Objective To investigate the influences of miR-34a on the radiosensitivity of H1299 cells.Methods CCK-8 kit was used to examine the viability of H1299 cells which were exposed to different doses (0,2,4,6 and 8 Gy) of 60Co γ-rays after transient transfection of pre-miR-34a.Apoptosis rate and cell cycle were measured with flow cytometry.The expression levels of miR-34a target genes,bcl-2,bax,CDK4,CDK6 and cyclinD1 were analyzed by real-time PCR.Results Compared to the control group of negative transfection,the cell viability in pre-miR-34a transfection group decreased significantly after irradiation at0,2,4,6,8 Gy (t=-2.39,-3.12,-4.98,-4.03,-3.06,P＜0.05) in a dose-dependent manner.After being irradiated with 6 Gy γ-rays,the apoptotic rate in pre-miR-34a transfection group was significantly increased (t =7.06,P ＜ 0.05) together with an accumulation of G0/G1 phase (t =3.94,P ＜ 0.05) and a reduction of S phase (t =6.23,P ＜ 0.05).The gene expression levels of bcl-2,CDK4 and CDK6 in pre-miR-34a transfection group were respectively decreased (t =3.39,12.88,6.21,P ＜ 0.05) of negative control.cyclinD1 was also decreased but no significance,while bax was increased to 1.94 times of negative control (t =-4.35,P ＜ 0.05) together with a decrease of bcl-2/bax.Conclusions miR-34a could promote cell apoptosis,induce G0/G1 phase accumulation,suppress cell activity,and in turn increase the radiosensitivity of H1299 cells.

Objective To explore the role of γ-synuclein(SNCG) siRNA in the radiosensitivity of breast cancer T47D cells.Methods SNCG siRNA was synthesized according to the coding sequence of SNCG mRNA and then transiently transferred into T 47D cell with lipofectamine .The expression of SNCG gene and protein was detected by RT-PCR and Western-blot, respectively.Cells were divided into three groups, SNCG siRNA interference group , negative control group and blank control group , which were irradiated with different doses of 60 Coγ-rays.Cell radiosensitivity was evaluated by colony formation assay , cell proliferation was assayed by CCK-8 kit, and the protein expressions of phosphorylated-AKT and mTOR were detected by Western blot assay .Results Compared with blank control cells , the expressions of SNCG gene and protein in the SNCG siRNA transferred T 47D cells were efficiently diminished .Cell colony formation results showed that , under 4, 6, 8 Gy irradiation, the cell survival of siRNA transfection group was lower than that of control group (t=5.449, 8.882, 21.503, P<0.05).CCK-8 experiments showed that the cell proliferation abilities of siRNA group at 24, 48, 72 h after 6 Gy irradiation were lower than those of control group (t=5.603, 4.839, 6.115, P<0.05).In addition, after 6 Gy irraddaition, the AKT and mTOR phosphorylation levels in the siRNA group were more obviously reduced compared with blank groups , but the total AKT and mTOR had no changes .Conclusions Transfection of SNCG siRNA can enhance the radiosensitivity of breast cancer cells probably by inhibiting p -AKT signal pathway .

Objective To investigate the expressions of lung cancer related genes and miRNA in peripheral blood of the residents surrounding the extremely high radon hot springs in Ruoergai County,Sichuan Province. Methods Peripheral blood samples were collected from the local residents.Expressions of lung cancer related genes (p53,k-ras) and miRNA (let-7a,miR-34a/b) were detected by real-time PCR and the protein expressions of p53 and k-ras were detected by Western blot.Results The expressions of p53 and k-ras mRNA of the residents in high radon area were 0.97 and 1.33 times of the control respectively (t =0.13,-1.12,P ＞0.05),and the p53 and k-ras protein levels were 0.70 and 1.23 times of the control respectively (t =0.72,0.46,P ＞ 0.05).The let-7a of the residents in high radon area was lower (t =1.63,P ＞ 0.05 ) while the miR-34a and miR-34b were significantly higher than those of the controls (t =- 3.20,- 3.32,P ＜ 0.05).Conclusions Based on the expressions of p53 and k-ras gene and miRNA,it can be concluded that the residents surrounding the high radon hot springs received radiation damage.

Objective To analyze the chromosome aberrations induced by partial radiation in human peripheral blood lymphocytes in vitro.Methods Heparinized whole blood samples were exposed to 2 Gy ~(60)Co 7-rays at 37℃ ,and then mixed with non-irradiated blood by different ratio.The slides were prepared after culturing and the unstable aberrations were analyzed.Results The chromosome aberrations had a good relationship with the ratio of irradiated blood.The chromosome aberrations in partial irradiated group were higher than that in the irradiated group.The estimated dose was 1.27 Gy when the ratio was 1 : 1 ,greater than the dose of 1 Gy.The estimated dose was 0.93 Gy when the ratio was 0.5＝1,also greater than 0.5 Gy.But when the ratio was 1:0,the radiation dose was accordant with the estimated dose.Conclusions Chromosome aberrations could be a biomarker for estimating the uneven irradiation.

Objective To investigate 60Co γ-ray induced damage in lymphocytes and the relationship between doses of 60Co γ-ray irradiation and the levels of phosphorylated H2AX and ATM.Methods Cells were irradiated with 60Co γ-rays in the range of 0-8 Gy.The levels of phosphorylated H2AX and ATM were detected by Western blot and FACScan,respectively.The micronucleus(MN)was analyzed by CB method to evaluate DNA damage.Results FACScan results showed the dose-effect relationship of γ-H2AX expression were linear.square at 0.5 h post-irradiation to different doses,and the fitting curve was shown as Y=3.96+11.29D-0.45D2.The level of phosphorylated ATM(p-ATM)was not changed significantly by using the same method.Western blot showed that p-ATM protein expression was significandy increased after irradiation compared with sham.irradiated group.The MN assay which represented DNA damage was sensitive to different doses.Conclusions γ-ray irradiation could induce the phosphorylation of H2AX and ATM,which may play an important role in indicating DNA damage.Both of H2AX and ATM have the potential as sensitive biomarker and biodosimeter for radiation damage.

Objective To investigate the effects of 60Co γ-ray partial radiation on chromosome aberration in human peripheral blood in vitro.Methods The samples of heparinized peripheral whole blood from 3 healthy persons were exposed to 60Co γ-rays at the doses between 0 and 8 Gy with the dose rate of 0.35 Gy/min at the temperature of 37 ℃ ,and then mixed with the unirradiated blood samples of the Microscopy was used to observe the chromosome aberration double ( centromere + centromere) and the biological dose was estimated thereby.ResultsThe amounts of double centromere + centromere were increased along with the dose of irradiation in all groups.The estimated biological dose was higher than the 1/3 of the irradiation dose when the dose was between 0.5 to 2 Gy,and was close to the 1/3 of the irradiation dose when the dose was between 4 to 8 Gy.Conclusion Chromosome aberration can be used as a biomarker in estimation of uneven irradiation.

Objective To explore the effect of radon and its progeny on the expression and mutations of p53 in lung tissue of mouse model. Methods Apoptosis was detected by terminal deoxynucleotidy transferase-mediated dUTP-biotin nick end labeling. The expression of p53 gene was analyzed by immunohistochemistry, Western blot and realtime-PCR. PCR-SSCP was used to detect the mutation of p53 in lung tissues. Results Compared with those in the control group, the apoptotic index were increased significantly in 30 WLM and 60 WLM groups( t = 18.11, -10.30,P ＜ 0.05 ). The p53 protein was increased significantly ( t = -11.08, P ＜ 0.05; t = - 7.00, P ＜ 0.0 ) ) in 30 WLM and 60 WLM groups. The mutation of p53 gene was not detected in lungs of radon-exposure mice. Conclusions Lung and bronchus might be the targets of radon and its progeny, and p53 gene plays an important role in the progression of radon-induced lung injury.

Objective To analyze the influence of ionizing radiation on the lymphocytes and its regulatory T cells in mice.Methods Mice were administered with whole body irradiation of γ-rays at different doses,and lymphocytes were separated from thymus and spleen,then the number of total cells were counted and the percentages of CD4 + T and CD4 + FOXP3 + CD25 + Treg lymphocytes were analyzed by using FACS.Results The lymphocyte numbers in thymus and spleen decreased in dosedependent manner and reached to the minimum at 4 d after irradiation (F =118.08,144.01,P ＜ 0.05).Exposure to higher dose(more than 1 Gy) decreased Treg number time-dependently in thymus,however increased it in spleen.On the contrary,exposure to lower dose (less than 0.75 Gy) increased Treg number in thymus.Besides,the percentage of Treg cells increased dose-dependently(in thymus,F =5.16,89.44,3.01,P ＜ 0.05 ; in spleen,F =52.02,32.13,27.45,P ＜ 0.05).Conclusions The radiation responses of lymphocytes and their Treg subpopulation vary with the different doses.Treg cells are resistant to high dose irradiation,however,their differentiation could be induced by low dose irradiation.In addition,the different time-dependent responses of lymphocytes and their subpopulation to ionizing radiation indicate the difference of lymphocyte maturation,differentiation and emigration.

Objective To explore the effects of high background radiation on the expressions of miR-16, miR-106b, miR-449a, miR-34a and let-7g in peripheral blood plasma of the residents .Methods Totally 110 healthy female long-term local residents aged over 50 years were randomly selected from the high background radiation area and the control area , while their age, body mass index(BMI) and other indicators were surveyed .The relative expression levels of miRNAs in peripheral blood plasma of these women were quantitatively detected by real-time fluorescence quantitative PCR ( RT-PCR) .Then t-test was used to analyze the cumulative dose , age and BMI between the high background and control group .Mann-Whitney U-test was used for statistical analysis of miRNA expression levels between two groups , and the multiple regression analysis was used finally .Results Compared with the control group , the cumulative dose of individuals in the high background group was about four times higher (t=42.803, P<0.05), and the levels of miR-16 and miR-106b in plasma of high background group were down-regulated, while the level of miR-449a was up-regulated ( Z =4.180, 2.422, 2.794, P <0.05 ).After controlling of confounding factors such as age and BMI , the expression levels of miR-16 and miR-106b were negatively correlated with the cumulative dose of individuals (P<0.05).On the contrary, no significant correlation was observed between the levels of miR-449a, miR-34a, let-7g and the individual cumulative dose (P>0.05).Conclusions miR-16 and miR-106b may serve as biomarkers for the early stage of low dose radiation health effects .

Objective To detect the changes of the percentage of micronucleated reticulocytes (MN-RET) in the peripheral blood of mice exposed to 60Co γ-rays,in order to provide evidence for a new biomarker of radiation biodosimetry.Methods ICR mice were irradiated in whole body with 0,0.5,1,2,4 and 8 Gy at a dose rate of 0.24 Gy/min.Peripheral blood was collected for MN-RET assay using a flow cytometry.Results The percentage of peripheral MN-RET increased steadily with irradiation doses up to 2 Gy and then had a downtrend beyond 2 Gy.The changes of MN-RET observed with a microscope were consistent with the results from flow cytometry.The dose response of the MN-RET fitted to a lineal model (R2 =0.9063),and the MN-RET at 2 Gy was significantly higher than that of nonirradiated control (t =-2.856,P ＜ 0.05).Conclusion Percentage of peripheral M N-RET could be an early,rapid and high-throughput radiation bio-dosimeter in certain range of doses.