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Differential Expression of Cell Surface Sialoglycoconjugates on Wild-Type and Cultured Ehrlich Tumor Cells as Revealed by Quantitative Lectin-Gold Ultrastructural Cytochemistry
Jurgen Roth, Wei-Ping Li, Randall N. Knibbs, Donald K. MacCallum, Zhiwei Song and Irwin J. Goldstein
Proceedings of the National Academy of Sciences of the United States of America
Vol. 91, No. 24 (Nov. 22, 1994), pp. 11353-11357
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/2366128
Page Count: 5
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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.
Proceedings of the National Academy of Sciences of the United States of America © 1994 National Academy of Sciences