DNA damage in human pleural mesothelial cells and lung epithelial cells induced by exposure to carbon nanotubes

我们研究了单壁碳纳米管(SWCNT)和多壁碳纳米管(MWCNT)暴露于人胸膜间皮细胞的潜在风险。用台盼蓝拒染法检测CNT的细胞毒性，用碱性彗星实验检测DNA损伤。采用高效液相色谱-电化学检测法测定DNA中8-氧脱氧鸟苷(8-OHdG)的浓度。免疫印迹法检测细胞内碱基切除修复酶的表达。我们观察了悬浮在分散介质中的纯化的碳纳米管对细胞增殖的抑制作用和对DNA损伤的诱导。但未发现8-OHdG在DNA中的积累。此外，参与hOGG1、hMTH1和MYH的碱基切除酶在MET-5A细胞中的表达水平在碳纳米管暴露后24小时内保持不变。碳纳米管可显著抑制人胸膜间皮细胞的增殖，减少DNA损伤。我们的结果表明，CNT诱导的遗传毒性机制不同于暴露于活性氧的机制，后者导致DNA氧化修饰和8-OHdG的产生。在CNT暴露后，需要进一步的研究来表征特定的DNA突变。

We investigated the potential risk of single-walled carbon nanotube(SWCNT) and multi-walled carbon nanotube(MWCNT) exposure in human pleural mesothelial cells. CNT cytotoxicity was determined using a trypan blue exclusion assay, and DNA damage was detected using an alkaline comet assay. The concentration of 8-oxodeoxyguanosine(8-OHdG) in DNA was measured using HPLC with electrochemical detection. The expression of base excision repair enzymes in the cell was estimated by immunoblot analysis. We observed inhibitory effects on cell proliferation and induction of DNA damage following exposure of cells to purified CNTs that were suspended in dispersion medium. However, accumulation of 8-OHdG in DNA was not found. In addition, the expression levels of base excision enzymes that are involved in hOGG1, hMTH1 and MYH in MeT-5A cells remained unchanged for 24 h after carbon nanotube exposure. CNTs significantly inhibit cell proliferation and decrease DNA damage in human pleural mesothelial cells. Our results indicate that the mechanism of CNT-induced genotoxicity is different from that of exposure to reactive oxygen species, which causes oxidative DNA modifications and 8-OHdG production. Further investigation is required to characterize the specific DNA mutations following CNT exposure.