2,2',4,4'-四溴联苯醚对视黄醛受体和雌激素受体的影响

目的:探讨2,2',4,4'-四溴联苯醚(BDE-47)对视黄醛受体(RXRα)和雌激素受体(ERα、ERβ)的影响,为阐明多溴联苯醚化合物神经内分泌干扰效应提供科学依据。方法:采用CCK-8法测定BDE-47对慢病毒转染技术构建的稳定高表达和低表达RXRα的MCF-7细胞系及正常细胞系的细胞毒性;并以BDE-47分别处理3种细胞,采用TBA法、XOD法及RT-PCR法测定超氧化物歧化酶(SOD)活力、丙二醛(MDA)含量及人类8-羟基鸟嘌呤DNA糖苷酶(hOGG1)mRNA表达量,采用RT-PCR和Western blot分析其对3种细胞系RXRα、ERα和ERβ的mRNA及蛋白表达的影响。结果:BDE-47对MCF-7细胞系具有明显的细胞毒性作用,作用24 h时,对RXRα正常表达、高表达和低表达的MCF-7细胞的半数抑制浓度(IC₅₀)分别为23.15、82.78、30.16 μmol/L;BDE-47可造成3种细胞的氧化损伤,RXRα受体高表达细胞对BDE-47的细胞毒性耐受性明显高于另外两种细胞,可一定程度提高细胞抗氧化损伤能力。BDE-47对3种细胞RXRα的表达有明显的抑制作用,可诱导RXRα正常表达与低表达细胞中ERα受体的表达增强、ERβ受体的表达降低;而在RXRα高表达细胞中ERα受体的表达降低、ERβ受体的表达增强,两种雌激素受体表达变化相反。结论:BDE-47可能抑制RXRα受体表达,继而干扰ERα、ERβ两种受体的表达和二者间的平衡,从而发挥其神经内分泌毒性效应。

Effects of 2, 2', 4, 4'-tetra polybrominated diphenyl ether on retinoid receptor and estrogen receptor

OBJECTIVE:To investigate effects and mechanisms of 2, 2', 4, 4'-tetra polybrominated diphenyl ether (BDE-47) on retinoid receptor (RXRα) and estrogen receptors (ERα, ERβ) in MCF-7 cells. METHODS:Stably expressed RXRα in MCF-7 cells at high and low levels were constructed via lentivirus transfection. After exposure of three transfected cell lines to polybrominated diphenyl (BDE-47), cell toxicity was analyzed using the Cell Counting Kit-8(CCK-8) assay. In addition, SOD vitality, MDA content and hOGG1 mRNA expression were analyzed using the TBA, XOD and RT-PCR assays, respectively. Expression levels in mRNA and protein for the three receptors (RXRα, ERα and ERβ) were determined by RT-PCR and Western blot respectively. RESULTS:BDE-47 induced significant cytotoxicity to MCF-7 cells. IC₅₀ of BDE-47 to MCF-7 cells with normal, high and low expressions of RXRα were 23.15, 82.78 and 30.16 μmol/L, respectively. Highest toxicity was observed at 24 h after the exposure to BDE-47. Moreover, BDE-47 induced oxidative damage. Cells with high expression of RXRα receptor had increased toxicity tolerance against BDE-47-induced oxidative damage. BDE-47 also significantly inhibited the expression of RXRα in the three cell lines. For ER, BDE-47 exposure increased the expression of ERα and inhibited the expression of ERβ in normal and low RXRα expression cells, and vice versa in high RXRα expression cells. CONCLUSION:BDE-47 exposure significantly reduced the expression levels in mRNA and protein of RXRα. In addition, the exposure up-regulated ERα and down-regulated ERβ in normal and low RXRα cell lines, but showed opposite effects in the high RXRα cell line. Thus, interference of RXRα expression and breaking the balance of ERα and ERβ may be an important mechanism for disruption of neuroendocrine by BDE-47.