硝基苯对肝癌细胞系的细胞毒性机制

A study on mechanism for cytotoxicity of nitrobenzene to hepatocarcinoma cell line

目的 探讨硝基苯对肝癌细胞系的细胞毒性机制。方法 用不同浓度的硝基苯作用于体外培养的人肝癌细胞株SMMC 772 12 4h ,用噻唑蓝法测定细胞毒性 ,同时加入活性氧清除剂观察对细胞死亡的保护作用 ;用流式细胞术测定细胞的周期分布 ;用单细胞凝胶电泳法测定细胞的DNA损伤情况。结果 浓度≥ 8mmol/L硝基苯可明显引起细胞死亡 (存活率 <82 % ) ,加入超氧化物歧化酶、过氧化氢酶或甘露醇后可部分抑制硝基苯的细胞毒性 (存活率分别为 93 7%、96 6 %和 93 2 % ) ;硝基苯可影响肝细胞的细胞周期 ,表现为G1期细胞比例减少 ,S期和G2 /M期细胞比例增多 ;硝基苯不引起肝细胞DNA链断裂。结论 硝基苯对体外培养的肝细胞具有一定的细胞毒性 ,活性氧在其中起了部分作用 ,硝基苯是一种非遗传毒物 。

Objective To study the mechanism for cytotoxicity of nitrobenzene to hepatocarcinoma cell line. Methods Cytotoxicity was determined with MTT assay in SMMC 7721 cell strain, human hepatocarcinoma cell, incubated with nitrobenzene at varied concentrations in vitro for 24 hours. The effect of an agent to clear reactive oxygen on protection from cell death was observed. Cell cycle of hepatocytes was also observed using flow cytometry and their DNA damage was detected with single cell gel electrophoresis assay. Results Nitrobenzene at concentration of 8 mmol/L or over could induce death of hepatocytes obviously with a survival rate of less than 82%, and addition of superoxide dismutase, hydrogen peroxidase or mannitol to the incubation media could inhibit its cytotoxicity partly, with survival rates of 93 7%, 96 6% and 93 2%, respectively. Nitrobenzene could affect cell cycle of hepatocytes, showing a decreased fraction of G 1 phase and increased fraction of S and G 2/M phase, but could not induce DNA strand breaks in them. Conclusions Nitrobenzene had cytotoxicity to hepatocytes cultured in vitro, in which reactive oxygen species may play a certain role. Nitrobenzene was a non genotoxicant and could cause cancer by promotion of cell proliferation.