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.