Thyroid hormone receptor α 1 (c-erb A α 1) suppressed transforming phenotype of nasopharyngeal carcinoma cell line

Only three thyroid hormone receptor (TR) isoforms, α1, β1, and β2, bind thyroid hormone (TH) and are considered to be true TRs. TRα2, unable to bind TH, binds to TH response element on DNA and has been shown to exert dominant negative action on TR α1. TRαs regulate many important processes such as proliferation, differentiation and apoptosis. To find out if TRαs played roles in growth control of nasopharyngeal carcinoma cells, tansfectant with inducible expression of TRα1 was generated from NPC-TW 04 cell lines. Induced expression of TRα1 in nasopharyngeal carcinoma cell reduced proliferation and colony-formation ability in agar. Tumor formation ability in nude mice was reduced in NPC cells with TRα1 expression than those without expression or vector-transfected cells. Our results supported the hypothesis that TRα1 functions as a tumor suppressor gene in nasopharyngeal carcinoma tumorigenesis.