ABSTRACT
Objective To investigate the mechanism of malignant transformation in human bronchial epithelial cell line BEP2D exposed to α-particles.Methods The levels of intracellular ROS and malonaldehyde (MDA) in BEP2D,RH22 (passage 22 of α-particle-irradiated BEP2D cells) and BERP35T-1 cells (derived from nude mice bearing malignant transformed cells generated from the passage 35 of α-particle-irradiated BEP2D cells) were assayed with DCFH-DA and MDA kit,respectively.The expressions of 8-OH-dG and γ-H2AX in BEP2D,RH23 (passage 23 of α-particle-irradiated BEP2D cells)and BERP35T-1 cells were also measured with immunocytochemistry and immunofluorescence staining.Results Compared to BEP2D cells,the levels of ROS ( t =4.30 and 3.94,P ＜ 0.05 ) and MDA ( t =4.89 and 15.10,P ＜0.05) increased in RH22 and BERP35T-1 cells.The expressions of 8-OH-dG (t =3.80 and 2.92,P ＜ 0.05 ) and γ-H2AX ( t =7.61 and 12.67,P ＜ 0.05 ) in RH23 and BERP35T-1 cells were also higher than those in BEP2D cells.Conclusions Oxidative stress induces lipid peroxidation and DNA damage leading to genomic instability,which could contribute to cellular malignant transforming process in the human bronchial epithelial cell line BEP2D with α-particle exposure.
ABSTRACT
Objective To identify the changes of DNA methylation profile in the process of malignant transformation of BEP2D cell induced by α particles.Methods The genomic DNAs were isolated from the malignant transformation BERP35T4 cells and immortalized human bronchial epithelial cell line BEP2D.Genomic DNAs were digested by MseI and ligated of PCR linkers.Methylated DNAs were digested by BstUI and amplified by PCR.The methylated DNA probes were prepared by labeling with Cy3 and Cy5 fluorescence dyes individually and hybridized to the methylation CpG-Island microarray.The hybridization results were scanned and analyzed.Intensity values were quality controlled and normalized.The normalized data were used to identify the differentially expressed genes based on a 1.5 fold difference of the expression level.Results There were 16 genes which showed changes of methylation level in malignant transformation BERP35T4 cells, 9 of them were hypermethylation and 7 were hypomethylation.These genes were including the SKIP gene, PPP3CC gene, MAP2K6 gene, KIR2DL1 gene, KIR2DL4 gene, KIR3DP1 gene, ZNF493 gene, ZNF100 gene, NKX2-5 gene, TFAP2D gene, DR1 gene, KCNJ16 gene, CCDC18 gene, FNBP1L gene, IRX4 gene, EPB41L3 gene, TCP10 gene and so on.Conclusions The DNA methylation might have effects on ionizing radiation drived tumorigenesis.
ABSTRACT
Objective To investigate the antioxidant ability and radiosensitivity in the malignant transformed human bronchial epithelial cell line BEP2D induced by α-particle exposure.Methods Glutathione Peroxidase (GPX),Catalase (CAT) and Glutathione (GSH) assay kits were employed to detect GPX and CAT enzyme abilities and the levels of GSH in BEP2D,RH21 ( passage 21 of α-particle-irradiated BEP2D cells),and BERP35T-1 cells (derived from nude mice bearing malignant transformed cells generated from cells of passage 35 of α-particle-irradiated BEP2D cells).MTT assay were used to test the growth rate of BEP2D,RH21 and BERP35T-1 cells treated with 0,30,60,90,120,and 150 μmoL/L H2O2.Colony-forming test and MTT assay were used to examine the cell survival fraction and the growth rate of BEP2D,RH21 and BERP35T-1 cells exposed to 0,2,4,and 8 Gy of γ-rays,respectively.Results GPX and CAT enzyme activities in RH21 and BERP35T-1 cells were obviously lower than in BEP2D( t = 5.75-67.92 ,P ＜ 0.05 ).CAT enzyme activity in BERP35T-1 was lower than that in RH21 cells (t =22.25 ,P ＜0.01 ).Compared to BEP2D cells,decreased level of GSH was detected in BERP35T-1 cells(t = 7.76,P ＜ 0.05 ),but there was no change in RH21.After treatment with 30,60,90,120,and 150 μmol/L H2O2,the growth rates of BEP2D were all higher than those of BERP35T-1 cells(t = 10.37-58.36,P ＜0.01 ).Meanwhile,the growth rates of BEP2D were all higher than those of RH21 cells after treatment with 60,90,120,and 150 μ mol/L H2O2 (t = 29.90-84.68,P ＜ 0.01 ).In addition,compared to BEP2D cells,decreased cell survival fraction and growth rate of BERP35T-1 cells were observed after irradiation with 2,4,and 8 Gy of y-rays ( t = 5.87-34.17,P ＜ 0.05 ).The cell survival fraction and growth rate of RH21 were all lower than those of BEP2D cells at 4 and 8 Gy post-irradition( t =6.33- 45.00,P ＜ 0.05 ).Conclusion The function of antioxidant system decreased in the α-particleinduced transformed cells,which could contribute to the acceleration of cellular malignant transforming process and radiosensitivity.