title: Different associations of estrogen receptor β isoforms, ERβ1 and ERβ2, expression levels with tumor size and survival in early- and late-onset breast cancer.
abstract: BACKGROUND
  In breast cancer, little is known about the consequences of co-expression of ERα with the second estrogen receptor, ERβ, and its isoforms in light of their joint prognostic value. Previously reported correlations have been based mostly on independent ERα and ERβ expression levels in breast tumors.
  
  
  OBJECTIVE
  To address whether the expression ratio of ERα and ERβ and its isoforms may be a more important parameter than their absolute levels, we analyzed relative mRNA expression ratios of ERβ1 to ERβ2 and ERα in 74 clinical samples of invasive breast cancer including 39 early-onset and 35 late-onset breast cancers. Expression levels were correlated with clinical and histopathological parameters and disease-free interval.
  
  
  RESULTS
  A specific correlation of ERβ1 expression levels with tumor size was detected in early-onset breast cancer patients and of ERβ2 levels with tumor size in late-onset patients. Expression of both ERβ isoforms inversely correlated with expression of the two estrogen regulated genes, progesterone receptor and pS2 in both groups. Higher levels of ERβ2 than ERβ1 isoform were associated with a better outcome in late-onset patients.
  
  
  CONCLUSIONS
  Our results suggest that different isoforms of ERβ may be involved in suppression of tumor growth in young and elder patients and may have different prognostic values.
authors.affiliation: Deutsches Krebsforschungszentrum (DKFZ), Molecular Genetics of Breast Cancer, Heidelberg, Germany.
authors.forename: Vesna
authors.initials: V
authors.lastname: Mandusic
authors.forename: Bogomir
authors.initials: B
authors.lastname: Dimitrijevic
authors.forename: Dragica
authors.initials: D
authors.lastname: Nikolic-Vukosavljevic
authors.forename: Zora
authors.initials: Z
authors.lastname: Neskovic-Konstantinovic
authors.forename: Ksenija
authors.initials: K
authors.lastname: Kanjer
authors.forename: Ute
authors.initials: U
authors.lastname: Hamann
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000378:metabolism*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D020033:Protein Isoforms / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D020033:Protein Isoforms; D012333:RNA, Messenger