BETA-CATENIN AND GAMMA-CATENIN EXPRESSION IN THYROID CARCINOMAS

Cadherins are calcium-dependent cell-cell adhesion molecules whose int racellular domain forms a complex with proteins required for their fun ction, called catenins. Down-regulation of cadherins has frequently be en detected in many types of human carcinomas, being associated with t umour progression. The present study investigates the immunohistochemi cal expression of E-cadherin and beta- and gamma-catenin in 27 human t hyroid carcinomas. E-cadherin immunoreactivity was found to be decreas ed at cell-cell contacts in 8/15 (53 per cent) papillary, 5/7 (71 per cent) follicular, and 5/5 (100 per cent) anaplastic carcinomas. Beta-c atenin membrane localization was found to be decreased in 6/15 (40 per cent) papillary, 2/7 (28 per cent) follicular, and 5/5 (100 per cent) anaplastic carcinomas. Gamma-catenin expression was partially or tota lly lost in 13/15 (86 per cent) papillary, 6/7 (85 per cent) follicula r, and 5/5 (100 per cent) anaplastic carcinomas. A normal pattern of e xpression for these three molecules was observed in areas of normal ti ssue in each sample. These data indicate that in addition to E-cadheri n, catenins are also down-regulated at cell-cell junctions in thyroid tumours and could represent potentially useful differentiation and/or transformation markers. The high frequency of alterations of gamma-cat enin expression found in thyroid carcinomas suggests an important role for this gene product in thyroid carcinogenesis. (C) 1998 John Wiley & Sons, Ltd.