Involvement of membrane sugar receptors and membrane glycoconjugates in the adhesion of 3LL cell subpopulations to cultured pulmonary cells

Abstract

Lewis lung carcinoma cells are able to bind sugar residues, mainly alpha-D-glucosyl and alpha-D-mannosyl derivatives as assessed by fluorescent neoglycoproteins binding assay. We have investigated the binding efficiency and shown that: 3LL tumor cells are heterogeneous with regards to their capability to recognize neoglycoproteins, as shown by fluorescence microscopy and flow cytofluorometry analyses; basically two distinct subpopulations could be evidenced which were called glucose-receptor-rich (or glucose-specific lectin-rich, GLR 3LL) and glucose-receptor-poor (or glucose-specific lectin-poor, GLP 3LL) cells; those two subpopulations could be separated on the basis of their binding properties to neoglycoprotein-substituted microcarriers onto which GLR 3LL cells were able to rapidly adhere (2 h) while GLP 3LL cells were not. Some aspects of the biological behavior of these two selected populations were investigated in order to determine the possible involvement of 3LL cell membrane sugar receptors in cell-cell recognition and adhesion to other cells: namely C57 B1/6 mouse pulmonary cells maintained in primary culture. The two 3LL sublines bind to pulmonary cells but their adhesion kinetics were markedly different. Adhesion inhibition studies showed the adhesion process to be dependent upon the specificity of membrane lectins present on both the tumor cell surface (alpha-D-glucose-specific) and on the pulmonary cells (alpha-L-fucose-specific). Surface sugar-specific receptors on mouse pulmonary cells were shown to bind beta-D-galactose-, alpha-L-fucose and alpha-L-rhamnose substituted serum albumin. A neoglycoprotein bearing alpha-L-rhamnose residues was an efficient binder under the conditions of cell adhesion experiments and a potent cell adhesion inhibitor. A fucose-containing neoglycoprotein was shown to have a high inhibitory activity when used concomitantly to alpha-D-glucose-containing neoglycoproteins. Adhesion inhibition experiments, performed with cells the sugar specific receptors of which have been selectively inactivated, showed that the alpha-L-fucose specific receptors on pulmonary cell surface are partly responsible for the specificity of this cell-cell recognition process.