title: Zinc pyrithione impairs zinc homeostasis and upregulates stress response gene expression in reconstructed human epidermis.
abstract: Zinc ion homeostasis plays an important role in human cutaneous biology where it is involved in epidermal differentiation and barrier function, inflammatory and antimicrobial regulation, and wound healing. Zinc-based compounds designed for topical delivery therefore represent an important class of cutaneous therapeutics. Zinc pyrithione (ZnPT) is an FDA-approved microbicidal agent used worldwide in over-the-counter topical antimicrobials, and has also been examined as an investigational therapeutic targeting psoriasis and UVB-induced epidermal hyperplasia. Recently, we have demonstrated that cultured primary human skin keratinocytes display an exquisite sensitivity to nanomolar ZnPT concentrations causing induction of heat shock response gene expression and poly(ADP-ribose) polymerase (PARP)-dependent cell death (Cell Stress Chaperones 15:309-322, 2010). Here we demonstrate that ZnPT causes rapid accumulation of intracellular zinc in primary keratinocytes as observed by quantitative fluorescence microscopy and inductively coupled plasma mass spectrometry (ICP-MS), and that PARP activation, energy crisis, and genomic impairment are all antagonized by zinc chelation. In epidermal reconstructs (EpiDerm™) exposed to topical ZnPT (0.1-2% in Vanicream™), ICP-MS demonstrated rapid zinc accumulation, and expression array analysis demonstrated upregulation of stress response genes encoding metallothionein-2A (MT2A), heat shock proteins (HSPA6, HSPA1A, HSPB5, HSPA1L, DNAJA1, HSPH1, HSPD1, HSPE1), antioxidants (SOD2, GSTM3, HMOX1), and the cell cycle inhibitor p21 (CDKN1A). IHC analysis of ZnPT-treated EpiDerm™ confirmed upregulation of Hsp70 and TUNEL-positivity. Taken together our data demonstrate that ZnPT impairs zinc ion homeostasis and upregulates stress response gene expression in primary keratinocytes and reconstructed human epidermis, activities that may underlie therapeutic and toxicological effects of this topical drug.
authors.affiliation: Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, 1515 North Campbell Avenue, Tucson, AZ 85724, USA.
authors.forename: Sarah D
authors.initials: SD
authors.lastname: Lamore
authors.forename: Georg T
authors.initials: GT
authors.lastname: Wondrak
mesh_terms: D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects* / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D006706:Homeostasis / Q000187:drug effects*; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009942:Organometallic Compounds / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects* / Q000235:genetics; D011725:Pyridines / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D015854:Up-Regulation / Q000187:drug effects*; D015032:Zinc / Q000378:metabolism*
chemical_list: D018840:HSP70 Heat-Shock Proteins; D009942:Organometallic Compounds; D011725:Pyridines; D015032:Zinc; C010423:pyrithione zinc