Effect of total-body Irradiation on gene expression in mouse whole blood

For victims of radiological accidents, rapid dose estimation and damage prediction are essential. Administering the gold-standard biodosimetry chromosome aberration assay requires highly skilled individuals and several days of labor; consequently, rapid turnaround is an important concern. Identification of new dose estimation markers and damage-predicting in vivo molecules to replace the chromosome aberration assay is crucial to improving the delivery time of medical treatment. Here, we investigated the applicability of mRNA levels using a mouse model. Female C57BL/6J mice were X-ray irradiated at various doses, and a DNA microarray was then performed to identify differentially expressed mRNAs in whole blood. The microarray analysis identified 14 radioresponsive mRNAs with more than fourfold differences by pattern matching in the expression at 24 h postirradiation. In particular, mRNA expression of Slfn4, Itgb5, Smim3, Tmem40, Litaf, Gp1bb and Cxx1c was significantly increased in a radiation-dose-dependent manner, as validated by reverse transcription quantitative polymerase chain reaction. We also performed an analysis using the cBioPortal for Cancer Genomics and found that the overall survival of ovarian adenocarcinoma patients with alterations in Smim3 and that of thymoma patients with alterations in Cxx1c had a worse prognosis than patients without these alterations. These findings suggest that the expression of several genes in whole blood was a sensitive and specific biomarker of radiation exposure and can be used as a rapid and reliable prospective molecular biomarker in radiological emergencies. Seven-week-old female C57BL/6JJcl mice were delivered from the breeding facilities of Clea Japan (Tokyo, Japan). Eight-week-old mice were randomly divided into 4 groups and subjected to varying TBI doses of 0, 0.5, 1 or 3 Gy of X-rays (150 kVp, 20 mA, 0.5-mm aluminum and 0.3-mm copper filters) at a dose rate of 1.0 Gy/min using an MBR-1520R X-ray generator (Hitachi Medical, Tokyo, Japan). All mice were housed in standard cages in a conventional clean room under a 12-h light/dark cycle. The mice had ad libitum access to sterilized standard laboratory mouse chow diet and drinking water. In the present study, the selection criteria applied prior to sacrifice were >20% loss of body weight and respiratory distress. After 24-h, mice treated with TBI only (TBI mice) and those that did not receive TBI (control mice) were anaesthetized with isoflurane (Powerful Isoful®; Zoetis, London, UK) and sacrificed for collection of whole blood.