Study On Using MicroRNA-575 As A Biomarker Of Damage Induced By Ionizing Radiation

ObjectiveIn this study,the effect of ionizing radiation(IR)on micro-ribonucleic acid-575(miR-575)level was investigated to primarily explore the feasibility of leukocytes miR-575 as a biomarker of IR.,improving the awareness of biological effects of IR and providing scientific reference for the health effects evaluation of radiation workers in China.MethodsThe present study included 232 subjects(117 males and 115 females)occupationally exposed to IR(radiation workers in hospitals),and their mean age was 36.66±4.87 years.A11 radiation workers were divided into four groups according to their job classification at the time of blood collection,as follow:diagnostic radiology(n=59),radiotherapy(n=58),nuclear medicine(n=58)and interventional radiology(n=57)groups.The annual effective dose was monitored during their entire working time using personal dose-meters,and questionnaires were used to collect their demographic date and other information needed.All subjects signed written consents,and 5 ml peripheral blood sample was obtained from each participant for hematological analysis(including WBC,RBC,PLT,LY counts and Hb content),MN assay,and leukocytes miR-575 detection.In addition,venous blood samples from 2 healthy donors were collected into EDTA-K2 vacuum tubes and were divided into four groups.Six samples in each group were irradiated with X-ray with 0 Gy,0.5 Gy,1 Gy,3 Gy,5 Gy and 8 Gy respectively,at dose with a dose rate of 2 Gy/min,over an area of 10×10 cm2,at room temperature.After irradiation,the blood samples were coded and cultured in 6 ml PRMI-1640 medium supplemented with 10%fetal bovine serum,0.2%gentamycin(80mg/ml).The cultures were incubated for 12 h,24 h,48 h,and 72 h respectively,at 37? in a humidified and dark incubator with 95%air/5%CO2.Cultures were centrifuged after harvesting,and the leukocytes were separated.The miR-575 level in the cells was detected by quantitative Real-time PCR(RT-qPCR)assay.Statistical analysis was performed using SPSS version 21.0,and all statistical tests were based on two-sided probability with significance level of 0.05.Results(1)Hematological results.The WBC,RBC,PLT,LY count and Hb content of all radiation workers were in the normal range.The mean value of WBC count of radiation workers in interventional group was significantly lower than that in diagnostic group(P<0.05).But there were insignificant difference in mean value of RBC,PLT,LY count,and Hb among four groups(P>0.05).(2)Annual effective dose measurement.There was statistically significant difference in effective dose among four groups(P<0.05).The effective dose in interventional radiology group was significant higher than that in diagnostic radiology,radiotherapy and nuclear medicine groups(P<0.05).A significantly higher was observed in nuclear medicine group compared to radiotherapy group(P<0.05).But there was insignificant difference between radiotherapy and diagnostic radiology groups,as well as between the diagnostic radiology and nuclear medicine groups(P>0.05).(3)Frequency of micronuclei in peripheral lymphocytes.No significant difference was found between different age groups(P>0.05).The frequency of micronuclei in female was significantly higher than that in male but it in ?1 mSv dose groups was insignificantly higher than other dose groups.What's more,no correlations were observed between micronuclei frequency and job title as well as occupation.(4)Leukocytes miR-575 level of radiation workers and its influence factors.There was no statistically significant difference in leukocytes miR-575 between different age,gender and occupation groups(P>0.05),but significant difference was found in different job title groups(P<0.05).The mean leukocytes miR-575 level of interventional radiation workers was significantly higher than that in diagnostic radiology,radiotherapy and nuclear medicine groups(P<0.05).However,no significant differences were observed between radiotherapy and diagnostic radiology group,as well as radiotherapy and nuclear medicine groups(P>0.05).Result of multiple regression analysis revealed that the effective dose,job classification and working period significantly affected the leukocytes miR-575 level of radiation workers(P<0.05),on the contrary,leukocytes miR-575 level were independent of age,gender and occupation(P>0.05).Leukocytes miR-575 increased along with the increase of effective dose and working period.(5)In vitro experiment.The impact of radiation dose on miR-575 level was extremely significant(P<0.05),while incubation time was independent of miR-575 level(P>0.05).Compared to shame(0Gy)group,miR-575 level in leukocytes of the cultures was significantly increased after irradiation of 0.5 Gy,1 Gy 3 Gy and 5 Gy(P<0.05).miR-575 level continuously increased and peaked at 5Gy of radiation dose,then decreased moderately.The dose-respond curve was fitted with quadratic function at dose range of 0-8 Gy,and the equation was as follow:Y=-0.0054D2+0.0432D+0.343(R2=0.929).ConclusionLeukocytes miR-575 level in radiation workers may be linked to the damage induced by ionizing radiation.The miR-575 has the potential to be used as a biomarker for damage caused by occupational exposure to low-dose ionizing radiation.It is also feasible to use it as a biomarker under the condition of acute high-dose ionizing radiation,but further study is needed.