中文摘要：

目的探讨叶酸在N-甲基-N-硝基-N-亚硝基胍（MNNG）致哈萨克族（哈族）食管正常上皮细胞增殖、细胞周期及凋亡中的作用。方法采用3因素3水平（33）析因设计将体外培养的哈族食管正常上皮细胞暴露于不同浓度叶酸（0.000、0.400、0.800μg/mL）和MNNG（0.000、0.750、1.500μg/mL）的培养液中作用48、72和96h后,采用噻唑蓝（MTT）法检测叶酸及MNNG对哈族食管上皮增殖的影响,流式细胞术检测细胞周期和细胞凋亡。结果随着叶酸浓度的降低和MNNG浓度增加,哈族食管正常上皮细胞形态发生了明显的变化,死细胞数目逐渐增多,细胞核出现不同程度的破裂,胞质不匀和细胞完整性损伤,细胞对MNNG损害的敏感性明显增加,96h时尤为严重;哈族食管正常上皮细胞的抑制率升高,差异有统计学意义（P〈0.05）;哈族食管正常上皮细胞G0＋G1期、S期和G2＋M期细胞比例不同,差异有统计学意义（P〈0.05）,细胞周期阻滞在S期和G2＋M期;哈族食管正常上皮细胞的凋亡率升高,差异有统计学意义（P〈0.05）。结论叶酸浓度降低对MNNG致哈族食管正常上皮细胞损伤有一定的促进作用。

英文摘要：

Objective To investigate the role of folic acid in MNNG-induced proliferation,cell cycle and apoptosis of Kazakh normal esophageal epithelial cell.Methods Using 3factors 3level（33）factorial design,Kazak normal esophageal epithelial cells were treated with different concentrations of folic acid（0.000,0.400 and 0.800μg/mL）and MNNG（0.000,0.750 and 1.500μg/mL）,cultured 48,72 and 96h,MTT assay was used to measure cell proliferation,and cell cycle and apoptosis rate were detected by flow cytometry and Annexin V-FITC/PI staining.Results With decreasing of folic acid concentration and increasing of MNNG concentration：Morphogenesis of Kazakh normal esophageal epithelial cell had significant changes,number of the dead cells were gradually increased,nuclei ruptured in varying degrees,cytoplasm was uneven and cell integrity was destroyed.Cell sensitivity to MNNG damage were increased significantly,particularly on 96h;Kazakh normal esophageal epithelium inhibition rate increased,which there was a significant difference（P〈0.05）;Proportion of G0＋G1phase,S phase and G2＋M phase of cells were significantly different（P〈0.05）,cell cycle arrest in S and G2 ＋ M phase;Apoptosis rate of Kazakh normal esophageal epithelium cell were increased,which there was a significant difference（P〈0.05）.Conclusion Reduction of folic acid concentrations promoted MNNG-induced Kazak normal esophageal epithelial cell injury.