Central Laboratory, Huangyan Hospital of Wenzhou Medical University, Taizhou First People's Hospital, Taizhou, Zhejiang Province, China.
Central Laboratory, Huangyan Hospital of Wenzhou Medical University, Taizhou First People's Hospital, Taizhou, Zhejiang Province, China.
Toxicol Lett. 2019 Sep 1;311:105-113. doi: 10.1016/j.toxlet.2019.05.001. Epub 2019 May 2.
Excessive accumulation of cadmium (Cd) in retina plays an important role in tobacco smoking-associated age-related macular degeneration (AMD). Plenty of evidence has revealed that the retinal pigment epithelium (RPE) is the primary site of pathology in AMD. Our current study demonstrated that Cd induced apoptosis in a human RPE cell line ARPE-19 cells, as it dose-dependently caused cell viability loss and activated caspase-3. The reactive oxygen species (ROS) were confirmed to be important mediators for Cd-triggered cell death in ARPE-19 cells. We found that endoplasmic reticulum (ER) stress was activated as its marker BiP was remarkably upregulated by Cd-exposure. Whereas the antioxidants N-acetylcysteine (NAC) and Tempol significantly suppressed the expression of BiP and CHOP, suggesting that ROS generation is an early trigger of Cd-activated ER stress. Furthermore, we found that Cd-induced oxidative stress significantly increased autophagic flux and p62 expression. A temporal impact of Cd exposure is possibly existed in p62 expression in ARPE-19 cells. Moreover, an ER stress inhibitor salubrinal diminished Cd-induced LC3BII expression and attenuated cytotoxicity, indicating that ER stress mediates autophagy and was implicated in apoptosis of Cd-exposed ARPE-19 cells. However, CHOP expression may not exert impact on the regulation of Cd-caused autophagy. Additionally, inhibition of autophagy with si-Beclin 1 and 3-Methyladenine significantly ameliorated Cd-induced CHOP expression and cytotoxicity, indicating that autophagy was detrimental in Cd-accumulated ARPE-19 cells, and a positive feedback regulation mechanism may exist between Cd-triggered ER stress and autophagy. Taken together, these results suggest that Cd-caused ER stress and autophagy are implicated in RPE cell death associated retinopathies especially related to smoking.
过量的镉（Cd）在视网膜中的积累在与吸烟相关的年龄相关性黄斑变性（AMD）中起着重要作用。大量证据表明，视网膜色素上皮（RPE）是 AMD 病理学的主要部位。我们目前的研究表明，Cd 以剂量依赖的方式诱导人 RPE 细胞系 ARPE-19 细胞凋亡，导致细胞活力丧失并激活 caspase-3。已证实活性氧（ROS）是 Cd 引发 ARPE-19 细胞死亡的重要介质。我们发现内质网（ER）应激被激活，因为其标志物 BiP 被 Cd 暴露显著上调。而抗氧化剂 N-乙酰半胱氨酸（NAC）和 Tempol 显著抑制 BiP 和 CHOP 的表达，表明 ROS 的产生是 Cd 激活 ER 应激的早期触发因素。此外，我们发现 Cd 诱导的氧化应激显著增加了自噬通量和 p62 的表达。Cd 暴露在 ARPE-19 细胞中 p62 表达可能存在时间依赖性。此外，ER 应激抑制剂 salubrinal 减弱了 Cd 诱导的 LC3BII 表达和细胞毒性，表明 ER 应激介导自噬，并参与 Cd 暴露的 ARPE-19 细胞凋亡。然而，CHOP 表达可能不会对 Cd 引起的自噬调节产生影响。此外，用 si-Beclin 1 和 3-甲基腺嘌呤抑制自噬显著改善了 Cd 诱导的 CHOP 表达和细胞毒性，表明自噬在 Cd 积累的 ARPE-19 细胞中是有害的，并且 Cd 触发的 ER 应激和自噬之间可能存在正反馈调节机制。总之，这些结果表明，Cd 引起的 ER 应激和自噬与 RPE 细胞死亡相关的视网膜病变有关，尤其是与吸烟有关。
