The relationship between Wilms’ tumor 1 (WT1) and paired box 8 (Pax-8) protein expressions in papillary and anaplastic thyroid carcinomas.
Background : We elucidated the expression of WT1 and its correlation with Pax-8 and TTF-1 as a differentiation promoter in thyroid cancer. Methods : We investigated the expression of WT1, Pax-8, and TTF-1 immunohistochemically in 60 primary tumors (30 well-differentiated and 15 poorly differentiated papillary carcinomas and 15 anaplastic thyroid carcinomas). Results : Positive staining of WT1 was found in the cytoplasm and nucleus of the cancer cells. Each positive rate of cytoplasmic staining of WT1 was 100% in the 45 papillary carcinomas and 93.3% in the 15 anaplastic carcinomas. The immunohistochemical scores for WT1 in well differentiated, poorly differentiated papillary carcinomas and anaplastic carcinomas were 5.90±1.7, 6.53±1.7, and 3.60±2.1, respectively. The scores for the well and poorly differentiated papillary carcinomas were significantly higher than those for the anaplastic carcinomas. The expression level of WT1 showed a significant correlation with both Pax-8 and TTF-1. Conclusions : This is the first report to demonstrate a positive correlation of the expression of WT1 with Pax-8 and TTF-1 in clinical cases. In thyroid cancer, the decrease in expression of WT1 with anaplastic transformation is assumed to be closely related to Pax-8 and TTF-1.
