BCL-2 AND BAX EXPRESSION IN THYROID-TUMORS - AN IMMUNOHISTOCHEMICAL AND WESTERN-BLOT-ANALYSIS

Bcl-2 and Bax proteins, which are involved in repressing and promoting programmed cell death, respectively, have been investigated immunohis tochemically and by Western blot analysis in a series of thyroid tumou rs. Three immunostaining patterns were identified. Benign lesions and well-differentiated thyroid carcinomas displayed a profile similar to that of normal follicular epithelium, in which Bcl-2 immunostaining wa s predominant. Thyroid carcinomas associated with an aggressive behavi our, such as the tall-cell variant of papillary carcinoma and the poor ly differentiated carcinomas, co-expressed both proteins. Finally, ana plastic carcinomas expressed only the Bar protein. Western blot analys es revealed that the anti-Bcl-2 antibody recognized two bands, of mole cular weights 21 kDa and 25 kDa. This was only seen in the tall-cell p apillary carcinomas and in the anaplastic carcinomas.