GROWTH-RELATED CHANGES IN SUGAR DETERMINANTS ON THE SURFACE OF C6 GLIOMA-CELLS IN CULTURE - A CYTOCHEMICAL LECTIN-BINDING STUDY

The cell surface sugar determinants (CSSD) were examined in C6 glioma cells in cultures at different conditions of growth by peroxidase conj ugates of the lectins: peanut agglutinin (PNA), Ricinus communis agglu tinin (RCA), Helix pomatia agglutinin (HPA), wheat germ agglutinin (WG A), lentil agglutinin (LCA), laburnum bork agglutinin (LABA), and lotu s agglutinin (TPA). It was found that the cells bound more intensively WGA, LCA, and RCA compared to PNA, HPA; the weakest staining was prov ided by LABA and TPA. Binding intensity for PNA significantly increase d after pretreatment of the cells with neuraminidase. This indicates t hat a part of the beta-D-galactose residues on the surface membrane of C6 glioma cells is covered by sialic acid. The process of sialization was increased during the culturing of C6 glioma cells. Addition of ci s-DDP or dBcAMP to cultures growing in medium with 10% of CS increased the number of Gal residues which are not covered by sialic acid. The expression of beta-D-galactose (Gal), N-acetyl-D-galactosamine (NAcDGa l), and fucose (Fuc) residues appeared to be most responsive to change s in growth conditions and degree of cell differentiation. The express ions of N-acetyl-D-glucosamine (NAcDGlc) and mannose (Man) residues we re high and seems did not depend on changing of the conditions of cult uring. In C6 glioma cells cultures in which the rate of cell division, formation of the cell processes, and adhesiveness of the cells to the substratum were reduced by growing cells in MEM+, expression of beta- Gal, NAcDGal, and Fuc was considerably reduced. The decrease of expres sion of beta-Gal, NAcDGal, and Fuc on the surface of cell membrane was more pronounced in MEM + with 1% of CS than in MEM + with 10% of CS. In DbcAMP and cis-DDP treated cultures, grown in medium with 1% serum, in which cell division was inhibited without obvious changes in cell adhesiveness to the substratum, binding of PNA NAcDGal. From these obs ervations it was concluded that the pattern of expression of sugar res idues on the cell surface varies according to the biological state of the cells and are easily affected by tissue culture conditions. (C) 19 95 Wiley-Liss, Inc.