title: Mutation analysis underlying the downregulation of the thyroid hormone receptor β1 gene in the Chinese breast cancer population.
abstract: OBJECTIVE
  There are a growing number of reports suggesting that the aberrant expression and mutation of the thyroid hormone receptor β1 (TRβ1) gene is associated with the development of human neoplasms. However, its exact role in the pathogenesis of breast cancer remains elusive. In the present study, we analyzed the mRNA expression and mutations of the TRβ1 gene in the Chinese breast cancer population.
  
  
  METHODS
  The expression of TRβ1 mRNA was examined by real-time quantitative reverse transcription polymerase chain reaction, and mutations in the TRβ1 gene in the hotspot region that spans exons 7-10 were analyzed by polymerase chain reaction single-strand conformation polymorphism and automated DNA sequencing.
  
  
  RESULTS
  TRβ1 mRNA expression was significantly reduced in all 105 breast cancer specimens examined. A total of 20 samples showed truncating mutations within the exons 7-10 of the TRβ1 gene, where eight cases harbored a frame shift mutation (five cases of c.850insA in exon 7 and three cases c.1028delA in exon 8), whereas missense mutations were observed in 12 breast cancer cases. The 20 cases with mutation in the TRβ1 gene showed a reduction in TRβ1 mRNA expression compared with that observed in matched normal tissues. The mutation was also correlated with menopausal stage and estrogen receptor status.
  
  
  CONCLUSIONS
  The findings of the present study suggest that the aberrant expression and mutations of the TRβ1 gene are associated with the development of breast cancer and that the mutations in the TRβ1 gene partly serve as the underlying mechanism for TRβ1 inactivation in the Chinese breast cancer population.
authors.affiliation: Department of Pathophysiology, College of Basic Medical, Lanzhou University, Lanzhou, Gansu Province, People's Republic of China.
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Ling
authors.affiliation: Medical Oncology, Lanzhou University First Hospital, Lanzhou, Gansu Province, People's Republic of China.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Ling
authors.affiliation: Department of Pathophysiology, College of Basic Medical, Lanzhou University, Lanzhou, Gansu Province, People's Republic of China.
authors.forename: Lu
authors.initials: L
authors.lastname: Fan
authors.affiliation: Department of Gastroenterology, Lanzhou General Hospital of Lanzhou Military Command of PLA, Lanzhou, Gansu Province, People's Republic of China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Pathophysiology, College of Basic Medical, Lanzhou University, Lanzhou, Gansu Province, People's Republic of China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
keywords: biomarker; breast cancer; mutation; thyroid hormone receptor β1