Animal models and drug administration
Male BALB/c nude mice (6-8 week-old) were provided by Jiangsu Gempharmatech co. Ltd. (Nanjing, China). The mice were kept under pathogen-free conditions in type IV Makrolon cages (6 mice per cage) in an air flow cabinet at 23°C, 12 h/12 h day/night cycle. Sterilized food and sterilized acidified water have been provided to the animals regularly. 1×106 LNCaP and PC3/AR+cells were injected subcutaneously into the right flank. After 6 days of injection, all mice formed tumors and the day was marked as day 0. Vehicle (0.05% DMSO in PBS), 10 and 30 µg/kg SBF-1 were intraperitoneally injected to every group respectively every day since day 0 for 45 days. At the same time, body weights and tumor volumes were measured. For tumor growth assay, mice were euthanized 14 days after drug treatment, and the weight of tumor was measured. Animal welfare and experimental procedures were carried out in accordance with the Guide for the Care and Use of Laboratory Animals (Ministry of Science and Technology of China, 2006) and the related ethical regulations of Nanjing University. All efforts were made to minimize animals’ suffering and to reduce the number of animals used.