Relationship between metastasis-associated phenotypes and N-glycan structure of surface glycoproteins in human hepatocarcinoma cells.
OBJECTIVE
To study the relation of N-glycan structure on cell surface glycoproteins to the metastatic phenotypes.


METHODS
Two human hepatocarcinoma 7721 cell lines transfected with sense or antisense cDNA of GnT-V, named GnT-V/7721 and GnT-V-AS/7721, respectively, were adopted, because GnT-V can change the antennary number and the content of the beta 1,6 GlcNAc branch in N-glycans. The effects of over- and under-expression of GnT-V on the metastasis-associated phenotype of the transfected cells were investigated and compared with the cells mock-transfected with the plasmid vector.


RESULTS
In GnT-V/7721 cells, GnT-V activity was increased by 92% compared with the mock cells. HRP-labeled lectin staining of transfected cells showed elevated intensity with HRP-L-PHA and reduced intensity with HRP-ConA, suggesting the increased antennary number and content of the beta 1,6 GlcNAc branch in N-glycans. Analysis of the N-glycan structure of [3H]-labeled glycopeptides prepared from cell-surface [3H] glycoproteins using DSA-affinity chromatography also revealed the above change of the N-glycan structure in a more quantitative manner. GnT-V/7721 cells showed a suppressed cell attachment to fibronectin (Fn) or laminin (Ln), and increased cell migration and invasion through matrigel. In contrast, GnT-V-AS/7721 cells showed reduction of both GnT-V activity and content of the beta 1,6 branch in N-linked glycans, elevation of cell attachment to Fn or Ln, and decline of cell migration and invasion through matrigel. These changes were just the opposite to those in GnT-V/7721 cells.


CONCLUSIONS
The alteration of N-glycan structure in surface glycoproteins resulting from the activity change of GnT-V contributes to the alterations in metastasis-associated phenotypes. The product of GnT-V, the beta 1,6 GlcNAc branch in N-linked glycans, is a structural factor of adhesion inhibition and invasion promotion. GnT-V is, therefore, closely related to cancer metastasis and its over-expression is an important molecular mechanism of metastasis.
Guo
H B
HB
Key Laboratory of Glycoconjugate Research, Ministry of Health, Department of Biochemistry, Shanghai Medical University, Shanghai, 200032, PR China.
Zhang
Y
Y
Chen
H L
HL
D006528:Carcinoma, Hepatocellular / Q000737:chemistry* / Q000473:pathology; D002846:Chromatography, Affinity; D006023:Glycoproteins / Q000737:chemistry*; D006801:Humans; D008113:Liver Neoplasms / Q000737:chemistry* / Q000473:pathology; D017351:N-Acetylglucosaminyltransferases / Q000502:physiology*; D009362:Neoplasm Metastasis; D010641:Phenotype; D011134:Polysaccharides / Q000737:chemistry*; D014162:Transfection; D014407:Tumor Cells, Cultured
D006023:Glycoproteins; D011134:Polysaccharides; D017351:N-Acetylglucosaminyltransferases