Reduced expression of α G lc NA c in B arrett's oesophagus adjacent to B arrett's adenocarcinoma – a possible biomarker to predict the malignant potential of B arrett's oesophagus

Aims Gastric gland mucin contains O ‐glycans exhibiting terminal α1,4‐linked N ‐acetylglucosamine residues (αGlc NA c). Recently we demonstrated that mice deficient in αGlc NA c in gastric gland mucin develop gastric adenocarcinoma spontaneously, indicating that αGlc NA c is a tumour suppressor for gastric cancer. However, the role of αGlc NA c in Barrett's oesophagus ( BO ) remains unknown. In this study, we investigated whether reduced αGlc NA c expression in BO is associated with development of Barrett's adenocarcinoma ( BAC ). Methods and results Thirty‐five BO lesions adjacent to BAC were examined by immunohistochemistry for αGlc NA c, MUC 6 and CDX 2. As controls, 35 BO lesions without BAC obtained from patients with oesophageal squamous cell carcinoma were also analysed. Expression of αGlc NA c relative to its scaffold MUC 6 in BO adjacent to BAC was reduced significantly compared to control BO . Decreased αGlc NA c expression in BO adjacent to BAC was particularly significant in patients with smaller tumour size (<20 mm) and minimal invasion of tumour cells to the superficial muscularis mucosae. There was also a significant inverse correlation between αGlc NA c and CDX 2 expression in BO adjacent to BAC . Conclusions Decreased expression of αGlc NA c compared with MUC 6 in BO is a possible hallmark in predicting BAC development.