Filiz Gulay, Caragounis Aphrodite, Bica Laura, Du Tai, Masters Colin L, Crouch Peter J, White Anthony R
Centre for Neuroscience and Department of Pathology, The University of Melbourne, Victoria 3010, Australia.
Int J Biochem Cell Biol. 2008;40(5):1030-42. doi: 10.1016/j.biocel.2007.11.003. Epub 2007 Nov 17.
A growing body of evidence supports a central role for biometals in neurodegenerative disorders. Biometals induce oxidative stress through the generation of reactive oxygen species and contribute to neuronal cell dysfunction in Alzheimer's disease (AD), prion disorders and Parkinson's disease (PD). Therapies based on modulation of biometal metabolism are currently being developed and the metal ligand, 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol or CQ) has been investigated for the treatment of AD. CQ has also shown therapeutic benefits in an animal model of PD. However, little is known about the neuroprotective processes of CQ in vivo. In this study, we examined the effect of CQ in BE(2)-M17 human neuroblastoma cells exposed to increased oxidative stress (hydrogen peroxide (H2O2) treatment). Although CQ alone induced a moderate toxic effect on cells, when added to H2O2-treated M17 cells, CQ induced a significant inhibition of H2O2 toxicity. This correlated with up-regulation of phosphoinositol-3-kinase (PI3K) activity in CQ-treated cells. The protective action of CQ was not observed in murine N2a neuroblastoma cells treated with H2O2 and this cell-line did not reveal CQ-mediated increases in PI3K activation. The protective effect was specific for CQ and was not induced by a number of different metal ligands. Inhibition of PI3K activity with LY294002 prevented CQ protection against H2O2 toxicity, demonstrating a crucial role for CQ activation of PI3K in protection against oxidative stress. Furthermore, CQ inhibited H2O2-mediated up-regulation of p53 activity in the M17 cells and this was dependent on PI3K activation. Our studies demonstrate that in human M17 cells, CQ can protect against oxidative stress by activating the PI3K-dependent survival pathway and blocking p53-mediated cell death. These findings have important implications for the development of protective metal ligand-based therapies for treatment of disorders involving oxidative stress.
越来越多的证据支持生物金属在神经退行性疾病中起核心作用。生物金属通过产生活性氧诱导氧化应激，并在阿尔茨海默病（AD）、朊病毒疾病和帕金森病（PD）中导致神经元细胞功能障碍。目前正在开发基于调节生物金属代谢的疗法，金属配体5-氯-7-碘-8-羟基喹啉（氯碘羟喹或CQ）已被研究用于治疗AD。CQ在PD动物模型中也显示出治疗益处。然而，关于CQ在体内的神经保护过程知之甚少。在本研究中，我们检测了CQ对暴露于增加的氧化应激（过氧化氢（H2O2）处理）的BE(2)-M17人神经母细胞瘤细胞的影响。尽管单独的CQ对细胞诱导了中度毒性作用，但当添加到H2O2处理的M17细胞中时，CQ显著抑制了H2O2毒性。这与CQ处理的细胞中磷酸肌醇-3-激酶（PI3K）活性的上调相关。在用H2O2处理的小鼠N2a神经母细胞瘤细胞中未观察到CQ的保护作用，并且该细胞系未显示CQ介导的PI3K激活增加。保护作用对CQ具有特异性，并且不是由许多不同的金属配体诱导的。用LY294002抑制PI3K活性可阻止CQ对H2O2毒性的保护作用，证明CQ激活PI3K在抵抗氧化应激的保护中起关键作用。此外，CQ抑制了M17细胞中H2O2介导的p53活性上调，这依赖于PI3K激活。我们的研究表明，在人M17细胞中，CQ可通过激活PI3K依赖性存活途径并阻断p53介导的细胞死亡来抵抗氧化应激。这些发现对于开发基于保护性金属配体的疗法以治疗涉及氧化应激的疾病具有重要意义。
