Prometastatic Effect ofN-Acetylglucosaminyltransferase V Is Due to Modification and Stabilization of Active Matriptase by Adding β1–6 GlcNAc Branching

Abstract

Oligosaccharide moieties of glycoproteins are structurally altered during development, carcinogenesis, and malignant transformations. It is well known that ␤1-6 GlcNAc branching, a product of UDP-GlcNAc ␣-mannoside ␤1-6-N-acetylglucosaminyltransferase (GnT-V), is associated with malignant transformation as the results of such alterations. However, the mechanism by which ␤1-6 GlcNAc branching is linked to metastasis remains unclear, because the identification of specific glycoprotein(s) that are glycosylated by GnT-V and its biological function have not been examined. We herein report that matriptase, which activates both urokinase-type plasminogen activator and hepatocyte growth factor, is a target protein for GnT-V. The overexpression of GnT-V in gastric cancer cells leads to severe peritoneal dissemination in athymic mice, which can be attributed to the increased expression of matriptase. This increase was due to the acquired resistance of matriptase to degradation, since it is glycosylated by GnT-V and a corresponding increase in the active form. These results indicate that this process is a key element in malignant transformation, as the direct result of oligosaccharide modification.N-Glycans are widely distributed on cell surfaces and secreted glycoproteins, where structural change is observed in development, carcinogenesis, and malignant transformation (1-3). Recent findings suggest that the structural changes in N-glycans are one of the critical steps for cellular transformation and are directly linked to malignant transformation. Previous studies have revealed that ␤1-6 GlcNAc branching on N-glycans, a product of UDP-GlcNAc ␣-mannoside ␤1-6-Nacetylglucosaminyltransferase (GnT-V 1 ; EC 2.4.1.155), is a key structure associated with tumor metastasis and malignant transformation (4 -6). Since we reported on the purification and cDNA cloning of human 8), numerous studies have reported that ␤1-6 GlcNAc branching is associated with malignant transformation, including tumor invasion and metastasis (9 -12). Gene transcription of GnT-V is regulated by proto-oncogenes such as the Ets family (13, 14), src (15) and erbB2 (16). The sequence analysis of the 5Ј-flanking region of GnT-V revealed the functional binding sites of the Ets family. In addition, certain transcription factors belonging to the Ets family are activated by the Ras-Raf-mitogen-activated protein kinase signaling pathway, which leads to cell proliferation and transformation (17). The Ras proto-oncogene sustains activating mutations in ϳ20% of all human tumors. Ras signaling is induced by other common mutations, such as the amplification of Neu/ErbB-2 in breast cancer (18). These findings suggest that elevated GnT-V activity in human tumors might commonly occur at the level of gene expression.A recent study using GnT-V knockout mice demonstrated that the expression of GnT-V is essential for tumor growth and metastasis (12). The author reported that GnT-V stimulated membrane ruffling and phosphatidylinositol 3-kinase-protein kinase B activation. Howeve...

Functional roles of glycogene and N‐glycan in multidrug resistance of human breast cancer cells

“…A major population of N-glycans detected in MCF-7 and MCF/ADR cells corresponded to high-mannose structures, and some high mannoses in particular peak 2, 8, 17 were dramatically increased in drug-resistant MCF/ADR cell line. Moreover, MCF/ADR cells showed a significant increase of fucosylated and sialylated oligosaccharides (peak 3,5,10,12,16,20,22). Therefore, monitoring of the N-glycan profile would be an important step in the prevention of tumor MDR and would increase our understanding of resistance mechanisms.…”

“…N-glycosylation of protein is increasingly being recognized as one of the most prominent biochemical alterations involved in tumorigenesis and metastasis (2,3). Both changes in the core structures and increased branching of N-linked oligosaccharides are associated with malignancy and metastasis (4).…”

Matriptase Activation, an Early Cellular Response to Acidosis

“…In addition, the protease can exhibit potent oncogenic activity via ras-dependent and ras-independent pathways when it is even slightly overexpressed in the skin of transgenic mice (9). Several tumor xenograft models also provide further evidence that matriptase is strongly associated with cancer cell proliferation, invasion, and metastasis (10,11). As is typical for classical serine proteases, matriptase is synthesized as a zymogen and must undergo activation by cleavage at Arg 614 (R2VVGG) to gain full proteolytic activity.…”

A novel β1,3‐N‐acetylglucosaminyltransferase (β3Gn‐T8), which synthesizes poly‐N‐acetyllactosamine, is dramatically upregulated in colon cancer

“…Tri/tetra-antennary (b1,6-branched) N-glycans containing polylactosamine on a b1,6-branch act on a variety of malignant phenotypes of tumor cells, affecting cell proliferation [20] and metastatic potential [21][22][23][24][25][26].…”