| BackgroundRadon-222 is a naturally radioactive gas generated from the decay of uranium-238. Radon-222 is responsible for approximately half of the human annual effective dose which came from natural background radiation in the world. As early as 1988, the International Agency for Research on Cancer (IARC) classified the radon and its progeny as carcinogenic factors. In 2005, the World Health Organization(WHO) launched a three-year global international radon project (IRP), and estimated the relationship between radon exposure and the global burden of disease (GDB). Data from cell, animal and miner studies, as well as residents of high radon background region, have all demonstrated the potential of radon exposure to induce biological damage. In this study, the concentration of radon in the spring is 102±11.4 Bq/L. The indoor radon concentration sharply increased to more than 200 Bq/m3 from background level (< 50 Bq/m3) in the process of using water, after about three hours, the indoor radon concentration gradually returned to background level. The concentration of radon daughter changed in line with radon concentration. Therefore, if lived in this environment for a long time, residents may be had radiation damage and health risk.ObjectiveUntil now the study about chromosome aberration and micronuclei and the expression of miRNA in peripheral blood of residents surrounding radon springs was less. Base on the preliminary experimental research, we will further explore the chromosome aberration and micronuclei in peripheral blood lymphocyte of lower radon levels to evaluate genetic damage of radon. Then on this basis, to investigate miRN As expression in peripheral blood in the early stage of radon exposure, we will analyze the expression of miRNA associated with the cell cycle in peripheral blood plasma and lymphocyte cell respectively. And it will provide the experimental data for recognition capacity of miRNA in peripheral blood as potential biomarkers for radon exposure.MethodsTwo groups were selected in Hebei province, Radon group was 43 residents surrounding hot springs with radon and control group was 44 residents with same living habit but not hot springs. In radon and control groups, the method of routine culture of whole blood (began with colchicines) was used to prepare chromosome and analyze chromosome aberration; Cytokinesis-block micronucleus method was used to measure micronucleus; QRT-PCR was used to detect miRNAs level. U test of poisson distribution was used for analysis of chromosome aberration and micronucleus rate, and χ2 test for analysis of micronucleus cell frequency, Poisson regression was adopted to analyze the association between micronucleus rate and radon exposure.; Mann-Whitney U test was used for statistical analysis of miRNA levels in plasma between radon and control group, and t test for statistical analysis of miRNA levels in lymphocyte cell, multivariate linear regression analysis were employed to test the association between miRNAs expression and radon exposure.ResultsCompared with control group, chromosome type aberration and chromatid type aberration of radon group had no significant statistical difference (u=0.66,0.17, p>0.05). "Dic+r" in radon group and the control were 0.11±0.05% and 0.13±0.05%, respectively. No significant differences (w=0.36, p>0.05) were found between the two groups but both much higher than the average spontaneous rate of chromosome of the healthy people (0.03%). In the radon group, there was also no significant statistical difference in chromosome type aberration and chromatid type aberration between male and female (w=0.03,p>0.05; u=2.00,p=0.046).In radon group the averages of micronucleus rate and micronucleus cell frequency were significantly higher than control group (u=8.26,χ2=47.76,p<0.01). In radon group, the micronucleus rate and micronucleus cell frequency were significantly increased with age (χ2=44.034,27.739, p<0.01); And the micro nucleus rate and micronucleus cell frequency of female were significantly higher than male (u=7.98,χ2=37.123, p<0.01). Controlling of confounding factors such as age, gender, smoking and drinking alcohol, the micronucleus rate was associated with radon exposure (χ2=62.51,p<0.01).In plasma of radon group the levels of miR-16, miR-106b, miR-34a, miR-449a and kt-7g were significantly increased compared with control group (Z=-2.278,-3.835,-2.084,-2.719,-2.721,p<0.05). After controlling of confounding factors such as age, gender, smoking and drinking, alteration of miR-16, miR-106b, miR-449a and let-7g in plasma were positively correlated with radon exposure (t=2.154,3.711, 2.319,2.015, p<0.05), but not associated with age, gender, smoking and drinking factors. No significant difference observed in the plasma levels of miR-34a between the two groups (t=1.772,p>0.05).Compared with control group, the levels of miR-106b, miR-449a and let-7g in lymphocyte cell of radon group were significantly increased (t=4.180,2.422,2.794, p<0.05). After controlling of confounding factors such as age, gender, smoking and drinking, alteration of miR-106b, miR-449a and let-7g in lymphocyte cell were positively correlated with radon exposure (t=4.091,2.716,2.440, p<0.05), but not associated with age, gender, smoking and drinking factors. No significant difference observed in the lymphocyte cell levels of miR-16 and miR-34a between the two groups (t=0.990,0.147,p>0.05).Conclusion1. The radon springs could cause the increase of the incidence of micronucleus in peripheral blood lymphocyte, but we could not demonstrate the spring with radon has radiation injure to its residents.2. Alteration of miR-106b, miR-449a and let-7g in plasma caused by radon exposure was in line with alteration of miR-106b, miR-449a and let-7g in lymphocyte.3. MiR-106b, miR-449a and let-7g levels could have recognition capacity as potential biomarkers for radon exposure. |
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