Matrix metalloproteinase-13 (MMP-13) is a proteolytic enzyme that belongs to a large family of extracellular matrix-degrading endopeptidases that are characterized by a zinc-binding motif at their catalytic sites. MMP-13 has a key role in the MMP activation cascade and appears to be critical in bone metabolism and homeostasis. It also has an important role in tumor invasion and metastasis. This commentary provides a detailed overview of the regulatory mechanisms, structure, and function of human MMP-13 and highlights the key factors involved in the biology of this important molecule.

This review outlines new concepts that are emerging for the functions of matrix metalloproteinases in colorectal cancer development and progression. The two main concepts that will be discussed are the role of matrix metalloproteinases in the early stages of colorectal tumour development and the functional mechanisms by which matrix metalloproteinases contribute to colorectal tumour invasion and metastasis. The matrix metalloproteinases are a group of enzymes, which have been best characterized for their ability to degrade extracellular matrix proteins and thus they have been extensively studied in tumour invasion. It is now becoming recognized that the matrix metalloproteinases have key roles in a variety of biological processes that are distinct from their well-defined role in matrix degradation. This group of enzymes has been shown to interact with a broad range of non-matrix proteins including growth factors and their receptors, mediators of apoptosis, and cell adhesion molecules. The elucidation of novel biological roles for the matrix metalloproteinases also challenges the current predominant concept of matrix metalloproteinases as enzymes only involved in matrix degradation. Recent studies have shown that several matrix metalloproteinases, especially matrilysin (MMP-7), interact with the specific molecular genetic and signalling pathways involved in colorectal cancer development. In particular, matrilysin is activated at an early stage of colorectal tumourigenesis by the beta-catenin signalling pathway. Furthermore, studies are now elucidating specific mechanisms by which individual matrix metalloproteinases, especially membrane-type matrix metalloproteinases, interact with specific cell adhesion molecules and cytoskeletal proteins and thus contribute dynamically to colorectal tumour invasion.

Results: The MMP/TIMP profile defined by hierarchical cluster analysis of the immunohistochemical score identifies a distinct group of colorectal cancers with poor prognosis (log-rank test, 12.22, P ‫؍‬ 0.0005). The median survival time of patients in this survival group was 18 months compared with a median survival of 49 months in the "good" survival group. Multivariate analysis showed that this profile was independently the most significant prognostic factor (P ‫؍‬ 0.001). Conclusions:This study has identified that the MMP/ TIMP profile is an independent indicator of poor prognosis in colorectal cancer.

Aims: The matrix metalloproteinases (MMPs) are a family of proteolytic enzymes collectively capable of degrading all extracellular matrix components, in particular fibrillar collagen. The importance of this group of proteins in the processes of tumour invasion and metastasis is now widely acknowledged. MMP-13 (collagenase 3) has a central role in the MMP activation cascade. The purpose of this study was to investigate the presence and activity of MMP-13 in colorectal cancer and relate these to clinicopathological features. Methods: Immunohistochemistry for MMP-13 was performed on formalin fixed, paraffin wax embedded sections of a large series of colorectal cancers (n = 249), all of which had uniform clinical and pathological information available. Immunoreactivity to MMP-13 was detected with a monoclonal antibody to MMP-13 using a Dako TechMate™500 automated immunostaining system. The presence and cellular localisation of MMP-13 was assessed using a semiquantitative scoring system. Gelatin zymography was used to detect and measure MMP-13 activity. The zymography was performed on a subset of the cases studied by immunohistochemistry using two groups of 10 paired Dukes's C tumours and normal samples, selected by either having "good" or "poor" survival. Results: Immunoreactivity to MMP-13 was identified in 91% of cases and immunoreactivity was localised to the cytoplasm of tumour cells. A high MMP-13 staining score showed a trend towards poorer survival. Tumours had significantly greater MMP-13 activity compared with normal colonic mucosa (p < 0.001). Furthermore, the tumour to normal tissue ratio was significantly higher in the poor survival group (p = 0.02). Conclusions: These results show that MMP-13 is frequently present and active in colorectal cancer and suggest that the activity of MMP-13 is associated with poorer survival in colorectal cancer.

Almost all perforated gastric ulcers can be effectively managed by laparotomy and omental patch repair. Initial biopsy and follow-up endoscopy with repeat biopsy is essential to avoid missing an underlying malignancy.