MEDULLARY THYROID CARCINOMA-ASSOCIATED AMYLOID IS COMPRISED OF CALCITONIN GENE-RELATED PEPTIDE II

摘要

Localized deposits of amyloid are commonly found in human medullary thyroid carcinoma (MTC). Heretofore, sequence analyses of this material had revealed the presence of calcitonin (CT) and/or its precursor, procalcitonin (PCT).1'2 We now report that this type of amyloid is composed of another closely related and, perhaps more relevant molecule; namely, calcitonin gene-related peptide II (CGRP II). This component (in addition to CT and PCT) was identified through chemical analyses of fibrils extracted from formalin-fixed, paraffin-embedded sections of amyloid-containing tumors from two patients with MTC. Immunohistochemical analyses using antisera specific for each of the 3 proteins, revealed diffuse staining of the thyroid tissues by the anti-CT and -PCT reagents, whereas the anti-CGRP II antibody reacted solely with the green birefringent congophilic deposits. The results of our chemical and immunologic studies indicate that the amyloid found in MTC is formed, not from CT or PCT, but rather, from CGRP II.