Altered terminal glycosylation of thyroglobulin in papillary thyroid carcinoma

Samples of thyroglobulin (Tg) were isolated from specimens of differentiated thyroid carcinoma of the papillary type and from normal adjacent glandular tissue, and the content of sialic acid was estimated. Also the in vitro incorporation of 14 C-sialic acid, in the form of both CMP (cytidine 5'-monophospho-) ― activated and non-activated N-acetyl-neuraminic acid, into Tg of malignant and morphologically normal thyroid. The sialic acid content of Tg preparations from papillary thyroid carcinomas varied considerably (0.27-0.92 mg/100 mg Tg). In six cancerous Tg samples the content of sialic acid was markedly lower than that in Tg from the corresponding apparently normal thyroid tissue (0.71: 1.11 mg per 100 mg Tg)