Are matrix-immobilized neoglycoproteins, plant and human lectins and carbohydrate--binding antibodies from human serum mediators of adhesion in vitro for carcinoma and lymphosarcoma cells?

Mediation of cell adhesion by defined molecules can be studied by their immobilization onto a nitrocellulose matrix and incubation with cells. In order to infer the capacity of deliberately selected protein-carbohydrate interactions to establish sugar-inhibitable cell adhesion, a panel of immobilized neoglycoproteins was employed for the murine lymphosarcoma lines RAW-117 with low (P) and high (H10) metastatic capacity, a human mammary carcinoma line (DU4475) and three human colon carcinoma lines (C205, SW480, SW620). Exhibiting an otherwise rather similar behavior relative to the line with low metastatic potential, the murine line RAW117-H10 bound strongly to the matrix with carboxyl group-bearing N-acetylneuraminic acid and glucuronic acid as well as rhamnose. Whereas the analysis of carbohydrate-mediated adhesion yielded comparable results for the three colon carcinoma lines, a markedly reduced number of adherent cells was counted for matrix-attached alpha- and beta-galactosyl, alpha-mannosyl and alpha-glucosyl moieties in the case of the mammary carcinoma line, raising evidence for cell lineage-dependent alterations of this property. From the carbohydrate-binding proteins, the plant lectin, concanavalin A and Viscum album agglutinin almost invariably served well as cell adhesion molecules. Appropriate cell surface sugar receptors, probed with neoglycoproteins, and glycoconjugates, probed with lectins, thus can contribute to adhesion in this model system. The immobilized human beta-galactoside-binding lectin (Mr 14kDa) caused adhesion of the murine lines and one colon carcinoma line (SW480). Neither C-reactive protein under conditions that induce its activity as lectin nor serum amyloid P component nor a lactose-binding immunoglobulin G fraction from human serum were reactive. However, cell adhesion to the alpha-galactoside-binding immunoglobulin G fraction of human serum was seen with the murine line of low metastatic capacity and the mammary carcinoma line. Cells of this line adhered also to the mannan-binding protein from human serum, supporting the view for its potential role in host defence against aberrantly glycosylated tumor cells.