TGF-β receptor I inhibitor enhances response to enzalutamide in a pre-clinical model of advanced prostate cancer

Channing Paller, Hong Pu, Diane E. Begemann, Cameron A. Wade, Patrick J. Hensley, Natasha Kyprianou

Research output: Contribution to journalArticle

Abstract

Background: Prostate cancer progression is navigated by the androgen receptor (AR) and transforming-growth factor-β (TGF-β) signaling. We previously demonstrated that aberrant TGF-β signaling accelerates prostate tumor progression in a transgenic mouse model of prostate cancer via effects on epithelial-mesenchymal transition (EMT), driving castration-resistant prostate cancer (CRPC). Methods: This study examined the antitumor effect of the combination of TGF-β receptor I (TβRI) inhibitor, galunisertib, and FDA-approved antiandrogen enzalutamide, in our pre-clinical model. Age-matched genotypically characterized DNTGFβRII male mice were treated with either galunisertib and enzalutamide, in combination or as single agents in three “mini”-trials and the effects on tumor growth, phenotypic EMT, and actin cytoskeleton were evaluated. Results: Galunisertib in combination with enzalutamide significantly suppressed prostate tumor growth, by increasing apoptosis and decreasing cell proliferation of tumor cell populations compared to the inhibitor as a monotherapy (P < 0.05). The combination treatment dramatically reduced cofilin levels, actin cytoskeleton regulator, compared to single agents. Treatment with galunisertib targeted nuclear Smad4 protein (intracellular TGF-β effector), but had no effect on nuclear AR. Consequential to TGF-β inhibition there was an EMT reversion to mesenchymal-epithelial transition (MET) and re-differentiation of prostate tumors. Elevated intratumoral TGF-β1 ligand, in response to galunisertib, was blocked by enzalutamide. Conclusion: Our results provide novel insights into the therapeutic value of targeting TGF-β signaling to overcome resistance to enzalutamide in prostate cancer by phenotypic reprogramming of EMT towards tumor re-differentiation and cytoskeleton remodeling. This translational work is significant in sequencing TGF-β blockade and antiandrogens to optimize therapeutic response in CRPC.

Original languageEnglish (US)
Pages (from-to)31-43
Number of pages13
JournalProstate
Volume79
Issue number1
DOIs
StatePublished - Jan 1 2019

Keywords

  • EMT
  • TGF-β inhibition strong
  • enzalutamide
  • therapeutic response

ASJC Scopus subject areas

  • Oncology
  • Urology

Fingerprint Dive into the research topics of 'TGF-β receptor I inhibitor enhances response to enzalutamide in a pre-clinical model of advanced prostate cancer'. Together they form a unique fingerprint.

  • Cite this