[Effects of cell malignant transformation induced by benzo[a]pyrene on DNA methylation transferases].

OBJECTIVE

To investigate the expression level and enzymatic activity of DNA methylation transferases (dnmts) in mouse embryonic fibroblast malignant transformed cells induced by benzopyrene (B[a]P).

METHODS

Two kinds of cell lines, pol beta wild-type cells (pol beta +/+) and malignant transformation cells induced by BaP (pol beta-T) were applied as cellular models. Pol beta +/+ cells were served as controls, RT-PCR and Western blot were used to measure the change of dnmts expression level in malignant transformation cells induced by BaP. The enzymatic activity of DNMTs was also detected with DNA methyltransferase (DNMT) activity/inhibition assay kit.

RESULTS

The mRNA and protein expression levels of dnmt1 and dnmt3b in pol beta-T cells (0.940 +/- 0.033 and 0.905 +/- 0.062) were much higher than that in pol beta +/+ cells (0.560 +/- 0.031 and 0.666 +/- 0.041), however the expression level of dnmt3a had no difference between these two cell lines. On the contrary, the enzymatic activity level of DNMTs in pol beta-T cells ((329.48 +/- 52.11) OD x h(-1) x mg(-1)) was much lower than that in pol beta +/+ cells ((253.70 +/- 20.56) OD x h(-1) x mg(-1)).

CONCLUSION

The over expression of dnmt1 and dnmt3b and the change of DNMTs activity may be contribute to the cell malignant transformation process induced by BaP.