Targeting FOXA1-mediated repression of TGF-β signaling suppresses castration-resistant prostate cancer progression
Bing Song, … , Ximing Yang, Jindan Yu
Bing Song, … , Ximing Yang, Jindan Yu
Published December 4, 2018
Citation Information: J Clin Invest. 2019;129(2):569-582. https://doi.org/10.1172/JCI122367.
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Research Article Genetics Oncology

Targeting FOXA1-mediated repression of TGF-β signaling suppresses castration-resistant prostate cancer progression

Abstract

Prostate cancer (PC) progressed to castration resistance (CRPC) is a fatal disease. CRPC tumors develop resistance to new-generation antiandrogen enzalutamide through lineage plasticity, characterized by epithelial-mesenchymal transition (EMT) and a basal-like phenotype. FOXA1 is a transcription factor essential for epithelial lineage differentiation. Here, we demonstrate that FOXA1 loss leads to remarkable upregulation of transforming growth factor beta 3 (TGFB3), which encodes a ligand of the TGF-β pathway. Mechanistically, this is due to genomic occupancy of FOXA1 on an upstream enhancer of the TGFB3 gene to directly inhibit its transcription. Functionally, FOXA1 downregulation induces TGF-β signaling, EMT, and cell motility, which is effectively blocked by the TGF-β receptor I inhibitor galunisertib (LY2157299). Tissue microarray analysis confirmed reduced levels of FOXA1 protein and a concordant increase in TGF-β signaling, indicated by SMAD2 phosphorylation, in CRPC as compared with primary tumors. Importantly, combinatorial LY2157299 treatment sensitized PC cells to enzalutamide, leading to synergistic effects in inhibiting cell invasion in vitro and xenograft CRPC tumor growth and metastasis in vivo. Therefore, our study establishes FOXA1 as an important regulator of lineage plasticity mediated in part by TGF-β signaling, and supports a novel therapeutic strategy to control lineage switching and potentially extend clinical response to antiandrogen therapies.

Authors

Bing Song, Su-Hong Park, Jonathan C. Zhao, Ka-wing Fong, Shangze Li, Yongik Lee, Yeqing A. Yang, Subhasree Sridhar, Xiaodong Lu, Sarki A. Abdulkadir, Robert L. Vessella, Colm Morrissey, Timothy M. Kuzel, William Catalona, Ximing Yang, Jindan Yu

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Figure 3

FOXA1 loss activates TGF-β signaling in PC cells.

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FOXA1 loss activates TGF-β signaling in PC cells. (A and B) LNCaP-Ctrl, ...
(A and B) LNCaP-Ctrl, LNCaP-RII, and VCaP cell lines were treated with DMSO or 5 ng/ml TGF-β1 ligand for 4 days, with or without subsequent 10 μM LY2157299 treatment for 1 day. Cells were then collected and analyzed by Western blotting. (B and C) Conditioned medium (CM) from FOXA1-knockdown cells induces TGF-β signaling. Conditioned media were collected from stable shCtr and shFOXA1 LNCaP-RII (B) or VCaP (C) cells and added to their corresponding parental cell line for 3 days for Western blot analysis (left panels). Conditioned media were also added to LNCaP-RII or VCaP cells, which had been transfected with a SBE-luciferase reporter construct for 2 days and then harvested for luciferase assay (right panels). RLA: relative luciferase activity; n = 3; *P < 0.05. (D) Heatmap showing the expression TGF-β pathway genes in control and FOXA1-knockdown LNCaP cells as profiled by RNA-seq. (E) TGFBR2 gene expressions are upregulated upon FOXA1 knockdown. LNCaP, VCaP, and C4-2B cells were infected with shCtr or shFOXA1-knockdown lentivirus followed by puromycin selection, and then analyzed by qRT-PCR (n = 3, *P < 0.05). (F and G) GSEA and heatmaps showing the enriched expression of a TGF-β3–induced gene signature in FOXA1-knockdown cells (F), which were rescued by 10 μM LY2157299 treatment (G).