title: Influence of thyroid hormone receptors on breast cancer cell proliferation.
abstract: BACKGROUND
  The involvement of thyroid hormones in the development and differentiation of normal breast tissue has been established. However, the association between breast cancer and these hormones is controversial. Therefore, the objective of the present study was to determine the protein expression pattern of thyroid hormone receptors in different human breast pathologies and to evaluate their possible relationship with cellular proliferation.
  
  
  METHODS
  The presence of thyroid hormone receptors was evaluated by immunohistochemistry and western blot analysis in 84 breast samples that included 12 cases of benign proliferative diseases, 20 carcinomas in situ and 52 infiltrative carcinomas.
  
  
  RESULTS
  TR-alpha was detected in the nuclei of epithelial cells from normal breast ducts and acini, while in any pathological type this receptor was located in the cytoplasm. However, TR-beta presented a nuclear location in benign proliferative diseases and carcinomas in situ and a cytoplasmatic location in normal breast and infiltrative carcinomas. The highest proliferation index was observed in carcinomas in situ, although in infiltrative carcinomas an inverse correlation between this index and the TR-alpha expression was encountered.
  
  
  CONCLUSIONS
  The results of this study reveal substantial changes in the expression profile of thyroid hormone receptors suggesting a possible deregulation that could trigger breast cancer development.
authors.affiliation: Department of Cell Biology and Genetics, University of Alcalá, 28871 Alcalá de Henares, Madrid, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Conde
authors.forename: R
authors.initials: R
authors.lastname: Paniagua
authors.forename: J
authors.initials: J
authors.lastname: Zamora
authors.forename: M J
authors.initials: MJ
authors.lastname: Blánquez
authors.forename: B
authors.initials: B
authors.lastname: Fraile
authors.forename: A
authors.initials: A
authors.lastname: Ruiz
authors.forename: M I
authors.initials: MI
authors.lastname: Arenas
mesh_terms: D015153:Blotting, Western; D001940:Breast / Q000378:metabolism; D001941:Breast Diseases / Q000378:metabolism* / Q000473:pathology; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002278:Carcinoma in Situ / Q000378:metabolism / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism / Q000473:pathology; D018275:Carcinoma, Lobular / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation; D018450:Disease Progression; D005260:Female; D018226:Fibroadenoma / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D011988:Receptors, Thyroid Hormone / Q000378:metabolism*
chemical_list: D011988:Receptors, Thyroid Hormone