Serum Proteins as New Biomarkers for Whole-Body Exposure to High- and Low-LET Ionizing Radiation

Involvement of GSTP1 in low dose radiation-induced apoptosis in GM12878 cells

BACKGROUND

Low-dose ionizing radiation-induced protection and damage are of great significance among radiation workers. We aimed to study the role of glutathione S-transferase Pi (GSTP1) in low-dose ionizing radiation damage and clarify the impact of ionizing radiation on the biological activities of cells.

RESULTS

In this study, we collected peripheral blood samples from healthy adults and workers engaged in radiation and radiotherapy and detected the expression of GSTP1 by qPCR. We utilized γ-rays emitted from uranium tailings as a radiation source, with a dose rate of 14 μGy/h. GM12878 cells subjected to this radiation for 7, 14, 21, and 28 days received total doses of 2.4, 4.7, 7.1, and 9.4 mGy, respectively. Subsequent analyses, including flow cytometry, MTS, and other assays, were performed to assess the ionizing radiation's effects on cellular biological functions. In peripheral blood samples collected from healthy adults and radiologic technologist working in a hospital, we observed a decreased expression of GSTP1 mRNA in radiation personnel compared to the healthy controls. In cultured GM12878 cells exposed to low-dose ionizing radiation from uranium tailings, we noted significant changes in cell morphology, suppression of proliferation, delay in cell cycle progression, and increased apoptosis. These effects were partially reversed by overexpression of GSTP1. Moreover, low-dose ionizing radiation increased GSTP1 gene methylation and downregulated GSTP1 expression. Furthermore, low-dose ionizing radiation affected the expression of GSTP1-related signaling molecules.

CONCLUSIONS

This study shows that low-dose ionizing radiation damages GM12878 cells and affects their proliferation, cell cycle progression, and apoptosis. In addition, GSTP1 plays a modulating role under low-dose ionizing radiation damage conditions. Low-dose ionizing radiation affects the expression of Nrf2, JNK, and other signaling molecules through GSTP1.

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.

Comparison of Proteomic Expression Profiles after Radiation Exposure across Four Different Species

There is a need to identify biomarkers of radiation exposure for use in development of circulating biodosimeters for radiation exposure and for clinical use as markers of radiation injury. Most research approaches for biomarker discovery rely on a single animal model. The current study sought to take advantage of a novel aptamer-based proteomic assay which has been validated for use in many species to characterize changes to the blood proteome after total-body irradiation (TBI) across four different mammalian species including humans. Plasma was collected from C57BL6 mice, Sinclair minipigs, and Rhesus non-human primates (NHPs) receiving a single dose of TBI at a range of 3.3 Gy to 4.22 Gy at 24 h postirradiation. NHP and minipig models were irradiated using a 60Co source at a dose rate of 0.6 Gy/min, the C57BL6 mouse model using an X-ray source at a dose rate of 2.28 Gy/min and clinical samples from a photon source at 10 cGy/min. Plasma was collected from human patients receiving a single dose of 2 Gy TBI collected 6 h postirradiation. Plasma was screened using the aptamer-based SomaLogic SomaScan® proteomic assay technology to evaluate changes in the expression of 1,310 protein analytes. Confirmatory analysis of protein expression of biomarker HIST1H1C, was completed using plasma from C57BL6 mice receiving a 2, 3.5 or 8 Gy TBI collected at days 1, 3, and 7 postirradiation by singleplex ELISA. Summary of key pathways with altered expression after radiation exposure across all four mammalian species was determined using Ingenuity Pathway Analysis (IPA). Detectable values were obtained for all 1,310 proteins in all samples included in the SomaScan assay. A subset panel of protein biomarkers which demonstrated significant (p < 0.05) changes in expression of at least 1.3-fold after radiation exposure were characterized for each species. IPA of significantly altered proteins yielded a variety of top disease and biofunction pathways across species with the organismal injury and abnormalities pathway held in common for all four species. The HIST1H1C protein was shown to be radiation responsive within the human, NHP and murine species within the SomaScan dataset and was shown to demonstrate dose dependent upregulation at 2, 3.5 and 8 Gy at 24 h postirradiation in a separate murine cohort by ELISA. The SomaScan proteomics platform is a useful screening tool to evaluate changes in biomarker expression across multiple mammalian species. In our study, we were able to identify a novel biomarker of radiation exposure, HIST1H1C, and characterize panels of radiation responsive proteins and functional proteomic pathways altered by radiation exposure across murine, minipig, NHP and human species. Our study demonstrates the efficacy of using a multispecies approach for biomarker discovery.

A Biomarker Panel of Radiation-Upregulated miRNA as Signature for Ionizing Radiation Exposure

Ionizing radiation causes serious injury to the human body and has long-time impacts on health. It is important to find optimal biomarkers for the early quick screening of exposed individuals. A series of miRNAs signatures have been developed as the new biomarkers for diagnosis, survival, and prognostic prediction of cancers. Here, we have identified the ionizing radiation-inducible miRNAs profile through microarray analysis. The biological functions were predicted for the top six upregulated miRNAs by 4 Gy γ-rays: miR-1246, miR-1307-3p, miR-3197, miR-4267, miR-5096 and miR-7641. The miRNA-gene network and target gene-pathway network analyses revealed that DNAH3 is the target gene associated with all the six miRNAs. GOLGB1 is related to 4 miRNAs and other 26 genes targeted by 3 miRNAs. The upregulation of fifteen miRNAs were further verified at 4 h and 24 h after 0 to 10 Gy irradiation in the human lymphoblastoid AHH-1 cells, and some demonstrated a dose-dependent increased. Six miRNAs, including miR-145, miR-663, miR-1273g-3p, miR-6090, miR-6727-5p and miR-7641, were validated to be dose-dependently upregulated at 4 h or 24 h post-irradiation in both AHH-1 and human peripheral blood lymphocytes irradiated ex vivo. This six-miRNA signature displays the superiority as a radiation biomarker for the translational application of screening and assessment of radiation exposed individuals.