Increased matrix metalloproteinase 2 concentration and transcript expression in advanced colorectal carcinomas

Colorectal cancer is one of the most common malignant tumors and entails a relatively poor prognosis. Clinical outcome depends on the extent of local and metastatic tumor spread. Results of in vivo and in vitro studies suggest that the balance between matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases TIMPs) is altered in neoplasia, contributing to the invasive and metastatic properties of malignant tumors. We quantified tissue concentrations of MMP-2 and TIMP-2 in 65 malignant colorectal lesions and corresponding normal mucosa by enzyme-linked immunosorbent assay, western blotting, and in situ hybridization. In situ hybridization and western blot analyses demonstrated a clear increase in both stromal expression of MMP-2 transcripts and protein in primary carcinomas. The protein concentration of MMP-2 was higher in all tumor stages, except stage I tumors, than in normal mucosa and adenomas. MMP-2 concentrations were not related to tumor differentiation or to colonic versus rectal location. Surprisingly, the MMP-2 concentration was not increased in metastases. Interestingly, tissue concentrations and epithelial mRNA expression of TIMP-2 decreased significantly in primary colorectal cancer (UICC stages III and IV) but increased in metastases. Therefore an increased ratio of MMP-2 to TIMP-2 is strongly associated with advanced tumor stages, but a decreased ratio was observed in metastases. These findings suggest that the MMP-2:TIMP-2 ratio may prove useful as a marker of local invasion but not of metastasis in colorectal cancer.