Objective Effects of co-exposure of Di-(2-ethylhexyl) phthalate and Benzo(a)pyrene on CYP1A1 and CYP3A4 enzyme activities were investigated in HepG2 cells.
Methods HepG2 cells were treated with either 64.0 μmol/L B(a)P alone or DEHP alone (62.5,125.0,250.0,500.0,1 000.0 μmol/L) or DEHP at the indicated concentrations plus 64.0 μmol/L B(a)P or dimethyl sulfoxide (DMSO,solvent control,<1 ‰) for 48 h and 72 h.The cell proliferation was evaluated by CCK8 assay.The activities of CYP 1A-associated deethylation of ethoxyresorufin (EROD) and CYP3A-associated ethoxycoumarin-O-deethylation (ECOD) were measured.Expressions of CYP1A1 and CYP3A4 at mRNA and protein were detected by quantitative real time PCR method and Western blot,respectively.
Results The cell viability was decreased significantly in all co-exposure of B(a)P and DEHP groups compared with the controls (P<0.01).However,the EROD and ECOD activities significantly increased,when compared with the DEHP alone treated group (P<0.05,P<0.01).Only up-regualtion of CYP1A1 transcriptional levels were observed in all co-exposure of B(a)P and DEHP groups.However,the levels of mRNA and protein expression of CYP3A4 were increased (P<0.01),when compared with the DEHP alone treated group.
Conclusion Co-exposure of DEHP at certain concentrations and B(a)P (64.0μmol/L) induced the increases in the EROD and ECOD activities,as well as the CYP1A1 transcriptional level and the CYP3A4 transcriptional and protein levels.
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