title: A dominant-negative mutant of androgen receptor coregulator ARA54 inhibits androgen receptor-mediated prostate cancer growth.
abstract: The ligand-bound androgen receptor (AR) regulates target genes via a mechanism involving coregulators such as androgen receptor-associated 54 (ARA54). We investigated whether the interruption of the AR coregulator function could lead to down-regulation of AR activity. Using in vitro mutagenesis and a yeast two-hybrid screening assay, we have isolated a mutant ARA54 (mt-ARA54) carrying a point mutation at amino acid 472 changing a glutamic acid to lysine, which acts as a dominant-negative inhibitor of AR transactivation. In transient transfection assays of prostate cancer cell lines, the mt-ARA54 suppressed endogenous mutated AR-mediated and exogenous wild-type AR-mediated transactivation in LNCaP and PC-3 cells, respectively. In DU145 cells, the mt-ARA54 suppressed exogenous ARA54 but not other coregulators, such as ARA55-enhanced or SRC-1-enhanced AR transactivation. In the LNCaP cells stably transfected with the plasmids encoding the mt-ARA54 under the doxycycline inducible system, the overexpression of the mt-ARA54 inhibited cell growth and endogenous expression of prostate-specific antigen. Mammalian two-hybrid assays further demonstrated that the mt-ARA54 can disrupt the interaction between wild-type ARA54 molecules, suggesting that ARA54 dimerization or oligomerization may play an essential role in the enhancement of AR transactivation. Together, our results demonstrate that a dominant-negative AR coregulator can suppress AR transactivation and cell proliferation in prostate cancer cells. Further studies may provide a new therapeutic approach for blocking AR-mediated prostate cancer growth.
authors.affiliation: George Whipple Laboratory for Cancer Research, Department of Pathology, University of Rochester Medical Center, Rochester, New York 14642, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyamoto
authors.forename: Mujib
authors.initials: M
authors.lastname: Rahman
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takatera
authors.forename: Hong-Yo
authors.initials: HY
authors.lastname: Kang
authors.forename: Shuyuan
authors.initials: S
authors.lastname: Yeh
authors.forename: Hong-Chiang
authors.initials: HC
authors.lastname: Chang
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nishimura
authors.forename: Naohiro
authors.initials: N
authors.lastname: Fujimoto
authors.forename: Chawnshang
authors.initials: C
authors.lastname: Chang
mesh_terms: D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics*; D015536:Down-Regulation; D005799:Genes, Dominant; D017930:Genes, Reporter; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008239:Lysine / Q000737:chemistry; D008297:Male; D008954:Models, Biological; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D017354:Point Mutation; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013997:Time Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; C118499:RNF14 protein, human; D008239:Lysine