Folic Acid In The Role Of MNNG On DNA Damage Of Kazakh Normal Esophageal Epithelial Cells

Objective: To explore the folic acid in the role of effect of N-methyl-N’-nitro-Nnitrosoguanidine(MNNG) on normal Kazakh’s esophageal epithelial cells in general biology and index of DNA damage, in order to provide the theoretical evidences for the prevention and treatment of esophageal cancer in Kazakh nationality. Method:(1)Cell proliferation assay was detected by MTT method, cell cycle was detected by flow cytometry,and the change of cell apoptosis was detected through Annexin V-FITC/PI double staining method.(2)The change of DNA damage level was detected by Comet assays.(3)The mRNA and protein level of APE1 and MGMT were tested by RT-PCR and Western-Blot. Results: With the decrease of the concentration of folic acid and the increases of the concentration of MNNG, the following results appeared:(1) Morphology of normal Kazakh esophageal epithelial cells had significant changes. The number of the dead cells were gradually increased, and different degree of rupture appeared in cell nucleus. The cytoplasm was uneven and the integrity of cell was destroyed. The cells’ sensitivity to the damage of MNNG were significant increased, particularly on 96 h.(2)The inhibition rate in normal Kazakh esophageal epithelial cells was higher, and there was a significant difference(P<0.01).(3) The cell cycle of normal Kazakh esophageal epithelial cells were significantly different in the proportion of G0+G1 phase, S phase and G2+M phase(P<0.01), and cell cycle was arrested in S and G2+M phase.(4) Cells apoptosis rate of Kazakh normal esophageal epithelial cells were significantly increased(P<0.01).(5) The Tail DNA、Tail length and Olive Tail moment level of Kazakh normal esophageal epithelial cells was significantly reduced(P<0.01).(6) The expression of mRNA and protein of APE1 in normal Kazakh esophageal epithelial cells were significantly increased(P<0.01).(7) The expression of mRNA and protein of MGMT gene were significantly increased(P<0.01). Conclusion: The reduction of the concentrations offolic acid promotes the Kazak normal esophageal epithelial cells’ damage which caused by MNNG. Sufficient folic acid play a protective role in the damage caused by MNNG.