Control of metastasis by Asn-linked, beta 1-6 branched oligosaccharides inmouse mammary cancer cells

Studies in cell lines and malignant human tissues have shown that increased cell-surface Asn-linked beta 1-6(GlcNAc beta 1-6Man) branching is associat ed with increased tumorigenic and metastatic properties, In this study, thr ee mouse mammary cancer cell lines were transfected with an expression vect or containing the mouse cDNA for N-acetylglucosaminyltransferase V (GlcNAcT -V EC 2.4.1.155), the glycosyltransferase responsible for initiating beta 1 -6 branching on Asn-linked carbohydrates. The cell lines were screened for increased cytotoxicity to L-PHA, a lectin specific for beta 1-6 branching s tructures. Cell lines exhibiting increased L-PHA cytotoxicity expressed inc reased levels of beta 1-6 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, transfec ted cell lines with increased beta 1-6 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 incre ase in polyN-acetyllactosamine and sialic acid content in the transfected c ell lines. These results demonstrate that a specific increase in beta 1-6 b ranching due to an elevation in GlcNAcT-V expression increases metastatic p otential.