Induction of radioresistant tumor xenograft in nude mice

Accordance to the established research protocol, a certain dose of radiation was used to repeatedly irradiate the tumor xenograft from nude mice with MDA-M-231 to induce radioresistant tumor xenografts, which were preserved for further experiments. This procedure was based on our clinical observations and experiences. First, only radioresistant tumor xenografts that had survived after high-dose irradiation (i.e., tumor tissues that could continue to be transplanted into nude mice and formed tumors) were used in this experiment. Second, in the later period of X-ray induction, the re-tumorigenesis and growth of the tumor xenografts dramatically slowed down after repeated irradiation (compared with the control). The mice experiment protocol was approved by the Animal Ethics Committee of Shanghai Medical College of Fudan University. During the experiments, all the animals were handled according to the AAALAC requirements.