TAS::75 0849::TAS

No satisfactory medical interventions for radiation enteritis are available yet. We have demonstrated that polyamine inhibition by a-difluoromethylornithine orDFMO, a selective and irreversible inhibitor of ornithine decarboxylase (ODC, the primary rate-limiting enzyme in the production of polyamines) significantly protects the gastrointestinal (GI) tract from whole-body radiation exposure. Here we propose to further develop it into a highly efficient radioprotector/radiomitigator for indications (1) radiotherapy associated enteritis and (2) GI injury due to nuclear accidents or incidents. Aim #1. Evaluate the radioprotecting/mitigating effect of DFMO on GI injury Aim #2. Evaluate the effect of DFMO on cancer radiosensitivity Methods: (1) For efficacy studies under Aim #1, we will use a mouse model of abdomen-pelvis irradiation. Morphological evaluations include crypt survival and crypt-villus recovery. Intestinal barrier integrity will be evaluated by measuring plasma citrulline and serum endotxoin levels. (2) Under Aim #2, we will first evaluate the effect of DFMO on cancer growth and radiosensitivity in HCT116 and HT29 cell lines, and then move to mouse models of colon cancer and simulate abdomen-pelvis radiotherapy. Methods involved are cell culture, invitro clonogenic assay of tumor cell growth, Xenograft implantation of HCT116 cells and HT29 cells and measuring tumor volume Relevance to public health: The concept proposed in this project, if proved, will lead to a full-scale development program to advance DFMO into a highly efficient drug for managing radiation enteritis in cancer patients as well as GI injury due to unintended radiation exposure.