Heat shock protein 70 inhibitors suppress androgen receptor expression in LNCaP95 prostate cancer cells

Kazuaki Kita, Masayuki Shiota*, Masako Tanaka, Asuka Otsuka, Masaki Matsumoto, Minoru Kato, Satoshi Tamada, Hiroshi Iwao, Katsuyuki Miura, Tatsuya Nakatani, Shuhei Tomita

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

Androgen deprivation therapy is initially effective for treating patients with advanced prostate cancer; however, the prostate cancer gradually becomes resistant to androgen deprivation therapy, which is termed castration-resistant prostate cancer (CRPC). Androgen receptor splice variant 7 (AR-V7), one of the causes of CRPC, is correlated with resistance to a new-generation AR antagonist (enzalutamide) and poor prognosis. Heat shock protein 70 (Hsp70) inhibitor is known to decrease the levels of full-length AR (AR-FL), but little is known about its effects against CRPC cells expressing AR-V7. In this study, we investigated the effect of the Hsp70 inhibitors quercetin and VER155008 in the prostate cancer cell line LNCaP95 that expresses AR-V7, and explored the mechanism by which Hsp70 regulates AR-FL and AR-V7 expression. Quercetin and VER155008 decreased cell proliferation, increased the proportion of apoptotic cells, and decreased the protein levels of AR-FL and AR-V7. Furthermore, VER155008 decreased AR-FL and AR-V7 mRNA levels. Immunoprecipitation with Hsp70 antibody and mass spectrometry identified Y-box binding protein 1 (YB-1) as one of the molecules regulating AR-FL and AR-V7 at the transcription level through interaction with Hsp70. VER155008 decreased the phosphorylation of YB-1 and its localization in the nucleus, indicating that the involvement of Hsp70 in AR regulation might be mediated through the activation and nuclear translocation of YB-1. Collectively, these results suggest that Hsp70 inhibitors have potential anti-tumor activity against CRPC by decreasing AR-FL and AR-V7 expression through YB-1 suppression.

Original languageEnglish
Pages (from-to)1820-1827
Number of pages8
JournalCancer Science
Volume108
Issue number9
DOIs
Publication statusPublished - 2017 Sep
Externally publishedYes

Keywords

  • Androgen receptor splice variant 7
  • Y-box binding protein 1
  • castration-resistant prostate cancer
  • heat shock protein 70
  • heat shock protein 70 inhibitor

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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