Matrilsin expression is a useful marker of submucosal invasion and lymph node metastasis in early stage signet ring cell carcinoma of the stomach

Background: Matrilysin (MMP-7) is considered to play an important role in tumor progression and metastasis. The aim of this study was to examine the MMP-7 expression of early-stage undifferentiated gastric carcinoma, and to investigate differences between gastric signet ring cell (SIG) and other undifferentiated carcinomas (non-SIG). Methods: Immunohistochemical staining of MMP-7 was performed using specimens from 150 patients with early-stage gastric undifferentiated carcinomas (76 SIG, 74 non-SIG). Results: SIG had a larger proportion of mucosal-confined carcinoma and a lower rate of lymphatic invasion than non-SIG (P < 0.05). The incidence of the positive expression of MMP-7 in submucosal SIG was significantly higher than that of mucosal SIG (P < 0.01). In contrast, MMP-7 expression was frequently found in mucosal non-SIG, suggesting an apparent difference in the invasiveness between mucosal SIG and non-SIG. The larger the size of the mucosal SIG, the more frequently MMP-7 positive expression was demonstrated (P < 0.05). There was a significant correlation between MMP-7 positive expression and lymph node metastasis of early SIG (P < 0.05). Conclusion: Early SIG revealed less invasiveness than non-SIG in terms of clinicopathologic features and MMP-7 expression. Preoperative estimation of the MMP-7 expression might be useful as a predictor of submucosal invasion and lymph node metastasis in early SIG.