Abstract: ACKGROUND AND AIM: To investigate the alteration of reactive oxygen species (ROS) level ,the activity of nuclear factor kappa B (NF_κB)and the expression of C_IAP2 in apoptosis of HL_60 cells induced by As2O3 (arsenic trioxide,ATO) . MATERIALS AND METHODS: HL_60 cells were treated with 7.5 μmol/L As2O3 alone or together with 500 μmol/L N_acetyl_L_cysteine(NAC) for 12 and 24 h. Intracellular ROS level was measured by flow cytometry (FCM), the activity of NF_κB p65 was determined by Western blot and the expression of C_IAP2 mRNA was determined by semi_quantitative RT_PCR. RESULTS: After treatment with 7.5 μmol/L As2O3 for 12 and 24 h, the level of ROS increased obviously, and the relative amount of NF_κB p65 were 49.3％±4.4％ and 23.1％±2.1％,and the relative expressions of C_IAP2 mRNA were 72.9％±5.8％ and 59.3％±4.4％.After co_treatment of 7.5 μmol/L As2O3 and 500 μmol/L NAC for 12 and 24 h in HL_60 cells, the level of ROS was decreased, the relative amount of NF_κB p65 were 65.4％±4.9％ and 37.1％±3.4％, and the relative expressions of C_IAP2 mRNA were 81.1％±5.8％ and 73.7％±4.9％. CONCLUSION: As2O3 could increase the level of ROS in HL_60 ,inhibited the activity of NF_κB and down_regulated the expression of C_IAP2 mRNA. Moreover, co_treatment of As2O3 and NAC could protect HL_60 cells from apoptosis through decreasing reactive oxygen species (ROS), prohibiting partly the suppression of the activity of NF_κB and the expression of C_IAP2 mRNA.

Key words: arsenic trioxide, ROS, NF_κB, C_IAP2, HL_60 cells