title: Wild-type and specific mutant androgen receptor mediates transcription via 17β-estradiol in sex hormone-sensitive cancer cells.
abstract: We previously encountered regulatory processes wherein dihydrotestosterone (DHT) exerted its inhibitory effect on parathyroid hormone-related protein (PTHrP) gene repression through the estrogen receptor (ER)α, but not the androgen receptor (AR), in breast cancer MCF-7 cells. Here, we investigated whether such aberrant ligand-nuclear receptor (NR) interaction is present in prostate cancer LNCaP cells. First, we confirmed that LNCaP cells expressed large amounts of AR at negligible levels of ERα/β or progesterone receptor. Both suppression of PTHrP and activation of prostate-specific antigen genes were observed after independent administration of 17β-estradiol (E2), DHT, or R5020. Consistent with the notion that the LNCaP AR lost its ligand specificity due to a mutation (Thr-Ala877), experiments with siRNA targeting the respective NR revealed that the AR monopolized the role of the mediator of shared hormone-dependent regulation, which was invariably associated with nuclear translocation of this mutant AR. Microarray analysis of gene regulation by DHT, E2, or R5020 disclosed that more than half of the genes downstream of the AR (Thr-Ala877) overlapped in the LNCaP cells. Of particular interest, we realized that the AR (wild-type [wt]) and AR (Thr-Ala877) were equally responsible for the E2-AR interactions. Fluorescence microscopy experiments demonstrated that both EGFP-AR (wt) and EGFP-AR (Thr-Ala877) were exclusively localized within the nucleus after E2 or DHT treatment. Furthermore, reporter assays revealed that some other cancer cells exhibited aberrant E2-AR (wt) signaling similar to that in the LNCaP cells. We herein postulate the presence of entangled interactions between wt AR and E2 in certain hormone-sensitive cancer cells.
authors.affiliation: Departments of Biochemistry, Teikyo University School of Medicine, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Susa
authors.forename: Reina
authors.initials: R
authors.lastname: Ikaga
authors.forename: Takashi
authors.initials: T
authors.lastname: Kajitani
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Iizuka
authors.forename: Hiroko
authors.initials: H
authors.lastname: Okinaga
authors.forename: Mimi
authors.initials: M
authors.lastname: Tamamori-Adachi
authors.forename: Tomoki
authors.initials: T
authors.lastname: Okazaki
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D001943:Breast Neoplasms / Q000378:metabolism*; D045744:Cell Line, Tumor; D013196:Dihydrotestosterone / Q000494:pharmacology; D004958:Estradiol / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D009154:Mutation; D044162:Parathyroid Hormone-Related Protein / Q000235:genetics / Q000378:metabolism; D011397:Promegestone / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000378:metabolism*; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*
chemical_list: D047628:Estrogen Receptor alpha; D044162:Parathyroid Hormone-Related Protein; D011944:Receptors, Androgen; D013196:Dihydrotestosterone; D004958:Estradiol; D011397:Promegestone