{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n The α1,4‐N‐acetylglucosaminyltransferase (A4GNT) is a key glycosyltransferase that catalyzes the transfer of N‐acetylglucosamine in an α1,4‐linkage to specific acceptor substrates on O‐glycans. This enzyme is predominantly expressed in mucin‐secreting cells of the gastric glands and in pancreatic ductal cells, where it is responsible for the biosynthesis of unique “class III” mucin structures characterized by terminal α1,4‐linked N‐acetylglucosamine residues."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "3"}]}, {"type": "t", "text": " These specialized glycan motifs not only confer distinct biochemical properties to the mucins – notably, high reactivity with specific lectins – but also serve dual protective functions. On one hand, they act as a natural antibiotic by inhibiting the growth of Helicobacter pylori, thereby limiting bacterial colonization of deeper gastric regions"}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": "; on the other hand, they function as tumor suppressors by downregulating cell proliferation, migration, and invasion in gastric and pancreatic epithelia."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": " Loss or reduction of A4GNT activity and its glycan products has been associated with the development and progression of premalignant lesions and adenocarcinomas in the stomach and pancreas, a finding further substantiated by in vivo studies using A4GNT‐deficient mouse models that spontaneously develop gastric cancer."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}, {"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": " Moreover, the presence of A4GNT transcripts in the peripheral blood has been exploited as an approach for detecting circulating cancer cells, highlighting its potential as a diagnostic and prognostic biomarker."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": " Recent studies also extend the clinical significance of A4GNT to other mucin‐rich neoplasms such as cervical gastric‐type adenocarcinoma, where its expression correlates with better patient outcomes."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "10"}]}, {"type": "t", "text": "\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "J Nakayama, J C Yeh, A K Misra, et al. 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