Objective To observe the DNA damage effect of Bisphenol A (BPA) in combination with benzoapyrene (BaP) on three human epithelial cell lines, i.e. human mammary epithelial cells (HMEC), MCF-10A, and MCF-7.
Methods Immunofluorescence was applied to observe the biomarker of DNA double-strand break in three human epithelial cells caused by a combination exposure to BPA (10-9 mol/L, 10-7 mol/L) and BaP (10-6 mol/L). The blank controls were administrated with dimethyl sulfoxide (DMSO) and the positive controls with 17-β-estradiol. Real-time polymerase chain reaction (PCR) was used to detect the relative mRNA expression levels of estrogen receptors (ESR1 and ESR2) in three cell lines.
Results No notable differences in the pH2AX positive rates were detected between the BPA alone and the control groups. The pH2AX positive rates were increased remarkably after treatment of BaP to HMECfrom (34.7& #177;2.2)% to (63.6& #177;1.2)%and MCF-7from (3.1& #177;0.3)% to (13.3& #177;0.4)% cell lines. Compare with the BaP alone group, combination of 10-7 mol/L BPA or 10-9 mol/L 17-β-estradiol with BaP increased the pH2AX positive rate to (15.1& #177;0.2)% and (17.5& #177;1.0)%, respectively. The expression levels of estrogen receptor genes varied among three cell lines, and the expression level of ESR1 gene in MCF-7 cells were 1 080 folds as high as in HMEC cells and 5 222 folds as in MCF-10A cells.
Conclusion Compare with the BaP alone exposure, the combination exposure to BPA and BaP can intensify the DNA double-strand break in MCF-7 cell line, and the effect may depend on the expression level of estrogen receptors.
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