Wild-type and cultured Ehrlich ascites tumour cells differ in tumorigenicity, lectin binding patterns and binding to basement membranes.

Abstract

Three different variants of the Ehrlich ascites tumour (EAT) cell were derived and the lectin surface reactivities, as well as the malignant characteristics of each variant, were studied. Wild-type cells (EAT-wt) were selected for growth on basement membranes and tissue culture plastic to give EAT-c cells. The EAT-c were passaged in mice by i.p. injection, giving rise to a third variant (EAT-c/m). Each of these three cell variants was characterized for: (i) specific lectin agglutinability patterns; (ii) the ability to produce ascites tumours in mice; (iii) the ability to produce solid tumours; and (iv) the attachment to and growth on basement membranes and purified extracellular matrix molecules. Analysis of the total protein and carbohydrate content of each cell line showed that there was an increase in the glycosylation of the EAT-c cells compared to EAT-wt cells. After repeated passage of the EAT-c/m cells in mice, the glycosylation level of the EAT-c/m cells returned to that of the EAT-wt cell line. In addition, the EAT-c cells displayed an increase in the number of terminal non-reducing sugars which could indicate either an increase degree of branching or the presence of additional N- and/or O-linked oligosaccharide chains of the cellular glycoproteins. This phenotype was retained by the EAT-c/m cells which had been passaged repeatedly in mice. The most significant increase was in the content of sialic acid-containing glycoproteins found in the EAT-c cells. The sialic acid-binding lectin Maackia amurensis leukoagglutinin (MAL) agglutinated all three EAT cell variants, while the sialic acid-binding Sambucus nigra (elderberry bark) lectin (SNA) agglutinated only the EAT-c and early-passage EAT-c/m cells. These findings indicate the presence of alpha 2,3-linked sialic acid on all three variants, but only the cultured cells and early-passage EAT-c/m cells possess the Neu5Ac alpha 2,6 linkage. The EAT-c cells attached avidly to wells coated with either laminin or fibronectin, as well as extracellular matrix produced by cultured bovine endothelial cells, but the EAT-wt and EAT-c/m cells did not. Paradoxically, the EAT-c cells were incapable of producing solid tumours when injected into a basement membrane-rich skeletal muscle bed, whereas the EAT-wt and EAT-c/m cells produced rapidly growing tumours when injected into the same environment. Lectin agglutination patterns established that ascitic tumour cells within the peritoneal cavity were derived from injected EAT-c cells.