Objective To study N-methyl-N'-nitro-N-nitroso-guanidine (MNNG) induced cell proliferation and apoptosis of human esophageal epithelial cell line Het-1A with human papillomavirus (HPV) 18 transfection.
Methods After transfecting lentiviral vectors of HPV18 E6 and E7 genes in Het-1A cells, the expressions of E6 and E7 were identified by fluorescence quantitative PCR. Both transfected group and control group were exposed to MNNG (0, 1, 5, and 10 μmol/L) for 24 h. MTT assay was applied to detect cell growth inhibition. Flow cytometry was processed to investigate the changes of cell cycle and apoptosis induced by MNNG (0, 1, 5, and 10 μmol/L) in HPV18 transfected group and control group.
Results In the HPV18 transfected group, cell proliferation was promoted, G1 phase was extended, S phase was shortened (P < 0.05), and the apoptosis rate was reduced (P < 0.05) compared with the control group. In the control group, MNNG lengthened cells in G1 phase, and cell apoptosis was increased (P < 0.05). In the transfected group with MNNG exposure, G2 phase was elongated compared with exclusive exposure to MNNG. Combined effects of HPV18 and MNNG increased the cell viability rate compared with the effect of exclusive exposure to MNNG at the same concentration. Combined effect of HPV18 and low or medium concentrations of MNNG reduced the apoptosis rate compared with exclusive exposure to MNNG(P < 0.05).
Conclusion Het-1A cells with HPV18 transfection and exposure to MNNG result in cell apoptosis inhibition, cell proliferation increase, gene mutation, and DNA damage.
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