Relation of matrix metalloproteinase-9 to different stages of tumors in the serum of gastric cancer.

The sera of 40 patients with gastric cancer and 11 patients as the control group were studied for the detection of matrix metalloproteinases. The malignant behavior of tumor cells mainly depends on the capability of invasion and the metastasis of cancer cells. After the components of the extracellular matrix (ECM) are degraded, tumor cells invade the surrounding tissue and the vascular or lymphatic vessels to form metastasis colonies at distant sites. Extracellular proteolytic enzymes implicate the invasion and metastasis of cancer. Proteolytic enzymes from tumors lead to the breakdown of basement membranes and the ECM, thereby, facilitating cancer cell invasion into the surrounding normal tissue. Proteinase activity is overexpressed in the serum of stage 3 and 4 tumors compared to stage 1 and 2 tumors. ProMMP-9 was detected in the serum of patients of gastric cancer by SDS polyacrylamide gel electrophoresis (SDS-PAGE) and SDS-PAGE zymography, with its molecular mass of 92 kDa. MMP-9 in serum plays an important role in the progression of gastric cancer.