Induction and Rejoining of DNA Double Strand Breaks Assessed by H2AX Phosphorylation in Melanoma Cells Irradiated with Proton and Lithium Beams

• Published in: International journal of radiation oncology, biology, physics Vol. 74; no. 4; pp. 1226 - 1235
• Main Authors: Ibañez, Irene L., M.D., M.Sc, Bracalente, Candelaria, M.Sc, Molinari, Beatriz L., Ph.D, Palmieri, Mónica A., M.Sc, Policastro, Lucía, Ph.D, Kreiner, Andrés J., Ph.D, Burlón, Alejandro A., Ph.D, Valda, Alejandro, Ph.D, Navalesi, Daniela, Davidson, Jorge, Ph.D, Davidson, Miguel, Ph.D, Vázquez, Mónica, B.S, Ozafrán, Mabel, Ph.D, Durán, Hebe, Ph.D
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.07.2009
• Subjects: BEAMS; Biomarkers - analysis; Biomarkers - metabolism; Cell Survival; DNA; DNA Breaks, Double-Stranded; DNA DSB; DNA Repair; Dose-Response Relationship, Radiation; GAMMA SOURCES; Hematology, Oncology and Palliative Medicine; Histones - analysis; Histones - metabolism; Humans; Ionizing radiation; IONIZING RADIATIONS; IRRADIATION; LET; Linear Energy Transfer; LITHIUM; Lithium - therapeutic use; Melanoma cells; Melanoma, Experimental - genetics; Melanoma, Experimental - metabolism; Melanoma, Experimental - radiotherapy; MELANOMAS; PHOSPHORYLATION; Proton Therapy; PROTONS; RADIATION DOSES; Radiation Tolerance; Radioisotopes - therapeutic use; Radiology; RADIOLOGY AND NUCLEAR MEDICINE; RADIOSENSITIVITY; STRAND BREAKS; SURVIVAL CURVES; γH2AX; Ionizing radiation; LET; Melanoma cells; γH2AX; DNA DSB
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2009.02.070

Purpose The aim of this study was to evaluate the induction and rejoining of DNA double strand breaks (DSBs) in melanoma cells exposed to low and high linear energy transfer (LET) radiation. Methods and Materials DSBs and survival were determined as a function of dose in melanoma cells (B16-F0) irradiated with monoenergetic proton and lithium beams and with a gamma source. Survival curves were obtained by clonogenic assay and fitted to the linear-quadratic model. DSBs were evaluated by the detection of phosphorylated histone H2AX (γH2AX) foci at 30 min and 6 h post-irradiation. Results Survival curves showed the increasing effectiveness of radiation as a function of LET. γH2AX labeling showed an increase in the number of foci vs. dose for all the radiations evaluated. A decrease in the number of foci was found at 6 h post-irradiation for low LET radiation, revealing the repair capacity of DSBs. An increase in the size of γH2AX foci in cells irradiated with lithium beams was found, as compared with gamma and proton irradiations, which could be attributed to the clusters of DSBs induced by high LET radiation. Foci size increased at 6 h post-irradiation for lithium and proton irradiations in relation with persistent DSBs, showing a correlation with surviving fraction. Conclusions Our results showed the response of B16-F0 cells to charged particle beams evaluated by the detection of γH2AX foci. We conclude that γH2AX foci size is an accurate parameter to correlate the rejoining of DSBs induced by different LET radiations and radiosensitivity.