Carcinogenesis Induced By Uranium Dust In Immortalized BEAS-2B Cells And The Protection Of DMSO To Inhibit The Damage In The Cells

Objective:The aim of this study was to explore the cytotoxic, genotoxic, carcinogenic effect on human bronchial epithelial (BEAS-2B) cells induced by uranium mine dust, and investigate the mechanism of carcinogenesis . All of these were to be researched the protection of DMSO to cytotoxic,genotoxic, clastogenic and mutagenic in BEAS-2B cells which caused by uranium mine dust.Methods: BEAS-2B cells were cultured in BEGM medium under 5% CO2 and 95% air in an incubator set at 37℃. The cells were exposed to uranium mine dust at different concentration (0, 0.5, 1.0, 1.5mg/ml in 5μm, 0.5, 1.0mg/ml in 70nm) for 24 hours, and meanwhile in all groups were supplemented with 0.5%DMSO for 24 hours. The level of LDH, ALP, GOT was detected. The damage of DNA and chromosome in cells was investigated using single cell gel electrophoresis and micronucleus test. The characteristics of the cellular biology and the malignant transformation phenotype of cells were identified through observing serum resistance, the multiplication time of different generation cells, the anchorage independent growth (semi-solid agar colony formation). Immunohistochemistry and PCR-SSCP were used to exam the protein and gene expression of p53. Also PCR- SSCP was used to examine the presence of alterations of Ki-ras gene in the malignant process of BEAS-2B cells induced by uranium mine dust.Results:The mutation frequency of BEAS-2B cells were significantly increased by uranium mine dust and the damaged degree will aggravate with high concentration. The level of LDH, ALP, GOT in the cell culture increased remarkably after induced by uranium mine dust. There was significantly dose-effect relationship between uranium mine dust with LDH, ALP, GOT in a special range. Uranium mine dust could cause DNA single strand breaks and micronucleus in BEAS-2B cells. The amount of comet cells, tail area, tail length and micronucleus ratio increased significantly induced by uranium mine dust. The anchorage independent growth colony formation was appeared in 10th generation cells after exposed to uranium mine dust groups. The transmission electron microscope was used to observe the ultrastructural damage in BEAS-2B cells. We could observe the cell membrane broke, microvillus reduced or disappeared, cell framework disordered and the karyotheca blurred induced by uranium mine dust. The protein expression of p53 in BEAS-2B cells exposed with uranium mine dust was positive in the uranium dust exposed group. The effects of cell damage induced by uranium mine dust would reduce effectively by 0.5%DMSO. But the damaged degree of the cells reduced by nano uranium mine dust group was more different as the other groups.Conclusons:1. Uranium mine dust could induce malignant transformation of BEAS-2B cells.2. The protein and gene expression of p53 was significantly increased by uranium mine dust. The gene expression of Ki-ras will be indicating the genome became more instable in the malignant process.3. 0.5%DMSO can inhibit the damage in BEAS-2B cells induced by uranium mine dust.4. But the damage of nano uranium mine dust to cells would be given attention in the future.