DNA methylome profiling in occupational radon exposure miners using an Illumina Infinium Methylation EPIC BeadChip.

Background: A causal relationship between occupational radon exposure in underground miners and lung cancer risk has been demonstrated through large cohort epidemiological studies. However, the mechanisms by which radon exposure causes adverse effects on lung tissue remain unclear. Epigenetic alterations such as DNA methylation may provide new insights into interactions at molecular levels induced by prolonged radon exposure. Methods: We used the Illumina Infinium Human Methylation 850 K BeadChip to detect and compare genome-wide DNA methylation profiles in peripheral blood samples from underground miners (n = 14) and aboveground workers (n = 9). Results: The average concentration of radon in underground workplaces was significantly higher than that of aboveground places (1,198 Bq·m-3 vs 58 Bq·m-3, p < 0.001). A total of 191 differentially methylated positions (DMPs) corresponding to 104 hub genes were identified when |Δß| ≥ 0.1 and p < 0.05, with 107 hypermethylated sites and 84 hypomethylated sites. GO and KEGG analysis revealed that differentially methylated genes between underground miners and aboveground workers were prominently enriched in pathways/networks involved in neurotransmitter regulation, immunomodulatory effects and cell adhesion ability. Furthermore, methylation changes of selected genes FERMT1, ALCAM, HLA-DPA1, PON1 and OR2L13 were validated by pyrosequencing, which may play vital roles in these biological processes induced by radon. Conclusion: In summary, the DNA methylation pattern of the underground miners exposed to radon was distinct from that of the aboveground workers. Such abnormalities in the genomic DNA methylation profile associated with prolonged radon exposure are worth studying in terms of neuro- and immune-system regulation, as well as cell adhesion ability in the future.

Alteration of genome-wide DNA methylation in non-uranium miners induced by high level radon exposure.

In China, according to statistics about underground non-uranium mine radon levels, 15% exceed the national standard intervention level of 1000 Bq/m3, and some mines may exceed 10,000 Bq/m3. The relationship between radon exposure in underground miners and lung cancer has already been established, but the mechanisms and biological processes underlying it are poorly understood. In order to identify the genome-wide DNA methylation profile associated with long-term radon exposure, we performed the Infinium Human Methylation 850 K BeadChip measurement in whole blood samples obtained from 15 underground non-uranium miners and 10 matched aboveground control workers. Radon concentrations in the air of workplaces and living environments were measured by CR-39 radon detectors, and annual effective doses were calculated using the detection data. Under the high radon concentration with an average value of 12,700 Bq·m-3, a total of 165 significant differentially methylated positions (127 hypermethylated sites and 38 hypomethylated sites) annotated to 71 genes were identified in underground miners (|Δß| ≥ 0.10, p < 0.05), and the average DNA methylation level of 165 DMPs was significantly higher than that of the control workers. Most DMPs were found on chromosome 1, and approximately one-quarter of them were located in genomic promoter regions. Through bioinformatics analysis and pyrosequencing validation, five candidate genes differentially methylated by radon, including TIMP2, EMP2, CPT1B, AMD1 and SLC43A2 were identified. GO and KEGG analysis implicated that long term radon exposure could induce the lung cancer related biological processes such as cell adhesion and cellular polarity maintenance. Our study provides evidence for the alterations of genome-wide DNA methylation profiles induced by long-term high level radon exposure, and new insights into searching for carcinogenic biomarkers of high radon exposure in future studies.

Screening for Potential Biomarkers in Peripheral Blood From Miners Exposed to Radon Radiation.

In this cohort study of 144 miners, 72 miners worked underground (the study group) and 72 miners worked aboveground (the control group). Based on questionnaire data and of radon concentration measurements, the cumulative radon exposure dose was calculated for each miner using the parameters recommended in International Commission on Radiological Protection Publication 137. Hematological parameters such as lymphocyte count (LYM) and neutrophil count (NE) were assessed, cell cycle phases and regulatory proteins were detected by flow cytometry, and microRNA (miRNA) microarray screening and real-time polymerase chain reaction (PCR) were used to detect miRNAs in plasma. The interrelationships between various potential biomarkers were analyzed using bioinformatics and statistical methods. The mean cumulative exposure dose of underground miners and controls was 982 and 48 mSv, respectively. Hematological parameters (such as LYM and NE) were significantly lower in the underground group. Cyclin-dependent kinase (CDK)-2, CDK4, CDK6, CyclinA2, CyclinD1, and CyclinE1 were significantly higher in the underground group. MicroRNA microarray screening showed that 5 miRNAs were downregulated (fold-change >2) in the underground group. The real-time PCR detection results of miR-19a, miR-30e, miR-335, and miR-451a were consistent with the screening results. LYM, NE, CDK2, CDK4, CDK6, Cyclin A2, Cyclin D1, Cyclin E1, miR-19a, miR-30e, miR-335, and miR451a are potential biomarkers of radon radiation damage.

Effects of Radon From Hot Springs on Lymphocyte Subsets in Peripheral Blood.

OBJECTIVE: To analyze changes in immune functions by detecting lymphocyte subsets in the peripheral blood of residents in the vicinity of radon from hot springs. METHODS: Two groups were randomly selected; 61 residents in the vicinity of the hot springs were assigned to the radon group, and 51 residents with a similar lifestyle and habits but no contact with hot springs were assigned to the control group. The percentages of lymphocyte subsets (CD3+, CD4+CD8-, CD4-CD8+, CD4+/CD8+, and TCR/CD3) in the 2 groups were evaluated on a FACS Aria flow cytometer. The absolute values of lymphocytes (LYMPH#) and percentages of lymphocytes (LYMPH%) were measured by an automatic blood analyzer. RESULTS: In the radon group, the numbers of CD3+ (Z = -0.140, P > .05) and CD4+CD8- (Z = -0.964, P > .05) T cells were higher, as compared with the controls, but this difference was not significant. In addition, the number of CD4-CD8+ (t = -2.141, P < .05) T cells was significantly lower in the radon group. Furthermore, the average ratios of CD4+/CD8+ (t = -2.201, P < .05) and TCR/CD3 (t = 2.047, P < .05) cells were significantly higher in the radon group than in the controls. Compared with the control group, the LYMPH# (t = -0.485, P > .05) and LYMPH% (Z = -0.835, P > .05) showed no significant change. CONCLUSION: Radon-rich hot springs could alter the proportions of lymphocyte subsets and possibly affect immunologic functions.

The protective effects of 1,2-propanediol against radiation-induced hematopoietic injury in mice.

Agents that provide protection against irradiation-induced hematopoietic injury are urgently needed for radiotherapy. We examined the effects of the small molecule, 1,2-propanediol (PPD), on total body irradiation (TBI)-induced hematopoietic injury in C57BL/6 mice. PPD administration 1 h before TBI significantly increased hematopoietic parameters such as white blood cell, platelet, red blood cell, and lymphocyte counts in vivo and enhanced the survival of mice exposed to TBI (7.0 and 7.5 Gy). PPD administration 1 h before TBI improved bone marrow (BM) and spleen recovery after TBI, with increases in both BM cellularity and spleen index. The number of colony-forming-units in bone marrow mononuclear cells (BMNCs) in vitro also increased significantly. PPD pretreatment increased the numbers of hematopoietic stem cells and hematopoietic progenitor cells in BM. Importantly, PPD also maintained endogenous antioxidant status by decreasing levels of malondialdehyde and increasing the expression of reduced glutathione, superoxide dismutase and catalase in the serum of irradiated mice. PPD alleviated the levels of apoptosis in HSCs induced by TBI, thus increasing the proportion of dividing BMNCs. These results suggest that PPD protects against TBI-induced hematopoietic injury through the increased activities of antioxidant enzymes and the inhibition of apoptosis in HSCs. PPD increased the serum levels of granulocyte-colony stimulating factor and interleukin-6 irrespective of TBI. In conclusion, these data suggest that PPD acts as a radioprotector against radiation-induced hematopoietic injury.

Laboratory Intercomparison of Cytogenetic Dosimetry Among 38 Laboratories in China.

A nationwide intercomparison exercise for estimating the irradiated dose was organized by the National Institute for Radiological Protection, Center for Disease Control and Prevention of China. Thirty-eight laboratories participated in this program. The main objective of this intercomparison exercise was to compare the participants' ability of operation and dose assessment basing on the frequencies of dicentrics and centric rings. Whole blood samples were irradiated with different dosages of 60Co γ-rays. Each laboratory collected 2 blind samples and prepared the slides independently. All participants presented the estimated dose reports within 30 days. The doses assessed by the participants were acceptable within the reference dose of ±20%. The mean absolute difference of estimated dose relative to the reference dose was calculated, which reflected the overall accuracy of dose estimates for each laboratory. The overall estimation results of blind blood samples for intercomparison showed a good agreement with the reference dose for each sample, with nearly 75% of the participants producing acceptable results.

Intercomparison in Cytogenetic Dosimetry among 22 Laboratories in China.

As part of a regional International Atomic Energy Agency-coordinated research project with the support from the National Health and Family Planning Commission of China, 22 laboratories participated in the intercomparison in cytogenetic dosimetry in China. Slides for chromosomal aberrations were prepared by the Department of Radiation Epidemiology, National Institute for Radiological Protection, which organized the exercise. Slides were sent to the other participating laboratories through Express Mail Service. For estimates of dose, each laboratory scored the frequency of dicentrics plus centric rings chromosomes. The whole blood samples were irradiated with 60Co γ-rays (1.3 Gy, 2.4 Gy and 1.5 Gy, 2.6 Gy). Each laboratory got one group of the slides. Ten of the 44 estimates of dose fell within ±5% of the true physical dose, 12 fell within ±5-10%, 9 fell within ±10-15%, 12 fell within ±15-20%, while only one sample fell ± >20%. The evaluation of the respective dose was achieved by 21 laboratories.

[Diabetic damage to male reproduction and its mechanism].

Diabetes is a metabolic disease caused by complicated factors, and its damage to the male reproductive system is threatening men's health. This article reviews the pathophysiological changes in the diabetes-damaged male reproductive system and the mechanism of these changes. Oxidative stress induced by hyperglycemia plays an important role in working damage to the reproductive system of diabetic males, for which some anti-oxidative substances may prove to be an effective cure.