Apical membrane expression of distinct sulfated glycans represents a novel marker of cholangiolocellular carcinoma

作者：Hoshino Hitomi; Ohta Makoto; Ito Makoto; Uchimura Kenji; Sakai Yasuhiro; Uehara Takeshi; Low Shulin; Fukushima Mana; Kobayashi Motohiro^*

来源：Laboratory Investigation, 2016, 96(12): 1246-1255.

DOI：10.1038/labinvest.2016.104

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver neoplasm, followed by hepatocellular carcinoma. ICC can be further subclassified as (i) perihilar and (ii) peripheral types, the latter histologically resembling small-sized intrahepatic bile ducts, such as interlobular bile ducts, cholangioles/ductules and the canals of Hering. Cholangiolocellular carcinoma (CoCC), now classified by the World Health Organization as a subtype of combined hepatocellular-cholangiocarcinoma, is currently regarded as a subtype of peripheral-type ICC. The present study was undertaken to determine whether sulfated glycans recognized by the MECA-79 monoclonal antibody could serve as a CoCC marker. Using immunohistochemistry, we show that MECA-79 sulfated glycans are preferentially expressed at the apical membrane of cholangiocytes found in small-sized intrahepatic bile ducts in normal liver and in canalicular structures formed in CoCC. We also report that apical membrane MECA-79 sulfated glycan expression colocalizes with that of mucin 1 (MUC1) core proteins. We also present immunoblotting of Chinese hamster ovary cells overexpressing FLAG tagged MUC1 to show that MUC1 serves as a MECA-79 scaffold. Furthermore, we report that SSP-25 human ICC cells overexpressing N-acetylglucosamine-6-O-sulfotransferase 2 (GIcNAc6ST-2), but not GIcNAc6ST-1, exhibit membrane expression of MECA-79 sulfated glycans, suggesting that GIcNAc6ST-2 catalyzes MECA-79 epitope biosynthesis in cholangiocytes. Moreover, both wild-type and GIcNAc6ST-1 knockout mice exhibit apical membrane MECA-79 expression in small-sized intrahepatic bile ducts, namely interlobular bile ducts, whereas MECA-79 expression was completely absent in comparable tissues from GIcNAc6ST-1 and GIcNAc6ST-2 double knockout mice. These data collectively indicate that apical membrane localization of MUC1 proteins decorated with GIcNAc6ST-2-dependent MECA-79 sulfated glycans may mark cholangiocytes with cholangiolar/ductular differentiation and could serve as a useful CoCC marker.

• 出版日期2016-12