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目的探讨2,2′,4,4′-四溴联苯醚(BDE-47)是否为孕烷X受体(pregnane X receptor,PXR)的诱导剂及其诱导PXR受体下游基因细胞色素P4503A4(CYP3A4)的转录表达能力。方法采用CCK-8法测定分析BDE-47对人肝肿瘤细胞株HepG2的细胞毒性作用,并以BDE-47分别处理双萤光素酶hPXR报告基因系统和稳定高表达hPXR的HepG2细胞株,观察其对CYP3A4的诱导作用和对其mRNA及蛋白表达的诱导作用。结果BDE-47对HepG2细胞有明显的细胞毒性作用,且在6～48h呈明显剂量-时间-效应关系(P<0.01)。48h为毒作用兴奋点,其半数抑制浓度(IC50)为110μmol/L。BDE-47能诱导CYP3A4表达量的增高,呈明显剂量-时间-效应关系(P<0.01)。Q-PCR和Western Blot分析发现,其对CYP3A4的mRNA转录和蛋白表达有显著诱导作用,并呈剂量-效应关系(P<0.01),对PXR受体诱导能力明显高于已知的阳性诱导物利福平。结论在本试验条件下,BDE-47是PXR受体的强力诱导剂,可能通过激活PXR受体而发挥其一系列毒性作用。
OBJECTIVE: To investigate whether 2,2 ’, 4,4’-tetrabromodiphenyl ether (BDE-47) is an inducer of pregnane X receptor (PXR) and its effect on downstream genes of PXR receptor cytochrome P4503A4 (CYP3A4) transcriptional competence. Methods The cytotoxicity of BDE-47 on human hepatocellular carcinoma cell line HepG2 was assayed by CCK-8 assay. The dual luciferase reporter gene system was treated with BDE-47 and the HepG2 cell line stably expressing hPXR was observed. Its induction of CYP3A4 and its induction of mRNA and protein expression. Results BDE-47 had obvious cytotoxicity on HepG2 cells and showed a dose-time-effect relationship at 6 ~ 48h (P <0.01). 48h excitotoxicity point, the median inhibitory concentration (IC50) of 110μmol / L. BDE-47 can induce the increase of CYP3A4 expression, showing a significant dose-time-effect relationship (P <0.01). Q-PCR and Western Blot analysis showed that CYP3A4 mRNA transcription and protein expression were significantly induced, and the dose-effect relationship (P <0.01), the PXR receptor induced ability was significantly higher than the known positive inducers Rifampin. Conclusion Under the experimental conditions, BDE-47 is a potent inducer of PXR receptors and may exert a series of toxic effects by activating PXR receptors.