Clinicopathological significance of aminopeptidase N/CD13 expression in human gastric carcinoma.

Background/Aims: Aminopeptidase N (APN)/ CD13 is a transmembrane ectoenzyme occurring in a wide variety of cells. Recently, APN/CD13 has been reported to be involved in tumor invasion and metastasis. However, precise functions in tumor cells, and its role in gastric carcinoma remain unclear. Methodology: To evaluate the role of APN/CD13 in gastric carcinoma, we conducted immunohistochemical staining for APN/CD13 in 121 gastric carcinoma specimens, using anti-APN monoclonal antibody. The relationship between APN/CD13 expression and various prognostic factors of gastric carcinoma were investigated. Results: Of the 121 patients with gastric carcinoma studied, 48 were strongly positive, 36 were weakly positive, and 37 were negative. Overall survival rate of the patients with negative APN/CD13 expression was significantly lower than that of the patients with positive APN/CD13 expression. APN/CD13 expression was negatively associated with lymph node metastasis. Multivariate analysis showed APN/CD13 expression to be a significant prognostic factor. Conclusions: Decreased expression of APN/CD13 was associated with a poor prognosis. Hence, our results demonstrate that the immunohistochemical detection of APN/CD13 could provide useful information as one of the prognostic factors in gastric cancer.