Dipeptidyl peptidase IV expression in endometrial endometrioid adenocarcinoma and its inverse correlation with tumor grade

OBJECTIVES: Dipeptidyl peptidase IV (DPPIV)/CD26 is a ceil surface aminopeptidase. This study investigated the expression and localization of DPPIV in endometrial endometrioid adenocarcinomas of different grades. STUDY DESIGN: Immunohistochemical analysis was performed by using DPPIV and regulated on activation, normal T-cell expressed and secreted (RANTES) specific monoclonal antibodies. Cell proliferation was evaluated by bromodeoxyuridine (BrdU) uptake assay. RESULTS: Immunohistochemical analyses showed that DPPIV was strongly or moderately stained in glandular cells of the normal secretory phase. In endometrial adenocarcinoma, the DPPIV expression decreased with advancing grade (P < .01). Furthermore, RANTES, one of the possible DPPIV substrates, was highly expressed in all grades of endometrial adenocarcinoma cells. The addition of RANTES to endometrial adenocarcinoma ceils increased proliferation in a concentration-dependent manner. CONCLUSION: DPPIV is expressed in normal endometrial glandular cells, but its expression in endometrial adenocarcinoma is down-regulated with increasing grade. Our data also suggest a regulatory role of this ectoenzyme in neoplastic transformation and progression of endometrial adenocarcinomas possibly by degrading certain bioactive peptides such as RANTES.