Objective To observe the changes in genomic DNA methylation profile of benzo(a)pyrene (BaP)-induced malignant transformation of human bronchial epithelial cells (16HBE).
Methods A malignant transformed 16HBE model was established by 40.0 μmol/L BaP administration. The dynamic cellular genome DNA methylation levels were qualitatively and quantitatively detected by 5-methylcytosine immunofluorescence and high-performance capillary electrophoresis, respectively. The DNA methyltransferase activity was also monitored.
Results At the selected time spots of 3, 6, 9, 12, 15, and 18 weeks during the 16HBE malignant transformation induced by BaP, the genomic DNA methylation levels decreased in a time-dependent manner, and the genomic DNA methylation percentages (mCpG%) at corresponding time spots were (4.62& #177;0.39)%, (3.82& #177;0.39)%, (4.07& #177;0.40)%, (3.27& #177;0.31)%, (2.63& #177;0.21)% and (2.48& #177;0.15)% respectively, while the mCpG% of the normal 16HBE cells was (4.78& #177;0.58)%. In addition, the methyltransferase activities of the BaP-treated 16HBE cells also decreased in a time-dependent manner.
Conclusion The reduced genomic DNA methylation level is an important feature in the process of BaP-induced malignant transformation of 16HBE cells, and the reduced DNA methyltransferase activity is the main cause.
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