Matrix metalloproteinase-7 expression in gastric carcinoma

Background/Aims - Matrix metalloproteinase-7 (MMP-7) belongs to the same family as matrix degrading metalloproteinase (MMPs) that may play an important part in cancer cell invasion and metastasis. This study reports on the MMP-7 mRNA expression level both in human gastric carcinomas and the normal gastric mucosa. Methods - From fresh specimens of 47 surgical pairs of primary gastric carcinomas and corresponding normal tissue specimens, cDNA was obtained by reverse transcription (RT) and thereafter MMP-7 mRNAs were detected by means of a polymerase chain reaction. The tumour/normal (T/N) ratio of MMP-7 expression was calculated after correcting for glyceraldehyde-3-phosphate dehydrogenase as an internal control. Results - The expression corrected levels of MMP-7 mRNA of the tumour was greater than that of the normal mucosa in 41 of 47 cases (87%). The 13 cases whose T/N ratio was more than 2.1 showed a deeper invasion of the gastric wall, and more frequent lymphatic or vascular permeations than the 34 cases whose T/N ratio was less than 2.0. An immunohistochemical study showed that MMP-7 was predominantly expressed in the cancer cells, weakly expressed in normal epithelial cells, and not expressed in the surrounding stromal cells. Conclusions - These findings suggest that the overexpression of MMP-7 may thus play an important part in tumour invasion in gastric carcinomas while, in addition, MMP-7 may also prove to be a useful marker for determining the biological aggressiveness of gastric carcinoma.