Increased expression of matrix metalloproteinase-7 in invasive early gastric cancer

Background Matrix metalloproteinase-7 (MMP-7), a proteolytic enzyme, is suspected to play an important role in the progression of various cancers. To clarify the clinical importance of MMP-7, we retrospectively analyzed MMP-7 expression in gastric epithelial tumors.Methods We tested 201 lesions (from 172 patients) of surgically or endoscopically resected gastric epithelial tumors (gastric cancer, 158 lesions; gastric adenoma, 32 lesions; hyperplastic polyp, 11 lesions). MMP-7 expression was immunohistochemically examined. Sections with immunostaining signals in more than 30% of tumor cells were judged to show positive expression.Results MMP-7 was expressed in 33.3% (67/201) of all lesions. MMP-7-positive tumors were significantly more frequent in diffuse-type adenocarcinomas (62.2%; 28/45) compared with intestinal-type lesions (31.9%; 36/113; P < 0.001). Cancers invading the submucosa or deeper (60.5%; 46/76) were showed positivity significantly more frequently than mucosal cancers (22.0%; 18/82; P < 0.001). MMP-7-positive lesions increased with the progression of gastric epithelial tumors, including adenomas, mucosal cancers, and cancers invading the submucosal layer or deeper (P < 0.001). MMP-7 expression occurred significantly more often in lymphatic invasion-positive cancers (65.1%; 41/63) than in lymphatic invasion-negative cancers (24.2%; 23/95; P < 0.001).Conclusions The MMP-7-positive rate increased with the progression of gastric epithelial tumors, such as adenoma, mucosal cancer, and cancer invading the submucosal layer or deeper. MMP-7 was significantly associated with aggressive pathological phenotypes of cancer. The detection of the MMP-7 protein may be useful in pretherapeutic diagnosis.