Wheat germ agglutinin binding to cells derived from in vivo grown solid tumors

Binding of Wheat Germ Agglutinin (WGA) to cell suspensions derived from in vivo grown solid rat tumors of independent origin and of different metastatic potential has been examined, and results compared with previous work in other systems. The assay used to assess binding was based on the reaction of iodine 125-labelled lectin to tumor cells in suspension and values expressed as per cent of values of a cell line used as internal standard. Inhibition studies showed that WGA binding was principally to sialic acid and/or N-acetyl glucosamine residues. Binding parameters Bmax (maximal binding) and Kd (affinity of binding), derived from Woolf plots and expressed as per cent of internal standard cell line, were found for rat tumors Mc7, Mc40A, Sp24 and Walker 256. It was observed that cell suspensions derived from the metastatic and most tumorigenic tumor, Walker 256, exhibited a different pattern of lectin binding to the other non-metastatic and less tumorigenic tumors; in particular, Kd values were lower. These results are in accord with work using cell lines selected in vitro and are further evidence for a correlation between the density and/or configuration of cell surface sialic acid residues and metastatic potential.