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Characterization of Apoptosis Induced by Emodin and Related Regulatory Mechanisms in Human Neuroblastoma Cells
Department of Obstetrics and Gynecology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan
Chang Gung University College of Medicine, Kaohsiung 83301, Taiwan
Department of Life Science, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan
Department of Bioscience Technology and Center for Nanotechnology, Chung Yuan Christian University, Chung Li 32023, Taiwan
Institute of Biomedical Technology, Chung Yuan Christian University, Chung Li 32023, Taiwan
* Author to whom correspondence should be addressed.
Received: 1 July 2013; in revised form: 26 September 2013 / Accepted: 26 September 2013 / Published: 9 October 2013
Abstract: Emodin (1,3,8-trihydroxy-6-methylanthraquinone), a major constituent of rhubarb, has a wide range of therapeutic applications. Recent studies have shown that emodin can induce or prevent cell apoptosis, although the precise molecular mechanisms underlying these effects are unknown. Experiments from the current study revealed that emodin (10–20 μM) induces apoptotic processes in the human neuroblastoma cell line, IMR-32, but exerts no injury effects at treatment doses below 10 μM. Treatment with emodin at concentrations of 10–20 μM led to a direct increase in the reactive oxygen species (ROS) content in IMR-32 cells, along with significant elevation of cytoplasmic free calcium and nitric oxide (NO) levels, loss of mitochondrial membrane potential (MMP), activation of caspases-9 and -3, and cell death. Pretreatment with nitric oxide (NO) scavengers suppressed the apoptotic biochemical changes induced by 20 μM emodin, and attenuated emodin-induced p53 and p21 expression involved in apoptotic signaling. Our results collectively indicate that emodin at concentrations of 10–20 μM triggers apoptosis of IMR-32 cells via a mechanism involving both ROS and NO. Based on the collective results, we propose a model for an emodin-triggered apoptotic signaling cascade that sequentially involves ROS, Ca2+, NO, p53, caspase-9 and caspase-3.
Keywords: emodin; apoptosis; oxidative stress; calcium; nitric oxide
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MDPI and ACS Style
Huang, F.-J.; Hsuuw, Y.-D.; Chan, W.-H. Characterization of Apoptosis Induced by Emodin and Related Regulatory Mechanisms in Human Neuroblastoma Cells. Int. J. Mol. Sci. 2013, 14, 20139-20156.
Huang F-J, Hsuuw Y-D, Chan W-H. Characterization of Apoptosis Induced by Emodin and Related Regulatory Mechanisms in Human Neuroblastoma Cells. International Journal of Molecular Sciences. 2013; 14(10):20139-20156.
Huang, Fu-Jen; Hsuuw, Yan-Der; Chan, Wen-Hsiung. 2013. "Characterization of Apoptosis Induced by Emodin and Related Regulatory Mechanisms in Human Neuroblastoma Cells." Int. J. Mol. Sci. 14, no. 10: 20139-20156.