title: Nrdp1-mediated regulation of ErbB3 expression by the androgen receptor in androgen-dependent but not castrate-resistant prostate cancer cells.
abstract: Patients with advanced prostate cancer (PCa) are initially susceptible to androgen withdrawal (AW), but ultimately develop resistance to this therapy (castration-resistant PCa, CRPC). Here, we show that AW can promote CRPC development by increasing the levels of the receptor tyrosine kinase ErbB3 in androgen-dependent PCa, resulting in AW-resistant cell cycle progression and increased androgen receptor (AR) transcriptional activity. CRPC cell lines and human PCa tissue overexpressed ErbB3, whereas downregulation of ErbB3 prevented CRPC cell growth. Investigation of the mechanism by which AW augments ErbB3, using normal prostate-derived pRNS-1-1 cells, and androgen-dependent PCa lines LNCaP, PC346C, and CWR22 mouse xenografts, revealed that the AR suppresses ErbB3 protein levels, whereas AW relieves this suppression, showing for the first time the negative regulation of ErbB3 by AR. We show that AR activation promotes ErbB3 degradation in androgen-dependent cells, and that this effect is mediated by AR-dependent transcriptional upregulation of neuregulin receptor degradation protein-1 (Nrdp1), an E3 ubiquitin ligase that targets ErbB3 for degradation but whose role in PCa has not been previously examined. Therefore, AW decreases Nrdp1 expression, promoting ErbB3 protein accumulation, and leading to AR-independent proliferation. However, in CRPC sublines of LNCaP and CWR22, which strongly overexpress the AR, ErbB3 levels remain elevated due to constitutive suppression of Nrdp1, which prevents AR regulation of Nrdp1. Our observations point to a model of CRPC development in which progression of PCa to castration resistance is associated with the inability of AR to transcriptionally regulate Nrdp1, and predict that inhibition of ErbB3 during AW may impair CRPC development.
authors.affiliation: VA Northern California Health Care System, Mather, California, USA.
authors.forename: Liqun
authors.initials: L
authors.lastname: Chen
authors.forename: Salma
authors.initials: S
authors.lastname: Siddiqui
authors.forename: Swagata
authors.initials: S
authors.lastname: Bose
authors.forename: Benjamin
authors.initials: B
authors.lastname: Mooso
authors.forename: Alfredo
authors.initials: A
authors.lastname: Asuncion
authors.forename: Roble G
authors.initials: RG
authors.lastname: Bedolla
authors.forename: Ruth
authors.initials: R
authors.lastname: Vinall
authors.forename: Clifford G
authors.initials: CG
authors.lastname: Tepper
authors.forename: Regina
authors.initials: R
authors.lastname: Gandour-Edwards
authors.forename: Xubao
authors.initials: X
authors.lastname: Shi
authors.forename: Xiao-Hua
authors.initials: XH
authors.lastname: Lu
authors.forename: Javed
authors.initials: J
authors.lastname: Siddiqui
authors.forename: Arul M
authors.initials: AM
authors.lastname: Chinnaiyan
authors.forename: Rohit
authors.initials: R
authors.lastname: Mehra
authors.forename: Ralph W
authors.initials: RW
authors.lastname: Devere White
authors.forename: Kermit L
authors.initials: KL
authors.lastname: Carraway
authors.forename: Paramita M
authors.initials: PM
authors.lastname: Ghosh
mesh_terms: D000728:Androgens / Q000172:deficiency; D000818:Animals; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009376:Neoplasms, Hormone-Dependent / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009919:Orchiectomy; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020893:Receptor, ErbB-3 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D013375:Substance Withdrawal Syndrome / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D015533:Transcriptional Activation; D044767:Ubiquitin-Protein Ligases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
chemical_list: D000728:Androgens; D012333:RNA, Messenger; D011944:Receptors, Androgen; C452580:RNF41 protein, human; D044767:Ubiquitin-Protein Ligases; D020893:Receptor, ErbB-3