A Disaccharide-Based Inhibitor of Glycosylation Attenuates Metastatic Tumor Cell Dissemination

Abstract

Purpose: The binding of hematogenously borne malignant cells that express the carbohydrate sialyl Lewis X (sLe X ) to selectin adhesion receptors on leukocytes, platelets, and endothelial cells facilitates metastasis.The glycosylation inhibitor, per-O-acetylated GlcNAch1,3Galh-O-naphthalenemethanol (AcGnG-NM), inhibits the biosynthesis of sLe X in tumor cells.To evaluate the efficacy of AcGnG-NM as an antimetastatic agent, we examined its effect on experimental metastasis and on spontaneous hematogenous dissemination of murine Lewis lung carcinoma and B16BL6 melanoma cells. Experimental Design: Tumor cells were treated in vitro with AcGnG-NM, and the degree of selectin ligand inhibition and experimental metastasis was analyzed in wild-type and P-selectindeficient mice. Conditions were developed for systemic administration of AcGnG-NM, and the presence of tumor cells in the lungs was assessed using bromodeoxyuridine labeling in vivo. The effect of AcGnG-NM on inflammation was examined using an acute peritonitis model. Results: In vitro treatment of Lewis lung carcinoma cells with AcGnG-NM reduced expression of sLe X -and P-selectin-dependent cell adhesion to plates coated with P-selectin. Treatment also reduced formation of lung foci when cells were injected into syngeneic mice. Systemic administration of the disaccharide significantly inhibited spontaneous dissemination of the cells to the lungs from a primary s.c. tumor, whereas an acetylated disaccharide not related to sLe X in structure had no effect. AcGnG-NM did not alter the level of circulating leukocytes or platelets, the expression of P-selectin ligands on neutrophils, or sLe X -dependent inflammation. Conclusion: Taken together, these data show that AcGnG-NM provides a targeted glycosidebased therapy for the treatment of hematogenous dissemination of tumor cells.

Selectins promote tumor metastasis

“…Glycometabolic inhibitors have been developed that indirectly reduce the production of selectin ligands by inhibition of relevant glycosyltransferases, in particular O-glycosylation of mucins and fucosyltransferases [144,145]. Treatment of cancer cells with a disaccharide-based inhibitor that serves as a decoy for the glycan synthesis led to reduction of cancer cell-associated sLe x structures and subsequently to attenuation of metastasis [146,147]. A recombinant soluble form of PSGL-1 was shown to inhibit the rolling of leukocytes in vivo, and prevents inflammation in different modes of inflammation [144,148,149].…”

Deoxygenated Disaccharide Analogs as Specific Inhibitors of β1–4-Galactosyltransferase 1 and Selectin-mediated Tumor Metastasis

“…4). (12,13). Neither 1 nor 2 was toxic to LLC cells up to 50 M based on trypan blue exclusion and growth rates (Fig.…”

“…Binding of monoclonal antibody CSLEX-1 and P-selectin Ig chimera to cells fixed with 1% paraformaldehyde was measured by an enzyme-linked immunosorbent assay as described (9,13). Background binding was measured after treatment with sialidase, which showed that nonspecific binding was less than 5%.…”

“…Furthermore, the disaccharides appear to selectively affect sLe X formation, since sLe a expression was unaffected (12). By blocking selectin ligand expression, these compounds block both experimental and spontaneous metastasis (12,13).…”

“…The binding of P-selectin-Ig chimera was measured by enzyme-linked immunosorbent assay, as described (13). The values represent the average of triplicate measurements, which varied by Ͻ10%.…”