Clinical significance of aminopeptidase N/CD13 expression in human pancreatic carcinoma.

PURPOSE We previously established a novel murine monoclonal antibody(MH8-11) that recognized aminopeptidase N (APN)/cluster of differentiation antigen 13 (CD13). This monoclonal antibody inhibited human umbilical vein endothelial cells migration and capillary-like tube formation of human umbilical vein endothelial cells on Matrigel. In this study, we investigated the expression of APN/CD13 and the intratumor microvessel density (IMD) as the number of microvessel counts in 50 patients with pancreatic carcinoma. EXPERIMENTAL DESIGN We investigated APN/CD13 gene expression using the reverse transcriptase-PCR. We also used immunohistochemistry with MH8-11 to investigate APN/CD13 protein expression. Moreover, we investigated the relationship between APN/CD13 expression and tumor angiogenesis by measuring the IMD. RESULTS APN/CD13 gene expression detected by reverse transcriptase-PCR was positive in 50.0% (25 of 50) of the tumors, and APN/CD13 protein positive was detected by immunohistochemistry in 48.0% (24 of 50). APN/CD13 gene expression agreed well with the immunohistochemical findings (90.0% concordance). APN/CD13 was also significantly associated with an increase of the IMD (r = 0.71, P = 0.0003). However, APN/CD13 expression was not associated with various prognostic factors. The median survival time of patients with APN/CD13 expression was significantly shorter than that of patients without APN/CD13 expression (P = 0.009), and multivariate analysis showed that the APN/CD13 status was a significant independent factor (P = 0.016). CONCLUSIONS Our data suggest that APN/CD13 may be a new prognostic marker for patients with pancreatic carcinoma and may have a relationship with the angiogenesis for this cancer.