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