title: The topical antimicrobial zinc pyrithione is a heat shock response inducer that causes DNA damage and PARP-dependent energy crisis in human skin cells.
abstract: The differentiated epidermis of human skin serves as an essential barrier against environmental insults from physical, chemical, and biological sources. Zinc pyrithione (ZnPT) is an FDA-approved microbicidal agent used worldwide in clinical antiseptic products, over-the-counter topical antimicrobials, and cosmetic consumer products including antidandruff shampoos. Here we demonstrate for the first time that cultured primary human skin keratinocytes and melanocytes display an exquisite vulnerability to nanomolar concentrations of ZnPT resulting in pronounced induction of heat shock response gene expression and impaired genomic integrity. In keratinocytes treated with nanomolar concentrations of ZnPT, expression array analysis revealed massive upregulation of genes encoding heat shock proteins (HSPA6, HSPA1A, HSPB5, HMOX1, HSPA1L, and DNAJA1) further confirmed by immunodetection. Moreover, ZnPT treatment induced rapid depletion of cellular ATP levels and formation of poly(ADP-ribose) polymers. Consistent with an involvement of poly(ADP-ribose) polymerase (PARP) in ZnPT-induced energy crisis, ATP depletion could be antagonized by pharmacological inhibition of PARP. This result was independently confirmed using PARP-1 knockout mouse embryonic fibroblasts that were resistant to ATP depletion and cytotoxicity resulting from ZnPT exposure. In keratinocytes and melanocytes, single-cell gel electrophoresis and flow cytometric detection of gamma-H2A.X revealed rapid induction of DNA damage in response to ZnPT detectable before general loss of cell viability occurred through caspase-independent pathways. Combined with earlier experimental evidence that documents penetration of ZnPT through mammalian skin, our findings raise the possibility that this topical antimicrobial may target and compromise keratinocytes and melanocytes in intact human skin.
authors.affiliation: Department of Pharmacology and Toxicology, College of Pharmacy, Arizona Cancer Center, University of Arizona, Tucson, AZ, USA.
authors.forename: Sarah D
authors.initials: SD
authors.lastname: Lamore
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Cabello
authors.forename: Georg T
authors.initials: GT
authors.lastname: Wondrak
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000287:Administration, Topical; D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology / Q000633:toxicity; D004249:DNA Damage; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response / Q000187:drug effects / Q000502:physiology; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D007641:Keratolytic Agents / Q000494:pharmacology / Q000633:toxicity; D008544:Melanocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009942:Organometallic Compounds / Q000494:pharmacology / Q000633:toxicity; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology / Q000633:toxicity; D012867:Skin / Q000166:cytology / Q000187:drug effects
chemical_list: D000890:Anti-Infective Agents; D006360:Heat-Shock Proteins; D007641:Keratolytic Agents; D009942:Organometallic Compounds; D011725:Pyridines; D000255:Adenosine Triphosphate; D011065:Poly(ADP-ribose) Polymerases; C010423:pyrithione zinc