Abstract: BACKGROUND AND AIM: To investigate the mechanisms for cytotoxicity of furazolidoze (FZD) to human hepatocarcinoma cell line (Hep G2). MATERIALS AND METHODS: After Hep G2 cells were exposed to FZD at the different concentrations(0、0.78、1.56、3.12、6.25、12.50、25.00、50.00 μg/ml)for 24 h, the proliferation effect was measured by MTT assay whilst the cell cycle distribution was assessed by flow cytometry. The mRNA of S stage checkpoint was evaluated by RT_PCR. RESULTS: MTT assay showed that Hep G2 survival rate decreased with increasing FZD concentration, whereas the survival rate was significantly higher with concentration above 6.25 μg/ml(P<0.05). Cell growth assay showed that the growth of Hep G2 was significantly slower than control. Treated with FZD (0－3.12 μg/ml), cells in S stage increased, while those in G1 stage decreased. The expression level of p21 increased and the expression of cyclinE, cyclinA ,Cdk2 decreased after treatment with FZD. CONCLUSION: FZD exhibited cytotoxicity to Hep G2 in vitro and induced cell arrest at S stage, and it may exert antiproliferative effect through activation of the S stage damage checkpoint.

Key words: furazolidoze, Hep G2, cytotoxicity, S stage arrest