title: Histone deacetylase inhibition affects sodium iodide symporter expression and induces 131I cytotoxicity in anaplastic thyroid cancer cells.
abstract: BACKGROUND
  Anaplastic thyroid cancers (ATCs) represent only 1%-2% of all thyroid tumors, but they account for up to 50% of the mortality. Treatment of differentiated thyroid carcinomas is well standardized and the use of radioiodine represents an essential step; in contrast, there is no standardized therapeutic approach for anaplastic tumors and their prognosis is poor. The resistance of ATC to radioiodine treatment is principally due to the absence of expression of the sodium iodide symporter (NIS), mainly due to epigenetic silencing. The acetylation status of histones is involved in the epigenetic control of gene expression and is usually disrupted in advanced thyroid cancer. Histone deacetylase inhibitors have been demonstrated as potent anticancer drugs with several different effects on cell viability and differentiation.
  
  
  METHODS
  Stabilized ATC cell lines (BHT-101 and CAL-62) and primary cultures from patients who underwent thyroidectomy for ATC were treated with the histone deacetylase inhibitor LBH589. After treatment, we evaluated the expression and function of NIS. Gene expression was evaluated by real-time polymerase chain reaction (RT-PCR), NIS promoter activity was determined with a luciferase reporter assay, and protein expression was assessed through immunofluorescence. We tested the protein function by (125)I uptake and efflux experiments; finally the cytotoxic effect of (131)I was determined with a clonogenic assay.
  
  
  RESULTS
  Our results demonstrate that treatment with LBH589 leads to NIS RNA expression as shown by RT-PCR and luciferase assay, and to protein expression as determined by immunofluorescence in vitro and by immunohistochemistry in xenograft tumors. Moreover, (125)I uptake and efflux experiments show the correct protein function and iodine retention, which translate into cytotoxicity effects, as demonstrated by a clonogenic assay with (131)I.
  
  
  CONCLUSIONS
  This study supplies a new potential strategy for the treatment of ATC by modifying gene expression with the aim of inducing responsiveness towards radioiodine therapy.
authors.affiliation: Department of Medical Sciences, University of Turin, Turin, Italy.
authors.forename: Mariateresa
authors.initials: M
authors.lastname: Pugliese
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Fortunati
authors.forename: Antonina
authors.initials: A
authors.lastname: Germano
authors.forename: Sofia
authors.initials: S
authors.lastname: Asioli
authors.forename: Francesca
authors.initials: F
authors.lastname: Marano
authors.forename: Nicola
authors.initials: N
authors.lastname: Palestini
authors.forename: Roberto
authors.initials: R
authors.lastname: Frairia
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Boccuzzi
authors.forename: Maria Graziella
authors.initials: MG
authors.lastname: Catalano
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D045744:Cell Line, Tumor; D005260:Female; D064593:Heterografts; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007457:Iodine Radioisotopes / Q000378:metabolism / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008875:Middle Aged; D009368:Neoplasm Transplantation; D000077767:Panobinostat; D027981:Symporters / Q000096:biosynthesis*; D065646:Thyroid Carcinoma, Anaplastic; D013964:Thyroid Neoplasms / Q000532:radiotherapy*; D000099209:Sodium-Iodide Symporters
chemical_list: D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D007211:Indoles; D007457:Iodine Radioisotopes; D000077767:Panobinostat; D027981:Symporters; D000099209:Sodium-Iodide Symporters