OBJECTIVETo explore the effects of bisphenol A (BPA) exposure on toxicity characteristic and OCT4 and SOX2 gene expression of mouse embryonic stem cells (mESC).

METHODSmESC were cultured, and treated with the doses of 10(-8), 10(-7), 10(-6), 10(-5), 10(-4) mol/L respectively of BPA and DMSO (the solvent control group)for 24 hours, and three groups of cells were treated with the same method. The morphological changes of mESC in the control and exposure groups were observed through an inverted microscope. Cell counting kit 8 (CCK8) was used to detect the effects of BPA on proliferation of mESC, and based on the results, the half inhibitory concentration (IC50) was calculated. Real-time fluorescent quantitative polymerase chain reaction (RT-QPCR) and western blotting were used to detect the expression of OCT4 and SOX2.

RESULTSBPA had certain toxicity on mESC, the treatment of BPA significantly increased cell toxicity in a concentration-dependent manner, and the IC50 was 4.3×10(-4) mol/L, combined with the BPA exposure concentration of the environment and the related literature, eventually taking the five concentrations of 10(-8), 10(-7), 10(-6), 10(-5), 10(-4) mol/L as the experimental groups. The mESC morphology were effected after the treatment of BPA for 24 h, compared with the control group, the number of cells decreased, appearing some floating cells, and the cell cloning became irregular and differentiation in the higher concentration groups. The OCT4 mRNA expression level in the 10(-7) mol/L (1.146 ± 0.087), 10(-6) mol/L (1.156 ± 0.030), 10(-5) mol/L (1.158 ± 0.103) and the 10(-4) mol/L (1.374 ± 0.053) dose group were all significantly higher than the control group (1.000 ± 0.000) (t values were -2.384, -2.953, -3.203, -4.021 respectively, P value all < 0.05). Meanwhile, the SOX2 mRNA expression level in the 10(-4) mol/L (1.113 ± 0.052) were higher than the control group (1.000 ± 0.000) (t value was -2.765, P value < 0.05). Moreover, the OCT4 protein expression level in the 10(-5) mol/L (1.360 ± 0.168) and 10(-4) mol/L (1.602 ± 0.151) were all significantly higher than the control group (1.000 ± 0.000) (t values were -3.538, -4.002 respectively, P value all < 0.05), while no obvious change of the SOX2 protein expression level was detected in all treated groups.

CONCLUSIONBPA in a certain dose range could upregulate the expression of OCT4 gene in mouse embryonic stem cells while had no significant effect on the expression of SOX2 gene.