Matrix metalloproteinase-2 expression in stromal tissues is a consistent prognostic factor in stage II colon cancer

For patients with stage II colon cancer, the usefulness of adjuvant chemotherapy remains controversial. Therefore, it is important to identify high-risk indicators. The biological prognostic factors for recurrence might allow further insight into the optimal treatment strategy for patients with node-negative disease. Matrix metalloproteinase-2 seems to be one of the essential factors for tumor invasion and lymph node metastasis. In this study, we analyzed the expression of cyclooxygenase-2 and matrix metalloproteinase-2 by immunohistochemical staining in 109 patients with stage II colon cancer. A positive correlation was observed between tumor cyclooxygenase-2 and tumor matrix metalloproteinase-2 expression (P = 0.0006) and between tumor cyclooxygenase-2 and stromal matrix metalloproteinase-2 expression (P < 0.0001). Stromal matrix metalloproteinase-2 expression was associated with disease-free survival (P = 0.0095) and was shown to be an independent risk factor for recurrence by multivariate analysis. In addition, we carried out an invasion assay in vitro to investigate whether cyclooxygenase-2 and matrix metalloproteinase-2 affected the tumor-invasive potential of colon cancer cell lines. The invasion assay showed that every cancer cell line acquired invasive potential in coculture with stromal cell lines and the cyclooxygenase-2 inhibitor suppressed this phenomenon by downregulating the matrix metalloproteinase-2 expression of stromal cells. In conclusion, these findings suggest that matrix metalloproteinase-2 expression in stromal cells can be a high-risk indicator for recurrence in patients with stage II colon cancer.