Clinical significance of tissue levels of matrix metalloproteinases and tissue inhibitors of metalloproteinases in gastric cancer

Background. Matrix metalloproteinases (MMPs) are one of the major classes of proteolytic enzymes involved in tumor invasion and metastasis, being inhibited by naturally occurring tissue inhibitors of metalloproteinases (TIMPs). In this study, we examined the expression of MMP-2, MMP-9, membrane-type 1 (MT1)-MMP, TIMP-1, and TIMP-2 in biopsy tissues of gastric cancer, and the correlation between their expression and clinicopathological parameters. Methods. Biopsy specimens from 66 patients with gastric carcinoma were available for this study. To determine the expression of MMP-2, MMP-9, MT1-MMP, TIMP-1, and TIMP-2, semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was carried out on tumor and normal tissues, respectively, sampled during diagnostic gastroscopic examination. Immunohistochemical staining of representative samples using monoclonal antibody directed against MT1-MMP was done, and the clinicopathological variables were reviewed retrospectively. Results. The expression level of MMPs and TIMPs was evaluated using the tumor:normal (T/N) ratios of MMPs and TIMPs. The T/N ratio of MT1-MMP mRNA showed a significant correlation with lymph node metastasis and tumor stage (P < 0.05). The other RT-PCR data of MMP-2, MMP-9, TIMP-1, and TIMP-2 did not show any significant correlation with clinicopathological parameters. Immunohistochemistry for MT1-MMP showed a positive immunoreaction in gastric adenocarcinoma and negative staining in normal mucosa. Conclusions. The correlation between the increased expression of MT1-MMP and clinicopathological variables reflects a role in predicting the aggressive behavior of gastric cancer. Because an RT-PCR assay can be performed on biopsy specimens obtained before surgery, an evaluation of MT1-MMP expression in biopsy specimens by RT-PCR may provide useful preoperative information on tumor aggressiveness.