Volume 130, Issue 5 pp. 991-1000
Mini Review

Repair of DNA damage induced by accelerated heavy ions—A mini review

Ryuichi Okayasu

Corresponding Author

Ryuichi Okayasu

International Open Laboratory and Heavy-ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan

Tel.: +81-43-382-3711, Fax: +81-43-255-0720

International Open Laboratory and Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555 JapanSearch for more papers by this author
First published: 20 September 2011
Citations: 103

Abstract

Increasing use of heavy ions for cancer therapy and concerns from exposure to heavy charged particles in space necessitate the study of the basic biological mechanisms associated with exposure to heavy ions. As the most critical damage induced by ionizing radiation is DNA double strand break (DSB), this review focuses on DSBs induced by heavy ions and their repair processes. Compared with X- or gamma-rays, high-linear energy transfer (LET) heavy ion radiation induces more complex DNA damage, categorized into DSBs and non-DSB oxidative clustered DNA lesions (OCDL). This complexity makes the DNA repair process more difficult, partially due to retarded enzymatic activities, leading to increased chromosome aberrations and cell death. In general, the repair process following heavy ion exposure is LET-dependent, but with nonhomologous end joining defective cells, this trend is less emphasized. The variation in cell survival levels throughout the cell cycle is less prominent in cells exposed to high-LET heavy ions when compared with low LET, but this mechanism has not been well understood until recently. Involvement of several DSB repair proteins is suggested to underlie this interesting phenomenon. Recent improvements in radiation-induced foci studies combined with high-LET heavy ion exposure could provide a useful opportunity for more in depth study of DSB repair processes. Accelerated heavy ions have become valuable tools to investigate the molecular mechanisms underlying repair of DNA DSBs, the most crucial form of DNA damage induced by radiation and various chemotherapeutic agents.

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