Title:Differences in Phosphorylated Histone H2AX Foci Formation and Removal of Cells Exposed to Low and High Linear Energy Transfer Radiation
Volume: 13
Issue: 6
Author(s): Thomas Ernst Schmid, Olga. Zlobinskaya and Gabriele Multhoff
Affiliation:
Keywords:
DNA double strand breaks, Linear energy transfer, Radiation, γ-H2AX foci, malignant tumors, radiobiological efficacy, DSBs, LET, NHEJ, HDR
Abstract: The use of particle ion beams in cancer radiotherapy has a long history. Today, beams of protons or heavy ions,
predominantly carbon ions, can be accelerated to precisely calculated energies which can be accurately targeted to tumors.
This particle therapy works by damaging the DNA of tissue cells, ultimately causing their death. Among the different
types of DNA lesions, the formation of DNA double strand breaks is considered to be the most relevant of deleterious
damages of ionizing radiation in cells. It is well-known that the extremely large localized energy deposition can lead to
complex types of DNA double strand breaks. These effects can lead to cell death, mutations, genomic instability, or carcinogenesis.
Complex double strand breaks can increase the probability of mis-rejoining by NHEJ. As a consequence differences
in the repair kinetics following high and low LET irradiation qualities are attributed mainly to quantitative differences
in their contributions of the fast and slow repair component. In general, there is a higher contribution of the slow
component of DNA double strand repair after exposure to high LET radiation, which is thought to reflect the increased
amount of complex DNA double strand breaks. These can be accurately measured by the γ-H2AX assay, because the
number of phosphorylated H2AX foci correlates well with the number of double strand breaks induced by low or / and
high LET radiation.
