages of the metastatic cascade. A balance between the expression of the genes encoding endogenous proteinases and inhibitors exists and when the production of proteinases exceeds that of inhibitors proteolysis occurs. Aims-To determine whether diVerences in the profile and activity of proteinases and inhibitors exist within breast tumour tissue (n = 51), surrounding background breast tissue (n = 43), normal breast tissue from breast reduction mammoplasty operations (n = 10), and cells of the breast cancer cell line, MCF-7. Methods-Proteinase (matrix metalloproteinase 1 (MMP-1), MMP-2, MMP-3, MMP-9, urokinase-type plasminogen activator (uPA), and tissue-type PA (tPA)) and inhibitor (tissue inhibitor of metalloproteinases; TIMP-1 and TIMP-2) expression and proteinase activity were compared using substrate zymography, western blotting, immunohistochemistry, and quenched fluorescent substrate hydrolysis. Breast cancer is the most common cancer in women; it aVects one in 12 women and over 15 000 women die from breast cancer in the UK each year. Tumour invasion and metastasis formation are the primary causes of cancer treatment failure and death. Results-The1 The process of metastasis is a complex cascade of organised, sequential, interrelated steps, including angiogenesis, local invasion, intravasation, and extravasation, 1 many of which require active degradation of the host tissue by proteolytic enzymes. The synthesis, secretion, and catalytic activity of proteinases appears to be tightly regulated and most are secreted as inactive zymogens.2 Highly potent natural proteinase inhibitors also exist, which limit the duration of active proteolysis. Under physiological conditions, the balance between proteolytic degradation and the regulatory inhibition of proteolysis controls normal proteolytic events-for example, tissue remodelling and wound healing. In these situations, only selective enzymes, or a cascade of functionally related proteinases, are produced in response to the signal. However, in certain pathological processes, including cancer, the balance between negative regulation and active proteolysis is disrupted so that proteolysis is no longer constrained. At least four classes of proteinases exist and they are most frequently classified according to their catalytic type. 4 These are the matrix metalloproteinases (MMPs or matrixins), and the serine, aspartic, and cysteine proteinases. 5 The coordinated and synergistic action of these four classes of proteinases can completely degrade all extracellular matrix (ECM) components. 3Of these four classes, the matrix metalloproteinases and the serine proteinase, urokinasetype plasminogen activator (uPA), are most extensively linked to cancer invasion and metastasis. Both the role of the MMP and PA systems in cancer and metastasis and their regulation of these processes have been reviewed previously. 5-8Proteinase expression has been studied extensively in many diVerent human cancers, including bre...

Background-The process of metastasis is complex, involving many interrelated stages, including proteolysis. Proteolysis occurs in both normal and pathological processes and involves the breakdown of the extracellular matrix and/or basement membrane by proteolytic enzymes. Normally, proteolysis is tightly controlled by specific endogenous proteinase inhibitors. However, in certain disease processes, including cancer, controlled but abnormal proteolysis seems to occur. Proteinases involved in tumour invasion and metastasis include the matrix metalloproteinases (MMPs) and the serine proteinases. Aims-To gain a greater understanding of the proteolytic process occurring in colorectal cancer and to determine which, if any, proteinases are upregulated. The process of metastasis is complex, involving many sequential and interrelated steps. In brief, metastasis involves detachment of a single or a group of tumour cells from the primary tumour, local invasion through the surrounding extracellular matrix (ECM), intravasation into blood or lymphatic vessels, survival in the circulation, extravasation at a secondary site, survival and proliferation at the secondary site, and finally the potential for this secondary growth to metastasise. 1 ECM turnover normally involves homeostatic control of cell division, matrix synthesis, and degradation (proteolysis), which is under the control of cytokines, growth factors, and cell-matrix interactions. ECM degradation by proteinases is involved in normal physiological processes and is a tightly controlled and regulated process. However, in certain disease states, including cancer invasion and metastasis, the balance of ECM turnover is not controlled or regulated normally and excessive proteolysis occurs. Methods-The 2Proteinases are known to be involved in tumour cell invasion and the resulting ECM degradation may occur at several stages of the metastatic cascade including angiogenesis, local invasion, intravasation, and extravasation. Several proteinases have been implicated in one or more of these processes, as well as being potential prognostic indicators of disease free survival and death; these proteinases include: cathepsin B, 3 cathepsin D, 4 and urokinase-type plasminogen activator (uPA). The ECM degradation required for tumour cell invasion is a tightly controlled process at the biochemical and cellular level. These processes are dependent not only on the total amount of secreted proenzymes, but also on the coordinated activation and inhibition of these enzymes. The cells often regulate proenzyme activation either on or close to the cell surface, permitting localised ECM degradation. 6Several proteinase classes exist including metalloproteinases, serine proteinases, aspartic proteinases, and cysteine proteinases. Within the metalloproteinase class, the matrix metalloproteinase (MMP) or matrixin family of enzymes is thought to be particularly important in ECM turnover. The serine proteinases, plasminogen activators (PAs), are also involved in ECM degradation by activatin...