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The j31-6 structure of N-linked oligosaccharides, formed by j8-1,6-N-acetylglucosaminyltransferase (GnT-V), is associated with metastatic potential. We established a highly metastatic subclone, B16-hm, from low metastatic B16-F1 murine melanoma cells. The gene encoding 18-1,4-N-acetylglucosaminyltransferase (GnT-III) was introduced into the B16-hm cells, and three clones that stably expressed high GnT-III activity were obtained. In these transfectants, the affinity to leukoagglutinating phytohemagglutinin was reduced, whereas the binding to erythroagglutinating phytohemagglutinin was increased, indicating that the level of 31-6 structure was decreased due to competition for substrate between intrinsic GnT-V and ectopically expressed GnT-III.Lung metastasis after intravenous injection of the transfectants into syngeneic and nude mice was significantly suppressed, suggesting that the decrease in 81-6 structure suppressed metastasis via a mechanism independent of the murine system. These transfectants also displayed decreased invasiveness into Matrigel and inhibited cell attachment to collagen and laminin. Cell growth was not affected. Our results demonstrate a causative role for p1-6 branches in invasion and cell attachment in the extravasation stage of metastasis.Malignant transformation is highly associated with alterations of N-linked oligosaccharides. The extensive and persistent changes in the population of protein-bound oligosaccharides in malignant cells have been proposed to disturb cell division, decrease intercellular adhesiveness, and mask immunogenicity (1). The glycopeptides in polyoma-transformed baby hamster kidney cells have unusually high molecular weights due to the presence of external sialic acid as well as galactose and GlcNAc (2). The predominant surface glycopeptide of baby hamster kidney cells transformed by Rous sarcoma virus was determined to be a triantennary, completely sialylated, complex glycopeptide containing a core region of Man, GlcNAc, and Fuc (3). Synthesis of these elongated branches is initiated by 13-1,6-N-acetylglucosaminyltransferase (GnT-V; EC 2.4.1.155), which catalyzes the formation of the (31-6 branch (4). GnT-V activity correlated well with the metastatic potential of rastransformed Rat2 fibroblasts, SP1 mammary carcinoma cells, the MDAY-D2 lymphoma cell line (5, 6), and human colon cancer cells (7). Rat2 fibroblasts transfected with H-ras or v-frs exhibited metastatic potential and had elevated GnT-V activity and increased (1-6 branches (8), whereas a mutant with decreased GnT-V activity from a highly metastatic tumor cell line had a decreased potential for metastasis in mice (6). These observations have suggested a positive correlation between ,B1-6 branching and metastatic capacity.One approach to analyzing the role of GnT-V and its product, (31-6 branches, in metastasis is to reduce GnT-V activity in malignant cells with a high tendency to metastasize. As shown in Fig. 1, both 1-1,4-N-acetylglucosaminyltransferase (GnT-III; EC 2.4.1.144) and GnT-V use the t...

Introduction of the beta1-4 N-acetylglucosaminyltransferase (GnT-III) gene was reported to suppress metastasis in highly metastatic B16-hm murine melanoma cells (Yoshimura, M., Nishikawa, A. , Ihara, Y., Taniguchi, S., and Taniguchi, N.(1995) Proc. Natl. Acad. Sci. U. S. A. 92, 8754-8758). In this study, the effect of GnT-III gene transfer on E-cadherin was studied, since E-cadherin acts as a suppressor of metastasis. E-cadherin expression at cell-cell contacts of B16-hm cells expressing high GnT-III activity was greater than controls without affecting transcription. Lectin blotting showed that E-cadherin from GnT-III transfectants was glycosylated by ectopically expressed GnT-III. The glycosylated E-cadherin exhibited the delayed turnover and the decreased release from cell surface, as compared with the native E-cadherin, resulting in the elevated expression at the cell-cell border of GnT-III transfectants. Furthermore, cell-cell aggregation was enhanced in GnT-III transfectants, indicating that the glycosylated E-cadherin is biologically functional. These results suggest that the glycosylated E-cadherin contributes to the suppression of metastasis by the introduction of GnT-III gene into melanoma cells.

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In cognitive function testing, the group that exhibited a complete response showed improvement primarily in parameters reflecting frontal lobe function. Complete responders also showed significantly greater blood flow increases in the basal ganglion and thalamus early during the treatment period. This indicates that the drug responsiveness of the basal ganglion and thalamus affects frontal lobe function and distinguishes complete responders from patients who do not exhibit such a response.