title: Oxidative stress due to radiation in CD34(+) hematopoietic progenitor cells: protection by IGF-1.
abstract: Radiation exerts direct as well as indirect effects on DNA through the generation of reactive oxygen species (ROS). Irradiated hematopoietic progenitor cells (HPCs) experience DNA strand breaks, favoring genetic instability, due to ROS generation. Our aim was to study the effect of a range of radiation doses in HPCs and the possible protective mechanisms activated by insulin-like growth factor-1 (IGF-1). ROS generation was evaluated, in the presence or absence of IGF-1 in liquid cultures of human HPCs-CD34(+) irradiated with 1-, 2- and 5-Gy X-rays, using a flow cytometry assay. Manganese superoxide dismutase (MnSOD) expression was studied by western blot analysis and visualized by an immunofluorescence assay. Apoptosis was estimated using the following assays: Annexin-V assay, DNA degradation assay, BCL-2/BAX mRNA and protein levels and caspase-9 protein immunofluorescence visualization. Viability and clonogenic potential were studied in irradiated HPCs. The generation of superoxide anion radicals at an early and a late time point was increased, while the hydrogen peroxide generation at a late time point was stable. IGF-1 presence further enhanced the radiation-induced increase of MnSOD at 24 h post irradiation. IGF-1 inhibited the mitochondria-mediated pathway of apoptosis by regulating the m-RNA and protein expression of BAX, BCL-2 and the BCL-2/BAX ratio and by decreasing caspase-9 protein expression. IGF-1 presence in culture media of irradiated cells restored the clonogenic capacity and the viability of HPCs as well. In conclusion, IGF-1 protects HPCs-CD34(+) from radiation effects, by eliminating the oxidative microenvironment through the enhancement of MnSOD activation and by regulating the mitochondria-mediated pathway of apoptosis.
authors: Division of Hematology, Department of Medicine, University of Patras, Patras, Rio, 26504, Greece.
authors: Konstantina
authors: K
authors: Floratou
authors: Efstathia
authors: E
authors: Giannopoulou
authors: Anna
authors: A
authors: Antonacopoulou
authors: Marina
authors: M
authors: Karakantza
authors: George
authors: G
authors: Adonakis
authors: Dimitrios
authors: D
authors: Kardamakis
authors: Panagiota
authors: P
authors: Matsouka
mesh_terms: D018952:Antigens, CD34 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D053938:DNA Fragmentation / Q000187:drug effects / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D019254:Genes, bcl-2 / Q000187:drug effects / Q000528:radiation effects; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D006801:Humans; D066298:In Vitro Techniques; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; C494826:BAX protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051028:bcl-2-Associated X Protein; D007334:Insulin-Like Growth Factor I; D013482:Superoxide Dismutase