Structural changes of carbohydrate chains of human thyroglobulin accompanying malignant transformations of thyroid glands

Abstract

Carbohydrate moieties were released from human thyroglobulins prepared from normal and transformed, thyroid tissues by hydrazinolysis. The oligosaccharides thus prepared were fractionated by DEAE-cellulose, Bio-Gel P-4, concanavalin-A-Sepharose and Ricinus-communis-agglutinin-Sepharose columns and were characterized by exo-glycosidase and endo-glycosidase digestions, methylation analysis and 400-MHz ¹H-NMR spectroscopy. These studies showed that the alterations accompanying malignancy occurred in complex-type carbohydrate chains and exhibited the following structural features: (a) a complex-type carbohydrate chain containing 1 phosphate in a diester linkage was present in all the malignant thyroglobulins. (b) Asialo-carbohydrate chains with biosynthetically incomplete structures were found in all of the malignant thyroglobulins. (c) Carbohydrate chains of higher molecular mass, which have repeating Gal-GlcNAc disaccharides and peripheral α-fucosyl residues were present in metastatic papillary carcinoma.