Differential Expression of Cell Surface Sialoglycoconjugates on Wild-Type and Cultured Ehrlich Tumor Cells as Revealed by Quantitative Lectin-Gold Ultrastructural Cytochemistry

• Published in: Proceedings of the National Academy of Sciences - PNAS 1994-11, Vol.91 (24), p.11353-11357
• Main Authors: Roth, J, Li, W P, Knibbs, R N, MacCallum, D K, Song, Z, Goldstein, I J
• Format: Article
• Language: English
• Subjects: Animals; Carcinoma, Ehrlich Tumor - metabolism; Carcinoma, Ehrlich Tumor - pathology; Cell growth; Cell lines; Cell Membrane - metabolism; Cell membranes; Cells; Cellular biology; CHO cells; Cultured cells; Endothelial cells; Glycoconjugates - metabolism; Gold; In Vitro Techniques; Intracellular Membranes - metabolism; Lectins; Mice; Microscopy, Electron - methods; Microvilli; N-Acetylneuraminic Acid; Sialic Acids - metabolism; Surface Properties; Tumor Cells, Cultured; Tumors
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.91.24.11353

Three variants of the classical Ehrlich ascites tumor (EAT) cell have been studied by quantitative, sialic acid-specific, lectin-gold ultrastructural cytochemistry. Electron microscopic examination revealed pronounced differences in the surface morphology of the three cell variants. The wild-type Ehrlich cells (EAT-wt), grown in the peritoneal cavity of mice, exhibited a smooth surface profile. A variant form selected for growth as monolayer on basement membrane (EAT-c) showed a complex surface profile with numerous microvilli. The third variant (EAT-c/m), the cultured cells reinoculated into mice and passaged 20-25 times as ascites, presented a smooth surface profile similar to the EAT-wt cells. Quantitative single as well as double lectin-gold labeling revealed significant differences in the nature of cell surface sialoglycoproteins. The most significant finding was the presence of cell surface Neu5Acα2-6Gal residues as detected with the Sambucus nigra lectin on EAT-c and EAT-c/m cells, whereas EAT-wt cells contained little or none of such carbohydrate sequences. On the contrary, labeling by Maackia amurensis lectin, which recognizes the Neu5Acα2-3Galβ1-4GlcNAc sequence, was intense on all three Ehrlich cell variants; it was 20-60 times greater than α-2,6-linked sialic acid-containing glycoconjugates. Specific cell surface lectin binding combined with morphologic study appears to have identified a small subpopulation of cells within the ascites tumor that are capable of attaching to and growing on a basement membrane.