Differential specificity of substrate-attached lectins stimulating spreading of GH3-cells under serum-free, hormone-supplemented culture conditions.

Most mammalian cells are capable of growth in culture only when they are supplied with an appropriate substrate to which they can adhere and spread. To prepare suitable substrates different lectins were attached onto polystyrene tissue-culture dishes after coating with polylysine. GH3-cells (a pituitary-tumor-cell line) were seeded into the culture dishes containing serum-free, hormone-supplemented medium. When succinylated Concanavalin A (s-Con A), which binds specifically to mannose residues, is attached to the surface an extraordinary spreading of GH3-cells is induced within 15 to 20 min after seeding. Other lectins with a different sugar-binding specificity are less effective in inducing cell spreading. However, the cell spreading depends not only on the substrate-attached lectins but also on the hormones used in the proliferation-culture of GH3-cells. Both types of molecules found in the microenvironment of a cell, the matrix-fixed sugar-binding proteins and the diffusive hormones, are responsible for the regulation of the behaviour of the mammalian cell. It is suggested that the interaction of the cell-surface carbohydrates with the plasma-membrane-bound lectins of contiguous cells plays a central role in such processes, especially in in-vivo.