目的探讨N-甲基-N'-硝基-N-亚硝基胍(MNNG)对哈萨克族正常食管上皮细胞增殖、细胞周期及凋亡的影响及N-亚硝胺类化合物致癌机制。方法将体外培养的哈萨克族正常食管上皮细胞暴露于不同浓度的MNNG(0,0.75,1.5 and 3μg/ml)培养液中,0...目的探讨N-甲基-N'-硝基-N-亚硝基胍(MNNG)对哈萨克族正常食管上皮细胞增殖、细胞周期及凋亡的影响及N-亚硝胺类化合物致癌机制。方法将体外培养的哈萨克族正常食管上皮细胞暴露于不同浓度的MNNG(0,0.75,1.5 and 3μg/ml)培养液中,0μg/ml MNNG为对照组。采用噻唑蓝(MTT)法检测MNNG对哈萨克族食管正常上皮细胞增殖的影响、流式细胞术检测MNNG对细胞周期的影响、AnnexinⅤ-FITC/PI双染法检测MNNG对细胞凋亡的影响。结果暴露于不同浓度的MNNG 24 h后,四组哈萨克族食管正常上皮细胞抑制率分别为0、12.880%、28.414%、44.401%,后三组与对照组0μg/ml比较差异有统计学意义(P<0.05);细胞周期阻滞在S期和G2/M期,细胞比值分别为(26.000±1.808)%、(29.867±3.769)%、(37.833±3.782)%、(47.100±2.427)%和(10.867±1.747)%、(16.133±1.498)%、(18.533±1.115)%、(14.267±1.848)%,与对照组比较差异有统计学意义(P<0.05);细胞凋亡率分别为(0.533±0.252)%、(1.767±0.252)%、(11.033±2.173)%、(26.767±1.955)%,与对照组比较差异有统计学意义(P<0.05)。结论 MNNG抑制哈萨克族正常食管上皮细胞增殖、阻滞细胞周期及诱导细胞凋亡。展开更多
AIM: To understand the effect of low concentration of Nmethyl-N′-nitro-nitrosoguanidine (MNNG), which is a widely distributed environmental mutagen and carcinogen especially for human gastric cancer, on DNA damage an...AIM: To understand the effect of low concentration of Nmethyl-N′-nitro-nitrosoguanidine (MNNG), which is a widely distributed environmental mutagen and carcinogen especially for human gastric cancer, on DNA damage and to study its possible pathway in regulating cell cycle arrest.METHODS: The DNA damage effect was measured by Comet assay. A specific phospho-(Ser/Thr) ATM/ATR substrate antibody was used to detect the damage sensor by Western blot. p38 kinase activity was measured by direct kinase assay,and immunoprecipitation for the possible connection between ATM/ATR and p38 MAPK. Flow cytometry analysis and p38MAPK specific inhibitor SB203580 were combined to detect the possible cell cycle arrest by p38 MAPK.RESULTS: With the same low concentration MNNG exposure (0.2μM 2.5 h), Comet assays indicated that strand breaks accumulated, Western blot and kinase assay showed ATM/ATR and p38 kinase activated, immunoprecipitation showed phospho-ATM/ATR substrate antibody combined with both p38 MAPK antibody and phospho-p38 MAPK antibody, p38MAPK pathway was involved in the G1-S arrest.CONCLUSION: Activation of ATM/ATR by MNNG induced DNA damage leads to activation of p38 MAPK, which involves in the G1 checkpoint in mammalian cells.展开更多
基金Natural Science Foundation of Zhejiang Province, No.29801
文摘AIM: To understand the effect of low concentration of Nmethyl-N′-nitro-nitrosoguanidine (MNNG), which is a widely distributed environmental mutagen and carcinogen especially for human gastric cancer, on DNA damage and to study its possible pathway in regulating cell cycle arrest.METHODS: The DNA damage effect was measured by Comet assay. A specific phospho-(Ser/Thr) ATM/ATR substrate antibody was used to detect the damage sensor by Western blot. p38 kinase activity was measured by direct kinase assay,and immunoprecipitation for the possible connection between ATM/ATR and p38 MAPK. Flow cytometry analysis and p38MAPK specific inhibitor SB203580 were combined to detect the possible cell cycle arrest by p38 MAPK.RESULTS: With the same low concentration MNNG exposure (0.2μM 2.5 h), Comet assays indicated that strand breaks accumulated, Western blot and kinase assay showed ATM/ATR and p38 kinase activated, immunoprecipitation showed phospho-ATM/ATR substrate antibody combined with both p38 MAPK antibody and phospho-p38 MAPK antibody, p38MAPK pathway was involved in the G1-S arrest.CONCLUSION: Activation of ATM/ATR by MNNG induced DNA damage leads to activation of p38 MAPK, which involves in the G1 checkpoint in mammalian cells.
