title: Upregulated β1-6 branch N-glycan marks early gliomagenesis but exhibited biphasic expression in the progression of astrocytic glioma.
abstract: Glioma is the world's commonest primary brain malignancy with much of its biology relating to translational and post-translational events still unknown. In this study, we investigated the clinicopathological significance of N-linked β1-6-GlcNAc branches and GnT-V enzyme in the development and progression of astrocytic glioma. Expression of GnT-V and its GlcNAc-β1-6 oligosaccharides by-product together with Con-A binding sugars were assessed immunohistochemically on tissue microarrays of 16 normal brain and 159 tissue samples of astrocytomas of variable grades and histology. Although tissues of both grade I astrocytomas and normal brain showed considerably higher GnT-V expression, GlcNAc-β1-6 expression was significantly high only in tissues of grade I astrocytomas (p < 0.001), which is attributable to elevated levels of the precursor Con-A binding sugar moieties (p < 0.001). The activity of GnT-V enzyme was found to be dependent on the degree of glioma pathogenesis, as the GlcNAc-β1-6 branched expression diminished with every progressive grade of glioma, reaching minimum in glioblastoma (p < 0.001). Having biphasic activity in gliomagenesis, the role of GnT-V in glioma was deciphered by generating different ectopic GnT-V expressions in U-87 cells, which showed the highest GnT-V expression among selected glioma cell lines. Transient GnT-V rescue was achieved in knockdown clones by transfection with GnT-V expression vector. Suppression of GnT-V in U-87 cells slowed cell proliferation with G0/G1 cell cycle phase arrest. Reduced tumorigenicity, invasiveness and cell-ECM interactions were also associated with suppressed in vitro GnT-V activity suggesting GnT-V may act as an oncoprotein. We report for the first time that GnT-V products are involved in early gliomagenesis but their reduced expression, correlating with low Con-A binding sugars level found in high tumor grades predicts the loss of total N-glycosylation in glioma development and may be of potential diagnostic and/or prognostic value in astrocytoma.
authors.affiliation: Department of Biochemistry, Institute of Glycobiology, Dalian Medical University 9 South Lvshun Road Western Section, Dalian 116044, Liaoning, China.
authors.forename: Arshad Ahmed
authors.initials: AA
authors.lastname: Padhiar
authors.affiliation: Department of Biochemistry, Institute of Glycobiology, Dalian Medical University 9 South Lvshun Road Western Section, Dalian 116044, Liaoning, China.
authors.forename: Jianhui
authors.initials: J
authors.lastname: Fan
authors.affiliation: Department of Pathology, The second affiliated hospital of Dalian Medical University Dalian 116011, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Department of Pathology, The First Affiliated Hospital and College of Basic Medical Sciences of China Medical University Shenyang, 110001, China.
authors.forename: Juanhan
authors.initials: J
authors.lastname: Yu
authors.affiliation: Department of Biochemistry, Institute of Glycobiology, Dalian Medical University 9 South Lvshun Road Western Section, Dalian 116044, Liaoning, China.
authors.forename: Shujing
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Biochemistry, Institute of Glycobiology, Dalian Medical University 9 South Lvshun Road Western Section, Dalian 116044, Liaoning, China.
authors.forename: Linhua
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Biochemistry, Institute of Glycobiology, Dalian Medical University 9 South Lvshun Road Western Section, Dalian 116044, Liaoning, China.
authors.forename: Bachir
authors.initials: B
authors.lastname: Niang
authors.affiliation: Department of Biochemistry, Institute of Glycobiology, Dalian Medical University 9 South Lvshun Road Western Section, Dalian 116044, Liaoning, China.
authors.forename: Max Efui
authors.initials: ME
authors.lastname: Annani-Akollor
authors.affiliation: Department of Pathology, The second affiliated hospital of Dalian Medical University Dalian 116011, China.
authors.forename: Lifen
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Respiratory Medicine, The Second Affiliated Hospital of Dalian Medical University Dalian 116011, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Biochemistry, Institute of Glycobiology, Dalian Medical University 9 South Lvshun Road Western Section, Dalian 116044, Liaoning, China ; School of Life Science and Medicine, Dalian University of Technology 2 Linggong Road, Dalian 116024, China.
authors.forename: Jianing
authors.initials: J
authors.lastname: Zhang
keywords: Con-A (Concanavalin A); GlcNAc-β1-6 linkage; N-Acetylglucosaminyltransferase V (GnT-V); astrocytic glioma; early gliomagenesis