Sialyl Le^x and Sialyl Le^a Expression in Human Extrahepatic Bile Duct Adenocarcinoma

Abstract

Sialyi Le^x (FH6) and sialyl Le^a (CA19—9) antigens, members of a family of high molecular weight glycoproteins, are ligands for E-selectin and may play important roles in tumor metastasis. However, expression patterns of sialyl Le^x and sialyl Le^a have not been established in human extrahepatic bile duct cancer. In this study, we examined sialyl Le^x and Le^a expression in human extrahepatic bile duct adenocarcinoma and their clinicopathological significance. Sialyl Le^x immunoreactivity was detected not only in cancer cells (cytoplasmic type; 57.7%, 30/52), but also in cancer stroma (stromal type; 19.2%, 10/52). Sialyl Le^a immunoreactivity was found in cancer cells (cytoplasmic type; 84.6%, 44/52) and in cancer stroma (stromal type; 63.5%, 33/52). Stromal sialyl Le^a expression was more frequent than stromal sialyl Le^x expression (p<0.001). According to TNM classification, cytoplasmic sialyl Le^x and sialyl Le^a expression was detected in 62.5% (30/48) and 85.4% (41/48) of the T2-3 cancers (T2-3 vs T1, sialyl Le^x, p = 0.015; and sialyl Le^a, p = 0.310). Cytoplasmic sialyl Le^a positive cancers frequently showed lymph node metastasis (p = 0.029). These obseivations suggested that sialyl Le^a expression plays more important roles than sialyl Le^x in metastasis of human extrahepatic bile duct adenocarcinoma.