Down-regulation of transcription elogation factor A (SII) like 4 (TCEAL4) in anaplastic thyroid cancer

To investigate the role of TCEAL4 in ATC carcinogenesis, we examined expression levels of TCEAL4 in ACLs as well as in other types of thyroid cancers and normal human tissue.Expression of TCEAL4 was down-regulated in all 11 ACLs as compared to either normal thyroid tissues or papillary and follicular thyroid cancerous tissues. TCEAL4 was expressed ubiquitously in all normal human tissues tested.To our knowledge, this is the first report of altered TCEAL4 expression in human cancers. We suggest that loss of TCEAL4 expression might be associated with development of ATC from DTC. Further functional studies are required.Anaplastic thyroid cancer (ATC) is one of the most lethal tumors of all human malignancies [1-3]. ATC is well known to often arise from transformation of differentiated thyroid cancer (DTC) of the papillary or follicular type [1-5]. However, little is known about the genetic mechanisms of the transformation of DTC to ATC. We have been attempting to identify new diagnostic markers and drug-target molecules in ATC by cDNA microarray technology, and lately have reported specific changes in expression of several genes in ATCs and cell lines derived from anaplastic thyroid cancers (ACL)s [6].In this paper, we describe a novel member of the group of down-regulated genes that was identified by expression profiling: transcription elongation factor A (SII)-like 4 (TCEAL4). NCBI accession number NM_024863, which is located a Xq22.1. The coding sequence is 1077 basepairs and the mRNA consists of 1516 basespairs according to the NCBI "Gene" database (Gene ID 79921). TCEAL4 encodes a member of the transcription elongation factor A (SII)-like (TCEAL) gene family. Members of this family contain TFA domains and may work as nuclear phosphoproteins that modulate transcription in a promoter context-dependent manner [7-9]. To date, genetic alterations of TCEAL4 in human cancers have not been described. In this study, we examined expression levels of TCEAL4 in anaplastic thy