• Open Access

Bone morphogenetic protein-6 induces castration resistance in prostate cancer cells through tumor infiltrating macrophages

Authors

  • Geun Taek Lee,

    1. Section of Urologic Oncology and Dean and Betty Gallo Prostate Cancer Center, The Cancer Institute of New Jersey and Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA
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  • Yeon Suk Jung,

    1. Section of Urologic Oncology and Dean and Betty Gallo Prostate Cancer Center, The Cancer Institute of New Jersey and Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA
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  • Yun-Sok Ha,

    1. Section of Urologic Oncology and Dean and Betty Gallo Prostate Cancer Center, The Cancer Institute of New Jersey and Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA
    2. Department of Urology, Chungbuk National University College of Medicine, Cheongju, Korea
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  • Jeong Hyun Kim,

    1. Section of Urologic Oncology and Dean and Betty Gallo Prostate Cancer Center, The Cancer Institute of New Jersey and Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA
    Current affiliation:
    1. Department of Urology, School of Medicine, Kangwon National University, Chuncheon, Korea
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  • Wun-Jae Kim,

    1. Department of Urology, Chungbuk National University College of Medicine, Cheongju, Korea
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  • Isaac Y. Kim

    Corresponding author
    • Section of Urologic Oncology and Dean and Betty Gallo Prostate Cancer Center, The Cancer Institute of New Jersey and Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA
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To whom correspondence should be addressed.

E-mail: kimiy@umdnj.edu

Abstract

Bone morphogenetic protein (BMP) is a pleiotropic growth factor that has been implicated in inflammation and prostate cancer (CaP) progression. We investigated the potential role of BMP-6 in the context of macrophages and castration-resistant prostate cancer. When the androgen-responsive murine (Tramp-C1 and PTENCaP8) and human (LNCaP) CaP cell lines were cocultured with macrophages in the presence of dihydrotestosterone, BMP-6 increased androgen-responsive promoter activity and cell count significantly. Subsequent studies revealed that BMP-6 increased the expression level of androgen receptor (AR) mRNA and protein in CaP cell lines only in the presence of macrophages. Simultaneously, the AR antagonists bicalutamide and MDV3100 partially or completely blocked BMP-6-induced macrophage-mediated androgen hypersensitivity in CaP cells. Abolishing interleukin-6 signaling with neutralizing antibody in CaP/macrophage cocultures inhibited the BMP-6-mediated AR upregulation in CaP cells. Using Tramp-C1 and PTENCaP8 cells with a tetracycline-inducible expression of BMP-6, the induction of BMP-6 in vivo resulted in a significant resistance to castration. However, this resistance was blocked after the removal of macrophages with clodronate liposomes. Taken together, these results show that BMP-6 induces castration resistance by increasing the expression of AR through macrophage-derived interleukin-6.

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