Glycosylation Signatures of Thyroglobulin in Papillary Thyroid Carcinoma

Thyroglobulin (Tg) is a clinically established biomarker for thyroid cancer; however, its diagnostic specificity remains limited due to confounding benign conditions.  This study investigated changes in the site-specific N-glycosylation profiles of the thyroglobulin protein derived from papillary thyroid cancerous and adjacent healthy tissues. Initially, paraffin was removed from the tissues, and the extracted proteins were subjected to proteolytic digestion into peptides. The generated peptides were analyzed using nano-liquid chromatography with tandem mass spectrometry (nLC-MS/MS). Nine distinct N-glycosylation sites were identified and quantified to determine the differences between the cancerous and the healthy tissue samples. Statistical tests were performed to evaluate the differences in glycoform between these groups. The glycoforms HexNAc(3)Hex(5) and HexNAc(3)Hex(6) at the Asn1365 site demonstrated notable discriminatory potential between cancerous and healthy tissues. The results of receiver operating characteristic (ROC) analysis suggest that these glycoforms may serve as promising biomarker candidates. This study reveals that alterations in the relative abundance of specific glycoforms at defined glycosylation sites of the thyroglobulin protein may hold biomarker potential specific to thyroid cancer, providing a foundation for future research.