title: Inhibition of cyclin D1 expression by androgen receptor in breast cancer cells--identification of a novel androgen response element.
abstract: Cyclin D1 gene (CCND1) is a critical mitogen-regulated cell-cycle control element whose transcriptional modulation plays a crucial role in breast cancer growth and progression. Here we demonstrate that the non-aromatizable androgen 5-α-dihydrotestosterone (DHT) inhibits endogenous cyclin D1 expression, as evidenced by reduction of cyclin D1 mRNA and protein levels, and decrease of CCND1-promoter activity, in MCF-7 cells. The DHT-dependent inhibition of CCND1 gene activity requires the involvement and the integrity of the androgen receptor (AR) DNA-binding domain. Site directed mutagenesis, DNA affinity precipitation assay, electrophoretic mobility shift assay and chromatin immunoprecipitation analyses indicate that this inhibitory effect is ligand dependent and it is mediated by direct binding of AR to an androgen response element (CCND1-ARE) located at -570 to -556-bp upstream of the transcription start site, in the cyclin D1 proximal promoter. Moreover, AR-mediated repression of the CCND1 involves the recruitment of the atypical orphan nuclear receptor DAX1 as a component of a multiprotein repressor complex also embracing the participation of Histone Deacetylase 1. In conclusion, identification of the CCND1-ARE allows defining cyclin D1 as a specific androgen target gene in breast and might contribute to explain the molecular basis of the inhibitory role of androgens on breast cancer cells proliferation.
authors.affiliation: Dipartimento Farmaco-Biologico, University of Calabria, Arcavacata di Rende (CS) 87036, Italy.
authors.forename: Marilena
authors.initials: M
authors.lastname: Lanzino
authors.forename: Diego
authors.initials: D
authors.lastname: Sisci
authors.forename: Catia
authors.initials: C
authors.lastname: Morelli
authors.forename: Cecilia
authors.initials: C
authors.lastname: Garofalo
authors.forename: Stefania
authors.initials: S
authors.lastname: Catalano
authors.forename: Ivan
authors.initials: I
authors.lastname: Casaburi
authors.forename: Claudia
authors.initials: C
authors.lastname: Capparelli
authors.forename: Cinzia
authors.initials: C
authors.lastname: Giordano
authors.forename: Francesca
authors.initials: F
authors.lastname: Giordano
authors.forename: Marcello
authors.initials: M
authors.lastname: Maggiolini
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Andò
mesh_terms: D000728:Androgens / Q000494:pharmacology; D001665:Binding Sites; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019938:Cyclin D1 / Q000235:genetics* / Q000378:metabolism; D057137:DAX-1 Orphan Nuclear Receptor / Q000378:metabolism; D013196:Dihydrotestosterone / Q000494:pharmacology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D011401:Promoter Regions, Genetic; D011944:Receptors, Androgen / Q000378:metabolism*; D020218:Response Elements
chemical_list: D000728:Androgens; D057137:DAX-1 Orphan Nuclear Receptor; D011944:Receptors, Androgen; D013196:Dihydrotestosterone; D019938:Cyclin D1