Increased plasma MMP-2 protein expression in lymph node-positive patients with colorectal cancer

Degradation of the extracellular matrix plays an important part during the invasion of cancer cells into the surrounding tissue. The matrix metalloproteinases (MMPs) have a central role in this process as demonstrated in different malignancies. The aim of this study was to investigate the presence of several MMPs from tumour, adjacent tumour-free colon segment and from plasma, in order to evaluate how these factors might be used as predictors in colorectal malignancy.

Seventy-two patients who underwent surgery because of a colorectal carcinoma were included. Biopsies from the tumour, macroscopically tumour-free bowel and plasma samples were analysed with enzyme-linked immunosorbent assay tests (ELISAs) quantifying protein expression of several MMPs.

We found highly elevated concentrations of MMP-1, MMP-2, MMP-3 and MMP-9 protein expression in tumour tissue compared with tumour-free tissue (p<0.0001). Elevated MMP-1 tumour levels were found in patients with Dukes' C cancers (p=0.02). Lymph node status correlated with the expression of MMP-2 in plasma, which was significantly increased in patients with lymph node metastasis compared with those without (p=0.002). MMP-2 in plasma was higher in T3 and T2 tumours than in T4 tumours (p=0.0083).

The MMPs we investigated were strongly elevated in tumour tissue compared with tumour-free bowel wall. Our results indicate that MMP-2 in plasma may possibly be used as a predictor in colorectal malignancy. The use of MMP-2 as a predicting tool in combination with different imaging techniques may give important preoperative information in patients with colorectal cancer.