Dose–Response Curves of the FDXR and RAD51 Genes with 6 and 18 MV Beam Energies in Human Peripheral Blood Lymphocytes

Abstract

BackgroundRapid dose assessment using biological dosimetry methods is essential to increase the chance of survival of exposed individuals in radiation accidents.ObjectivesWe compared the expression levels of the FDXR and RAD51 genes at 6 and 18 MV beam energies in human peripheral blood lymphocytes. The results of our study can be used to analyze radiation energy in biological dosimetry.MethodsFor this in vitro experimental study, from 36 students in the medical physics and virology departments, seven voluntary, healthy, non-smoking male blood donors of Khuzestan ethnicity with no history of exposure to ionization radiation were selected using simple randomized sampling. Sixty-three peripheral blood samples were collected from the seven healthy donors. Human peripheral blood was then exposed to doses of 0, 0.2, 0.5, 2, and 4 Gy with 6 and 18 MV beam energies in a Linac Varian 2100C/D (Varian, USA) at Golestan hospital in Ahvaz, Iran. After RNA extraction and cDNA synthesis, the expression levels of FDXR and RAD51 were determined 24 hours post-irradiation using the gel-purified reverse transcription polymerase chain reaction (RT-PCR) technique and TaqMan strategy (by real-time PCR).ResultsThe expression level of FDXR gene was significantly increased at doses of 2 Gy and 4 Gy in the 6 - 18 MV energy range (P < 0.001 and P < 0.008, respectively). The medians with interquartile ranges (IQRs) of the copy numbers of the FDXR gene at 2 Gy and 4 Gy doses under 6 and 18 MV beam energies were 2393.59 (1798.21, 2575.37) and 2983.00 (2199.48, 3643.82) and 3779.12 (3051.40, 5120.74) and 5051.26 (4704.83, 5859.17), respectively. However, RAD51 gene expression levels only showed a significant difference between samples at a dose of 2 Gy with 6 and 18 MV beam energies, respectively (P < 0.040). The medians with IQRs of the copy numbers of the RAD51 gene were 2092.77 (1535.78, 2705.61) and 3412.57 (2979.72, 4530.61) at beam energies of 6 and 18 MV, respectively.ConclusionsThe data suggest that the expression analysis of the FDXR gene, contrary to that of the RAD51 gene, may be suitable for assessment of high-energy X-ray. In addition, RAD51 is not a suitable gene for dose assessment in biological dosimetry.

Candidate gene biodosimetry markers of exposure to external ionizing radiation in human blood: A systematic review

“…When sensitivity is fixed at 100% in order to decrease the number of false negatives, although results differed, TNFSF4, FDXR and ZMAT3 still have a good performance score. Although ZMAT3 has been less studied, TNFSF4 and FDXR are known to be radiation-responsive and are often used in candidate gene approaches and validation panels [ 58 – 63 ]. Recently, a study provided an in vivo dose-response of the FDXR gene, both for very low doses or partial body exposure, showing good correlation between physically and biologically assessed doses, thus confirming the great potential of this gene as candidate radiation dosimetry biomarker [ 64 ].…”