SUPPRESSION OF PULMONARY METASTASIS IN MURINE B16 MELANOMA-CELLS BY TRANSFECTION OF A SIALIDASE CDNA

A cytosolic sialidase cDNA was transfected into a highly metastatic an d invasive cell line, B16-BL6, derived from the murine B16 melanoma. S table transfection of a cytosolic sialidase expression vector yielded 4 transfectants with high content of the exogenous sialidase protein a s well as enzyme activity. These transfectants exhibited markedly decr eased experimental pulmonary metastasis, invasiveness in collagen gels and cell motility on colloidal gold-coated glass plates but no change in cell attachment to fibronectin, collagen type VI or laminin. To ca st light on the underlying mechanisms, cellular constituents of the tr ansfectants were analyzed. Sialidase over-expression did not lead to a ny significant changes in cell surface carbohydrates or intracellular glycoproteins, as revealed by lectin flow cytometry and lectin blottin g, respectively. Thin layer chromatography of intracellular glycolipid s, however, revealed decreased ganglioside GM3 and increased lactosylc eramide as major changes. (C) 1997 Wiley-Liss, Inc.