Sarma Sailendra Nath, Blais Jules M, Chan Hing Man
a Department of Biology , University of Ottawa , Ottawa , ON , Canada.
J Toxicol Environ Health A. 2017;80(5):285-300. doi: 10.1080/15287394.2017.1314840. Epub 2017 Jun 9.
Polycyclic aromatic compounds (PAC) are ubiquitous environmental pollutants originating from incomplete combustion processes. While the toxicity of parent PAC such as benzo[a]pyrene (BaP) is well characterized, effects of other alkyl-PAC dibenzothiophene (DBT) and retene (Ret) are not well established. The aim of this study was to examine the underlying relative neurotoxic mechanisms attributed to BaP (parent PAH), DBT and Ret (alkyl-PACs) using human neuroblastoma SK-N-SH cells. The lethal concentrations (LC and LC) were found at approximately 10 µM and 40 µM, respectively after 24-h exposure of SK-N-SH cells. It was hypothesized that PAC trigger reactive oxygen species (ROS) production, leading to activation of apoptotic signaling pathways. Differentiated neuronal cells were treated with three compounds at (0.5-40 µM) for 24 h. There was a significant concentration-dependent increase in levels of ROS, even at sub-lethal levels of 1 µM Ret. The mitochondrial membrane potential (MMP) was significantly decreased. Real-time RT-PCR results showed up-regulation of pro-apoptotic genes and down-regulation of antioxidative genes expression in BaP-, DBT-, and Ret-treated SK-N-SH cells. Cytochrome c protein levels and lipid peroxidation (LPO) were also significantly elevated in a concentration-related manner. Data demonstrated that BaP-, DBT-, or Ret-induced neuronal cell damage involved oxidative stress generation through mitochondria-mediated apoptosis pathway. Alkyl-PAC also exhibited higher potency in ROS induction and reduction of MMP than parent PAC. These findings may be important for environmental risk assessment attributed to exposure to PAC.
多环芳烃化合物（PAC）是源自不完全燃烧过程的普遍存在的环境污染物。虽然母体PAC如苯并[a]芘（BaP）的毒性已得到充分表征，但其他烷基PAC二苯并噻吩（DBT）和惹烯（Ret）的影响尚未明确。本研究的目的是使用人神经母细胞瘤SK-N-SH细胞研究归因于BaP（母体多环芳烃）、DBT和Ret（烷基PAC）的潜在相对神经毒性机制。在SK-N-SH细胞暴露24小时后，分别在约10 μM和40 μM处发现致死浓度（LC和LC）。据推测，PAC会触发活性氧（ROS）的产生，从而导致凋亡信号通路的激活。将分化的神经元细胞用三种化合物（0.5 - 40 μM）处理24小时。即使在1 μM Ret的亚致死水平下，ROS水平也有显著的浓度依赖性增加。线粒体膜电位（MMP）显著降低。实时RT-PCR结果显示，在BaP、DBT和Ret处理的SK-N-SH细胞中，促凋亡基因上调，抗氧化基因表达下调。细胞色素c蛋白水平和脂质过氧化（LPO）也以浓度相关的方式显著升高。数据表明，BaP、DBT或Ret诱导的神经元细胞损伤涉及通过线粒体介导的凋亡途径产生氧化应激。与母体PAC相比，烷基PAC在诱导ROS和降低MMP方面也表现出更高的效力。这些发现可能对因接触PAC而进行的环境风险评估具有重要意义。
