The Prostate 67:1152^1162 (2007)
Androgen Receptor or Estrogen Receptor-b Blockade Alters DHEA-,DHT-, and E2-Induced Proliferation and PSAProduction in Human Prostate Cancer Cells
Julia T. Arnold,1* Xunxian Liu,1 Jeffrey D. Allen,1 Hanh Le,1 Kimberly K. McFann,2 and Marc R. Blackman1 1Endocrine Section, Laboratory of Clinical Investigation, Division of Intramural Research, National Center for Complementary and Alternative Medicine, National Institutes of Health, Bethesda, Maryland 2University of Colorado Health Sciences Center, Denver,Colorado
BACKGROUND. Dehydroepiandrosterone (DHEA) is an endogenous steroid that is metabolized to androgens and/or estrogens in the human prostate. DHEA levels decline with age, and use of DHEA supplements to retard the aging process is of unproved effectiveness and safety. LNCaP and LAPC-4 prostate cancer cells were used to determine whether DHEA- modulated proliferation and prostate specific antigen (PSA) production were mediated via the androgen receptor (AR) and/or ERb. 1 METHODS. Cells were treated with DHEA, DHT, or E2 and antagonists to AR (Casodex - bicalutamide) or ER (ICI 182,780) or siRNA to the respective receptors. Proliferation was assessed by MTT assay and PSA mRNA and protein secretion were measured by quantitative real-time PCR and ELISA. Associations of AR and ERb were analyzed by co-immunoprecipita- tion studies and fluorescent confocal microscopy. RESULTS. DHEA-, T-, and E2-induced proliferation of LNCaP cells was blunted by Casodex but not by ICI treatment. In LNCaP cells, Casodex and ICI suppressed hormone-induced PSA production. In LAPC-4 cells, DHT-stimulated PSA mRNA was inhibited by Casodex and ICI, and the minimal stimulation by DHEA was inhibited by ICI. Use of siRNAs confirmed involvement of AR and ERb in hormone-induced PSA production while AR-ERb co-association was suggested by immunoprecipitation and nuclear co-localization. CONCLUSIONS. These findings support involvement of both AR and ERb in mediating DHEA-, DHT-, and E2-induced PSA expression in prostate cancer cells. Prostate 67: 1152–1162, 2007. # 2007 Wiley-Liss, Inc.
KEY WORDS: DHEA; DHT; E2; AR; ERb; PSA; Casodex; ICI 182,780
INTRODUCTION [3]. Whether the effects of DHEA in LNCaP cells result from binding of DHEA or its androgenic metabolites Dehydroepiandrosterone (DHEA), the most abun- to the mutant AR are uncertain [2]. In comparison, dant endogenous adrenal steroid produced by men and women, declines markedly with aging. It is increas- ingly consumed as an over-the-counter dietary supple- Grant sponsor: Intramural Research Program of the National Center ment for its purported anti-aging effects, yet its for Complementary and Alternative Medicine, National Institutes of usefulness and long-term safety remain uncertain [1]. Health, Bethesda; Grant number: MD20892. DHEA stimulates cell growth and gene and protein *Correspondence to: Julia T. Arnold, PhD, Endocrine Section, LCI, expression in human LNCaP prostate cancer epithelial NCCAM, 9 Memorial Drive, Rm 1N105, Bethesda, MD 20892-0933. cells, and its effects are delayed and reduced compared E-mail: [email protected] Received 12 January 2007; Accepted 20 February 2007 with those of DHT and T, but similar to those of E2 [2]. DOI 10.1002/pros.20585 LNCaP cells harbor a mutated androgen receptor (AR) Published online 14 May 2007 in Wiley InterScience that allows for direct binding of DHEA and E2 to the AR (www.interscience.wiley.com).