Genetic Damage of Human Bronchial Epithelial Cells Caused by Cigarette Smoke Combined with Nano-TiO2

Objective To investigate the genetic damage of human bronchial epithelial cells (HBE) caused by cigarette smoke combined with nano-TiO2.Methods 16-HBE cells were exposed to cigarette smoke extract (CSE) and nano-TiO2(mg/L) at the doses of 0 mg/L CSE+0 mg/L nano-TiO2,50 mg/L CSE+0 mg/L nano-TiO2,75 mg/L CSE+0 mg/L nano-TiO2,100 mg/L CSE+0 mg/L nano-TiO2,0 mg/L CSE+10 mg/L nano-TiO2,50 mg/L CSE+10 mg/L nano-TiO2,75 mg/L CSE+10 mg/L nano-TiO2,100 mg/L CSE+10 mg/L nano-TiO2. After 24 h exposure,HBE viability was evaluated by the methyl thiazolyl tetrazolium (MTT) assay,single cell gel electrophoresis (SCGE,comet assay) was employed to assess DNA damage,chromosomal aberration was measured by micronucleus test. Results Except the group exposed to 10 mg/L nano-TiO2,HBE viability of the other treatment groups were lower than that of the control group and Comet % of the other treatment groups were higher than that of the control group (P0.05). Ltail of the groups exposed to 75 mg/L and 100 mg/L CSE and all the combined groups were higher than that of the control group (P0.05). Tail DNA% of the groups exposed to CSE and nano-TiO2 at doses of 100 mg/L CSE+0 mg/L nano-TiO2 and 100 mg/L CSE+10 mg/L nano-TiO2 were higher than that of the control group (P0.05). TM and OTM of the groups exposed to CSE and nano-TiO2 of 100 mg/L CSE+0 mg/L nano-TiO2,75 mg/L CSE+10 mg/L nano-TiO2 and 100 mg/L CSE+10 mg/L nano-TiO2 were higher compared with the control group (P0.05). Except the group exposed to 10 mg/L nano-TiO2,micro-nuclear rates of the other treatment groups were higher than that of the control group (P 0.01). No interaction was seen between cigarette smoke and nano-TiO2. CSE was positively correlated with Comet% and micro-nuclear rates of HBE in the groups only exposed to NaF or the combined groups (P0.01). Conclusion Treated with higher dosage of CSE,HBE show more serious DNA breakage and chromosomal aberration with dose-dependent manner,however,there is no interaction between cigarette smoke and nano-TiO2.