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目的分析不同受照剂量和不同受照时间对人周围血淋巴细胞生长抑制和DNA损伤基因45(Gadd45)mRNA相对表达水平的影响,探讨Gadd45基因作为生物剂量计的可能性。方法 1剂量-效应关系研究。以0.00、0.10、0.25、0.50、1.00、2.00、3.00和5.00 Gy剂量X射线离体照射健康人周围血样,分离淋巴细胞进行检测;2时间-效应关系研究。以2.00 Gy剂量X射线离体照射健康人周围血样,分离淋巴细胞后分别于培养0、3、6、12、24和48 h时收获细胞。采用实时荧光定量聚合酶链反应法检测Gadd45 mRNA相对表达水平。结果 1 0.00~0.50 Gy剂量范围内,Gadd45 mRNA相对表达水平随照射剂量的增加而增加,回归方程为y=1.056 9+7.132 2 x[决定系数(R2)=0.992,P<0.01]。0.50 Gy剂量组Gadd45 mRNA相对表达水平达到峰值,为0.00 Gy剂量组的4.53倍;0.50~5.00 Gy剂量范围内,Gadd45 mRNA相对表达水平呈波动性下降。22.00 Gy剂量照射后3~12 h,Gadd45 mRNA相对表达水平随照射时间的增加而增加,回归方程为y=-6.366 0+4.965 0 x(R2=0.932,P<0.05)。照射后12 h时间组Gadd45 mRNA相对表达水平达到峰值,为0 h时间组的57.68倍;Gadd45 mRNA相对表达水平在照射后24~48 h大幅度下降,照射后48 h时间组为0 h时间组的2.08倍。结论 X射线照射可致Gadd45 mRNA表达上调,在一定剂量和时间范围内具有良好的剂量-效应和时间-效应关系;但Gadd45基因作为新型生物剂量计仍需进一步研究验证。
Objective To analyze the effects of different doses and different exposure time on the relative expression of Gadd45 mRNA in peripheral blood lymphocytes and the possibility of using Gadd45 as a biological dosimeter. Method 1 dose-response relationship. The peripheral blood samples of healthy volunteers were irradiated by x-rays at doses of 0.00,0.10,0.25,0.50,1.00,2.00,3.00 and 5.00 Gy separately, and the lymphocytes were separated for detection. The time-effect relationship was studied. The peripheral blood samples of healthy people were irradiated with x-ray dose of 2.00 Gy. After the lymphocytes were separated, the cells were harvested at 0, 3, 6, 12, 24 and 48 h respectively. The relative expression level of Gadd45 mRNA was detected by real-time fluorescence quantitative polymerase chain reaction. Results The relative expression level of Gadd45 mRNA in the dose range of 0.00-0.50 Gy increased with the increase of irradiation dose. The regression equation was y = 1.056 9 + 7.132 2 x [R2 (r) = 0.992, P <0.01]. The relative expression level of Gadd45 mRNA in the 0.50 Gy dose group reached the peak, which was 4.53 times higher than that in the 0.00 Gy dose group. The relative expression level of Gadd45 mRNA decreased in the dose range of 0.50 ~ 5.00 Gy. The relative expression level of Gadd45 mRNA increased with irradiation time from 3 to 12 h after irradiation with 22.00 Gy dose. The regression equation was y = -6.366 0 + 4.965 0 x (R2 = 0.932, P <0.05). The relative expression level of Gadd45 mRNA at 12 h after irradiation reached the peak value, which was 57.68 times of that at 0 h time point. The relative expression level of Gadd45 mRNA decreased significantly at 24 h to 48 h after irradiation, and at 0 h time point 2.08 times. Conclusion Xadradiation can up-regulate the expression of Gadd45 mRNA, and it has good dose-effect and time-effect relationship within a certain dose and time range. However, Gadd45 gene needs further study and verification as a novel biological dosimeter.