Two-miRNA-based finger-stick assay for estimation of absorbed ionizing radiation dose

Serum microRNA profile of rhesus macaques following ionizing radiation exposure and treatment with a medical countermeasure, Ex-Rad

Exposure to ionizing radiation (IR) presents a formidable clinical challenge. Total-body or significant partial-body exposure at a high dose and dose rate leads to acute radiation syndrome (ARS), the complex pathologic effects that arise following IR exposure over a short period of time. Early and accurate diagnosis of ARS is critical for assessing the exposure dose and determining the proper treatment. Serum microRNAs (miRNAs) may effectively predict the impact of irradiation and assess cell viability/senescence changes and inflammation. We used a nonhuman primate (NHP) model-rhesus macaques (Macaca mulatta)-to identify the serum miRNA landscape 96 h prior to and following 7.2 Gy total-body irradiation (TBI) at four timepoints: 24, 36, 48, and 96 h. To assess whether the miRNA profile reflects the therapeutic effect of a small molecule ON01210, commonly known as Ex-Rad, that has demonstrated radioprotective efficacy in a rodent model, we administered Ex-Rad at two different schedules of NHPs; either 36 and 48 h post-irradiation or 48 and 60 h post-irradiation. Results of this study corroborated our previous findings obtained using a qPCR array for several miRNAs and their modulation in response to irradiation: some miRNAs demonstrated a temporary increased serum concentration within the first 24-36 h (miR-375, miR-185-5p), whereas others displayed either a prolonged decline (miR-423-5p) or a long-term increase (miR-30a-5p, miR-27b-3p). In agreement with these time-dependent changes, hierarchical clustering of differentially expressed miRNAs showed that the profiles of the top six miRNA that most strongly correlated with radiation exposure were inconsistent between the 24 and 96 h timepoints following exposure, suggesting that different biodosimetry miRNA markers might be required depending on the time that has elapsed. Finally, Ex-Rad treatment restored the level of several miRNAs whose expression was significantly changed after radiation exposure, including miR-16-2, an miRNA previously associated with radiation survival. Taken together, our findings support the use of miRNA expression as an indicator of radiation exposure and the use of Ex-Rad as a potential radioprotectant.

Naringenin regulates cigarette smoke extract-induced extracellular vesicles from alveolar macrophage to attenuate the mouse lung epithelial ferroptosis through activating EV miR-23a-3p/ACSL4 axis

BACKGROUND

Alveolar macrophages are one of the momentous regulators in pulmonary inflammatory responses, which can secrete extracellular vesicles (EVs) packing miRNAs. Ferroptosis, an iron-dependent cell death, is associated with cigarette smoke-induced lung injury, and EVs have been reported to regulate ferroptosis by transporting intracellular iron. However, the regulatory mechanism of alveolar macrophage-derived EVs has not been clearly illuminated in smoking-related pulmonary ferroptosis. Despite the known anti-ferroptosis effects of naringenin in lung injury, whether naringenin controls EVs-mediated ferroptosis has not yet been explored.

PURPOSE

We explore the effects of EVs from cigarette smoke-stimulated alveolar macrophages in lung epithelial ferroptosis, and elucidate the EV miRNA-mediated pharmacological mechanism of naringenin.

STUDY DESIGN AND METHODS

Differential and ultracentrifugation were conducted to extract EVs from different alveolar macrophages treatment groups in vitro. Both intratracheal instilled mice and treated epithelial cells were used to investigate the roles of EVs from alveolar macrophages involved in ferroptosis. Small RNA sequencing analysis was performed to distinguish altered miRNAs in EVs. The ferroptotic effects of EV miRNAs were examined by applying dual-Luciferase reporter assay and miRNA inhibitor transfection experiment.

RESULTS

Here, we firstly reported that EVs from cigarette smoke extract-induced alveolar macrophages (CSE-EVs) provoked pulmonary epithelial ferroptosis. The ferroptosis inhibitor ferrostatin-1 treatment reversed these changes in vitro. Moreover, EVs from naringenin and CSE co-treated alveolar macrophages (CSE+Naringenin-EVs) markedly attenuated the lung epithelial ferroptosis compared with CSE-EVs. Notably, we identified miR-23a-3p as the most dramatically changed miRNA among Normal-EVs, CSE-EVs, and CSE+Naringenin-EVs. Further experimental investigation showed that ACSL4, a pro-ferroptotic gene leading to lipid peroxidation, was negatively regulated by miR-23a-3p. The inhibition of miR-23a-3p diminished the efficacy of CSE+Naringenin-EVs.

CONCLUSION

Our findings firstly provided evidence that naringenin elevated the EV miR-23a-3p level from CSE-induced alveolar macrophages, thereby inhibiting the mouse lung epithelial ferroptosis via targeting ACSL4, and further complemented the mechanism of cigarette-induced lung injury and the protection of naringenin in a paracrine manner. The administration of miR-23a-3p-enriched EVs has the potential to ameliorate pulmonary ferroptosis.

microRNA blood signature for localized radiation injury

A radiological accident, whether from industrial, medical, or malicious origin, may result in localized exposure to high doses of ionizing radiations, leading to the development of local radiation injury (LRI), that may evolve toward deep ulceration and necrosis of the skin and underlying tissues. Early diagnosis is therefore crucial to facilitate identification and management of LRI victims. Circulating microRNAs (miRNA) have been studied as potential diagnostic biomarkers of several diseases including hematological defects following whole-body irradiation (WBI). This study aims to identify a blood miRNA signature associated with LRI in a preclinical C57BL/6J mouse model of hindlimb irradiation using different 10-MV X-ray doses that lead to injuries of different severities. To this end, we first performed broad-spectrum plasma miRNA profiling, followed by a targeted validation step, on two independent animal cohorts. Using a multivariate sparse partial least square discriminant analysis, we identified a panel of eight circulating miRNAs able to segregate mice according to LRI severity. Interestingly, these miRNAs were previously associated with WBI (miR-150-5p, miR-342-3p, miR-146a-5p), inflammation (miR-18a-5p, miR-148b-3p, miR-532-5p) and skin diseases (miR-139-5p, miR-195-5p). Our results suggest the use of circulating miRNAs as suitable molecular biomarkers for LRI prognosis and diagnosis.

Regulation of Circulating miR-342-3p Alleviates the Radiation-Induced Immune System Injury

Ionizing radiation in space, radiation devices or nuclear disasters are major threats to human health and public security. Expanding countermeasures for dealing with accidental or occupational radiation exposure is crucial for the protection of radiation injuries. Circulating microRNAs (miRNAs) have emerged as promising radiation biomarkers in recent years. However, the origin, distribution and functions of radiosensitive circulating miRNAs remain unclear, which obstructs their clinical applications in the future. In this study, we found that mmu-miR-342-3p (miR-342) in mouse serum presents a stable and significant decrease after X-ray total-body irradiation (TBI). Focusing on this miRNA, we investigated the influences of circulating miR-342 on the radiation-induced injury. Through tail vein injection of Cy5-labeled synthetic miR-342, we found the exogenous miR-342-Cy5 was mainly enriched in metabolic and immune organs. Besides, the bioinformatic analysis predicted that miR-342 might involve in immune-related processes or pathways. Further, mice were tail vein injected with synthetic miR-342 mimetics (Ago-miR-342) after irradiation to upregulate the level of miR-342 in circulating blood. The results showed that the upregulation of circulating miR-342 alleviated the radiation-induced depletion of CD3+CD4+ T lymphocytes and influenced the levels of IL-2 and IL-6 in irradiated mice. Moreover, the injection of Ago-miR-342 improved the survival rates of mice with acute radiation injury. Our findings demonstrate that upregulation of circulating miR-342 alleviates the radiation-induced immune system injury, which provides us new insights into the functions of circulating miRNAs and the prospect as the targets for mitigation of radiation injuries.

RNA N6-methyladenosine modification-based biomarkers for absorbed ionizing radiation dose estimation

Radiation triage and biological dosimetry are critical for the medical management of massive potentially exposed individuals following radiological accidents. Here, we performed a genome-wide screening of radiation-responding mRNAs, whose N6-methyladenosine (m6A) levels showed significant alteration after acute irradiation. The m6A levels of three genes, Ncoa4, Ate1 and Fgf22, in peripheral blood mononuclear cells (PBMCs) of mice showed excellent dose-response relationships and could serve as biomarkers of radiation exposure. Especially, the RNA m6A of Ncoa4 maintained a high level as long as 28 days after irradiation. We demonstrated its responsive specificity to radiation, conservation across the mice, monkeys and humans, and the dose-response relationship in PBMCs from cancer patients receiving radiation therapy. Finally, NOCA4 m6A-based biodosimetric models were constructed for estimating absorbed radiation doses in mice or humans. Collectively, this study demonstrated the potential feasibility of RNA m6A in radiation accidents management and clinical applications.

Identification of the Kupffer cell-derived circulating IGFBP-3 as a universal radiation biomarker for heavy ion, proton, and X-ray exposure

The minimally invasive biomarkers that can facilitate a rapid dose assessment are valuable for the early medical treatment when accidental or occupational radiation exposure happens. Our previous proteomic research identified one kind of circulating protein, Insulin-like Growth Factor Binding Protein 3 (IGFBP-3), which showed a significant increase after total body exposure of mice to carbon ions and X-rays. However, several critical issues such as the responses to diverse radiation, the origin and underlying mechanism in radiation response obstruct the utilization of circulating IGFBP-3 as a reliable radiation biomarker. In this study, mice were subjected to total or partial body irradiation with carbon ions, protons or X-rays, or treated with chloroform as a comparison. The level of IGFBP-3 in serum and different organs were measured via Enzyme Linked Immunosorbent Assay (ELISA), Western blot (WB) and Immunohistochemistry (IHC). A significant increase of IGFBP-3 was discovered in serum and liver tissue post-irradiation with three kinds of radiation, but absent when challenged with chloroform. Likewise, a similar response was also observed in blood samples from patients receiving radiotherapy. Moreover, the effect of radiation on three main hepatic cells was investigated, the findings indicated that IGFBP-3 could be detected in the culture medium of Kupffer cells (MKC) alone and was elevated in cells and cultured medium of MKC post-irradiation. Additionally, we observed a co-expression effect between P53 and IGFBP-3 in liver tissues and MKC post-irradiation. Along with down-regulation of Trp53 by siRNA, the response of IGFBP-3 to radiation was attenuated. The present study demonstrated that circulating IGFBP-3 could be a promising universal biomarker for complex environmental radiation exposure, and the upregulation of IGFBP-3 is attributed to the MKC in a P53-dependent manner. Circulating IGFBP-3 assays would offer rapid, convenient and effective dose and toxicity assessment methods in occupational exposure or radiation disaster management.

Comparative Analysis of miRNA Expression after Whole-Body Irradiation Across Three Strains of Mice

Whole- or partial-body exposure to ionizing radiation damages major organ systems, leading to dysfunction on both acute and chronic timescales. Radiation medical countermeasures can mitigate acute damages and may delay chronic effects when delivered within days after exposure. However, in the event of widespread radiation exposure, there will inevitably be scarce resources with limited countermeasures to distribute among the affected population. Radiation biodosimetry is necessary to separate exposed from unexposed victims and determine those who requires the most urgent care. Blood-based, microRNA signatures have great potential for biodosimetry, but the affected population in such a situation will be genetically heterogeneous and have varying miRNA responses to radiation. Thus, there is a need to understand differences in radiation-induced miRNA expression across different genetic backgrounds to develop a robust signature. We used inbred mouse strains C3H/HeJ and BALB/c mice to determine how accurate miRNA in blood would be in developing markers for radiation vs. no radiation, low dose (1 Gy, 2 Gy) vs. high dose (4 Gy, 8 Gy), and high risk (8 Gy) vs. low risk (1 Gy, 2 Gy, 4 Gy). Mice were exposed to whole-body doses of 0 Gy, 1 Gy, 2 Gy, 4 Gy, or 8 Gy of X rays. MiRNA expression changes were identified using NanoString nCounter panels on blood RNA collected 1, 2, 3 or 7 days postirradiation. Overall, C3H/HeJ mice had more differentially expressed miRNAs across all doses and timepoints than BALB/c mice. The highest amount of differential expression occurred at days 2 and 3 postirradiation for both strains. Comparison of C3H/HeJ and BALB/c expression profiles to those previously identified in C57BL/6 mice revealed 12 miRNAs that were commonly expressed across all three strains, only one of which, miR-340-5p, displayed a consistent regulation pattern in all three miRNA data. Notably multiple Let-7 family members predicted high-dose and high-risk radiation exposure (Let-7a, Let-7f, Let-7e, Let-7g, and Let-7d). KEGG pathway analysis demonstrated involvement of these predicted miRNAs in pathways related to: Fatty acid metabolism, Lysine degradation and FoxO signaling. These findings indicate differences in the miRNA response to radiation across various genetic backgrounds, and highlights key similarities, which we exploited to discover miRNAs that predict radiation exposure. Our study demonstrates the need and the utility of including multiple animal strains in developing and validating biodosimetry diagnostic signatures. From this data, we developed highly accurate miRNA signatures capable of predicting exposed and unexposed subjects within a genetically heterogeneous population as quickly as 24 h of exposure to radiation.

Serum miRNA-based signature indicates radiation exposure and dose in humans: A multicenter diagnostic biomarker study

PURPOSE

Mouse and non-human primate models showed that serum miRNAs may be used to predict the biological impact of radiation doses. We hypothesized that these results can be translated to humans treated with total body irradiation (TBI), and that miRNAs may be used as clinically feasible biodosimeters.

METHODS

To test this hypothesis, serial serum samples were obtained from 25 patients (pediatric and adults) who underwent allogeneic stem-cell transplantation and profiled for miRNA expression using next-generation sequencing. miRNAs with diagnostic potential were quantified with qPCR and used to build logistic regression models with lasso penalty to reduce overfitting, identifying samples drawn from patients who underwent total body irradiation to a potentially lethal dose.

RESULTS

Differential expression results were consistent with previous studies in mice and non-human primates. miRNAs with detectable expression in this and two prior animal sets allowed for distinction of the irradiated from non-irradiated samples in mice, macaques and humans, validating the miRNAs as radiation-responsive through evolutionarily conserved transcriptional regulation mechanisms. Finally, we created a model based on the expression of miR-150-5p, miR-30b-5p and miR-320c normalized to two references and adjusted for patient age with an AUC of 0.9 (95%CI:0.83-0.97) for identifying samples drawn after irradiation; a separate model differentiating between high and low radiation dose achieved AUC of 0.85 (95%CI: 0.74-0.96).

CONCLUSIONS

We conclude that serum miRNAs reflect radiation exposure and dose for humans undergoing TBI and may be used as functional biodosimeters for precise identification of people exposed to clinically significant radiation doses.

Biomarkers for Biodosimetry and Their Role in Predicting Radiation Injury

Radiation-related normal tissue injury sustained during cancer radiotherapy or in a radiological or mass casualty nuclear incident is a major health concern. Reducing the risk and mitigating consequences of radiation injury could have a broad impact on cancer patients and citizens. Efforts to discover biomarkers that can determine radiation dose, predict tissue damage, and aid medical triage are underway. Exposure to ionizing radiation causes changes in gene, protein, and metabolite expression that needs to be understood to provide a holistic picture for treating acute and chronic radiation-induced toxicities. We present evidence that both RNA (mRNA, microRNA, long noncoding RNA) and metabolomic assays may provide useful biomarkers of radiation injury. RNA markers may provide information on early pathway alterations after radiation injury that can predict damage and implicate downstream targets for mitigation. In contrast, metabolomics is impacted by changes in epigenetics, genetics, and proteomics and can be considered a downstream marker that incorporates all these changes to provide an assessment of what is currently happening within an organ. We highlight research from the past 10 years to understand how biomarkers may be used to improve personalized medicine in cancer therapy and medical decision-making in mass casualty scenarios.

Biomarkers to Predict Lethal Radiation Injury to the Rat Lung

Currently, there are no biomarkers to predict lethal lung injury by radiation. Since it is not ethical to irradiate humans, animal models must be used to identify biomarkers. Injury to the female WAG/RijCmcr rat has been well-characterized after exposure to eight doses of whole thorax irradiation: 0-, 5-, 10-, 11-, 12-, 13-, 14- and 15-Gy. End points such as SPECT imaging of the lung using molecular probes, measurement of circulating blood cells and specific miRNA have been shown to change after radiation. Our goal was to use these changes to predict lethal lung injury in the rat model, 2 weeks post-irradiation, before any symptoms manifest and after which a countermeasure can be given to enhance survival. SPECT imaging with 99mTc-MAA identified a decrease in perfusion in the lung after irradiation. A decrease in circulating white blood cells and an increase in five specific miRNAs in whole blood were also tested. Univariate analyses were then conducted on the combined dataset. The results indicated that a combination of percent change in lymphocytes and monocytes, as well as pulmonary perfusion volume could predict survival from radiation to the lungs with 88.5% accuracy (95% confidence intervals of 77.8, 95.3) with a p-value of < 0.0001 versus no information rate. This study is one of the first to report a set of minimally invasive endpoints to predict lethal radiation injury in female rats. Lung-specific injury can be visualized by 99mTc-MAA as early as 2 weeks after radiation.

A Review of Radiation-Induced Alterations of Multi-Omic Profiles, Radiation Injury Biomarkers, and Countermeasures

Increasing utilization of nuclear power enhances the risks associated with industrial accidents, occupational hazards, and the threat of nuclear terrorism. Exposure to ionizing radiation interferes with genomic stability and gene expression resulting in the disruption of normal metabolic processes in cells and organs by inducing complex biological responses. Exposure to high-dose radiation causes acute radiation syndrome, which leads to hematopoietic, gastrointestinal, cerebrovascular, and many other organ-specific injuries. Altered genomic variations, gene expression, metabolite concentrations, and microbiota profiles in blood plasma or tissue samples reflect the whole-body radiation injuries. Hence, multi-omic profiles obtained from high-resolution omics platforms offer a holistic approach for identifying reliable biomarkers to predict the radiation injury of organs and tissues resulting from radiation exposures. In this review, we performed a literature search to systematically catalog the radiation-induced alterations from multi-omic studies and radiation countermeasures. We covered radiation-induced changes in the genomic, transcriptomic, proteomic, metabolomic, lipidomic, and microbiome profiles. Furthermore, we have covered promising multi-omic biomarkers, FDA-approved countermeasure drugs, and other radiation countermeasures that include radioprotectors and radiomitigators. This review presents an overview of radiation-induced alterations of multi-omics profiles and biomarkers, and associated radiation countermeasures.

Current Nanomedicine for Targeted Vascular Disease Treatment: Trends and Perspectives

Nanotechnology has been developed to deliver cargos effectively to the vascular system. Nanomedicine is a novel and effective approach for targeted vascular disease treatment including atherosclerosis, coronary artery disease, strokes, peripheral arterial disease, and cancer. It has been well known for some time that vascular disease patients have a higher cancer risk than the general population. During atherogenesis, the endothelial cells are activated to increase the expression of adhesion molecules such as Intercellular Adhesion Molecule 1 (ICAM-1), Vascular cell adhesion protein 1 (VCAM-1), E-selectin, and P-selectin. This biological activation of endothelial cells gives a targetability clue for nanoparticle strategies. Nanoparticle formation has a passive targeting pathway due to the increased adhesion molecule expression on the cell surface as well as increased cell activation. In addition, the VCAM-1-targeting peptide has been widely used to target the inflamed endothelial cells. Biomimetic nanoparticles using platelet and leukocyte membrane fragment strategies have been promising techniques for targeted vascular disease treatment. Cyclodextrin, a natural oligosaccharide with a hydrophobic cavity, increase the solubility of cholesterol crystals at the atherosclerotic plaque site and has been used to deliver the hydrophobic drug statin as a therapeutic in a targeted manner. In summary, nanoparticles decorated with various targeting molecules will be an effective and promising strategy for targeted vascular disease treatment.

Haptoglobin is an early indicator of survival after radiation-induced severe injury and bone marrow transplantation in mice

Background

Hematopoietic stem cell transplantation (HSCT) is the main treatment for acute radiation sickness, especially after fatal radiation. The determination of HSCT for radiation patients is mainly based on radiation dose, hemogram and bone marrow injury severity. This study aims to explore a better biomarker of acute radiation injury from the perspective of systemic immune response.

Methods

C57BL/6J female mice were exposed to total body irradiation (TBI) and partial body irradiation (PBI). Changes in haptoglobin (Hp) level in plasma were shown at different doses and time points after the exposure and treatment with amifostine or bone marrow transplantation. Student’s t-test/two tailed test were used in two groups. To decide the Hp levels as a predictor of the radiation dose in TBI and PBI, multiple linear regression analysis were performed. The ability of biomarkers to identify two groups of different samples was determined by the receiver operating characteristic (ROC) curve. The results were expressed as mean ± standard deviation (SD). Significance was set at P value < 0.05, and P value < 0.01 was set as highly significant. Survival distribution was determined by log-rank test.

Results

In this study, we found that Hp was elevated dose-dependently in plasma in the early post-irradiation period and decreased on the second day, which can be used as a molecular indicator for early dose assessment. Moreover, we detected the second increase of Hp on the 3rd and 5th days after the lethal irradiation at 10 Gy, which was eliminated by amifostine, a radiation protection drug, while protected mice from death. Most importantly, bone marrow transplantation (BMT) on the 3rd and 5th day after 10 Gy radiation improved the 30-days survival rate, and effectively accelerated the regression of secondary increased Hp level.

Conclusions

Our study suggests that Hp can be used not only as an early molecule marker of radiation injury, but also as an important indicator of bone marrow transplantation therapy for radiation injury, bringing new scientific discoveries in the diagnosis and treatment of acute radiation injury from the perspective of systemic immunity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03162-x.

Screening of miRNAs in White Blood Cell as a Radiation Biomarkers for Rapid Assessment of Acute Radiation Injury

Accidental radiation exposure is a threat to human health that necessitates effective clinical diagnosis. Suitable biomarkers are urgently needed for early assessment of exposure dose. Existing technologies being used to assess the extent of radiation have notable limitations. As a radiation biomarker, miRNA has the advantages of simple detection and high throughput. In this study, we screened for miRNAs with dose and time dependent responses in peripheral blood leukocytes via miRNA sequencing in establishing the animal model of acute radiation injury. Four radiation-sensitive and stably expressed miRNAs were selected out in the 24 h group of leukocyte miRNAs: mmu-miR-130b-5p, mmu-miR-148b-5p, mmu-miR-184-3p, mmu-miR-26a-2-3p, and five were screened in the 48 h group of leukocyte miRNAs: mmu-miR-130b-5p, mmu-miR-423-5p, mmu-miR-676-3p, mmu-miR-150-5p, mmu-miR-342-3p.The correlation curves between their expression and irradiation dose were plotted. Then, the results were validated by RT-qPCR in mouse peripheral blood. As a result, mmu-miR-150-5p and mmu-miR-342-3p showed the highest correlation at 48h after irradiation, and mmu-miR-130b-5p showed good correlation at both 24 h and 48 h after irradiation. In a conclusion, the miRNAs that are sensitive to ionizing radiation with dose dependent effects were selected out, which have the potential of forming a rapid assessment scheme for acute radiation injury.

Assessment of bone dose response using ATR-FTIR spectroscopy: A potential method for biodosimetry

The health care application of ionizing radiation has expanded worldwide during the last several decades. While the health impacts of ionizing radiation improved patient care, inaccurate handling of radiation technology is more prone to potential health risks. Therefore, the present study characterizes the bone dose response using bovine femurs from a slaughterhouse. The gamma irradiation was designed into low-doses (0.002, 0.004 and 0.007 kGy) and high-doses (1, 10, 15, 25, 35, 50 and 60 kGy), all samples received independent doses. The combination of FTIR spectroscopy and PLS-DA allows the detection of differences in the control group and the ionizing dose, as well as distinguishing between high and low radiation doses. In this way, our findings contribute to future studies of the dose response to track ionizing radiation effects on biological systems.

Analysis of circRNA-miRNA-mRNA Regulatory Network in Peripheral Blood of Radiation Workers

The health of radiation workers has always been our focus. Epidemiological investigation shows that long-term exposure to low-dose ionizing radiation can affect human health, especially cancer and cardiovascular disease, and there are many studies on it. However, up to now, there have been few reports on the research of blood and biological samples from radiation workers. In this study, radiation workers and healthy control groups were strictly screened, and the transcriptome of mRNA and circRNA was sequenced by extracting their peripheral venous blood. At the same time, appropriate data sets were selected in the GEO database for bioinformatics analysis, and circRNA-miRNA-mRNA network was constructed. We identified 9 different circular ribonucleic acids, 3 tiny ribonucleic acids, and 2 central genes (NOD 2 and IRF 7). These differentially expressed genes and non-coding RNA are closely related to ionizing radiation damage, and play an important role as biological markers. In conclusion, this study may provide new insights into the role of the circRNA-miRNA-mRNA regulatory network in the health of radiation workers, and provides a new strategy for the future study of radiation biology.

MicroRNAs as Biomarkers for Ionizing Radiation Injury

Accidental radiation exposures such as industrial accidents and nuclear catastrophes pose a threat to human health, and the potential or substantial injury caused by ionizing radiation (IR) from medical treatment that cannot be ignored. Although the mechanisms of IR-induced damage to various organs have been gradually investigated, medical treatment of irradiated individuals is still based on clinical symptoms. Hence, minimally invasive biomarkers that can predict radiation damage are urgently needed for appropriate medical management after radiation exposure. In the field of radiation biomarker, finding molecular biomarkers to assess different levels of radiation damage is an important direction. In recent years, microRNAs have been widely reported as several diseases’ biomarkers, such as cancer and cardiovascular diseases, and microRNAs are also of interest to the ionizing radiation field as radiation response molecules, thus researchers are turning attention to the potential of microRNAs as biomarkers in tumor radiation response and the radiation toxicity prediction of normal tissues. In this review, we summarize the distribution of microRNAs, the progress on research of microRNAs as markers of IR, and make a hypothesis about the origin and destination of microRNAs in vivo after IR.

The transcriptomic revolution and radiation biology

PURPOSE

This article will briefly review the origins and evolution of functional genomics, first describing the experimental technology, and then some of the approaches applied to data analysis and visualization. It will emphasize application of functional genomics to radiation biology, using examples from the author's work to illustrate several key types of analysis. It concludes with a look at non-coding RNA, alternative reading of the genome, and single-cell transcriptomics, some of the innovative areas that may help to shape future research in radiation biology and oncology.

CONCLUSIONS

Transcriptomic approaches have provided insight into many areas of radiation biology and medicine, and innovations in technology and data analysis approaches promise continued contributions to radiation science in the future.

Circulating tRNA-Derived Small RNAs as Novel Radiation Biomarkers of Heavy Ion, Proton and X-ray Exposure

The effective and minimally invasive radiation biomarkers are valuable for exposure scenarios in nuclear accidents or space missions. Recent studies have opened the new sight of circulating small non-coding RNA (sncRNA) as radiation biomarkers. The tRNA-derived small RNA (tsRNA) is a new class of sncRNA. It is more abundant than other kinds of sncRNAs in extracellular vesicles or blood, presenting great potential as promising biomarkers. However, the circulating tsRNAs in response to ionizing radiation have not been reported. In this research, Kunming mice were total-body exposed to 0.05-2 Gy of carbon ions, protons, or X-rays, and the RNA sequencing was performed to profile the expression of sncRNAs in serum. After conditional screening and validation, we firstly identified 5 tsRNAs including 4 tRNA-related fragments (tRFs) and 1 tRNA half (tiRNA) which showed a significant level decrease after exposure to three kinds of radiations. Moreover, the radiation responses of these 5 serum tsRNAs were reproduced in other mouse strains, and the sequences of them could be detected in serum of humans. Furthermore, we developed multi-factor models based on tsRNA biomarkers to indicate the degree of radiation exposure with high sensitivity and specificity. These findings suggest that the circulating tsRNAs can serve as new minimally invasive biomarkers and can make a triage or dose assessment from blood sample collection within 4 h in exposure scenarios.

Early-response multiple-parameter biodosimetry and dosimetry: risk predictions

The accepted generic multiple-parameter and early-response biodosimetry and dosimetry assessment approach for suspected high-dose radiation (i.e. life-threatening) exposure includes measuring radioactivity associated with the exposed individual (if appropriate); observing and recording prodromal signs/symptoms; obtaining serial complete blood counts with white-blood-cell differential; sampling blood for the chromosome-aberration cytogenetic bioassay using the 'gold standard' dicentric assay (premature chromosome condensation assay for exposures >5 Gy photon acute doses equivalent), measurement of proteomic biomarkers and gene expression assays for dose assessment; bioassay sampling, if appropriate, to determine radioactive internal contamination; physical dose reconstruction, and using other available opportunistic dosimetry approaches. Biodosimetry and dosimetry resources are identified and should be setup in advance along with agreements to access additional national, regional, and international resources. This multifaceted capability needs to be integrated into a biodosimetry/dosimetry 'concept of operations' for use in a radiological emergency. The combined use of traditional biological-, clinical-, and physical-dosimetry should be use in an integrated approach to provide: (a) early-phase diagnostics to guide the development of initial medical-management strategy, and (b) intermediate and definitive assessment of radiation dose and injury. Use of early-phase (a) clinical signs and symptoms, (b) blood chemistry biomarkers, and (c) triage cytogenetics shows diagnostic utility to predict acute radiation injury severity.

Utility of circulating microRNA-150 for rapid evaluation of bone marrow depletion after radiation, and efficiency of bone marrow reconstitution

PURPOSE

Total body irradiation (TBI) is a common myeloablative preparative regimen used in acute myeloid and lymphoblastic leukemia patients prior to allogenic hematopoietic stem cell transplantation (HSCT). The inefficient clearance of tumor cells and radiation-induced toxicity to normal tissues is attributed to relapse and morbidity in a significant fraction of patients. Developing biomarkers that provide an individual's physiological response to radiation will allow personalized treatment and follow-up. We investigated the utility of circulating microRNA150-5p (miR150) for evaluation of radiation dose response.

MATERIALS AND METHODS

Age-, gender-, and strain-matched wild type and miR150 null (knock out, KO) mice were subjected to TBI and evaluated for the impact of circulating miR150 expression on survival and hematological endpoints. Dose- and time-dependent changes of the miR150 level in bone marrow were assessed using flow cytometry. The functional roles of miR150 in cellular response to radiation were evaluated using apoptosis assay. miR150 expression in leukemic cell lines and in blood collected from leukemia patients with diverse outcomes were evaluated by quantitative RT-PCR.

RESULTS

Absence of miR150 in mice conferred resistance to radiation injury and resulted in accelerated recovery of lymphoid and myeloid cells after ablative or partially ablative TBI in mice. Overexpression of miR150 resulted in a higher percentage of cells at G2/M phases of cell cycle which is associated with increased sensitivity and susceptibility to apoptotic cell death after radiation. Levels of circulating miR150 were found to be decreased after radiation in leukemia patients and exhibited an inverse correlation with recurrence.

CONCLUSION

Current study demonstrates the utility of a miR150-based blood test for rapid evaluation of the efficiency of marrow ablation and recovery following radiation and HSCT. The internally controlled blood test will potentially provide near real-time evaluation of functional marrow that will allow optimal dosing based on an individual's physiological response to radiation.

The highs and lows of ionizing radiation and its effects on protein synthesis

Ionizing radiation (IR) is a constant feature of our environment and one that can dramatically affect organismal health and development. Although the impacts of high-doses of IR on mammalian cells and systems have been broadly explored, there are still challenges in accurately quantifying biological responses to IR, especially in the low-dose range to which most individuals are exposed in their lifetime. The resulting uncertainty has led to the entrenchment of conservative radioprotection policies around the world. Thus, uncovering long-sought molecular mechanisms and tissue responses that are targeted by IR could lead to more informed policymaking and propose new therapeutic avenues for a variety of pathologies. One often overlooked target of IR is mRNA translation, a highly regulated cellular process that consumes more than 40% of the cell's energy. In response to environmental stimuli, regulation of mRNA translation allows for precise and rapid changes to the cellular proteome, and unsurprisingly high-dose of IR was shown to trigger a severe reprogramming of global protein synthesis allowing the cell to conserve energy by preventing the synthesis of unneeded proteins. Nonetheless, under these conditions, certain mRNAs encoding specific proteins are translationally favoured to produce the factors essential to repair the cell or send it down the path of no return through programmed cell death. Understanding the mechanisms controlling protein synthesis in response to varying doses of IR could provide novel insights into how this stress-mediated cellular adaptation is regulated and potentially uncover novel targets for radiosensitization or radioprotection. Here, we review the current literature on the effects of IR at both high- and low-dose on the mRNA translation machinery.

Whole blood gene expression within days after total-body irradiation predicts long term survival in Gottingen minipigs

Gottingen minipigs mirror the physiological radiation response observed in humans and hence make an ideal candidate model for studying radiation biodosimetry for both limited-sized and mass casualty incidents. We examined the whole blood gene expression profiles starting one day after total-body irradiation with increasing doses of gamma-rays. The minipigs were monitored for up to 45 days or time to euthanasia necessitated by radiation effects. We successfully identified dose- and time-agnostic (over a 1-7 day period after radiation), survival-predictive gene expression signatures derived using machine-learning algorithms with high sensitivity and specificity. These survival-predictive signatures fare better than an optimally performing dose-differentiating signature or blood cellular profiles. These findings suggest that prediction of survival is a much more useful parameter for making triage, resource-utilization and treatment decisions in a resource-constrained environment compared to predictions of total dose received. It should hopefully be possible to build such classifiers for humans in the future.

Long and short non-coding RNA and radiation response: a review

Once thought of as arising from "junk DNA," noncoding RNAs (ncRNAs) have emerged as key molecules in cellular processes and response to stress. From diseases such as cancer, coronary artery disease, and diabetes to the effects of ionizing radiation (IR), ncRNAs play important roles in disease progression and as biomarkers of damage. Noncoding RNAs regulate cellular processes by competitively binding DNA, mRNA, proteins, and other ncRNAs. Through these interactions, specific ncRNAs can modulate the radiosensitivity of cells and serve as diagnostic and prognostic biomarkers of radiation damage, whether from incidental exposure in radiotherapy or in accidental exposure scenarios. Analysis of RNA expression after radiation exposure has shown alterations not only in mRNAs, but also in ncRNAs (primarily miRNA, circRNA, and lncRNA), implying an important role in cellular stress response. Due to their abundance and stability in serum and other biofluids, ncRNAs also have great potential as minimally invasive biomarkers with advantages over current biodosimetry methods. Several studies have examined changes in ncRNA expression profiles in response to IR and other forms of oxidative stress. Furthermore, some studies have reported modulation of radiosensitivity by altering expression levels of these ncRNAs. This review discusses the roles of ncRNAs in the radiation response and evaluates prior research on ncRNAs as biomarkers of radiation damage. Future directions and applications of ncRNAs in radiation research are introduced, including the potential for a clinical ncRNA assay for assessing radiation damage and for the therapeutic use of RNA interference (RNAi).

Transcriptomics for radiation biodosimetry: progress and challenges

PURPOSE

Transcriptomic-based approaches are being developed to meet the needs for large-scale radiation dose and injury assessment and provide population triage following a radiological or nuclear event. This review provides background and definition of the need for new biodosimetry approaches, and summarizes the major advances in this field. It discusses some of the major model systems used in gene signature development, and highlights some of the remaining challenges, including individual variation in gene expression, potential confounding factors, and accounting for the complexity of realistic exposure scenarios.

CONCLUSIONS

Transcriptomic approaches show great promise for both dose reconstruction and for prediction of individual radiological injury. However, further work will be needed to ensure that gene expression signatures will be robust and appropriate for their intended use in radiological or nuclear emergencies.