title: Androgen receptor expression predicts breast cancer survival: the role of genetic and epigenetic events.
abstract: BACKGROUND
  Breast cancer outcome, including response to therapy, risk of metastasis and survival, is difficult to predict using currently available methods, highlighting the urgent need for more informative biomarkers. Androgen receptor (AR) has been implicated in breast carcinogenesis however its potential to be an informative biomarker has yet to be fully explored. In this study, AR protein levels were determined in a cohort of 73 Grade III invasive breast ductal adenocarcinomas.
  
  
  METHODS
  The levels of Androgen receptor protein in a cohort of breast tumour samples was determined by immunohistochemistry and the results were compared with clinical characteristics, including survival. The role of defects in the regulation of Androgen receptor gene expression were examined by mutation and methylation screening of the 5' end of the gene, reporter assays of the 5' and 3' end of the AR gene, and searching for miRNAs that may regulate AR gene expression.
  
  
  RESULTS
  AR was expressed in 56% of tumours and expression was significantly inversely associated with 10-year survival (P = 0.004). An investigation into the mechanisms responsible for the loss of AR expression revealed that hypermethylation of the AR promoter is associated with loss of AR expression in breast cancer cells but not in primary breast tumours. In AR negative breast tumours, mutation screening identified the same mutation (T105A) in the 5'UTR of two AR negative breast cancer patients but not reported in the normal human population. Reporter assay analysis of this mutation however found no evidence for a negative impact on AR 5'UTR activity. The role of miR-124 in regulating AR expression was also investigated, however no evidence for this was found.
  
  
  CONCLUSIONS
  This study highlights the potential for AR expression to be an informative biomarker for breast cancer survival and sets the scene for a more comprehensive investigation of the molecular basis of this phenomenon.
authors.affiliation: School of Chemistry and Molecular Biosciences, The University of Queensland, St, Lucia 4072 Queensland, Australia.
authors.forename: Kate M
authors.initials: KM
authors.lastname: Peters
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Edwards
authors.forename: Shalima S
authors.initials: SS
authors.lastname: Nair
authors.forename: Juliet D
authors.initials: JD
authors.lastname: French
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Bailey
authors.forename: Kathryn
authors.initials: K
authors.lastname: Salkield
authors.forename: Sandra
authors.initials: S
authors.lastname: Stein
authors.forename: Sarah
authors.initials: S
authors.lastname: Wagner
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Francis
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Clark
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Brown
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality* / Q000473:pathology; D045744:Cell Line, Tumor; D015331:Cohort Studies; D019175:DNA Methylation / Q000502:physiology; D044127:Epigenesis, Genetic; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D016019:Survival Analysis
chemical_list: D009363:Neoplasm Proteins; D012333:RNA, Messenger; D011944:Receptors, Androgen