title: siRNA Lipid Nanoparticle Potently Silences Clusterin and Delays Progression When Combined with Androgen Receptor Cotargeting in Enzalutamide-Resistant Prostate Cancer.
abstract: OBJECTIVE
  Lipid nanoparticle (LNP) formulations facilitate tumor uptake and intracellular processing through an enhanced permeation and retention effect (EPR), and currently multiple products are undergoing clinical evaluation. Clusterin (CLU) is a cytoprotective chaperone induced by androgen receptor (AR) pathway inhibition to facilitate adaptive survival pathway signaling and treatment resistance. In our study, we investigated the efficacy of siRNA tumor delivery using LNP systems in an enzalutamide-resistant (ENZ-R) castration-resistant prostate cancer (CRPC) model.
  
  
  METHODS
  Gene silencing of a luciferase reporter gene in the PC-3M-luc stable cell line was first assessed in subcutaneous and metastatic PC-3 xenograft tumors. Upon validation, the effect of LNP siRNA targeting CLU in combination with AR antisense oligonucleotides (ASO) was assessed in ENZ-R CRPC LNCaP in vitro and in vivo models.
  
  
  RESULTS
  LNP LUC-siRNA silenced luciferase expression in PC-3M-luc subcutaneous xenograft and metastatic models. LNP CLU-siRNA potently suppressed CLU and AR ASO-induced CLU and AKT and ERK phosphorylation in ENZ-R LNCaP cells in vitro, more potently inhibiting ENZ-R cell growth rates and increased apoptosis when compared with AR-ASO monotherapy. In subcutaneous ENZ-R LNCaP xenografts, combinatory treatment of LNP CLU-siRNA plus AR-ASO significantly suppressed tumor growth and serum PSA levels compared with LNP LUC-siRNA (control) and AR-ASO.
  
  
  CONCLUSIONS
  LNP siRNA can silence target genes in vivo and enable inhibition of traditionally non-druggable genes like CLU and other promising cotargeting approaches in ENZ-R CRPC therapeutics.
authors.affiliation: The Vancouver Prostate Centre and Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada. Department of Urology, Graduate School of Medicine, Yamaguchi University, Ube, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Paulo J C
authors.initials: PJ
authors.lastname: Lin
authors.affiliation: The Vancouver Prostate Centre and Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Eliana
authors.initials: E
authors.lastname: Beraldi
authors.affiliation: The Vancouver Prostate Centre and Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.affiliation: The Vancouver Prostate Centre and Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada. Department of Urology, Graduate School of Medicine, Yamaguchi University, Ube, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Kawai
authors.affiliation: The Vancouver Prostate Centre and Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Leong
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Katsumi
authors.affiliation: The Vancouver Prostate Centre and Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Ladan
authors.initials: L
authors.lastname: Fazli
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Fraser
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Pieter R
authors.initials: PR
authors.lastname: Cullis
authors.affiliation: The Vancouver Prostate Centre and Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada. m.gleave@ubc.ca.
authors.forename: Martin
authors.initials: M
authors.lastname: Gleave
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics; D001549:Benzamides; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D051152:Clusterin / Q000235:genetics*; D004195:Disease Models, Animal; D018450:Disease Progression; D019008:Drug Resistance, Neoplasm; D015870:Gene Expression; D020868:Gene Silencing; D017930:Genes, Reporter; D006801:Humans; D008055:Lipids; D008297:Male; D051379:Mice; D057054:Molecular Imaging / Q000379:methods; D053758:Nanoparticles; D009362:Neoplasm Metastasis; D009570:Nitriles; D016376:Oligonucleotides, Antisense / Q000235:genetics; D010669:Phenylthiohydantoin / Q000031:analogs & derivatives / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000473:pathology*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000235:genetics / Q000473:pathology; D034741:RNA, Small Interfering / Q000235:genetics*; D011944:Receptors, Androgen / Q000235:genetics*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D051152:Clusterin; D008055:Lipids; D009570:Nitriles; D016376:Oligonucleotides, Antisense; D034741:RNA, Small Interfering; D011944:Receptors, Androgen; D010669:Phenylthiohydantoin; C540278:enzalutamide