title: ASC-J9 suppresses castration-resistant prostate cancer growth through degradation of full-length and splice variant androgen receptors.
abstract: Early studies suggested androgen receptor (AR) splice variants might contribute to the progression of prostate cancer (PCa) into castration resistance. However, the therapeutic strategy to target these AR splice variants still remains unresolved. Through tissue survey of tumors from the same patients before and after castration resistance, we found that the expression of AR3, a major AR splice variant that lacks the AR ligand-binding domain, was substantially increased after castration resistance development. The currently used antiandrogen, Casodex, showed little growth suppression in CWR22Rv1 cells. Importantly, we found that AR degradation enhancer ASC-J9 could degrade both full-length (fAR) and AR3 in CWR22Rv1 cells as well as in C4-2 and C81 cells with addition of AR3. The consequences of such degradation of both fAR and AR3 might then result in the inhibition of AR transcriptional activity and cell growth in vitro. More importantly, suppression of AR3 specifically by short-hairpin AR3 or degradation of AR3 by ASC-J9 resulted in suppression of AR transcriptional activity and cell growth in CWR22Rv1-fARKD (fAR knockdown) cells in which DHT failed to induce, suggesting the importance of targeting AR3. Finally, we demonstrated the in vivo therapeutic effects of ASC-J9 by showing the inhibition of PCa growth using the xenografted model of CWR22Rv1 cells orthotopically implanted into castrated nude mice with undetectable serum testosterone. These results suggested that targeting both fAR- and AR3-mediated PCa growth by ASC-J9 may represent the novel therapeutic approach to suppress castration-resistant PCa. Successful clinical trials targeting both fAR and AR3 may help us to battle castration-resistant PCa in the future.
authors.affiliation: Department of Pathology, University of Rochester Medical Center, Rochester, NY 14642, USA.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yamashita
authors.forename: Kuo-Pao
authors.initials: KP
authors.lastname: Lai
authors.forename: Kun-Lung
authors.initials: KL
authors.lastname: Chuang
authors.forename: Defeng
authors.initials: D
authors.lastname: Xu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyamoto
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Tochigi
authors.forename: See-Tong
authors.initials: ST
authors.lastname: Pang
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Arai
authors.forename: Hsing-Jien
authors.initials: HJ
authors.lastname: Kung
authors.forename: Shuyuan
authors.initials: S
authors.lastname: Yeh
authors.forename: Chawnshang
authors.initials: C
authors.lastname: Chang
mesh_terms: D000726:Androgen Antagonists / Q000494:pharmacology; D000813:Anilides / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D002369:Castration; D045744:Cell Line, Tumor; D003474:Curcumin / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009570:Nitriles / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D011944:Receptors, Androgen / Q000235:genetics* / Q000378:metabolism; D014105:Tosyl Compounds / Q000494:pharmacology
chemical_list: D000726:Androgen Antagonists; D000813:Anilides; D000970:Antineoplastic Agents; D003474:Curcumin; D009570:Nitriles; D020033:Protein Isoforms; D011944:Receptors, Androgen; D014105:Tosyl Compounds; C471106:ASC-J9 compound; C053541:bicalutamide