NEOEXPRESSION OF THE EPITHELIAL ADHESION COMPLEX ANTIGENS IN THYROID-TUMORS IS ASSOCIATED WITH PROLIFERATION AND SQUAMOUS DIFFERENTIATION MARKERS

Integrin dimer alpha(6) beta(4) is a transmembrane component of an epi thelial cell adhesion complex that consists of hemidesmosomes (HDs), b asement membrane (BM)-associated laminin-5 (Ln-5), and anchoring filam ents/type VII collagen, all of which are absent from normal thyroid fo llicular epithelium. In the present study, the expression of epithelia l cell adhesion complex antigens in thyroid tumours was investigated u sing immunohistochemistry. In addition to integrin subunits alpha(6) a nd beta(4), immunoreactivity was found for all chains of Ln-5, alpha 3 , beta 3 and gamma 2, type VII collagen and hemidesmosomal antigen, HD 1, in most thyroid carcinomas associated with tumour anaplasia and pap illary growth pattern and located at the border of parenchymal cells a nd connective tissue or blood vessel walls. In addition, a more restri cted expression of bullous pemphigoid antigens 180 and 230 (BP180 and BP230), constituents of HDs, was found in some papillary and anaplasti c carcinomas and atypical adenomas. Adhesion complex antigens were loc ated to regions of cells which were immunoreactive for cytokeratin (ck )-5 and proliferating cell nuclear antigen Ki-67, The results suggest that in thyroid carcinomas, the emergence of adhesion complex antigens is associated with squamous differentiation and high proliferative ac tivity. (C) 1998 John Wiley & Sons, Ltd.