title: Androgen receptor inhibits estrogen receptor-alpha activity and is prognostic in breast cancer.
abstract: There is emerging evidence that the balance between estrogen receptor-alpha (ER(alpha)) and androgen receptor (AR) signaling is a critical determinant of growth in the normal and malignant breast. In this study, we assessed AR status in a cohort of 215 invasive ductal breast carcinomas. AR and (ER(alpha)) were coexpressed in the majority (80-90%) of breast tumor cells. Kaplan-Meier product limit analysis and multivariate Cox regression showed that AR is an independent prognostic factor in (ER(alpha))-positive disease, with a low level of AR (less than median of 75% positive cells) conferring a 4.6-fold increased risk of cancer-related death (P = 0.002). Consistent with a role for AR in breast cancer outcome, AR potently inhibited (ER(alpha))transactivation activity and 17beta-estradiol-stimulated growth of breast cancer cells. Transfection of MDA-MB-231 breast cancer cells with either functionally impaired AR variants or the DNA-binding domain of the AR indicated that the latter is both necessary and sufficient for inhibition of (ER(alpha)) signaling. Consistent with molecular modeling, electrophoretic mobility shift assays showed binding of the AR to an estrogen-responsive element (ERE). Evidence for a functional interaction of the AR with an ERE in vivo was provided by chromatin immunoprecipitation data, revealing recruitment of the AR to the progesterone receptor promoter in T-47D breast cancer cells. We conclude that, by binding to a subset of EREs, the AR can prevent activation of target genes that mediate the stimulatory effects of 17beta-estradiol on breast cancer cells.
authors.affiliation: Dame Roma Mitchell Cancer Research Laboratories, Discipline of Medicine, University of Adelaide, Hanson Institute, Adelaide, South Australia, Australia.
authors.forename: Amelia A
authors.initials: AA
authors.lastname: Peters
authors.forename: Grant
authors.initials: G
authors.lastname: Buchanan
authors.forename: Carmela
authors.initials: C
authors.lastname: Ricciardelli
authors.forename: Tina
authors.initials: T
authors.lastname: Bianco-Miotto
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Centenera
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Harris
authors.forename: Shalini
authors.initials: S
authors.lastname: Jindal
authors.forename: Davendra
authors.initials: D
authors.lastname: Segara
authors.forename: Li
authors.initials: L
authors.lastname: Jia
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Moore
authors.forename: Susan M
authors.initials: SM
authors.lastname: Henshall
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Birrell
authors.forename: Gerhard A
authors.initials: GA
authors.lastname: Coetzee
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sutherland
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Butler
authors.forename: Wayne D
authors.initials: WD
authors.lastname: Tilley
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D019556:COS Cells; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D004273:DNA, Neoplasm / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D011379:Prognosis; D011944:Receptors, Androgen / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements; D015398:Signal Transduction; D015533:Transcriptional Activation
chemical_list: D004273:DNA, Neoplasm; D047628:Estrogen Receptor alpha; D011944:Receptors, Androgen