ESTRO 37 Abstract book

ESTRO 37

S586

the HaCaT (immortalized human keratinocytes) cell lines were collected at the indicated time points (1 or 15 h) after irradiation (0, 2, 5, and 10 Gy) and subjected to western blot analysis. From these analysis, we set the dose to 5 Gy for time-dependent response analysis. Phosphorylation of SMC1 (Ser-360 and Ser-957) levels were estimated after 5 Gy of irradiation in normal cell lines. WI38VA13 (human fibroblasts) and HaCaT (human keratinocytes) were also collected at the indicated time points (0, 1, 3, 6, 12, 18, 24, 36, and 48 h) after irradiation and subjected to western blot analysis. To investigate dose- and time-dependent response of phosphorylated SMC1 in human lymphoblasts cell lines, phosphorylation of SMC1 responding to the different doses of radiation (0 Gy, 2 Gy, 5 Gy and 10 Gy) in human lymphoblasts cells (A) GM10832, (B) GM10834, and (C) GM10860 were analyzed at indicated time (1, 5, and 15 h) after irradiation. Phospho-SMC1 (Ser-957) and phospho- SMC1 (Ser-360) levels were confirmed by western blotting analysis. Based on the results of the normal cell lines and the human lymphoblast cell lines, peripheral blood mononuclear cells (PBMCs) of twenty humans were tested. Twenty healthy, non-pregnant adults who had not previously received chemotherapy or radiation therapy were recruited. Informed consent was obtained under the review of the institutional review board at Asan Medical Center. PBMCs were obtained from the study subjects, irradiated, and the SMC1 phosphorylation levels were assessed by western blotting. Results In this study, we showed that phosphorylation of SMC1 at Ser-957 and Ser-360 was increased by irradiation in a dose-dependent manner and disappeared gradually after 1-3 hr of peak after irradiation. We also discovered a new phosphorylation site at Ser-360 and showed by western blotting that it is more sensitive to radiation than Ser- 957, especially at low doses. We demonstrated a robust ex-vivo response of phospho-SMC1 Ser-360 in human PBMCs to ionizing radiation exposure. Conclusion Detection of phosphorylation at Ser-360 in SMC1 could be used as a marker of radiation exposure. We demonstrated the feasibility of measuring blood cell-based changes in the phosphorylation level for using an ex-vivo radiation exposure method even after exposure to low doses of radiation. PO-1043 Development of zebrafish embryo model for radiobiology research on laser driven hadron beams E.R. Szabó 1 , T. Tőkés 1 , R. Polanek 1 , Z. Szabó 1 , S. Brunner 1 , S. Czifrus 2 , A. Fenyvesi 3 , B. Biró 3 , E. Beyreuther 4 , J. Pawelke 4 , K. Hideghéty 1 1 ELI-ALPS- ELI-HU Non-Profit Ltd., Scientific Application Division- Biomedical Application Group, Szeged, Hungary 2 Budapest University of Technology and Economics, Institute of Nuclear Techniques, Budapest, Hungary 3 Hungarian Academy of Sciences, Institute for Nuclear Research, Debrecen, Hungary 4 Helmholtz-Zentrum Dresden – Rossendorf- Dresden- Germany- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus- Technische Universität Dresden, Dresden, Germany Purpose or Objective High power lasers provide the basis of new particle acceleration, resulting in short particle pulses of ultrahigh dose rate. At the actual status of the development, low energy, limited size beams are

available under technical conditions for radiobiology experiments. Our main aim was to introduce, optimize and validate a vertebrate system for in vivo experiments to study the biological effects of novel hadron beams. Material and Methods Series of zebrafish embryos in different ages (from 1 hour post-fertilization (hpf) to 72 hpf), in different holders like tubes and 96 well plates varying the number (n) of embryos/well were prepared. For irradiation we used fission neutron (0, 1.25, 1.875, 2, 2.5 Gy), cyclotron- based neutron (0, 2, 4, 6.8, 8.12, 10.28 Gy) and proton (0, 5, 10, 15, 20 and 30 Gy) at two positions along the proton depth-dose curve (at the plateau and at the middle of Spread Out Bragg Peak ), furthermore, with reference linear accelerator photon (0, 5, 10, 15, 20 Gy) beams (n=96 in each group), repeated several times (≥3). Thereafter, survival, any type of organ developmental disturbance (pericardial edema, spine curvature, shortening of the body length and micro-opthalmia) were detected each days up to 7 post irradiation days (pid). Histological evaluation (size of the eye, brain necrosis, intestinal changes, liver vacuolization, hyper eosinophilic necrotic muscle-fibers) and molecular changes were evaluated with RT-PCR method at certain time points post irradiation. Results A higher vulnerability and radiation sensitivity could be observed at earlier stages of the embryogenesis (1-12 hpf). The LD 50 was determined with the well reproducible survival curves, resulting in a relative biological effectivity (RBE) between 10 and 4.8 for the 1 MeV and 14 MeV neutrons and around 1.1-1.4 for protons at the two positions, respectively. The morphological distortions shown close correlation to the dose delivered and their evaluation on the 4 th pid exhibited a good agreement to the survival derived RBE. The gravity of the histopathological changes on the basis of semi- quantitative analysis corresponded well to the macro morphological abnormalities (eye layer disorganization, degree of brain necrosis, increased numbers of the goblet cells in the gastrointestinal tract, and muscle fibrosis). Conclusion Numerous features of the zebrafish embryo model makes it amenable for large scale of radiobiological investigations. On the basis of our experimental series the optimal embryonal age (hpf), radiation setup and observation time points for assessment of the different biological endpoints could be established. The defined parameters proved to be suitable for reliable RBE determination. PO-1044 In vivo imaging of microvascular changes in irradiated oral mucosa by optical coherence tomography A. Maslennikova 1 , M. Sirotkina 2 , E. Sedova 3 , A. Moiseev 4 , S. Ksenofontov 4 , G. Gelikonov 4 , L. Matveev 4 , E. Kiseleva 2 , V. Zaitsev 4 , E. Zagaynova 2 , F. Feldstein 2 , N. Gladkova 3 , A. Vitkin 5 1 Regional Oncology Hospital, Radiation therapy, Nizhny Novgorod, Russian Federation 2 Nizhny Novgorod State Medical Academy, Institute of Biomedical Technologies, Nizhny Novgorod, Russian Federation 3 Nizhny Novgorod State Medical Academy, Oncology, Nizhny Novgorod, Russian Federation 4 Institute of Applied Physics, Nano-optics and highly sensitive optical measurement, Nizhny Novgorod, Russian Federation