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-lake-activation antigens, VLA) were investigated in b enign and malignant human thyroid tumors. We compared tissue samples o f normal glands, nodular goiters, adenomas and carcinomas. We also exa mined 3 thyroid-carcinoma cell lines cultured in vitro. The expression of sub-units 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 t he heterogeneity of the expression of beta(1) integrins observed in ot her tumors, thyroid neoplastic lesions showed an remarkable constant V LA profile. In all tumors, benign as well as malignant, and in carcino ma cell lines, all sub-units of beta(1) integrins were expressed at hi gh 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 gl ands and nodular goiters, expression of alpha(4) was restricted to neo plastic lesions; this integrin can be therefore considered an antigen associated with thyroid tumors. It has been reported that in normal gl ands and in nodular goiters, the expression of beta(1), integrins is r estricted to the basal-cell membrane. Immunofluorescence on tissue sec tions showed instead that, in adenomas and carcinomas, the polarized d istribution of these integrins on the cell membrane is lost. (C) 1994 Wiley-Liss, Inc.