N-Glycans in cancer progression

KS Lau, JW Dennis - Glycobiology, 2008 - academic.oup.com
Glycobiology, 2008academic.oup.com
N-Glycan branching in the medial-Golgi generates ligands for lattice-forming lectins (eg,
galectins) that regulate surface levels of glycoproteins including epidermal growth factor
(EGF) and transforming growth factor-β (TGF-β) receptors. Moreover, functional classes of
glycoproteins differ in N-glycan multiplicities (number of N-glycans/peptide), a genetically
encoded feature of glycoproteins that interacts with metabolic flux (UDP-GlcNAc) and N-
glycan branching to differentially regulate surface levels. Oncogenesis increases β1, 6-N …
Abstract
N-Glycan branching in the medial-Golgi generates ligands for lattice-forming lectins (e.g., galectins) that regulate surface levels of glycoproteins including epidermal growth factor (EGF) and transforming growth factor-β (TGF-β) receptors. Moreover, functional classes of glycoproteins differ in N-glycan multiplicities (number of N-glycans/peptide), a genetically encoded feature of glycoproteins that interacts with metabolic flux (UDP-GlcNAc) and N-glycan branching to differentially regulate surface levels. Oncogenesis increases β1,6-N-acetylglucosaminyltransferase V (encoded by Mgat5) expression, and its high-affinity galectin ligands promote surface retention of growth receptors with a reduced dependence on UDP-GlcNAc. Mgat5−/− tumor cells are less metastatic in vivo and less responsive to cytokines in vitro, but undergo secondary changes that support tumor cell proliferation. These include loss of Caveolin-1, a negative regulator of EGF signaling, and increased reactive oxygen species, an inhibitor of phosphotyrosine phosphatases. These studies suggest a systems approach to cancer treatment where the surface distribution of receptors is targeted through metabolism and N-glycan branching to induce growth arrest.
Oxford University Press