Purpose: To study the relationship between the methylation status of the Bаk1 promoter and the frequency of chromosomal aberrations in human blood lymphocytes under chronic low-intensity external ionizing radiation.
Material and methods: The study was performed on 41 people (31 men and 10 women, aged from 36 to 83 years) who are former or current employees of the Siberian Group of Chemical Enterprises, who have been exposed or haven't been exposed to chronic low-intensity external radiation in the course of their professional activities. The workers included in the study were divided into two groups: the first – 15 people who did not have exposure, the second – 26 people who had external exposure (gamma radiation, total dose 89–716 mSv). Whole blood was used to isolate DNA and evaluate chromosomal aberrations in lymphocytes. The methylation status of the Bаk1 promoter was determined using methylsensitive PCR, which was performed after pretreatment of the isolated DNA with methylsensitive AoxI restrictase. The obtained quantitative data were analyzed using the Statistica 10. The differences were considered statistically significant at p ≤ 0.05.
Results: The methylation status of the Bаk1 promoter in the study groups does not differ (p = 0.18). The study of the effect of external radiation dose on the methylation status of the Bak1 promoter showed that the unmethylated promoter prevails in workers with an average radiation dose of 273.37 ± 43.82 mSv, while the methylated promoter – in workers with an average radiation dose of 183.63 ± 20.58 mSv (p = 0.03). The unmethylated promoter Bаk1 is associated with an increased frequency of chromatid fragments in the blood lymphocytes of group 2 workers (p = 0.03).
Conclusion: The status of methylation of the Bаk1 promoter in human blood lymphocytes under chronic low-intensity ionizing radiation does not change, but it is observed to depend on the radiation dose and is associated with an increased frequency of chromosomal aberrations (chromatid fragments). Thus, the unmethylated Bаk1 promoter prevails when the external radiation dose is increased. An increase in the frequency of chromatid fragments is associated with an unmethylated Bаk1 promoter. In addition, exposure to chronic low-intensity external radiation is accompanied by a decrease in the frequency of chromosomal fragments in the blood lymphocytes of workers of the Siberian Group of Chemical Enterprises.
Thermal and non-thermal health effects of low intensity non-ionizing radiation: An international perspective
