Decrease in thyroid adenoma associated (THADA) expression is a marker of dedifferentiation of thyroid tissue

For the analysis THADA and 18S rRNA gene expression assays were performed on 34 normal tissue samples, including thyroid, salivary gland, heart, endometrium, myometrium, lung, blood, and adipose tissue as well as on 85 thyroid hyper- and neoplasias, including three adenomas with a 2p21 translocation. In addition, NIS (sodium-iodide symporter) gene expression was measured on 34 of the pathological thyroid samples.Results illustrated that THADA expression in normal thyroid tissue was significantly higher (p < 0.0001, exact Wilcoxon test) than in the other tissues. Significant differences were also found between non-malignant pathological thyroid samples (goiters and adenomas) and malignant tumors (p < 0.001, Wilcoxon test, t approximation), anaplastic carcinomas (ATCs) and all other samples and also between ATCs and all other malignant tumors (p < 0.05, Wilcoxon test, t approximation). Furthermore, in thyroid tumors THADA mRNA expression was found to be inversely correlated with HMGA2 mRNA. HMGA2 expression was recently identified as a marker revealing malignant transformation of thyroid follicular tumors. A correlation between THADA and NIS has also been found in thyroid normal tissue and malignant tumors.The results suggest THADA being a marker of dedifferentiation of thyroid tissue.Benign thyroid tumors and hyperplasias of follicular epithelial origin belong to the cytogenetically best analyzed human epithelial tumors.Cytogenetic aberrations have been detected in approximately 20% of these lesions [1]. Translocations of chromosomal band 2p21 are the second most frequent structural chromosomal rearrangement, representing a particular cytogenetic subgroup [2]. The target gene has been identified and referred to as thyroid adenoma associated (THADA) [3].The full length cDNA of THADA consists of 6,134 bp distributed over 38 exons [GenBank: NM_022065]. There are two splice-variants, one lacking exons 27 and 28 [3], and the other without exons 16 and 17. The THADA protei