Thyroid transcription factor-2 gene expression in benign and malignant thyroid lesions

Thyroid transcription factor-2 (TTF-2) is a recently cloned thyroid-specifi c gene and is central to the development and differentiation of the thyroid follicular cell. Information regarding transcript levels in normal and dis eased adult human thyroids is lacking. We have investigated TTF-2 gene expr ession in various thyroid pathologies and assessed its potential in preoper ative diagnosis of thyroid nodular disease, which is a common clinical prob lem. We have used reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH) and detected TTF-2 transcripts in 60% of 12 5 samples of adult human thyroids tested by RT-PCR (64% of 35) or ISH (59% of 90). In normal thyroid tissues TTF-2 transcript levels are low, 18 of 36 were weakly positive and 18 of 36 negative when tested by ISH. In the beni gn lesions, TTF-2 transcripts were detected either by RT-PCR or ISH in 8 of 8 Graves disease; 3 of 7 Hashimoto's; 2 of 2 follicular hyperplasia; 15 of 21 follicular adenoma; 11 of 13 multinodular goiters and 0 of 1 hyalinizin g trabecular adenoma. In the malignant thyroid lesions, TTF-2 transcripts w ere detected in 8 of 18 follicular cancers; 0 of 2 anaplastic carcinoma, an d 11 of 17 papillary cancers. Compared with normal thyroids, transcripts we re more abundant in 24% of thyroid lesions tested by ISH. In conclusion, we report for the first time on TTF-2 gene expression in normal and diseased adult human thyroids.