Galbanic acid decreases androgen receptor abundance and signaling and induces G 1 arrest in prostate cancer cells

Yong Zhang, Kwan Hyun Kim, Wei Zhang, Yinglu Guo, Sung Hoon Kim, Junxuan Lü

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

Androgen receptor (AR) signaling is crucial for the genesis and progression of prostate cancer (PCa). We compared the growth responses of AR(+) LNCaP and LNCaP C4-2 vs. AR(-) DU145 and PC-3 PCa cell lines to galbanic acid (GBA) isolated from the resin of medicinal herb Ferula assafoetida and assessed their connection to AR signaling and cell cycle regulatory pathways. Our results showed that GBA preferentially suppressed AR(+) PCa cell growth than AR(-) PCa cells. GBA induced a caspase-mediated apoptosis that was attenuated by a general caspase inhibitor. Subapoptotic GBA downregulated AR protein in LNCaP cells primarily through promoting its proteasomal degradation, and inhibited AR-dependent transcription without affecting AR nuclear translocation. Whereas docking simulations predicted binding of GBA to the AR ligand binding domain with similarities and differences with the AR antagonist drug bicalutamide (Bic), LNCaP cell culture assays did not detect agonist activity of GBA. GBA and Bic exerted greater than additive inhibitory effect on cell growth when used together. Subapoptotic GBA induced G 1 arrest associated with an inhibition of cyclin/CDK4/6 pathway, especially cyclin D 1 without the causal involvement of cyclin-dependent kinase (CDK) inhibitory proteins P21 Cip1 and P27 Kip1. In summary, the novelty of GBA as an anti-AR compound resides in the distinction between GBA and Bic with respect to AR protein turnover and a lack of agonist effect. Our observations of anti-AR and cell cycle arrest actions plus the anti-angiogenesis effect reported elsewhere suggest GBA as a multitargeting drug candidate for the prevention and therapy of PCa.

Original languageEnglish (US)
Pages (from-to)200-212
Number of pages13
JournalInternational Journal of Cancer
Volume130
Issue number1
DOIs
StatePublished - Jan 11 2012

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All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

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