Vladimir G. Druzhinin

The application of the cytokinesis-block micronucleus assay on peripheral blood lymphocytes for the assessment of genome damage in long-term residents of areas with high radon concentration

Estimating the effects of small doses of ionising radiation on DNA is one of the most important problems in modern biology. Different cytogenetic methods exist to analyse DNA damage; the cytokinesis-block micronucleus assay (CBMN) for human peripheral blood lymphocytes is a simple, cheap and informative cytogenetic method that can be used to detect genotoxic-related markers. With respect to previous studies on radiation-induced genotoxicity, children are a poorly studied group, as evidenced by the few publications in this area. In this study, we assessed radon genotoxic effects by counting micronuclei (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) in the lymphocytes of children who are long-term residents from areas with high radon concentrations. In the exposed group, radon was found to cause significant cytogenetic alterations. We propose that this method can be employed for biomonitoring to screen for a variety of measures.

Associations of DNA-repair gene polymorphisms with a genetic susceptibility to ionizing radiation in residents of areas with high radon (222Rn) concentration

Abstract Purpose: To investigate the individual radiosensitivity of the human genome in long-term residents of areas with high radon concentration. Materials and methods: The materials used for this investigation were venous blood samples extracted from children living in the boarding school of Tashtagol (Kemerovo Region, Russia). Cytogenetic damage assessment was performed using the cytokinesis-block micronucleus assay (CBMN) on peripheral blood lymphocytes. PCR, gel electrophoresis and product detection using a transilluminator were used to determine polymorphisms in the genes ADPRT (rs 1136410), hOGG1 (rs 1052133), NBS1 (rs 1805794), XRCC1 (rs 25487), XpC (rs 2228001), XpD (rs 13181), and XpG (rs 17655). Statistical analysis was performed using nonparametric methods. To ensure accurate results, FDR-correction for multiple comparisons was performed. Results: We discovered a significant increase in the frequency of binucleated lymphocytes with micronuclei (MN) in carriers of the His/His genotype of the XpG gene Asp1104His polymorphism in comparison to heterozygous and homozygous carriers of the Asp allele. In addition, the Ala/Ala genotype for the ADPRT gene Val762Ala polymorphism and the Glu/Gln genotype for the NBS1 gene Glu185Gln polymorphism were associated with the elevated frequency of binucleated lymphocytes with nucleoplasmic bridges (NPB). Conclusions: As a result of this study, the elevated frequency of cytogenetic damage in people with particular DNA-repair gene polymorphisms in response to chronic exposure to radon was demonstrated. It was shown that the genes and corresponding polymorphisms (the XpG gene Asp1104His polymorphism, the ADPRT gene Val762Ala polymorphism and the NBS1 gene Glu185Gln polymorphism) can be used as molecular genetic markers of increased individual radiosensitivity in long-term residents of areas with high concentrations of radon.

Assessing the level of chromosome aberrations in peripheral blood lymphocytes in long-term resident children under conditions of high exposure to radon and its decay products.

In this study, the frequency and spectrum of chromosomal aberrations were analysed in samples of peripheral blood from 372 (mean age = 12.24 ± 2.60 years old) long-term resident children in a boarding school (Tashtagol city, Kemerovo Region, Russian Federation) under conditions of high exposure to radon and its decay products. As a control group, we used blood samples from people living in Zarubino village (Kemerovo Region, Russian Federation). We discovered that the average frequencies of single and double fragments, chromosomal exchanges, total number of aberrations, chromatid type, chromosome type and all types of aberrations were significantly increased in the exposed group. This is evidence of considerable genotoxicity to children living under conditions of high exposure to radon compared to children living under ecological conditions without increased radon radiation.

Chromosome aberrations in peripheral blood lymphocytes of lung cancer patients exposed to radon and air pollution.

Lung cancer is one of the most common forms of cancer. The aim of this study was to validate chromosome aberrations in peripheral blood lymphocytes of lung cancer patients living in a region with high air pollution and increased background radon levels as a biomarker of cancer risk. A total of 417 lung cancer patients and 468 control participants were analysed using a chromosome aberration assay in peripheral blood lymphocytes. The results showed that chromatid-type aberrations (2.26±1.58 vs. 1.60±1.58) and chromosome-type aberrations (CSAs) (0.96±1.36 vs. 0.42±0.70) in lung cancer patients were increased significantly in comparison with the controls. The most significant two-fold increase was detected for CSAs (nonsmoking patients: 0.84±1.54 vs. 0.41±0.73%, smoking patients: 0.99±1.31 vs. 0.44±0.67%). The frequency of dicentric and ring chromosomes, double minutes and rogue cells was significantly higher (P=0.002, 0.00002, 0.01, 0.0007) in the lung cancer patients. As both analysed groups lived in the same environment, our results show that increased radon levels were not the only source for the detected genome damage. Using binomial logistic regression, the estimated odds ratios and 95% confidence intervals adjusted for the main confounders (smoking, occupational exposure, age) were 1.31 (1.20–1.40) for chromatid-type aberrations, 1.28 (1.17–1.33), and 1.68 (1.49–1.88) for CSAs. It may be suggested that lung cancer patients show a significant increase in genome damage that may be caused by an interplay between exposure and individual low capacity of DNA repair, leading to genome instability.

Genome damage in testicular seminoma patients seven years after radiotherapy

Abstract Purpose: Testicular seminoma cancer incidence has significantly increased over the last few decades, and although it is successfully treated by radiotherapy, long-term health risks are still unclear. The aim of the study was to show long-term genome damage in patients with seminoma after radiotherapy. Materials and methods: Chromosome aberration (CA) and micronucleus (MN) assays seven years after radiotherapy with a total dose of 25 Gy were conducted in 10 testicular seminoma patients aged 23–49 years and results were compared with 10 healthy control subjects matched for age and smoking status. Results: Although mean CA frequency did not deviate from control values, significantly increased frequencies of dicentrics, double minutes, and ring chromosomes were detected in seminoma patients. MN frequency in binuclear lymphocytes of patients was similar to controls (4.60/1000 vs. 5.82/1000, respectively). Significantly higher MN frequency was detected in mononuclear lymphocytes of patients than in controls (2.55/1000 vs. 0.73/1000, respectively). Average percentage of centromere-positive MN was 62.6% in seminoma patients. Conclusion: This study shows the persistence of unstable CA in seminoma patients seven years after radiotherapy and the relevance of long-term follow up. MN frequency in mononuclear lymphocytes was shown to be relevant biomarker of long-term genome damage.

Research of the Influence of the LIG4 Gene Polymorphism on the Chromosomal Aberration Level in Human Lymphocytes, with Background And Excessive Exposure to a Radon

The effects of LIG4 gene polymorphisms rs1805388 (Thr9lle) and rs1805389 (Ala3Val) on the level of chromosomal aberrations in the lymphocytes of peripheral blood was estimated for children that live and study in conditions of normal and supernormal radon exposure in several locations in Kemerovskaya oblast. A statistically significant difference of the cytogenetic values among genotypic groups with the use of marker rs1805388 was not shown. At the same time, in the group of Val carriers (marker rs1805389) from the second cohort of our analysis revealed a significant increase of the amount of paired fragments in comparison to homozygotes Ala/Ala.

Associations of polymorphisms in the cytokine genes IL1β (rs16944), IL6 (rs1800795), IL12b (rs3212227) and growth factor VEGFA (rs2010963) with anthracosilicosis in coal miners in Russia and related genotoxic effects

Anthracosilicosis (AS), a prevalent form of pneumoconiosis among coal miners, results from the accumulation of carbon and silica in the lungs from inhaled coal dust. This study investigated genotoxic effects and certain cytokine genes polymorphic variants in Russian coal miners with АS. Peripheral leukocytes were sampled from 129 patients with AS confirmed by X-ray and tissue biopsy and from 164 asymptomatic coal miners. Four single-nucleotide polymorphisms were genotyped in the extracted DNA samples: IL1β T-511C (rs16944), IL6 C-174G (rs1800795), IL12b A1188C (rs3212227) and VEGFA C634G (rs2010963). Genotoxic effects were assessed by the analysis of chromosome aberrations in cultured peripheral lymphocytes. The mean frequency of chromatid-type aberrations and chromosome-type aberrations, namely, chromatid-type breaks and dicentric chromosomes, was found to be higher in AS patients [3.70 (95% confidence interval {CI}, 3.29-4.10) and 0.28 (95% CI, 0.17-0.38)] compared to the control group [2.41 (95% CI, 2.00-2.82) and 0.09 (95% CI, 0.03-0.15)], respectively. IL1β gene T/T genotype (rs16944) was associated with AS [17.83% in AS patients against 4.35% in healthy donors, odds ratio = 4.77 (1.88-12.15), P < 0.01]. A significant increase in the level of certain chromosome interchanges among AS donors is of interest because such effects are typical for radiation damage and caused by acute oxidative stress. IL1β T allele probably may be considered as an AS susceptibility factor among coal miners.