Differential response of adherent and unanchored melanoma cells to bromodeoxyuridine evidenced by specific lectin‐binding protein changes

The possible differential response of adherent and nonadherent cells of the same tumor type to pyrimidine analogues has been investigated. We show that bromodeoxyuridine (BUdR) increases interactions of attached cells with their substrate without markedly affecting the cell adhesion properties of the same cells when these are not anchored. However, evidence for an adhesion‐independent response of both cell types to BUdR has been obtained with lectin binding assays using 125I‐labelled Lens culinaris agglutinin (LCA). This revealed a greatly increased binding of LCA to a large glycoconjugate in all cultures exposed to the halogenated pyrimidine. Attachment‐dependent effects of BUdR were manifested in flattened cells by a greater LCA‐binding to a 240‐kDa protein and by increased interaction of 125labelled wheat‐germ agglutinin (WGA) with a 200‐kDa protein and a large glycoconjugate sharply defined in electrophoresis. Although both tumor cell aggregates and anchored cells exhibit detectable responses to pyrimidine analogues such as BUdR, the corresponding effects are thus manifested unequally in cells with different adhesion properties.