HNK-1 Glycan Functions as a Tumor Suppressor for Astrocytic Tumor

Abstract

Astrocytic tumor is the most prevalent primary brain tumor. However, the role of cell surface carbohydrates in astrocytic tumor invasion is not known. In a previous study, we showed that polysialic acid facilitates astrocytic tumor invasion and thereby tumor progression. Here, we examined the role of HNK-1 glycan in astrocytic tumor invasion. A Kaplan-Meier analysis of 45 patients revealed that higher HNK-1 expression levels were positively associated with increased survival of patients. To determine the role of HNK-1 glycan, we transfected C6 glioma cells, which lack HNK-1 glycan expression, with ␤1,3-glucuronyltransferase-P cDNA, generating HNK-1-positive cells. When these cells were injected into the mouse brain, the resultant tumors were 60% smaller than tumors emerging from injection of the mock-transfected HNK-1-negative C6 cells. HNK-1-positive C6 cells also grew more slowly than mocktransfected C6 cells in anchorage-dependent and anchorage-independent assays. C6-HNK-1 cells migrated well after treatment of anti-␤1 integrin antibody, whereas the same treatment inhibited cell migration of mock-transfected C6 cells. Similarly, ␣-dystroglycan containing HNK-1 glycan is different from those containing the laminin-binding glycans, supporting the above conclusion that C6-HNK-1 cells migrate independently from ␤1-integrin-mediated signaling. Moreover, HNK-1-positive cells exhibited attenuated activation of ERK 1/2 compared with mock-transfected C6 cells, whereas focal adhesion kinase activation was equivalent in both cell types. Overall, these results indicate that HNK-1 glycan functions as a tumor suppressor.HNK-1 glycan is a glucuronylated and sulfated carbohydrate expressed in a cell type-specific manner (1). HNK-1 glycan was originally characterized as an epitope recognized by a monoclonal antibody raised against human natural killer cells (2). The structure of HNK-1 glycan-positive glycolipid was identified as SO 3 3glucuronic acid ␤133Gal␤134GlcNAc␤133 Gal␤13 4Glc␤13ceramide (3). HNK-1 glycan SO 3 33GlcA␤133Gal is unique and is expressed on both glycolipids (4, 5), N-glycans, and O-glycans (1, 6 -8). HNK-1 glycans have been found on several cell adhesion molecules, including the neural cell adhesion molecule (NCAM), 3 myelin-associated glycoprotein, contactin, P0, GluR2, RPTP␤, and CD24 (9 -14). In humans and rats, HNK-1 glycan is found on migrating neural crest cells, cerebellar neurons, Schwann cells, and myelinated motor neurons. Neurite outgrowth of mouse motor neurons is facilitated by an HNK-1 glycolipid substratum. Similarly, neurite outgrowth is inhibited by HNK-1 glycan but not by non-sulfated HNK-1 precursor glycan (15, 16). These results indicate that sulfated HNK-1 glycan plays a critical role in cell-cell interaction and in cell migration.HNK-1 glycan is sequentially synthesized by two enzymes. The ␤1,3-glucuronyltransferase 1 (GlcAT-P, B3gat1) add ␤1,3-linked glucuronic acid (GlcA) to galactose (17), followed by addition of 3-sulfate to GlcA by the HNK-1 sulfotransferase (HNK-1ST, Chst10) (18...

CD57high Neuroblastoma Cells Have Aggressive Attributes Ex Situ and an Undifferentiated Phenotype in Patients

“…In contrast, C6 cells transfected with GlcAT-P cDNA (named G14 cells, [20]) express CD57. To verify the blocking capacity of the HNK-1 anti-CD57 antibody (BD) a 24-well transwell chamber system (8 µm pore size; BD Biosciences) was used.…”

Two opposing roles of O-glycans in tumor metastasis

“…β-1,6- N -acetylglucosaminyltransferase III suppressed lung metastasis of melanoma cells by inhibiting tumor cell attachment to extracellular matrices in the extravasation stage of metastasis [3]. Recently, it was reported that HNK-1 glycan suppressed astrocytic tumor invasion and metastasis [4]. …”

In Vivo Regulation of Steroid Hormones by the Chst10 Sulfotransferase in Mouse

“…This antigen has also been found in neuronal cells (32, 33). HNK-1 antigen found on adhesion molecules such as neural cell adhesion molecule (32, 33), MAG (34), L2 (35), P0 (36), GluR2 (37), RPTPβ (38), and CD24 (39) is suggested to modulate adhesion of HNK-1-positive cell types (35). Neurite outgrowth by mouse motor neurons is facilitated by an HNK-1 glycolipid substratum (40).…”