Expression pattern of the pendrin and sodium/iodide symporter genes in human thyroid carcinoma cell lines and human thyroid tumors

Objective: In the present study we analyzed the pattern of pendrin (PDS) an d sodium/iodide symporter (NIS) gene expression in some thyroid carcinoma c ell lines and a series of thyroid tumoral tissues. Methods: Total RNA was extracted from all cell lines and from 53 tissues, a nd gene expression was examined by RT-PCR. Semiquantitative 'multiplex' RT- PCR was used to assess variations in PDS gene expression among various thyr oid pathologies. Pendrin expression was determined in the thyroid cell line s by Western blot analysis. Results: PDS mRNA was expressed in all the cells investigated: conversely, NIS mRNA was detectable only in the B-CPAP cells. Pendrin protein was expre ssed in B-CPAP and WRO cell lines, reduced in FRO and absent in ARO cells. PDS gene expression was not detected in 5 of 25 differentiated thyroid carc inomas (DTC) while NIS gene was not expressed in six carcinomas. A concorda nce expression of both PDS and NIS transcripts was found in 20 DTC. In cont rast. 2 neoplastic thyroid tissues carrying undetectable PDS mRNA maintaine d NIS transcript, and 3 thyroid carcinomas negative for NIS mRNA retained t he expression of PDS gene. A semiquantitative analysis showed that the mean PDS mRNA levels were significantly decreased in DTC tissues. Conclusions: Our data demonstrate that pendrin expression: (i) is present i n the more differentiated thyroid carcinoma cell lines studied: (ii) is red uced or absent in DTC tissues; (iii) may not correlate with the NIS express ion. These alterations may contribute to the loss of iodine concentration a bility detected in thyroid tumors.