Xiang Ping, Liu Rong-Yan, Sun Hong-Jie, Yang Yun-Wen, Cui Xin-Yi, Ma Lena Q
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046, People's Republic of China.
The State Key Laboratory of Pharmaceutical Biotechnology, College of Life Science, Nanjing University, Nanjing 210046, People's Republic of China.
Environ Res. 2017 Jul;156:834-842. doi: 10.1016/j.envres.2017.02.028. Epub 2017 Mar 16.
As a replacement for polybrominated diphenyl ethers, bis-(2-ethylhexyl) tetrabromophthalate (TBPH) is widely used as a novel flame retardant and has been detected in many environmental matrix including human blood. TBPH can be metabolized into mono-(2-ethyhexyl) tetrabromophthalate (TBMEHP) by carboxylesterase. However, their adverse effects on human vascular endothelium and their potential impacts on human cardiovascular disease are unknown. In this study, their adverse effects and associated molecular mechanisms on human vascular endothelial cells (HUVECs) were investigated. A concentration-dependent inhibition on HUVECs' viability and growth was observed for TBMEHP but not for TBPH. TBMEHP induced a marked G/G cell cycle arrest and robust cell apoptosis at 1μg/mL by inducing expression of p53, GADD45α and cyclin dependent kinase (CDK) inhibitors (p21and p27) while suppressing the expression of cyclin D1, CDK2, CDK6, and Bcl-2. Unlike TBMEHP, TBPH caused early apoptosis after G/M phase arrest only at 10μg/mL via up-regulation of p21 and down-regulation of CDK2 and CDK4. TBMEHP decreased mitochondrial membrane potential and increased caspase-3 activity at 1μg/mL, suggesting that activation of p53 and mitochondrial pathway were involved in the cell apoptosis. The data showed that TBPH and TBMEHP induced different cell cycle arrest and apoptosis through different molecular mechanisms with much higher toxicity for TBMEHP. Our study implies that the metabolites of TBPH, possibly other novel brominated flame retardants, may be of potential concern for human cardiovascular disease.
作为多溴二苯醚的替代品，双（2-乙基己基）四溴邻苯二甲酸酯（TBPH）作为一种新型阻燃剂被广泛使用，并且已在包括人体血液在内的许多环境基质中被检测到。TBPH可被羧酸酯酶代谢为单（2-乙基己基）四溴邻苯二甲酸酯（TBMEHP）。然而，它们对人体血管内皮的不良影响以及对人类心血管疾病的潜在影响尚不清楚。在本研究中，研究了它们对人血管内皮细胞（HUVECs）的不良影响及相关分子机制。观察到TBMEHP对HUVECs的活力和生长有浓度依赖性抑制作用，而TBPH则没有。TBMEHP在1μg/mL时通过诱导p53、GADD45α和细胞周期蛋白依赖性激酶（CDK）抑制剂（p21和p27）的表达，同时抑制细胞周期蛋白D1、CDK2、CDK6和Bcl-2的表达，诱导明显的G/G期细胞周期阻滞和强烈的细胞凋亡。与TBMEHP不同，TBPH仅在10μg/mL时通过上调p21和下调CDK2及CDK4导致G/M期阻滞之后的早期凋亡。TBMEHP在1μg/mL时降低线粒体膜电位并增加caspase-3活性，表明p53激活和线粒体途径参与了细胞凋亡。数据表明，TBPH和TBMEHP通过不同分子机制诱导不同的细胞周期阻滞和凋亡，其中TBMEHP的毒性要高得多。我们的研究表明，TBPH的代谢产物，可能还有其他新型溴化阻燃剂，可能是人类心血管疾病的潜在隐患。
