Cyclic AMP–Response Element Modulator Inhibits the Promoter Activity of the Sodium Iodide Symporter Gene in Thyroid Cancer Cells

Background: Comprehension of the regulatory mechanism involved in the sodium iodide symporter (NIS) expression is of great relevance for thyroid cancer. In fact, restoration of NIS expression would be a strategy to treat undifferentiated thyroid cancer. Previous in vitro findings suggest that the cyclic AMP–response element (CRE) modulator (CREM) is involved in control of NIS expression. In this work, we examined the expression of CREM in a series of thyroid cancer tissues and its action on NIS promoter in human thyroid cancer cells. Methods: Expression of mRNA levels for CREM, PAX8 and NIS was measured by quantitative reverse transcriptase–polymerase chain reaction (RT-PCR) in 6 normal thyroid tissues, 22 papillary, 12 follicular and 4 anaplastic thyroid cancers. The effect of CREM on transcriptional activity of the NIS promoter was investigated by transient transfection of human thyroid cell lines. Results: Compared to normal tissues, NIS and PAX8 mRNA levels were significantly reduced in all types of t...