Integration of RNA-seq and ATAC-seq analyzes the effect of low dose neutron-γ radiation on gene expression of lymphocytes from oilfield logging workers.

Objective: Although radiation workers are exposed to much lower doses of neutron-γ rays than those suffered in nuclear explosions and accidents, it does not mean that their health is not affected by radiation. Lower doses of radiation do not always cause morphological aberrations in chromosomes, so more sophisticated tests must be sought to specific alterations in the exposed cells. Our goal was to characterize the specific gene expression in lymphocytes from logging workers who were continuously exposed to low doses of neutron-γ radiation. We hypothesized that the combination of cell type-specific transcriptomes and open chromatin profiles would identify lymphocyte-specific gene alterations induced by long-term radiation with low-dose neutron-γ-rays and discover new regulatory pathways and transcriptional regulatory elements. Methods: Lymphocytes were extracted from workers who have been occupationally exposed to neutron-γ and workers unexposed to radiation in the same company. mRNA-seq and ATAC-seq (Assay for Transposase-Accessible Chromatin with high-throughput sequencing) were performed, followed integrative analysis to identify specific gene regulatory regions induced by neutron-γ radiation. A qPCR assay was then performed to verify the downregulation of RNA coding for ribosomal proteins and flow cytometry was used to detect ribosomal protein expression and cell cycle alterations. Results: We identified transcripts that were specifically induced by neutron-γ radiation and discovered differential open chromatin regions that correlated with these gene activation patterns. Notably, we observed a downward trend in the expression of both differentially expressed genes and open chromatin peaks. Our most significant finding was that the differential peak upregulated in ATAC-seq, while the differential gene was downregulated in the ribosome pathway. We confirmed that neutron-γ radiation leads to transcriptional inhibition by analyzing the most enriched promoters, examining RPS18 and RPS27A expression by qPCR, and analyzing protein-protein interactions of the differential genes. Ribosomal protein expression and cell cycle were also affected by neutron-γ as detected by flow cytometry. Conclusion: We have comprehensively analyzed the genetic landscape of human lymphocytes based on chromatin accessibility and transcript levels, enabling the identification of novel neutron-γ induced signature genes not previously known. By comparing fine-mapping of open chromatin and RNA reads, we have determined that neutron-γ specifically leads to downregulation of genes in the ribosome pathway, with pseudogenes potentially playing a crucial role.

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.

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.

CHMP4C Disruption Sensitizes the Human Lung Cancer Cells to Irradiation.

Human lung cancer is highly invasive and the most malignant among human tumors. Adenocarcinoma as a specific type of non-small cell lung cancer occurs with high frequency and is also highly resistant to radiation therapy. Thus, how to avoid radiation resistance and improve radiotherapy effectiveness is a crucial question. In the present study, human lung cancer A549 and H1299 cells were irradiated using γ-rays from a Co60 irradiator. Protein expression was detected by Western blotting. Cell cycle and apoptosis were measured by flow cytometry. Surviving fraction was determined by colony formation assay. γH2AX and 53BP1 foci formation were examined by fluorescence microscopy. In the results, we show that CHMP4C, a subunit of Endosomal sorting complex-III (ESCRT-III), is involved in radiation-induced cellular response. Radiation-induced Aurora B expression enhances CHMP4C phosphorylation in non-small cell lung cancer (NSCLC) cells, maintaining cell cycle check-point and cellular viability as well as resisting apoptosis. CHMP4C depletion enhances cellular sensitivity to radiation, delays S-phase of cell cycle and reduces ionizing radiation (IR)-induced γH2AX foci formation. We found that Aurora B targets CHMP4C and inhibition of Aurora B exhibits similar effects with silencing of CHMP4C in radioresistance. We also confirm that CHMP4C phosphorylation is elevated after IR both in p53-positive and-negative cells, indicating that the close correlation between CHMP4C and Aurora B signaling pathway in mediating radiation resistance is not p53 dependent. Together, our work establishes a new function of CHMP4C in radiation resistance, which will offer a potential strategy for non-small cell lung cancer by disrupting CHMP4C.