title: Vitamin K3 (menadione)-induced oncosis associated with keratin 8 phosphorylation and histone H3 arylation.
abstract: The vitamin K analog menadione (K3), capable of both redox cycling and arylating nucleophilic substrates by Michael addition, has been extensively studied as a model stress-inducing quinone in both cell culture and animal model systems. Exposure of keratin 8 (k-8) expressing human breast cancer cells (MCF7, T47D, SKBr3) to K3 (50-100 microM) induced rapid, sustained, and site-specific k-8 serine phosphorylation (pSer73) dependent on signaling by a single mitogen activated protein kinase (MAPK) pathway, MEK1/2. Normal nuclear morphology and k-8 immunofluorescence coupled with the lack of DNA laddering or other features of apoptosis indicated that K3-induced cytotoxicity, evident within 4 h of treatment and delayed but not prevented by MEK1/2 inhibition, was due to a form of stress-activated cell death known as oncosis. Independent of MAPK signaling was the progressive appearance of K3-induced cellular fluorescence, principally nuclear in origin and suggested by in vitro fluorimetry to have been caused by K3 thiol arylation. Imaging by UV transillumination of protein gels containing nuclear extracts from K3-treated cells revealed a prominent 17-kDa band shown to be histone H3 by immunoblotting and mass spectrometry (MS). K3 arylation of histones in vitro followed by electrospray ionization-tandem MS analyses identified the unique Cys110 residue within H3, exposed only in the open chromatin of transcriptionally active genes, as a K3 arylation target. These findings delineate new pathways associated with K3-induced stress and suggest a potentially novel role for H3 Cys110 as a nuclear stress sensor.
authors.affiliation: Program of Cancer and Developmental Therapeutics, Buck Institute for Age Research, 8001 Red-wood Blvd., Novato, CA 94945, USA.
authors.forename: Gary K
authors.initials: GK
authors.lastname: Scott
authors.forename: Christian
authors.initials: C
authors.lastname: Atsriku
authors.forename: Patrick
authors.initials: P
authors.lastname: Kaminker
authors.forename: Jason
authors.initials: J
authors.lastname: Held
authors.forename: Brad
authors.initials: B
authors.lastname: Gibson
authors.forename: Michael A
authors.initials: MA
authors.lastname: Baldwin
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Benz
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D006657:Histones / Q000378:metabolism*; D006801:Humans; D053533:Keratin-8; D007633:Keratins / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D013050:Spectrometry, Fluorescence; D021241:Spectrometry, Mass, Electrospray Ionization; D013438:Sulfhydryl Compounds / Q000378:metabolism; D024483:Vitamin K 3 / Q000494:pharmacology*
chemical_list: D006657:Histones; C426203:KRT8 protein, human; D053533:Keratin-8; D013438:Sulfhydryl Compounds; D007633:Keratins; D024483:Vitamin K 3; D020928:Mitogen-Activated Protein Kinases