Low-dose radiation-induced responses: focusing on epigenetic regulation.

PURPOSE

With the widespread use of ionising radiation, the risks of low-dose radiation have been increasingly highlighted for special attention. This review introduces the potential role of epigenetic elements in the regulation of the effects of low-dose radiation.

MATERIALS AND METHODS

The related literature has been analysed according to the topics of DNA methylation, histone modifications, chromatin remodelling and non-coding RNA modulation in low-dose radiation responses.

RESULTS

DNA methylation and radiation can reciprocally regulate effects, especially in the low-dose radiation area. The relationship between histone methylation and radiation mainly exists in the high-dose radiation area; histone deacetylase inhibitors show a promising application to enhance radiation sensitivity, both in the low-dose and high-dose areas; phosphorylated histone 2 AX (H2AX) shows a low sensitivity with 1-15 Gy irradiation as compared with lower dose radiation; and histone ubiquitination plays an important role in DNA damage repair mechanisms. Moreover, chromatin remodelling has an integral role in the repair of DNA double-strand breaks and the response of chromatin to ionising radiation. Finally, the effect of radiation on microRNA expression seems to vary according to cell type, radiation dose, and post-irradiation time point.

CONCLUSION

Small advances have been made in the understanding of epigenetic regulation of low-dose radiation responses. Many questions and blind spots deserve to be investigated. Many new epigenetic elements will be identified in low-dose radiation responses, which may give new insights into the mechanisms of radiation response and their exploitation in radiotherapy.