SUPPRESSION OF LUNG METASTASIS OF B16 MOUSE MELANOMA BY N-ACETYLGLUCOSAMINYLTRANSFERASE-III GENE TRANSFECTION

The beta 1-6 structure of N-linked oligosaccharides, formed by beta-1, 6-N-acetylglucosaminyltransferase (GnT-V), is associated with metastat ic potential. We established a highly metastatic subclone, B16-hm, fro m low metastatic B16-F1 murine melanoma cells. The gene encoding beta- 1,4-N-acetylglucosaminyltransferase (GnT-III) was introduced into the B16-hm cells, and three clones that stably expressed high GnT-III acti vity were obtained. In these transfectants, the affinity to leukoagglu tinating phytohemagglutinin was reduced, whereas the binding to erythr o agglutinating photohemagglutinin was increased,indicating beta 1-6 s tructure was decreased due to competition for substrate between intrin sic GnT-V and ectopically expressed GnT-III. Lung metastasis after int ravenous injection of the transfectants into syngeneic and nude mice w as significantly suppressed, suggesting that the decrease in beta 1-6 structure suppressed metastasis via a mechanism independent of the mur ine system. These transfectants also displayed decreased invasiveness into Matrigel and inhibited cell attachment to collagen and laminin, C ell growth was not affected. Our results demonstrate a causative role for beta 1-6 branches in invasion and cell attachment in the extravasa tion stage of metastasis.