Cotargeting Androgen Receptor and Clusterin Delays Castrate-Resistant Prostate Cancer Progression by Inhibiting Adaptive Stress Response and AR Stability.

Abstract

Although androgen receptor (AR) pathway inhibitors prolong survival in castrate-resistant prostate cancer (CRPC), resistance rapidly develops and is often associated with increased stress-activated molecular chaperones like clusterin (CLU) and continued AR signaling. Because adaptive pathways activated by treatment facilitate development of acquired resistance, cotargeting the stress response, activated by AR inhibition and mediated through CLU, may create conditional lethality and improve outcomes. Here, we report that CLU is induced by AR antagonism and silencing using MDV3100 and antisense, respectively, to become highly expressed in castrate- and MDV3100-resistant tumors and cell lines. CLU, as well as AKT and mitogen-activated protein kinase (MAPK) signalosomes, increase in response to MDV3100-induced stress. Mechanistically, this stress response is coordinated by a feed-forward loop involving p90rsk (RPS6KA)-mediated phosphoactivation of YB-1 with subsequent induction of CLU. CLU inhibition repressed MDV3100-induced activation of AKT and MAPK pathways. In addition, when combined with MDV3100, CLU knockdown accelerated AR degradation and repressed AR transcriptional activity through mechanisms involving decreased YB-1-regulated expression of the AR cochaperone, FKBP52. Cotargeting the AR (with MDV3100) and CLU (with OGX-011) synergistically enhanced apoptotic rates over that seen with MDV3100 or OGX-011 monotherapy and delayed CRPC LNCaP tumor and prostate-specific antigen (PSA) progression in vivo. These data indicate that cotargeting adaptive stress pathways activated by AR pathway inhibitors, and mediated through CLU, creates conditional lethality and provides mechanistic and preclinical proof-of-principle to guide biologically rational combinatorial clinical trial design.

• Authors: Hiroaki Matsumoto, Yoshiaki Yamamoto, Masaki Shiota, Hidetoshi Kuruma, Eliana Beraldi, Hideyasu Matsuyama, Amina Zoubeidi, Martin Gleave
• Journal: Cancer research (Cancer Res) Vol. 73 Issue 16 Pg. 5206-17 (Aug 15 2013) ISSN: 1538-7445 [Electronic] United States
• PMID: 23786771 (Publication Type: Journal Article)

Chemical References

• AR protein, human
• Benzamides
• Clusterin
• Molecular Chaperones
• Nitriles
• OGX-011
• Receptors, Androgen
• Thionucleotides
• Phenylthiohydantoin
• enzalutamide
• Proto-Oncogene Proteins c-akt
• Mitogen-Activated Protein Kinases
• Prostate-Specific Antigen
• Proteasome Endopeptidase Complex
• Tacrolimus Binding Proteins
• tacrolimus binding protein 4

Topics

• Animals
• Apoptosis (drug effects, genetics)
• Benzamides
• Castration (methods)
• Cell Line, Tumor
• Clusterin (genetics, metabolism)
• Disease Progression
• Gene Expression Regulation, Neoplastic (drug effects, genetics)
• Gene Silencing (drug effects)
• Humans
• Male
• Mice
• Mice, Nude
• Mitogen-Activated Protein Kinases (genetics, metabolism)
• Molecular Chaperones (genetics, metabolism)
• Nitriles
• Phenylthiohydantoin (analogs & derivatives, pharmacology)
• Prostate-Specific Antigen (genetics, metabolism)
• Prostatic Neoplasms, Castration-Resistant (drug therapy, genetics, metabolism, pathology)
• Proteasome Endopeptidase Complex (genetics, metabolism)
• Proto-Oncogene Proteins c-akt (genetics, metabolism)
• Receptors, Androgen (genetics, metabolism)
• Signal Transduction (drug effects, genetics)
• Stress, Physiological (drug effects, genetics)
• Tacrolimus Binding Proteins (genetics, metabolism)
• Thionucleotides (pharmacology)
• Transcription, Genetic (drug effects, genetics)