title: ERG/AKR1C3/AR Constitutes a Feed-Forward Loop for AR Signaling in Prostate Cancer Cells.
abstract: OBJECTIVE
  Intratumoral androgen synthesis in prostate cancer contributes to the development of castration-resistant prostate cancer (CRPC). Several enzymes responsible for androgen biosynthesis have been shown to be overexpressed in CRPC, thus contributing to CRPC in a castrated environment. The TMPRSS2-ERG transcription factor has been shown to be present in primary prostate cancer tumors as well as CRPC tumors. We hypothesize that TMPRSS2-ERG fusions regulate androgen biosynthetic enzyme (ABE) gene expression and the production of androgens, which contributes to the development of CRPC.
  
  
  METHODS
  We used a panel of assays, including lentivirus transduction, gene expression, chromatin immunoprecipitation and sequencing, liquid chromatography-mass spectrometric quantitation, immunocytochemistry, immunohistochemistry, and bioinformatics analysis of gene microarray databases, to determine ERG regulation of androgen synthesis.
  
  
  RESULTS
  We found that ERG regulated the expression of the ABE AKR1C3 in prostate cancer cells via direct binding to the AKR1C3 gene. Knockdown of ERG resulted in reduced AKR1C3 expression, which caused a reduction in both DHT synthesis and PSA expression in VCaP prostate cancer cells treated with 5α-androstanedione (5α-Adione), a DHT precursor metabolite. Immunohistochemical staining revealed that ERG was coexpressed with AKR1C3 in prostate cancer tissue samples.
  
  
  CONCLUSIONS
  These data suggest that AKR1C3 catalyzes the biochemical reduction of 5α-Adione to DHT in prostate cancer cells, and that ERG regulates this step through upregulation of AKR1C3 expression. Elucidation of ERG regulation of ABEs in CRPC may help to stratify TMPRSS2-ERG fusion-positive prostate cancer patients in the clinic for anti-androgen receptor-driven therapies; and AKR1C3 may serve as a valuable therapeutic target in the treatment of CRPC.
authors.affiliation: Department of Urology, Wayne State University School of Medicine, Detroit, Michigan.
authors.forename: Katelyn
authors.initials: K
authors.lastname: Powell
authors.affiliation: Department of Urology, Wayne State University School of Medicine, Detroit, Michigan.
authors.forename: Louie
authors.initials: L
authors.lastname: Semaan
authors.affiliation: Department of Urology, Wayne State University School of Medicine, Detroit, Michigan.
authors.forename: M Katie
authors.initials: MK
authors.lastname: Conley-LaComb
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Irfan
authors.initials: I
authors.lastname: Asangani
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Yi-Mi
authors.initials: YM
authors.lastname: Wu
authors.affiliation: Department of Urology, Wayne State University School of Medicine, Detroit, Michigan.
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Ginsburg
authors.affiliation: Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada.
authors.forename: Julia
authors.initials: J
authors.lastname: Williams
authors.affiliation: Department of Pathology and Forensic Medicine, University of Sao Paulo at Ribeirão Preto, Brazil.
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Squire
authors.affiliation: Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan.
authors.forename: Krishna R
authors.initials: KR
authors.lastname: Maddipati
authors.affiliation: Department of Urology, Wayne State University School of Medicine, Detroit, Michigan. Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan. Department of Oncology, Wayne State University School of Medicine, Detroit, Michigan.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Cher
authors.affiliation: Department of Urology, Wayne State University School of Medicine, Detroit, Michigan. Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan. Department of Oncology, Wayne State University School of Medicine, Detroit, Michigan. schinni@med.wayne.edu.
authors.forename: Sreenivasa R
authors.initials: SR
authors.lastname: Chinni
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000096:biosynthesis* / Q000235:genetics; D000074425:Aldo-Keto Reductase Family 1 Member C3; D000726:Androgen Antagonists / Q000008:administration & dosage; D000728:Androgens / Q000096:biosynthesis / Q000235:genetics; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D006911:Hydroxyprostaglandin Dehydrogenases / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D011467:Prostate / Q000187:drug effects / Q000473:pathology; D064129:Prostatic Neoplasms, Castration-Resistant / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D011944:Receptors, Androgen / Q000235:genetics; D012697:Serine Endopeptidases / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics*; D000071230:Transcriptional Regulator ERG
chemical_list: D000726:Androgen Antagonists; D000728:Androgens; C072312:ERG protein, human; D015514:Oncogene Proteins, Fusion; D011944:Receptors, Androgen; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D015096:3-Hydroxysteroid Dehydrogenases; D006911:Hydroxyprostaglandin Dehydrogenases; C487341:AKR1C3 protein, human; D000074425:Aldo-Keto Reductase Family 1 Member C3; D012697:Serine Endopeptidases; C421305:TMPRSS2 protein, human