Control of metastasis by Asn-linked, B1-6 branched oligosaccharides in mouse mammary cancer cells

Studies in cell lines and malignant human tissues have shown that increased cell-surface Asn-linked β1-6(GlcNAcβ1-6Man) branching is associated with increased tumorigenic and metastatic properties. In this study, three mouse mammary cancer cell lines were transfected with an expression vector containing the mouse cDNA for N-acetylglucosaminyltransferase V (GlcNAcT-V EC 2.4.1.155), the glycosyltransferase responsible for initiating β1-6 branching on Asn-linked carbohydrates. The cell lines were screened for increased cytotoxicity to L-PHA, a lectin specific for β1-6 branching structures. Cell lines exhibiting increased L-PHA cytotoxicity expressed increased levels of β1-6 branching structures. Northern blots detected the presence of GlcNAcT-V transcribed from the expression vector in the L-PHA sensitive cell lines. After injection into the tail veins of mice, transfected cell lines with increased β1-6 branching on the cell surface formed elevated levels of lung tumors relative to control transfected cell lines (P < 0.002). Western blots of membrane proteins from GlcNAcT-V transfected and control cells probed with the lectins DSA and WGA did not show an increase in polyN-acetyl-lactosamine and sialic acid content in the transfected cell lines. These results demonstrate that a specific increase in β1-6 branching due to an elevation in GlcNAcT-V expression increases metastatic potential.