多氯联苯和苯并(a)芘联合作用对HepG2细胞CYP1A1和微核的影响

Combined Effect of PCBs and B(a)P on CYP1A1 Activities and Micronuclei Formation of HepG2 Cells

目的探讨多氯联苯(PCBs)153通过诱导P450酶活力对苯并(a)芘[B(a)P]遗传毒性的影响。方法PCB153设3个剂量组(1、10、100μmol/L),B(a)P设1个剂量组(50μmol/L),DMSO为溶剂对照组,3-甲基胆蒽(3-MC)为阳性对照组。以不同浓度的PCB153(1、10、100μmol/L)染毒HepG2细胞48h后再与B(a)P联合染毒24h。通过荧光分光光度法测定HepG2细胞CYP1A1酶活力(EROD)。同时采用胞质分裂阻滞法微核试验(CBMNT)分析细胞的微核,计算微核率和核分裂指数(NDI)。结果与溶剂对照组相比,1、10、100μmol/L的PCB153和50μmol/L的B(a)P单独染毒均可诱导EROD活力增加,差异有统计学意义(P<0.05)。与溶剂对照组比较,100μmol/L的PCB153和50μmol/L的B(a)P可诱导微核率显著升高,差异有统计学意义(P<0.01)。与B(a)P单独染毒组比较,B(a)P和PCB153联合染毒时,EROD活力和微核率均显著升高,差异有统计学意义(P<0.05或P<0.01)。与溶剂对照组比较,100μmol/L的PCB153和50μmol/L的B(a)P及所有联合染毒组均使HepG2细胞NDI明显降低,差异有统计学意义(P<0.05或P<0.01)。结论PCB153对B(a)P的遗传毒性作用具有一定的促进作用,这种促进可能与PCB153诱导P450酶活力有关。

Objective To study the effect ofpolychlorinated biphenyl （PCB）153 on genotoxicity of B （a）P through inducing P450 enzymic activity. Methods HepG2 cells were treated with PCB153 at different concentrations （1, 10, 100 μmol/L） for 48 h alone and then treated with B（a）P （50 μmol/L） and PCB153 in combination for another 24 h. DMSO and 3-MC were used as solvent control and positive control respectively. EROD activity and mieronuelei （MN） were detected hy using fluorescence speetrophotometry and a cytokinesis-hlock micronucleus assay （CBMNT） respectively. The frequencies of MN （‰） and nuclei division index （NDI） were calculated. Results Compared with the solvent control, PCB153 at concentrations of 1, 10 and 100μmol/L induced a significant increase in EROD activities in HepG2 cells and the enhancement of MN frequencies were showed only in HepG2 cells treated with B（a）P. Compared with B（a）P treatment only, EROD activities and MN frequencies increased significantly in HepG2 cells treated with B（a）P and PCB153 in combination, NDI was decreased only in HepG2 cells treated with B（a）P. Conclusion PCB153 might have synergic effect on genotoxic properties of B（a）P. CYP 1A1 enzyme induction may play a role in the facilitative effect.