SiO2粉尘介导的DNA损伤及其影响因素的研究

目的 研究小剂量（7.5-120.0μg/ml)SiO2粉尘对中国仓鼠肺成纤维细胞（CHLF）的DNA损伤作用。方法 采用彗星试验，按SiO2粉尘不同的作用浓度和时间分组来观察DNA损伤，通过去铁胺（DFX）和盐酸维拉帕米（Ver)的作用间接观察钙离子和羟自由基对DNA损伤的影响。以彗星尾长作为DNA损伤程度的评价指标。结果 与对照组相比，SiO2明显增加了CHLF的DNA迁移距离，差异有显著性（P＜0．01）；在7．5－120．0μg/ml剂量范围内，彗星尾长随SiO2剂量的增加而增加，2h组的DNA损伤比1h组更严重。0.5-2.0mmol/L DFX和2.5-20.0μg/ml Ver能有效减轻90μg/ml SiO2所致的DNA损伤，其保护作用随浓度加大而增加。结论 小剂量SiO2有致CHLF DNA损伤的作用，损伤过程中有羟自由基和钙离子的参与，抗氧化剂和钙拮抗剂可对抗SiO2对机体DNA的损伤作用。

Study on silica induced DNA damage and its influence factor

OBJECTIVE: To detect DNA damage in Chinese Hamster Lung Fibroblast(CHLF) exposed to low doses of silica particles(7.5 - 120.0 micrograms/ml). METHODS: Comet assay was used to detect DNA damage. The cells were divided into various groups by doses and incubation time of silica particles to observe silica-induced DNA damage; and the influence of hydroxyl radicals and calcium ion in DNA damage by using deferoxamine and verapamil was also studied. The tail lengths of comet were used to measure DNA damage. RESULTS: The tail lengths were significantly longer in exposed cells, compared to matched controls(P < 0.01), and were increased in a dose-dependent manner from 7.5-120.0 micrograms/ml. The tail lengths of two-hour group were longer than one-hour group. When exposed to 90 micrograms/ml silica particles, 0.5-2.0 mmol/L deferoxamine and 2.5-20.0 micrograms/ml verapamil could attenuate silica-induced DNA damage effectively, their protective effects were increased in a concentration-dependent manner. CONCLUSION: Small dose of SiO2 could induce CHLF DNA damage. Calcium ion and hydroxyl radical may take part in this process, antioxidant and calcium antagonate may protect SiO2 induced DNA damage.