Aims: The matrix metalloproteinase (MMP)/tissue inhibitor of metalloproteinase (TIMP) system has a major role in tumour invasion and metastasis. Roles in pathways involved in early tumour development are also being identified for this system, and the aim of this study was to define the expression profile of the major MMPs and TIMPs in colorectal polyp cancers.
Methods and results: The expression and cellular localization of individual MMPs and TIMPs was determined in colorectal polyp cancers by immunohistochemistry. All the MMPs and TIMPs showed immunoreactivity in carcinomatous epithelium. MMP1 (P < 0.001), MMP2 (P = 0.003), MMP3 (P = 0.004), TIMP1 (P = 0.01) and TIMP2 (P < 0.001) showed significant increases in immunoreactivity in carcinomatous epithelium compared with adenomatous epithelium. MMP7 showed immunoreactivity in carcinomatous epithelium, but showed no immunoreactivity in either normal epithelium or adenomatous epithelium. MMP and TIMP expression was limited in normal epithelium to MMP1, MMP2 and TIMP3.
Conclusions: This study defines the expression profile of MMPs and TIMPs in colorectal polyp cancers and shows that the increased expression of MMPs and TIMPs occurs at an early stage of colorectal neoplasia. It provides evidence to support the hypothesis that these molecules have a key involvement in the early stages of tumour development.