Two Strategies for the Development of Mitochondrion-Targeted Small Molecule Radiation Damage Mitigators

Abstract

Purpose-To evaluate the effectiveness of mitigation of acute ionizing radiation damage by mitochondria-targeted small molecules.Materials and Methods-We evaluated the nitroxide-linked alkene peptide isostere JP4-039, the nitric oxide synthase inhibitor-linked alkene peptide esostere MCF201-89, and the p53/mdm2/ mdm4 inhibitor BEB55 in radiation mitigation by clonogenic survival curves with the murine hematopoietic progenitor cell line 32D cl 3, human bone marrow stromal (KM101) and pulmonary epithelial (IB3) cell line. The p53 dependent mechanism of action was tested with p53 +/+ and p53 −/− murine bone marrow stromal cell lines. C57BL/6 NHsd female mice were injected I.P. after 9.5 Gy total body irradiation (TBI) with JP4-039, MCF201-89, or BEB55 individually or in combination.Results-Each drug, JP4-039, MCF201-89, or BEB55, individually or as a mixture of all 3 compounds, increased the survival of 32D cl 3 cells and IB3 cells significantly over control irradiated cells (p=0.0021, p=0.0011, p=0.0038, and p=0.0073, respectively), and (p=0.0193, p=0.0452, p=0.0017, and p=0.0019 respectively). KM101 cells were protected by individual drugs (p=0.0007, p=0.0235, p=0.0044, respectively). JP4-039 and MCF201-89 increased irradiation survival of both p53+/+ (p=0.0396 and p=0.0071, respectively) and p53−/− cells (p=0.0007 and p=0.0188 respectively), while BEB55 was ineffective with (p53−/−) cells. Drugs administered individually or as a mixtures of all 3 after TBI significantly increased mouse survival (p=0.0234, 0.0009, 0.0052 and 0.0167 respectively).Corresponding Author: Joel S. Greenberger M.D., Department of Radiation Oncology, University of Pittsburgh Cancer Institute, 5150 Centre Avenue, Rm. 533, Pittsburgh, PA 15232, Tel: 412-647-3602, Fax: 412-647-1161, greenbergerjs@upmc

Pharmacologic Profiling of Phosphoinositide 3-Kinase Inhibitors as Mitigators of Ionizing Radiation–Induced Cell Death

“…The in vivo mitigation assays were performed as previously described elsewhere (Rwigema et al, 2011;Zellefrow et al, 2012). C57BL/6NTac female mice (15 mice/treatment group) were irradiated to 9.25 Gy and injected i.p.…”

Identification of Druggable Targets for Radiation Mitigation Using a Small Interfering RNA Screening Assay

“…Colony formation was determined as previously described (2, 8, 12). Briefly, 32D cl 3 cells (5 × 10 5 cells/ml) were exposed to 0–8 Gy using a Shepard Mark I model 68 cesium irradiator (dose rate 75 cGy/min) and 1 h later vehicle or test compound was added to the Interleukin 3-supplemented semisolid methycellulose-containing medium in which cells were incubated for 7 days at which time colonies >50 cells were counted.…”

“…Cells were incubated at 37°C for 5 days, at which time the cells were stained with crystal violet and colonies of >50 cells were counted. The data for all cell types were fitted using linear quadratic and single-hit, multitarget models as previously described (2, 8, 12). …”

“…For irradiation mitigation experiments, cells were irradiated, plated in methylcellulose medium containing LY294002 (0–10 µ M ) and incubated at 37°C for 7 days. Colonies of >50 cells were counted and the data were analyzed using linear quadratic and single-hit, multitarget models (2, 8, 12). …”

Are We Ready for a Radiological Terrorist Attack Yet? Report From the Centers for Medical Countermeasures Against Radiation Network

“…Unbiased high throughput screening of chemical- or RNA-based libraries, as well as targeted exploration of defined agents and cells (5), have identified novel mitigators. For example, mitochondrion-targeted agents, such as the GS-nitroxide, JP4-039, effectively mitigate hematopoietic ARS at >24 hours post-radiation (6). Interestingly, many newly identified mitigators counter the pro-inflammatory effects of radiation, and the link between radiation-induced cytokines and the vascular system suggests possible avenues of research, including the autologous transfer of endothelial progenitor cells (7).…”