title: Nuclear NF-κB contributes to chlorpyrifos-induced apoptosis through p53 signaling in human neural precursor cells.
abstract: Chlorpyrifos (CPF) is one of the most widely used organophosphate insecticides with several harmful effects, including neurotoxicity. Although many studies have addressed the neurotoxicity induced by CPF, most data on neurodevelopmental damage was obtained from animal models. We are the first group to use human neural precursor cells (hNPCs) derived from human embryonic stem cells (hESCs) as a developing neuron model to evaluate the mechanisms involved in CPF-induced neurotoxicity. CPF was cytotoxic to these cells in a concentration-dependent manner, as shown by decreased cell viability and increased lactate dehydrogenase release. Furthermore, CPF reduced the expression of AKT and ERK proteins which are involved in intracellular survival pathways. Exposure of hNPCs to CPF led to the production of reactive oxygen species (ROS), and the antioxidant N-acetyl-cystein (NAC) attenuated ROS production induced by CPF. In addition, CPF increased cytochrome c release into the cytosol and activated caspase-9 and -3, indicating that cell death induced by CPF was due to apoptosis in hNPCs. Consistent with these findings, CPF treatment reduced the level of Bcl-2 protein and increased the level of Bax protein. Especially, CPF increased the translocation of BAX into the mitochondria. CPF also induced nuclear accumulation of NF-κB and p53 proteins in a concentration-dependent manner, and their inhibitors attenuated CPF-induced cytotoxicity. In addition, an inhibitor of NF-κB nuclear translocation blocked the increase of p53 in CPF-treated hNPCs. These findings show that CPF induced hNPCs death in part through NF-κB activation via ROS generation, enabling the interaction of p53 with Bcl-2 and Bax and subsequent release of cytochrome c. Collectively, these results represent a unique molecular characterization of CPF-induced cytotoxicity in hNPCs. These data suggest that CPF may affect neurodevelopment in a manner similar to that of several known and suspected neurotoxicants.
authors.affiliation: Department of Pharmacology, College of Medicine, Hanyang University, Seoul, Republic of Korea; Hanyang Biomedical Research Institute, Seoul, Republic of Korea.
authors.forename: Jeong Eun
authors.initials: JE
authors.lastname: Lee
authors.affiliation: Hanyang Biomedical Research Institute, Seoul, Republic of Korea; Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea.
authors.forename: Mi Sun
authors.initials: MS
authors.lastname: Lim
authors.affiliation: Hanyang Biomedical Research Institute, Seoul, Republic of Korea; Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea.
authors.forename: Jae Hyeon
authors.initials: JH
authors.lastname: Park
authors.affiliation: Hanyang Biomedical Research Institute, Seoul, Republic of Korea; Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea.
authors.forename: Chang Hwan
authors.initials: CH
authors.lastname: Park
authors.affiliation: Department of Pharmacology, College of Medicine, Hanyang University, Seoul, Republic of Korea; Hanyang Biomedical Research Institute, Seoul, Republic of Korea; Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, Republic of Korea. Electronic address: hckoh@hanyang.ac.kr.
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Koh
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002478:Cells, Cultured; D004390:Chlorpyrifos / Q000037:antagonists & inhibitors / Q000633:toxicity*; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007306:Insecticides / Q000037:antagonists & inhibitors / Q000633:toxicity; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D058953:Neural Stem Cells / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D007306:Insecticides; D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D008315:Malondialdehyde; D045304:Cytochromes c; D007770:L-Lactate Dehydrogenase; D053148:Caspase 3; D053453:Caspase 9; D004390:Chlorpyrifos; D000111:Acetylcysteine
keywords: Chlorpyrifos; Human neural precursor cells; NF-κB; Reactive oxidative species; p53