5-AED enhances survival of irradiated mice in a G-CSF-dependent manner, stimulates innate immune cell function, reduces radiation-induced DNA damage and induces genes that modulate cell cycle progression and apoptosis

Radiation Countermeasures Program, Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, 8901 Wisconsin Ave, Bethesda, MD 20889-5603, USA.
Journal of Radiation Research (Impact Factor: 1.8). 07/2012; 53(6). DOI: 10.1093/jrr/rrs060
Source: PubMed


The steroid androst-5-ene-3ß,17ß-diol (5-androstenediol, 5-AED) elevates circulating granulocytes and platelets in animals and humans, and enhances survival during the acute radiation syndrome (ARS) in mice and non-human primates. 5-AED promotes survival of irradiated human hematopoietic progenitors in vitro through induction of Nuclear Factor-κB (NFκB)-dependent Granulocyte Colony-Stimulating Factor (G-CSF) expression, and causes elevations of circulating G-CSF and interleukin-6 (IL-6). However, the in vivo cellular and molecular effects of 5-AED are not well understood. The aim of this study was to investigate the mechanisms of action of 5-AED administered subcutaneously (s.c.) to mice 24 h before total body γ- or X-irradiation (TBI). We used neutralizing antibodies, flow cytometric functional assays of circulating innate immune cells, analysis of expression of genes related to cell cycle progression, DNA repair and apoptosis, and assessment of DNA strand breaks with halo-comet assays. Neutralization experiments indicated endogenous G-CSF but not IL-6 was involved in survival enhancement by 5-AED. In keeping with known effects of G-CSF on the innate immune system, s.c. 5-AED stimulated phagocytosis in circulating granulocytes and oxidative burst in monocytes. 5-AED induced expression of both bax and bcl-2 in irradiated animals. Cdkn1a and ddb1, but not gadd45a expression, were upregulated by 5-AED in irradiated mice. S.c. 5-AED administration caused decreased DNA strand breaks in splenocytes from irradiated mice. Our results suggest 5-AED survival enhancement is G-CSF-dependent, and that it stimulates innate immune cell function and reduces radiation-induced DNA damage via induction of genes that modulate cell cycle progression and apoptosis.

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Available from: Vijay K Singh, Feb 25, 2015
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    • "We also have reported that radiation exposure induces elevation of circulating G-CSF and that administering a neutralizing antibody to G-CSF exacerbates the deleterious effects of radiation exposure, suggesting that G-CSF induced in response to irradiation plays an important protective role in recovery (Singh et al., 2012d). Recently, we have demonstrated that the use of the G-CSF antibody abrogates the radioprotective efficacy of few radiation countermeasures (Singh et al., 2010; Kulkarni et al., 2013; Krivokrysenko et al., 2012; Grace et al., 2012). Our current study demonstrates that DT3 is a potent stimulator of several cytokines including G-CSF, and that the radioprotective efficacy of DT3 is mediated through G-CSF. "
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    • "Genistein administration stimulated serum granulocyte-colony stimulating factor (G-CSF) after sham irradiation or gamma-irradiation [32]. Recent study showed the radioprotective effect of some agents is mediated the through G-CSF induction [33,34]. Further previous our study also showed that G-CSF attenuated intestinal damage after radiation exposure [7]. "
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