BACKGROUND: The incidence of extrahepatic bile duct carcinoma (EBDC) has been increasing, especially in aged people, but the glycobiology of the tumor is not elucidated. In this study we investigated the expressions of three glycosyltransferases in 35 patients with EBDC and 35 patients with benign biliary duct disease (BBDD) as well as their clinicopathological significance.
 METHOD:  The patients were divided into several subgroups by tumor differentiation, TNM stage, and invasion by the standards recommended by UICC. Tumor samples were immediately frozen in liquid nitrogen after resection, followed by mRNA determination of enzymes in the tissue using a mRNA selective reverse trancriptase-polymerase chain reaction kit. The mRNA levels of different groups were semi-quantitatively compared.
RESULTS: The mRNA levels of N-acetylglucosaminyltransferase V (GnT-V) and a subtype of α 2,3 sialyltransferases for N-glycans, ST3Gal-III were elevated 7.75 and 5.39 times in EBDC as compared with BBDD, respectively, and they were correlated to several clinicopathological factors including tumor advancement, differentiation, metastasis, and invasiveness. The mRNA expression of another sialyltransferase, ST6Gal-I, was also 0.63-fold higher in EBDC than in BBDD, but not involved in the clinicopathological characteristics.
CONCLUSION:  The elevated expression of these three glycosyltransferases can be considered as an important molecular event in the occurrence and progression of EBDC.