Insulin-like growth factor-I receptors in nonfunctioning thyroid nodules.
We have recently demonstrated the production of insulin-like growth factor-I (IGF-I) as well as the presence of type I IGF receptors in human thyroid cells in primary culture. The role of IGF-I in the control of thyroid cell growth has been well established. In order to investigate the involvement of IGF-I in abnormal thyroid growth, the density of IGF-I receptors in solitary, cold, micro- and macro-follicular thyroid adenomas, and in extranodular histological normal tissue was studied. Forty-three euthyroid patients with isolated cold nodules were selected for the study. In 30 patients the presence of IGF-I receptors was evaluated by using quantitative immunohistochemistry; in 10 patients by using radioligand binding studies, and in 3 patients by using affinity labeling. Cross-linking and binding studies clearly demonstrated the presence of a homogeneous class of binding sites for type I IGF receptors. Furthermore, radioligand studies did not show any significant differences in receptor density between the 2 types of thyroidal tissues. Conversely, the computerized analysis of 900 fields of nodular and normal thyroid tissues immunostained with the monoclonal antibody alpha-IR3, strongly indicated that higher concentrations of IGF-I receptors were present in the epithelial cells of non-functioning thyroid nodules than in the adjacent extranodular thyroid tissues. These studies strongly suggest that the same type I IGF receptor is present in thyroid follicular adenomas as in histological normal thyroid tissue removed from the same patient. The higher concentration of IGF-I receptors as documented by immunostaining in the adenomas suggests that IGF-I may contribute to the abnormal growth of the neoplasms.
Vannelli
G B
GB
Department of Human Anatomy and Histology, University of Florence, Italy.
Barni
T
T
Modigliani
U
U
Paulin
I
I
Serio
M
M
Maggi
M
M
Fiorelli
G
G
Balboni
G C
GC
D000236:Adenoma / Q000737:chemistry; D000328:Adult; D001345:Autoradiography; D005260:Female; D006044:Goiter, Nodular / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D011956:Receptors, Cell Surface / Q000032:analysis / Q000378:metabolism*; D017451:Receptors, Somatomedin; D013960:Thyroid Function Tests; D013964:Thyroid Neoplasms / Q000737:chemistry; D014407:Tumor Cells, Cultured
D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin