Goscinski MA, Suo ZH, Nesland JM, Flørenes VA, Giercksky KE. Dipeptidyl peptidase IV expression in cancer and stromal cells of human esophageal squamous cell carcinomas, adenocarcinomas and squamous cell carcinoma cell lines. APMIS 2008;116:823–31. Dipeptidyl peptidase IV (DPPIV) is a transmembrane serine protease which is involved in the process of tumor invasion and development of metastases in human cancers. The aim of this study was to investigate the expression of DPPIV in cancer and stromal cells of both esophageal adenocarcinoma and squamous cell carcinoma (SCC). Tissue material from 159 patients was analyzed using immunohistochemistry. Western blotting was performed on cell lines and fresh frozen tissue sections. Results were compared with clinicopathological features. Evaluation of the immunohistochemical findings revealed significant differences between DPPIV expression in carcinoma cells and stromal cells, depending on the histological tumor type. A significantly higher level of DPPIV was found in adenocarcinomas compared to SCCs while no DPPIV was detected in normal esophageal epithelium. Overexpression of DPPIV in patients with adenocarcinoma was additionally associated with distant metastases. Thus, differences of DPPIV level in esophageal carcinomas compared with normal epithelium showed that esophageal malignancies were associated with an increased amount of cell surface-bound DPPIV. Radiotherapy in patients had no impact on DPPIV expression in analyzed tissue samples. There was no correlation between DPPIV expression in cancer or stromal cells and survival of the patients.