Enhanced cell surface expression of matrix metalloproteinases and their inhibitors, and tumor-induced host response in progression of human gastric carcinoma

The cell surface and/or intracellular expression of the matrix metalloproteinases (MMP -2, 7, and -9 and MT1-MMP) and their inhibitors (TIMP-2 and -4) were investigated in tumor and tumor-infiltrating lymphocytes (TIL) in gastric carcinoma (n = 15) from the primary locus, metastatic gastric carcinoma (n = 20) from malignant ascites, and benign gastric mucosa ( n D 20) for the control. The quantitative analysis was based on the percentage of positive cells by flow cytometry. The results clearly showed increased cell surface expression of MMP-2, -7, and -9, MT1-MMP, and TIMP-2 and -4 in both tumor cells and TIL during the development of invasion and/or metastasis of gastric carcinoma. There were equilateral correlations with cancer progression and frequency of cell surface expression of MMPs and their inhibitors, TIMPs, suggesting not only the aggressive nature of particularly metastatic gastric carcinoma, but also the presence of MMPs complexed with TIMPs on tumor cells and TIL. The enhanced cell surface expression of MMPs and TIMPs on TIL within metastatic carcinoma nests showed the result of a host response induced by tumors. These suggest that the increased cell surface expression of MMPs and TIMPs, and tumor-induced host response play a key role in gastric cancer invasion and/or metastasis.