A Mitochondria-Targeted Nitroxide/Hemigramicidin S Conjugate Protects Mouse Embryonic Cells Against Gamma Irradiation

Journal Article · Sat Mar 01 04:00:00 EST 2008 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2007.10.047· OSTI ID:21039796

Jianfei, Jiang; Belikova, Natalia A ^[1]; Hoye, Adam T ^[1]; Qing, Zhao ^[1]; Epperly, Michael W; Greenberger, Joel S ^[1]; Wipf, Peter ^[1]; Kagan, Valerian E ^[1]

---

1. Center for Medical Countermeasures Against Radiation, University of Pittsburgh, Pittsburgh, PA (United States)

Purpose: To evaluate the in vitro radioprotective effect of the mitochondria-targeted hemigramicidin S-conjugated 4-amino-2,2,6,6-tetramethyl-piperidine-N-oxyl (hemi-GS-TEMPO) 5-125 in {gamma}-irradiated mouse embryonic cells and adenovirus-12 SV40 hybrid virus transformed human bronchial epithelial cells BEAS-2B and explore the mechanisms involved in its radioprotective effect. Methods and Materials: Cells were incubated with 5-125 before (10 minutes) or after (1 hour) {gamma}-irradiation. Superoxide generation was determined by using dihydroethidium assay, and lipid oxidation was quantitated by using a fluorescence high-performance liquid chromatography-based Amplex Red assay. Apoptosis was characterized by evaluating the accumulation of cytochrome c in the cytosol and externalization of phosphatidylserine on the cell surface. Cell survival was measured by means of a clonogenic assay. Results: Treatment (before and after irradiation) of cells with 5-125 at low concentrations (5, 10, and 20 {mu}M) effectively suppressed {gamma}-irradiation-induced superoxide generation, cardiolipin oxidation, and delayed irradiation-induced apoptosis, evaluated by using cytochrome c release and phosphatidylserine externalization. Importantly, treatment with 5-125 increased the clonogenic survival rate of {gamma}-irradiated cells. In addition, 5-125 enhanced and prolonged {gamma}-irradiation-induced G{sub 2}/M phase arrest. Conclusions: Radioprotection/mitigation by hemi-GS-TEMPO likely is caused by its ability to act as an electron scavenger and prevent superoxide generation, attenuate cardiolipin oxidation in mitochondria, and hence prevent the release of proapoptotic factors from mitochondria. Other mechanisms, including cell-cycle arrest at the G{sub 2}/M phase, may contribute to the protection.

• OSTI ID: 21039796
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 3 Vol. 70; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
ADENOVIRUS
APOPTOSIS
BUILDUP
CARDIOLIPIN
CELL CYCLE
EMBRYONIC CELLS
FLUORESCENCE
GAMMA RADIATION
HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY
IN VITRO
INDIUM 125
IRRADIATION
MICE
MITOCHONDRIA
OXIDATION
PIPERIDINES