Integrins in thyroid tissue:: upregulation of α2β1 in anaplastic thyroid carcinoma

Objective: To evaluate the integrin pattern in the normal thyroid gland and in different pathological disorders including malignant tumors, because the aggressiveness of several malignant tumors correlates with alterations in the expression of one or more integrins. Design: We examined the expression of integrins and E-cadherin immunohistochemically in a large and well-defined sample of normal and pathological human thyroid tissue. Methods: Cryosections of 58 thyroid tissue specimens from normal tissue, thyrotoxicosis, nodular goiter, oxyphilic adenoma, follicular adenoma, follicular carcinoma, papillary carcinoma and anaplastic carcinoma, and three lymph node metastases were investigated immunohistochemically using monoclonal antibodies specifically recognizing the integrin beta 1-, beta 4-, alpha 1-, alpha 2-, alpha 3-, alpha 5-and alpha 6-subunits, or E-cadherin. Results: All thyroid epithelial cells expressed integrin alpha 1-and alpha 3-subunits. Immunostaining of the beta 4-subunit and the alpha 6-subunits was found only in tumors. The staining pattern in the three lymph node metastases from papillary carcinomas did not differ from that in their primaries. Anaplastic carcinomas demonstrated neoexpression of the integrin alpha 2-subunit, E-cadherin was detected in all tissues except anaplastic carcinomas. Conclusions: Neoexpression of alpha 6 beta 4 was seen in most malignant tumors, whereas alpha 2 was exclusively found in anaplastic carcinomas. in. the latter, a loss of E-cadherin expression was also seen. These changes in cell adhesion molecule expression strongly suggest an association with the acquisition of proliferative and invasive properties.