title: The quinone methide aurin is a heat shock response inducer that causes proteotoxic stress and Noxa-dependent apoptosis in malignant melanoma cells.
abstract: Pharmacological induction of proteotoxic stress is rapidly emerging as a promising strategy for cancer cell-directed chemotherapeutic intervention. Here, we describe the identification of a novel drug-like heat shock response inducer for the therapeutic induction of proteotoxic stress targeting malignant human melanoma cells. Screening a focused library of compounds containing redox-directed electrophilic pharmacophores employing the Stress & Toxicity PathwayFinder(TM) PCR Array technology as a discovery tool, a drug-like triphenylmethane-derivative (aurin; 4-[bis(p-hydroxyphenyl)methylene]-2,5-cyclohexadien-1-one) was identified as an experimental cell stress modulator that causes (i) heat shock factor transcriptional activation, (ii) up-regulation of heat shock response gene expression (HSPA6, HSPA1A, DNAJB4, HMOX1), (iii) early unfolded protein response signaling (phospho-PERK, phospho-eIF2α, CHOP (CCAAT/enhancer-binding protein homologous protein)), (iv) proteasome impairment with increased protein-ubiquitination, and (v) oxidative stress with glutathione depletion. Fluorescence polarization-based experiments revealed that aurin displays activity as a geldanamycin-competitive Hsp90α-antagonist, a finding further substantiated by molecular docking and ATPase inhibition analysis. Aurin exposure caused caspase-dependent cell death in a panel of human malignant melanoma cells (A375, G361, LOX-IMVI) but not in non-malignant human skin cells (Hs27 fibroblasts, HaCaT keratinocytes, primary melanocytes) undergoing the aurin-induced heat shock response without impairment of viability. Aurin-induced melanoma cell apoptosis depends on Noxa up-regulation as confirmed by siRNA rescue experiments demonstrating that siPMAIP1-based target down-regulation suppresses aurin-induced cell death. Taken together, our data suggest feasibility of apoptotic elimination of malignant melanoma cells using the quinone methide-derived heat shock response inducer aurin.
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Davis
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724.
authors.forename: Shuxi
authors.initials: S
authors.lastname: Qiao
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Lesson
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Rojo de la Vega
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724.
authors.forename: Sophia L
authors.initials: SL
authors.lastname: Park
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724.
authors.forename: Carol M
authors.initials: CM
authors.lastname: Seanez
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724.
authors.forename: Vijay
authors.initials: V
authors.lastname: Gokhale
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Cabello
authors.affiliation: From the Department of Pharmacology and Toxicology, College of Pharmacy and Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724 wondrak@pharmacy.arizona.edu.
authors.forename: Georg T
authors.initials: GT
authors.lastname: Wondrak
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism*; D017209:Apoptosis; D001312:Aurintricarboxylic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D045744:Cell Line, Tumor; D002470:Cell Survival; D004354:Drug Screening Assays, Antitumor; D005434:Flow Cytometry; D005978:Glutathione / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism*; D018869:Heat-Shock Response / Q000235:genetics; D006801:Humans; D045563:Indolequinones / Q000737:chemistry; D020128:Inhibitory Concentration 50; D015603:Keratinocytes / Q000187:drug effects; D008544:Melanocytes / Q000187:drug effects; D008545:Melanoma / Q000188:drug therapy*; D053078:Membrane Potential, Mitochondrial; D008958:Models, Molecular; D018384:Oxidative Stress; D016133:Polymerase Chain Reaction; D034741:RNA, Small Interfering / Q000378:metabolism; D012878:Skin Neoplasms / Q000188:drug therapy*; D015854:Up-Regulation
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D006360:Heat-Shock Proteins; D045563:Indolequinones; C476420:NOXA1 protein, human; D034741:RNA, Small Interfering; C068040:quinone methide; D001312:Aurintricarboxylic Acid; C017037:aurin; D005978:Glutathione
keywords: Apoptosis; Aurin; Drug Discovery; Heat Shock Protein 90 (Hsp90); Heat Shock Response; Melanoma; Noxa; Oxidative Stress; Proteotoxic Stress