Sensitization of Radioresistant Prostate Cancer Cells by Resveratrol Isolated from Arachis hypogaea Stems

Resveratrol (RV, 3,4ʹ,5-trihydroxystilbene) is naturally produced by a wide variety of plants including grapes and peanuts (Arachis hypogaea). However, the yield of RV from peanut stem and its potential radiosensitizing effects in prostate cancer (PCa) have not been well investigated. In this study, we characterized RV in peanut stem extract (PSE) for the first time and showed that both RV and PSE dose-dependently induced cell death in DOC-2/DAB2 interactive protein (DAB2IP)-deficient PCa cells with the radioresistant phenotype. Furthermore, the combination of radiation with either RV or PSE induced the death of radioresistant PCa cells through delayed repair of radiation-induced DNA double-strand break (DSB) and prolonged G2/M arrest, which induced apoptosis. The administration of RV and PSE effectively enhanced radiation therapy in the shDAB2IP PCa xenograft mouse model. These results demonstrate the promising synergistic effect of RV and PSE combined with radiation in the treatment of radioresistant PCa.