AIM: To investigate the effects of 5-aminosalicylic acid (5-ASA) in combination with nimesulide on the proliferation of HT-29 colon carcinoma cells and its potential mechanisms. METHODS: Inhibitory effects of drugs (5-ASA,nimesulide and their combination) on HT-29 colon carcinoma cells were investigated by thiazolyl blue tetrazolium bromide (MTT) assay. Cellular apoptosis and proliferation were detected by TUNEL assay and immunocytochemical staining,respectively. RESULTS: Pretreatment with 5-ASA or nimesulide at the concentration of 10-1000 μmol/L inhibited proliferation of HT-29 colon carcinoma cells in a dose-dependent manner in vitro (t = 5.122,P < 0.05; t = 3.086,P < 0.05,respectively). The inhibition rate of HT-29 colon carcinoma cell proliferation was also increased when pretreated with 5-ASA (100 μmol/L) or nimesulide (100 μmol/L) for 12-96 h,which showed an obvious time-effect relationship (t = 6.149,P < 0.05; t = 4.159,P < 0.05,respectively). At the concentration of 10-500 μmol/L,the apoptotic rate of HT-29 colon carcinoma cells significantly increased (t = 18.156,P < 0.001; t = 19.983,P < 0.001,respectively),while expression of proliferating cell nuclear antigen (PCNA) was remarkably decreased (t = 6.828,P < 0.05; t = 14.024,P < 0.05,respectively). 5-ASA in combination with nimesulide suppressed the proliferation of HT-29 colon carcinoma cells more than either of these agents in a dose-dependent and time-dependent manner (t = 5.448,P < 0.05; t = 4.428,P < 0.05,respectively). CONCLUSION: 5-ASA and nimesulide may inhibit the proliferation of HT-29 colon carcinoma cells and coadministration of these agents may have additional chemopreventive potential. AIM: To investigate the effects of 5-aminosalicylic acid (5-ASA) in combination with nimesulide on the proliferation of HT-29 colon carcinoma cells and its potential mechanisms. METHODS: Inhibitory effects of drugs (5-ASA, nimesulide and their combination ) on HT-29 colon carcinoma cells were investigated by thiazolyl blue tetrazolium bromide (MTT) assay. Cellular apoptosis and proliferation were detected by TUNEL assay and immunocytochemical staining, respectively. RESULTS: Pretreatment with 5-ASA or nimesulide at the concentration of 10- The inhibition rate of HT-29 colon carcinoma cells in a dose-dependent manner in vitro (t = 5.122, P <0.05; t = 3.086, cell proliferation was also increased when pretreated with 5-ASA (100 μmol / L) or nimesulide (100 μmol / L) for 12-96 h, which showed an obvious time-effect relationship (t = 6.149, 4.159, P <0.05, respectively). At the concentration of 10-500 The apoptotic rate of HT-29 colon carcinoma cells significantly increased (t = 18.156, P <0.001; t = 19.983, P <0.001, respectively) 5-ASA in combination with nimesulide suppressed the proliferation of HT-29 colon carcinoma cells more than either of these agents in a dose-dependent and time- CONCLUSION: 5-ASA and nimesulide may inhibit the proliferation of HT-29 colon carcinoma cells and coadministration of these agents may have additional chemopreventive potential (t = 5.448, P <0.05; .