Treatment sensitivities of hormone-sensitive and hormone-resistant (HR) prostate cancer. (a) Prostate cancer (hormone-sensitive (HS) and the corresponding castration-resistant prostate cancer (CRPC)) cells were treated with ADT (10 μM enzalutamide for 3 days before irradiation) and irradiation with 0 or 4 Gy, and survival fractions were constructed using colony-forming assay data 10 days after treatment. (b) The in vitro effects of treatment-induced apoptosis as evaluated by FACS with Annexin V-PI staining. The y axis represents the ratio normalized by the value of TRAMP-HR under control conditions. (c) DNA damage as evaluated by immunofluorescence staining with p-H2AX. The y axis represents the ratio normalized by the value of HS cells with irradiation. Scale bars: 50 μm. (d) The effect of ADT on the radiosensitivity of prostate cancer (LNCaP, TRAMP-C1, and the corresponding CRPC cells), as demonstrated by tumor growth delay of the ectopic tumor after 15 Gy irradiation, and representative images 12 days after 15 Gy irradiation with or without ADT. The y axis shows the tumor volume ratio at each time point, divided by the tumor volume at irradiation. Data represent the means of experiments (three animals in one experiment, performed three times independently), * p < 0.05.