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Hedayati M, Haffner MC, Coulter JB, Raval RR, Zhang Y, Zhou H, Mian O, Knight EJ, Razavi N, Dalrymple S, Isaacs JT, Santos A, Hales R, Nelson WG, Yegnasubramanian S, DeWeese TL. Androgen Deprivation Followed by Acute Androgen Stimulation Selectively Sensitizes AR-Positive Prostate Cancer Cells to Ionizing Radiation. Clin Cancer Res 2016; 22:3310-3319. [PMID: 26831716 DOI: 10.1158/1078-0432.ccr-15-1147] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 01/10/2016] [Indexed: 11/16/2022]
Abstract
PURPOSE The current standard of care for patients with locally advanced prostate cancer is a combination of androgen deprivation and radiation therapy. Radiation is typically given with androgen suppression when testosterone levels are at their nadir. Recent reports have shown that androgen stimulation of androgen-deprived prostate cancer cells leads to formation of double-strand breaks (DSB). Here, we exploit this finding and investigate the extent and timing of androgen-induced DSBs and their effect on tumor growth following androgen stimulation in combination with ionizing radiation (IR). EXPERIMENTAL DESIGN Androgen-induced DNA damage was assessed by comet assays and γH2A.X foci formation. Effects of androgen stimulation and radiation were determined in vitro and in vivo with xenograft models. RESULTS We document that androgen treatment of androgen-deprived prostate cancer cell lines resulted in a dose- and time-dependent induction of widespread DSBs. Generation of these breaks was dependent on androgen receptor and topoisomerase II beta but not on cell-cycle progression. In vitro models demonstrated a synergistic interaction between IR and androgen stimulation when IR is given at a time point corresponding with high levels of androgen-induced DSB formation. Furthermore, in vivo studies showed a significant improvement in tumor growth delay when radiation was given shortly after androgen repletion in castrated mice. CONCLUSIONS These results suggest a potential cooperative effect and improved tumor growth delay with androgen-induced DSBs and radiation with implications for improving the therapeutic index of prostate cancer radiation therapy. Clin Cancer Res; 22(13); 3310-9. ©2016 AACRSee related commentary by Chua and Bristow, p. 3124.
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Affiliation(s)
- Mohammad Hedayati
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Michael C Haffner
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jonathan B Coulter
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Raju R Raval
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Yonggang Zhang
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Haoming Zhou
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Omar Mian
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Emma J Knight
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Nina Razavi
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Susan Dalrymple
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - John T Isaacs
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Aileen Santos
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Russell Hales
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - William G Nelson
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD.,Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Srinivasan Yegnasubramanian
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Theodore L DeWeese
- Department of Radiation Oncology and Molecular Radiation Sciences, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD.,Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine, Baltimore, MD
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