title: Prolonged Effects of Silver Nanoparticles on p53/p21 Pathway-Mediated Proliferation, DNA Damage Response, and Methylation Parameters in HT22 Hippocampal Neuronal Cells.
abstract: It is widely accepted that silver nanoparticles (AgNPs) are toxic to biological systems. However, little is known about their actions at molecular level and the cytophysiological effects after AgNP removal. As nanoparticles are suggested a promising tool to transport drugs to the brain for use in neurological conditions, we used HT22 mouse hippocampal neuronal cells as a model to study AgNP-mediated effects after their removal from the cell culture medium. We selected a relatively low concentration of AgNPs, 5 μg/ml, treated the cells for 48 h, and evaluated AgNP-induced cytophysiological effects after 96 h of AgNP removal. AgNP removal did not result in cytotoxicity. In contrast, AgNPs modulated HT22 cell cycle and proliferation and induced oxidative stress and 53BP1 recruitment, which were accompanied by elevated levels of p53 and p21. AgNP-associated diminution in lamin B1 pools did not significantly affect the structure of the nucleus. No disruption in F-actin dynamics was observed upon AgNP treatment. Moreover, we showed for the first time that AgNPs stimulated changes in DNA methylation: the augmentation in 5-methylcytosine (5-mC) and DNMT1, DNMT2, DNMT3a, and DNMT3b levels were observed. The upregulation of DNMT2 may be a part of cellular stress response to AgNP treatment. Taken together, AgNP removal resulted in p53/p21-mediated inhibition of cell proliferation, oxidant-based DNA damage response, and changes in DNA methylation patterns, which suggests that more attention should be paid to the possible outcomes in individuals exposed to nano-sized biomaterials.
authors: Department of Genetics, University of Rzeszow, Rejtana 16C, 35-959, Rzeszow, Poland.
authors: Jennifer
authors: J
authors: Mytych
authors: Department of Plant Physiology, University of Rzeszow, Werynia 502, 36-100, Kolbuszowa, Poland.
authors: Jacek
authors: J
authors: Zebrowski
authors: Department of Biochemistry and Cell Biology, University of Rzeszow, Zelwerowicza 4, 35-601, Rzeszow, Poland. alewinska@o2.pl.
authors: Anna
authors: A
authors: Lewinska
authors: Department of Genetics, University of Rzeszow, Rejtana 16C, 35-959, Rzeszow, Poland. mawnuk@gmail.com.
authors: Maciej
authors: M
authors: Wnuk
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects / Q000502:physiology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D004249:DNA Damage / Q000187:drug effects* / Q000502:physiology; D019175:DNA Methylation / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D053768:Metal Nanoparticles / Q000633:toxicity*; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D012834:Silver / Q000633:toxicity*; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016159:Tumor Suppressor Protein p53; D012834:Silver
keywords: DNA methylation; DNMTs; HT22 cells; Oxidative stress; Silver nanoparticles