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1 June 2006 DNA Fragmentation Induced in Human Fibroblasts by Accelerated 56Fe Ions of Differing Energies
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Abstract

Belli, M., Campa, A., Dini, V., Esposito, G., Furusawa, Y., Simone, G., Sorrentino, E. and Tabocchini, M. A. DNA Fragmentation Induced in Human Fibroblasts by Accelerated 56Fe Ions of Differing Energies. Radiat. Res. 165, 713–720 (2006).

DNA fragmentation was studied in the fragment size range 0.023–5.7 Mbp after irradiation of human fibroblasts with iron-ion beams of four different energies, i.e., 200 MeV/nucleon, 500 MeV/nucleon, 1 GeV/nucleon and 5 GeV/nucleon, with γ rays used as the reference radiation. The double-strand break (DSB) yield (and thus the RBE for DNA DSB induction) of the four iron-ion beams, which have LETs ranging from 135 to 442 keV/μm, does not vary greatly as a function of LET. As a consequence, the variation of the cross section for DSB induction mainly reflects the variation in LET. However, when the fragmentation spectra were analyzed with a simple theoretical tool that we recently introduced, the results showed that spatially correlated DSBs, which are absent after γ irradiation, increased markedly with LET for the iron-ion beams. This occurred because iron ions produce DNA fragments smaller than 0.75 Mbp with a higher probability than γ rays (a probability that increases with LET). These sizes include those expected from fragmentation of the chromatin loops with Mbp dimensions. This result does not exclude a correlation at distances smaller than the lower size analyzed here, i.e. 23 kbp. Moreover, the DSB correlation is dependent on dose, decreasing when dose increases; this can be explained with the argument that at increasing dose there is an increasing fraction of fragments produced by DSBs caused by separate, uncorrelated tracks.

Mauro Belli, Alessandro Campa, Valentina Dini, Giuseppe Esposito, Yoshiya Furusawa, Giustina Simone, Eugenio Sorrentino, and Maria Antonella Tabocchini "DNA Fragmentation Induced in Human Fibroblasts by Accelerated 56Fe Ions of Differing Energies," Radiation Research 165(6), (1 June 2006). https://doi.org/10.1667/RR3574.1
Received: 29 December 2005; Accepted: 1 February 2006; Published: 1 June 2006
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