Clinical significance of tumor-associated antigen RCAS1 expression in human pancreatic ductal adenocarcinoma.

Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is a human tumor-associated antigen that induces cell cycle arrest and/or apoptosis in RCAS1 receptor-expressing immune cells. The aim of the present study was to evaluate the clinical significance of RCAS1 expression in human pancreatic adenocarcinoma. Immunohistochemical analysis of RCAS1 expression was performed on paraffin-embedded tissue sections obtained from 76 pancreatic adenocarcinoma patients. RCAS1 positivity and overexpression and intensity of the staining were correlated with clinicopathological parameters, proliferative capacity and patient survival. Of the 76 adenocarcinoma patients, 65 (86%) tested positive for RCAS1; of these 65 RCAS1-positive cases, 36 (55%) showed RCAS1 overexpression. RCAS1 positivity was statistically significantly correlated with the histopathological grade of the tumor (P = 0.026), and it showed a trend to be correlated with tumor size (P = 0.071). RCAS1 intensity and overexpression of staining showed a trend to be correlated with the histopathological grade of the tumor (P = 0.061 and P = 0.089, respectively), whereas RCAS1 positivity and the overexpression and intensity of staining were not statistically significantly correlated with the proliferative capacity of the tumor or any other clinicopathological parameter examined nor with patients' survival. Our data provide evidence for the implication of RCAS1 in pancreatic neoplasia. However, the prediction of survival using RCAS1 expression as a marker seems uncertain for this type of cancer.