title: Cationic polystyrene nanospheres induce autophagic cell death through the induction of endoplasmic reticulum stress.
abstract: Nanoparticles (NPs) have been used to produce a wide range of products that have applications in imaging and drug delivery in medicine. Due to their chemical stability, well-controlled sizes and surface charges, polystyrene (PS) NPs have been developed as biosensors and drug delivery carriers. However, the possible adverse biological effects and underlying mechanisms are still unclear. Recently, autophagy has been implicated in the regulation of cell death. In this study, we evaluated a library of PS NPs with different surface charges. We found that NH2-labeled polystyrene (NH2-PS) nanospheres were highly toxic with enhanced uptake in macrophage (RAW 264.7) and lung epithelial (BEAS-2B) cells. Furthermore, NH2-PS could induce autophagic cell death. NH2-PS increased autophagic flux due to reactive oxygen species (ROS) generation and endoplasmic reticulum (ER) stress caused by misfolded protein aggregation. The inhibition of ER stress decreased cytotoxicity and autophagy in the NH2-PS-treated cells. In addition, the Akt/mTOR and AMPK signaling pathways were involved in the regulation of NH2-PS-triggered autophagic cell death. These results suggest an important role of autophagy in cationic NP-induced cell death and provide mechanistic insights into the inhibition of the toxicity and safe material design.
authors.affiliation: Department of Environmental and Occupational Health, National Cheng Kung University, Tainan, Taiwan. yjwang@mail.ncku.edu.tw.
authors.forename: Hui-Wen
authors.initials: HW
authors.lastname: Chiu
authors.forename: Tian
authors.initials: T
authors.lastname: Xia
authors.forename: Yu-Hsuan
authors.initials: YH
authors.lastname: Lee
authors.forename: Chun-Wan
authors.initials: CW
authors.lastname: Chen
authors.forename: Jui-Chen
authors.initials: JC
authors.lastname: Tsai
authors.forename: Ying-Jan
authors.initials: YJ
authors.lastname: Wang
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D002412:Cations / Q000737:chemistry; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D054118:Nanospheres / Q000737:chemistry* / Q000633:toxicity; D011137:Polystyrenes / Q000737:chemistry*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D002412:Cations; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; D011137:Polystyrenes; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases