| BackgroundThere is great significance in the biological makers for the emergent medical rescue and effective cure of people exposed to ionizing radiation (IR). The markers should be accurate, specific, sensitive, non-invasive, as well as easy and fast to dose assessment. At present, chromosome aberration analysis of peripheral blood lymphocytes is currently accepted and used for biological dose assessment. Although it is accurate and stable, this method is time-consuming and requires complex analysis, which can affect efficiency and accuracy of radiation damage detection. As a kind of post-transcriptional regulator, miRNAs are implicated in the regulating of DNA damage response (DDR) induced by IR and IR plays a role in regulating miRNA expression. In addition, the expression of miRNAs exhibits a dose and time-dependence. This suggests that miRNA expression can be used as biomarkers of radiation exposure. Besides, IR induces target gene expression that suggests miRNA plays a central role in response to IR.ObjectiveIn vitro and animal study showed that IR can induce the expression of miR-21, miR-221, miR-210 and miR-150. And there is dose dependence. This suggests that miRNA expression can be used as biomarkers of radiation exposure. Based on the preliminary experimental research, we will take the radiotherapy patients as the simulation object of non-uniform irradiation, and analyze the expression of miR-210-3p, miR-221-3p, miR-21-5p and miR-150-5p in blood plasma of patients, and the expression of related target genes, lymphocytic cell cycle and apoptosis were analyzed. It will provide the reliable guidance for exploring the early radiation biomarkers of non-uniform irradiation injuries.MethodsBlood samples were collected from 13 patients before radiotherapy (OGy) and 24 h after radiotherapy at 2,10,20,30Gy, and 10 healthy healthy women volunteers. The expression of miRNAs in plasma of all patients is detected with qRT-PCR. The miRNA with difference significant will be analyzed by the receiver-operating characteristic curve (ROC curve) to calculate the area under curve, sensitivity and specificity. We will use Youden index for the identification of the optimal cutoff point. Besides, we will use flow cytometry (FCM) to analyze the expression changes of related target genes, the change of lymphocytic cell cycle and apoptosis.Results1. The levels of miR-210-3p, miR-221-3p, miR-21-5p and miR-150-5p in samples before radiotherapy were not statistically different from healthy volunteers (p>0.05). And the levels of miR-210-3p, miR-221-3p, miR-21-5p showed no significant difference among different groups after radiotherapy (p>0.05). And there was no significant difference between the expression of miR-150-5p before radiotherapy and after 2Gy radiotherapy (p>0.05). A gradual decrease was found in levels of miR-150-5p with increasing accumulative radiation dose (X2=18.76,p<0.05). After 10Gy,20Gy,30Gy, the expression reduced was 0.808 (Z=11.23, p>0.05),0.605 (Z=18.85, p<0.05),0.565 (Z=22.85, p<0.05) fold respectively. There was no significant difference in miR-150-5p expression between positive group and negative group in human epidermal growth factor receptor 2 (HER2), estrogen receptor (ER) or progesterone receptor (PR) (p>0.05).2. Compared with the group before radiotherapy, the levels of p53 showed no significant difference among different groups after radiotherapy (t=1.198, 0.050, 1.912,1.770, p>0.05); The levels of PTEN showed decreasing trend with accumulative radiation dose, but the PTEN expression has no significant difference (t=0.514,0.674,0.225,0.997, p>0.05).3. Compared with the group before radiotherapy, the peripheral blood lymphocyte cell cycle after 20Gy radiotherapy showed an accumulation in G2/M and S stage.While there is no change in G0/G1 stage. But there was no significant difference (p>0.05). And lymphocyte cell apoptosis hadn’t been detected.Conclusion1. Ionizing radiation induce decrease of miR-150 expression, and showed a dose dependent decrease in blood plasma. miR-150 may have potential value as the early radiation biomarkers of non-uniform irradiation.2. Under the condition of partial irradiation, PTEN as the target gene of miR-21 and miR-221, showed decreasing trend within a narrow range, and have great individual differences; And the p53 gene were not found in all of patients.3. An accumulation in G2/M and S stage was found in peripheral blood lymphocytes, but lymphocyte cell apoptosis hadn’t been detected, maybe the radiation-induced damage has been repaired. |
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