Objective To observe the effects of cyclooxygenase-2 (Cox-2)selective inhibitor NS-398 on proliferation and apoptosis of colorectal carcinoma HCT-8 cells and to investigate its mechanism.Methods HCT-8 cells in the logarith-mic phase were added with 0,10,20,40,80 and 160 μmol/L NS-398 to intervene.The inhibition rate of colorectal carci-noma HCT-8 cells was detected by CCK-8 kit,apoptosis rate was determined by flow cytometry and the cells were stained by Hoechst 33342 and observed under fluorescent inverted microscope further.After HCT-8 cells were treated by 0,40,80 and 160 μmol/L NS-398 for 24 hours,the protein expression of Cox-2 and Survivin were detected by immunocytochemical staining.ELISA analysis were performed to detect PGE2 concentration in the culture supernatant of HCT-8,and mean-while,the activities of Caspase-3 /7 were analyzed by automatic fluorescence enzyme-linked immunoassay detector.Results NS-398 inhibited the proliferation of HCT-8 cells in a time-and concentration-dependent manner,and there were signifi-cantly differences among the 40,80 and 160 μmol/L NS-398 concentration groups (all P <0.05).Flow cytometry re-vealed,the apoptosis rates were 12%,17% and 26% after treated by 40,80 and 160 μmol/L NS-398 for 24 hours,which was in a dose-dependent manner.Hoechst 33342 staining revealed,the apoptosis increased and cell nucleus showed high-density fluorescence with the increase of NS-398 concentration.The expression of Cox-2 and Survivin decreased significant-ly after treated by 40,80 and 160 μmol/L NS-398 for 24 hours,and the level of PGE2 production also significantly de-creased as compared with the group of 0 μmol/L NS-398.Meanwhile,the activity of Caspase-3 /7 was activated by NS-398 in a dose-dependent manner.Conclusion Cox-2 selective inhibitor NS-398 can inhibit proliferation and induce apoptosis of the colorectal carcinoma HCT-8 cells by down-regulating the expression of Cox-2 and Survivin,PGE2 production and up-regulating the activity of Caspase-3 /7.%目的：观察Cox-2选择性抑制剂NS-398对人结肠癌细胞株HCT-8增殖及凋亡的影响，并探讨其机制。方法取对数生长期的 HCT-8细胞，加入终浓度为0、10、20、40、80、160μmol／L 的 NS-398进行干预，采用 CCK-8法测定 NS-398对人结肠癌 HCT-8细胞的抑制率；采用流式细胞术（FCM）检测细胞凋亡率，Hoechst 33342染色观察凋亡细胞核形态；0、40、80、160μmol／L 的 NS-398作用癌细胞24 h 后，免疫细胞化学法检测癌细胞 Cox-2、Survivin蛋白表达；ELISA 法检测 NS-398作用前后培养液中 PGE2含量；酶标仪检测 Caspase-3／7的活性。结果NS-398作用后结肠癌 HCT-8细胞增殖受到抑制，抑制作用呈时间、浓度依赖性，40、80、160μmol／L 的 NS-398作用后细胞生长抑制率比较差异有统计学意义（P 均＜0．05）；FCM结果显示，40、80、160μmol／L 的 NS-398作用24 h 后，细胞凋亡率分别为12％、17％及26％，且呈剂量依赖性；Hoechst 33342染色显示，随着 NS-398浓度的增加，核呈致密浓染状，荧光强度增加，细胞凋亡增加。40、80、160μmol／L 的 NS-398作用24 h 后，癌细胞 Cox-2、Survivin 蛋白表达较0μmol／L 的 NS-398显著减少，细胞培养上清液中 PGE2含量较0μmol／L 的 NS-398明显下降；同时随 NS-398浓度的增加，Caspase-3／7活性上调，呈剂量－效应关系。结论NS-398可抑制人结肠癌 HCT-8细胞增殖，诱导细胞凋亡，其机制可能与抑制 Cox-2和 Survivin 蛋白表达、上调 Caspase-3／7活性及抑制 PGE2生成有关。
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