GalNAc DSLc4-enriched Microdomain Involved Cell Adhesion and Signal Transduction through Carbohydrate-Carbohydrate Interaction in Human Renal Carcinoma TOS-1 Cells

M Satoh MD^a, A Ito MD^a, S Saito^a, H Aoki^a, K Mitsuzuka^a, K Numahata^a, S Tokuyama^a, Y Arai^a, S Hakomori^b

^aDivision of Urology, Graduate School of Medicine, Tohoku University, Sendai, Japan, ^bPacific Northwest Research Institute, Seattle, WA, United States

TOS-1 cells are characterized by the predominant presence of ganglioside GalNAc DSLc4 and adhere to lung tissue and adrenal gland medulla dependent with DSGG interaction. We now report that adhesion process is based essentially on glycosphingolipid-enriched microdomain(GEM) at the TOS-1 cell surface, since >90% of DSGG present in the original cells found in GEM, and GEM is enriched in several signal transduction molecules, e.g. c-Src, Ras, and focal adhesion kinase(FAK). GEM was isolated as a low density membranous fraction by homogenization of TOS-1 cells in lysis buffer containing 1% Triton X-100,followed by sucrose density gradient centrifugation. A close association of DSGG with c-Src, Rho, and FAK was indicated by the co-immunoprecipitation of DSGG present in GEM by anti DSGG monoclonal antibody RM2, followed by Western blotting with antibodies directed to these transducer molecules. The following data indicate that GEM is a structural and functional unit for initiation of GalNAc DSLc4-dependent cell adhesion

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in poster session 797 (Manifestations of cancer).