Core 2 β1,6‐N‐acetylglucosaminyltransferases and α1,3‐fucosyltransferases regulate the synthesis of O‐glycans on selectin ligands on oral cavity carcinoma cells

Abstract

Selectin‐dependent cell binding has importance in the extravasation of blood‐circulating tumor cells and in the generation of metastases. Cell surface glycoproteins decorated with sialylated, fucosylated epitopes, such as sialyl Lewisx (sLex), are ligands for selectins. Not only terminal sLex moieties but also proximal core structures contribute to the formation of binding epitopes for selectins. Core 2 β1,6‐N‐acetylglucosaminyltransferases (C2GnT) and α1,3‐fucosyltransferases (α1,3‐FucT) have been suggested to be the rate‐limiting enzymes in the synthesis of selectin ligands. We analyzed oral cavity epithelial carcinoma cell lines and showed their expression of RNA transcripts for C2GnT and α1,3‐FucT, identified α1,3‐FucT enzyme activities, and analyzed the cell surface sLex expression levels. Neither the pattern of expressed enzymes nor the α1,3‐FucT activity directly predicted the binding capacity of E‐selectin. However, only the sLex‐expressing cell lines were capable of binding to E‐selectin, but not to P‐selectin, thus putatively promoting the selectin‐mediated metastasis. These findings suggest that C2GnT in combination with α1,3‐Fuc‐T contribute to the selectin‐mediated metastasis in oral cavity carcinomas.