[Frontiers in Bioscience E3, 1443-1455, June 1, 2011]

ST6GalNAc-I controls expression of sialyl-Tn antigen in gastrointestinal tissues

Nuno T. Marcos1, Eric P. Bennett2, Joana Gomes1, Ana Magalhaes1, Catarina Gomes1, Leonor David1,3, Imran Dar2, Charlotte Jeanneau2, Shawn DeFrees4, Dorrit Krustrup5, Lotte K. Vogel2, Elin H. Kure6, Joy Burchell7, Joyce Taylor-Papadimitriou7, Henrik Clausen2, Ulla Mandel2, Celso A. Reis1,3

1Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), 4200 Porto, Portugal; 2Copenhagen Center for Glycomics (CCG), School of Dentistry and Department of Cellular and Molecular Medicine, University of Copenhagen, DK2200 Copenhagen, Denmark; 3Medical Faculty of the University of Porto, 4200 Porto, Portugal; 4Neose Technologies, Horsham, PA, USA; 5Department of Pathology, Rigshospitalet, Copenhagen University Hospital, Denmark; 6The Cancer Center and Department of Pathology, Oslo University Hospital, Ullevaal, 0407 Oslo, Norway; 7Breast Cancer Biology, King's College London, London, UK

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Material and methods
3.1. Recombinant expression of soluble ST6GalNAc-I
3.2. Generation of monoclonal antibodies
3.3. CHO ldlD-MUC1F cells stably transfected with ST6GalNAc-I or ST6GalNAc-II
3.4. Patients and tissues
3.5. Immunofluorescence
4. Results
4.1. Monoclonal antibodies to ST6GalNAc-I
4.2. Glycophenotype of CHO ldlD-MUC1F cells stably transfected with ST6GalNAc-I and ST6GalNAc-II.
4.3. Expression of ST6GalNAc-I and sialyl-Tn in normal gastric mucosa.
4.4. Expression of ST6GalNAc-I and sialyl-Tn in intestinal metaplasia.
4.5. Expression of ST6GalNAc-I and sialyl-Tn in gastric carcinoma.
4.6. Expression of ST6GalNAc-I and sialyl-Tn in normal colorectal mucosa.
4.7. Expression of ST6GalNAc-I and sialyl-Tn in colorectal adenocarcinoma.
5. Discussion
6. Acknowledgments
7. References

1. ABSTRACT

Sialyl-Tn is a simple mucin-type carbohydrate antigen aberrantly expressed in gastrointestinal adenocarcinomas and in the precursor lesion intestinal metaplasia. Sialyl-Tn tumour expression is an independent indicator of poor prognosis. We have previously shown in vitro that ST6GalNAc-I and ST6GalNAc-II sialyltransferases can synthesize sialyl-Tn. The aim of the present study was to establish whether ST6GalNAc-I is the major enzyme responsible for the expression of sialyl-Tn. We used a model of CHO-ldlD cells producing only MUC1-Tn glycoform and showed that ST6GalNAc-I is the key-enzyme leading to sialyl-Tn biosynthesis. We developed novel monoclonal antibodies specific for ST6GalNAc-I and evaluated its expression in gastrointestinal tissues. ST6GalNAc-I was detected in normal colon mucosa co-localized with O-acetylated sialyl-Tn. Expression was largely unaltered in colorectal adenocarcinomas. In contrast, we found that ST6GalNAc-I is weakly expressed in normal gastric mucosa, but over-expressed in intestinal metaplasia, co-localized with sialyl-Tn. In gastric carcinomas ST6GalNAc-I was also associated with sialyl-Tn, but with heterogeneous staining and partial co-localization. Our results showed ST6GalNAc-I as the major enzyme controlling the expression of cancer-associated sialyl-Tn antigen in gastrointestinal tissues.