title: HEX expression and localization in normal mammary gland and breast carcinoma.
abstract: BACKGROUND
  The homeobox gene HEX is expressed in several cell types during different phases of animal development. It encodes for a protein localized in both the nucleus and the cytoplasm. During early mouse development, HEX is expressed in the primitive endoderm of blastocyst. Later, HEX is expressed in developing thyroid, liver, lung, as well as in haematopoietic progenitors and endothelial cells. Absence of nuclear expression has been observed during neoplastic transformation of the thyroid follicular cells. Aim of the present study was to evaluate the localization and the function of the protein HEX in normal and tumoral breast tissues and in breast cancer cell lines.
  
  
  METHODS
  HEX expression and nuclear localization were investigated by immunohistochemistry in normal and cancerous breast tissue, as well as in breast cancer cell lines. HEX mRNA levels were evaluated by real-time PCR. Effects of HEX expression on Sodium Iodide Symporter (NIS) gene promoter activity was investigated by HeLa cell transfection.
  
  
  RESULTS
  In normal breast HEX was detected both in the nucleus and in the cytoplasm. In both ductal and lobular breast carcinomas, a great reduction of nuclear HEX was observed. In several cells from normal breast tissue as well as in MCF-7 and T47D cell line, HEX was observed in the nucleolus. MCF-7 treatment with all-trans retinoic acid enhanced HEX expression and induced a diffuse nuclear localization. Enhanced HEX expression and diffuse nuclear localization were also obtained when MCF-7 cells were treated with inhibitors of histone deacetylases such as sodium butyrate and trichostatin A. With respect to normal non-lactating breast, the amount of nuclear HEX was greatly increased in lactating tissue. Transfection experiments demonstrated that HEX is able to up-regulate the activity of NIS promoter.
  
  
  CONCLUSIONS
  Our data indicate that localization of HEX is regulated in epithelial breast cells. Since modification of localization occurs during lactation and tumorigenesis, we suggest that HEX may play a role in differentiation of the epithelial breast cell.
authors.affiliation: Dipartimento di Scienze e Tecnologie Biomediche, Università di Udine, Italy. pupp.cin@tin.it
authors.forename: Cinzia
authors.initials: C
authors.lastname: Puppin
authors.forename: Fabio
authors.initials: F
authors.lastname: Puglisi
authors.forename: Lucia
authors.initials: L
authors.lastname: Pellizzari
authors.forename: Guidalberto
authors.initials: G
authors.lastname: Manfioletti
authors.forename: Marta
authors.initials: M
authors.lastname: Pestrin
authors.forename: Maura
authors.initials: M
authors.lastname: Pandolfi
authors.forename: Andrea
authors.initials: A
authors.lastname: Piga
authors.forename: Carla
authors.initials: C
authors.lastname: Di Loreto
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Damante
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D006262:Health; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007774:Lactation; D042361:Mammary Glands, Human / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D027981:Symporters / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology; D000099209:Sodium-Iodide Symporters
chemical_list: D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases; D018398:Homeodomain Proteins; D027981:Symporters; D014157:Transcription Factors; D014212:Tretinoin; D000099209:Sodium-Iodide Symporters; C078492:HHEX protein, human