Objective To investigate the effects of Nutlin -3a on p53 mutant colon cancer cells and to study the mechanism of these effects. Methods p53 mutant colon cancer cell line( Caco-2 )was treated with different concentrations of Nutlin-3a(0,2. 5,5. 0,10. 0,20. 0,40. 0,60. 0,80. 0 μmol/L)for 72 h. MTT assay was used to analyze the inhibitory effect of Nutlin-3a on cellular proliferation. Colony-forming assay was utilized to detect Caco-2 cellular re-proliferation abili-ty after withdrawal from Nutlin-3a. Western blotting analysis was employed to detect levels of cellular p73α and p21 protein in Caco-2. Results According to MTT assay results,there were significant differences in absorbance value and cell inhibition rate between control group and Nutlin-3a groups with different concentrations and among different times(P<0. 05);there was sig-nificant interaction between Nutlin-3a concentration and treatment time;there were significant differences in absorbance value and cell inhibition rate between control group and Nutlin-3a groups with different concentrations(P<0. 05);there were signif-icant differences in absorbance value and cell inhibition rate of different groups among different times(P<0. 05). According to western blotting analysis results, there were significant differences in levels of cellular p73α and p21 protein between control group and Nutlin-3a groups with different concentrations(P <0. 05). According to western blotting analysis results,there were significant differences in levels of cellular p73αand p21 protein between control group and Nutlin-3a groups with different concentrations(P<0. 05). According to colony-forming assay results,there were significant differences in Caco-2 cell count between control group and Nutlin-3a groups with different concentrations and among different times(P<0. 05);there was sig-nificant interaction between Nutlin-3a concentration and treatment time;there were significant differences in Caco-2 cell count between control group and Nutlin-3a groups with different concentrations(P<0. 05);there were significant differences in Caco-2 cell count of different groups among different times(P<0. 05). Conclusion When using Nutlin-3a to treat p53 mutant colon cancer,not only the inhibitory and killing effects of Nutlin-3a on cells but also effect of Nutlin-3a on cell cycle should be considered. When the concentration of Nutlin-3a is between 2. 5~20. 0 μmol/L,Nutlin-3a plays the best role on treating p53 mutant colon cancer in vitro.%目的：探讨Nutlin-3a对p53突变型结肠癌细胞生长的作用及其机制。方法用不同浓度（0、2.5、5.0、10.0、20.0、40.0、60.0、80.0μmol/L） Nutlin-3a处理人体结肠癌细胞株Caco-272 h，MTT法检测其对癌细胞生长的抑制作用；Western blotting法检测Nutlin-3a对Caco-2细胞内p73α及p21蛋白表达的影响；细胞集落形成分析检测癌细胞在撤药后重新增殖状态。结果对照组及不同浓度Nutlin-3a组不同时间吸光度及细胞生长抑制率比较，差异均有统计学意义（P<0.05）；Nutlin-3a浓度与处理时间存在交互作用（P<0.05）；对照组及不同浓度Nutlin-3a组吸光度及细胞生长抑制率比较，差异有统计学意义（P<0.05）；不同时间间差异有统计学意义（P<0.05）。对照组及不同浓度 Nutlin-3a组p73α及p21蛋白表达比较，差异有统计学意义（ P<0.05）。细胞集落形成分析结果显示，对照组及不同浓度Nutlin-3a组不同时间Caco-2细胞数量比较，差异均有统计学意义（ P<0.05）；Nutlin-3a浓度与处理时间存在交互作用（P<0.05）；对照组及不同浓度Nutlin-3a组Caco-2细胞数量比较，差异有统计学意义（P<0.05）；不同时间间差异有统计学意义（P<0.05）。结论使用Nutlin-3a治疗p53突变型结肠癌时，考虑其对肿瘤细胞抑制及杀伤作用的同时，应考虑到其对残存细胞细胞周期的影响，在体外2.5~20.0μmol/L的Nutlin-3a对p53突变型结肠癌的治疗作用最为理想。
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