Loss of polarity and de novo expression of the beta 1 family of integrins in thyroid tumors.
The expression and cell-membrane distribution of the beta 1 family of integrins (very-late-activation antigens, VLA) were investigated in benign and malignant human thyroid tumors. We compared tissue samples of normal glands, nodular goiters, adenomas and carcinomas. We also examined 3 thyroid-carcinoma cell lines cultured in vitro. The expression of subunits of the beta 1 family of integrins was assessed by flow cytometry and specific antibodies in dispersed single-cell suspensions and by immunofluorescence on frozen tissue sections. In contrast to the heterogeneity of the expression of beta 1 integrins observed in other tumors, thyroid neoplastic lesions showed a remarkably constant VLA profile. In all tumors, benign as well as malignant, and in carcinoma cell lines, all sub-units of beta 1 integrins were expressed at high levels. While sub-units alpha 1, alpha 3, alpha 5, alpha 6 and occasionally alpha 2 were also present in a cell sub-set of normal glands and nodular goiters, expression of alpha 4 was restricted to neoplastic lesions; this integrin can be therefore considered an antigen associated with thyroid tumors. It has been reported that in normal glands and in nodular goiters, the expression of beta 1 integrins is restricted to the basal-cell membrane. Immunofluorescence on tissue sections showed instead that, in adenomas and carcinomas, the polarized distribution of these integrins on the cell membrane is lost.
Vitale
M
M
Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università Federico II, Naples, Italy.
Bassi
V
V
Illario
M
M
Fenzi
G
G
Casamassima
A
A
Rossi
G
G
D018265:Carcinoma, Papillary, Follicular / Q000737:chemistry* / Q000648:ultrastructure; D002462:Cell Membrane / Q000737:chemistry; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006042:Goiter / Q000378:metabolism; D006801:Humans; D039041:Integrin alpha4beta1; D016023:Integrins / Q000032:analysis*; D046911:Macromolecular Substances; D016029:Receptors, Very Late Antigen / Q000032:analysis; D013961:Thyroid Gland / Q000737:chemistry; D013964:Thyroid Neoplasms / Q000737:chemistry* / Q000648:ultrastructure
D039041:Integrin alpha4beta1; D016023:Integrins; D046911:Macromolecular Substances; D016029:Receptors, Very Late Antigen