Objective:To discuss the influence of tachyzoite of Toxoplasma gondii(T.gondii) RH strain on proliferation and apoptosis of hepatoma carcinoma(HCC) H7402 cell.Methods:The HCC H7402 cell in logarithmic phase and tachyzoite of T.gondii RH strain in different concentrations(1×10~7/mL,2×10~7/mL.4×10~7/mL,8×10~7mL and 16×10~7/mL) were co-cultured.CCK-8was utilized to determine the inhibition rate of T.gondii tachyzoite on H7402 cell growth.Flow cytometry was used to detect the change of cell cycle.RT-PCR method was used to detect the expression of cyclinB1 and cdc2-two genes related to cell cycle.Western blot method was used to detect the expression of apoptosis-related proteins Caspase-3 and Bcl-2.Results:The tachyzoite of T.gondii RH strain can inhibit the proliferation of HCC H7402 cells.The inhibition rate of tumor cell growth increased with the increase of concentration of T.gondii tachyzoite.With the increase of concentration of T.gondii tachyzoite,the proportion of G_0/G_1 phase of H7402 cell increased,the proportion of S phase decreased,and PI value decreased accordingly.The expression of cyclinB1 and cdc2 genes decreased with the increase of the concentration of T.gondii tachyzoite.With the increase of the concentration of tachyzoite of T.gondii RH strain,the expression quantity of Caspase-3 in H7402 cell increased,but the expression quantity of Bcl-2protein decreased.Conclusions:T.gondii can inhibit the in vitro proliferation of HCC H7402 cell,and induce its apoptosis.This effect shows a trend of concentration-dependent increase.Moreover,it is related to the down-regulation of cyclinB1 and cdc2(cell cycle-related genes),the increase of apoptosis-related protein Caspase-3.and the decreasc of Bcl-2 expression. Objective: To discuss the influence of tachyzoite of Toxoplasma gondii (T.gondii) RH strain on proliferation and apoptosis of hepatoma carcinoma (HCC) H7402 cell. Methods: The HCC H7402 cell in logarithmic phase and tachyzoite of T.gondii RH strain in different (1 × 10-7 / mL, 2 × 10-7 / mL.4 × 10-7 / mL, 8 × 10-7mL and 16 × 10-7 / mL) were co-cultured. CCK-8was utilized to determine the inhibition rate of T.gondii tachyzoite on H7402 cell growth. Flow cytometry was used to detect the change of cell cycle. RT-PCR method was used to detect the expression of cyclinB1 and cdc2-two genes related to cell cycle. Western blot method was used to detect the expression of apoptosis-related proteins Caspase-3 and Bcl-2. Results: The tachyzoite of T.gondii RH strain can inhibit the proliferation of HCC H7402 cells.The inhibition rate of tumor cell growth increased with the increase of concentration of T.gondii tachyzoite.With the increase of concentration of T. gondii tachyzoite, the proportion of G_0 / G_1 phase of H7402 cell increased, the proportion of S phase decreased, and PI value decreased accordingly. The expression of cyclinB1 and cdc2 genes decreased with the increase of the concentration of T.gondii tachyzoite .With the increase of the concentration of tachyzoite of T.gondii RH strain, the expression quantity of Caspase-3 in H7402 cell increased, but the expression quantity of Bcl-2 protein decreased. Conclusions: T.gondii can inhibit the in vitro proliferation of HCC H7402 cell, and induce its apoptosis. This effect shows a trend of concentration-dependent increase. Moreover, it is related to the down-regulation of cyclinB1 and cdc2 (cell cycle-related genes), the increase of apoptosis-related protein Caspase-3.and the decreasc of Bcl-2 expression.