title: Stress responses of human dermal fibroblasts exposed to zinc pyrithione.
abstract: Zinc pyrithione is used as a topical agent in a range of medicinal and cosmetic applications. Despite its extensive use and reported beneficial effects in treatment of various dermal problems, its potential toxicity towards skin cells remains relatively underexplored. In this work we investigated effects of nM zinc pyrithione on cell stress response pathways of primary human skin fibroblasts during 24h of exposure. We demonstrate that zinc pyrithione-induced cytotoxity in dermal fibroblasts is dose-dependent and it associates with increased intracellular zinc concentrations and activated stress response pathways including p53 and stress kinase p38. Higher zinc pyrithione concentrations (500nM and above) stimulate oxidative stress and moderate DNA damage which occur in the presence of activated p38 kinase. Cells further upregulate the expression of p53 which increases its transcriptional activity while mitogenic signaling exemplified by mTOR (mammalian target of rapamycin) expression is suppressed and these steps lead to mitochondrial, caspase-dependent apoptosis. Conversely, lower zinc concentrations (125nM) fail to induce oxidative stress and significant DNA damage; however, treated cells still activate p38 and upregulate the expression and transcriptional activity of p53 and its target gene p21 as well as the expression of p16 in the presence of active mTOR pathway and a changed DNA methylation pattern. The end result is premature senescence phenotype. Specific pharmacological inhibitors as well as gene knockdown technology prove that an interaction between p38, p53 and mTOR might be responsible for these observed endpoints. Taken together, exposure of dermal fibroblasts to varying concentrations of zinc pyrithione may result in either cell death-apoptosis or cellular premature senescence which attests to the ability of this compound to affect this type of cells in an in vitro model system.
authors.affiliation: Department of Medical Biology and Genetics, Charles University in Prague, Faculty of Medicine in Hradec Kralove, Simkova 870, Hradec Kralove 500 38, Czech Republic. rudolf@lfhk.cuni.cz
authors.forename: Emil
authors.initials: E
authors.lastname: Rudolf
authors.forename: Miroslav
authors.initials: M
authors.lastname: Cervinka
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects; D004247:DNA / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D007641:Keratolytic Agents / Q000633:toxicity*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009942:Organometallic Compounds / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects; D011725:Pyridines / Q000633:toxicity*; D012867:Skin / Q000166:cytology / Q000187:drug effects*; D013312:Stress, Physiological / Q000187:drug effects*; D016159:Tumor Suppressor Protein p53 / Q000502:physiology
chemical_list: D007641:Keratolytic Agents; D009942:Organometallic Compounds; D011725:Pyridines; D016159:Tumor Suppressor Protein p53; D004247:DNA; D020928:Mitogen-Activated Protein Kinases; C010423:pyrithione zinc