Wheat germ agglutinin-binding protein changes in highly malignant Friend leukemia cells metastasizing to the liver

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Abstract
We have used binding of radioactive lectins (i.e. Concanavalin A (ConA), Wheat Germ Agglutinin (WGA) andRicinus communis agglutinin I (RCAI)) to membrane glycoproteins separated in SDS gel electrophoresis, to detect specific carbohydrate changes in plasma membrane proteins ofin vivo passaged Friend erythroleukemia cells (FLC). These cells are highly metastatic to the liver, whereas the originalin vitro passaged tumor cells do not metastasize. Marked qualitative differences in the high molecular weight region of the gels (100–200 kD) were observed between the WGA binding glycoproteins of metastaticin vivo passaged FLC and nonmetastaticin vitro passaged FLC. Furthermore, the binding of WGA to plasma membrane proteins ofin vivo passaged FLC was much greater than the binding of WGA to plasma membrane proteins ofin vitro passaged FLC. Lectin binding experiments after sialic acid removal byin situ mild acid hydrolysis of FLC glycoproteins indicated that an increased sialylation of the 120 and 145 kD glycoproteins was responsible for the increased WGA reactivity ofin vivo passaged FLC plasma membranes. Besides the increased sialylation, other changes in glycosylation of the 100–200 kD glycoproteins ofin vivo passaged FLC were observed: (1) qualitative differences between the WGA binding patterns of the two cell types were restored after treatment of the gels with mild acid and subsequent Smith degradation; (2) after chemical removal of sialic acid residues from the gels, qualitative differences in the RCA binding patterns to the glycoproteins of the two cell types were apparent.

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