Biomaterial Database

Evidence for the metabolism of tumor promoter organic hydroperoxides into free radicals by human carcinoma skin keratinocytes: an ESR-spin trapping study. 1989

M Athar, and H Mukhtar, and D R Bickers, and I U Khan, and B Kalyanaraman

Department of Dermatology, University Hospitals of Cleveland, Case Western Reserve University, OH.

Humans are exposed to various peroxy and hydroperoxy compounds which are in use in the cosmetic, pharmaceutical and polymer industries and which are also generated as a result of the peroxidative metabolic conversion of certain lipids. This study was designed to determine whether the organic hydroperoxides, tert-butyl hydroperoxide, cumene hydroperoxide and tert-butyl peroxybenzoate are metabolized by human carcinoma skin keratinocytes to free radicals. Incubation of keratinocytes prepared from cutaneous squamous cell carcinoma in phosphate-buffered saline (pH 7.4) containing desferrioxamine with tert-butyl hydroperoxide, cumene hydroperoxide and tert-butyl peroxybenzoate in the presence of spin trap (3,5-dibromonitrosobenzene sulfonic acid) resulted in the generation of corresponding methyl radical adducts. Prior heating of the cells to 100 degrees C abolished the generation of radical adducts. The addition of ethanol to the reaction mixture also inhibited formation of radical adducts. These data provide the first direct evidence that human carcinoma skin cells can generate free radicals from organic hydroperoxides. Since free radicals are suggested to be involved in the cascade of events occurring during tumor promotion this metabolic capacity may be an important determinant of human cancer risk for hydroperoxides.

UI	MeSH Term	Description	Entries
D007633	Keratins	A class of fibrous proteins or scleroproteins that represents the principal constituent of EPIDERMIS; HAIR; NAILS; horny tissues, and the organic matrix of tooth ENAMEL. Two major conformational groups have been characterized, alpha-keratin, whose peptide backbone forms a coiled-coil alpha helical structure consisting of TYPE I KERATIN and a TYPE II KERATIN, and beta-keratin, whose backbone forms a zigzag or pleated sheet structure. alpha-Keratins have been classified into at least 20 subtypes. In addition multiple isoforms of subtypes have been found which may be due to GENE DUPLICATION.	Cytokeratin,Keratin Associated Protein,Keratin,Keratin-Associated Proteins,alpha-Keratin,Associated Protein, Keratin,Keratin Associated Proteins,Protein, Keratin Associated,alpha Keratin
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009603	Nitroso Compounds	Organic compounds containing the nitroso (-N	Compounds, Nitroso
D010545	Peroxides	A group of compounds that contain a bivalent O-O group, i.e., the oxygen atoms are univalent. They can either be inorganic or organic in nature. Such compounds release atomic (nascent) oxygen readily. Thus they are strong oxidizing agents and fire hazards when in contact with combustible materials, especially under high-temperature conditions. The chief industrial uses of peroxides are as oxidizing agents, bleaching agents, and initiators of polymerization. (From Hawley's Condensed Chemical Dictionary, 11th ed)	Peroxide
D002294	Carcinoma, Squamous Cell	A carcinoma derived from stratified SQUAMOUS EPITHELIAL CELLS. It may also occur in sites where glandular or columnar epithelium is normally present. (From Stedman, 25th ed)	Carcinoma, Epidermoid,Carcinoma, Planocellular,Carcinoma, Squamous,Squamous Cell Carcinoma,Carcinomas, Epidermoid,Carcinomas, Planocellular,Carcinomas, Squamous,Carcinomas, Squamous Cell,Epidermoid Carcinoma,Epidermoid Carcinomas,Planocellular Carcinoma,Planocellular Carcinomas,Squamous Carcinoma,Squamous Carcinomas,Squamous Cell Carcinomas
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D004578	Electron Spin Resonance Spectroscopy	A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.	ENDOR,Electron Nuclear Double Resonance,Electron Paramagnetic Resonance,Paramagnetic Resonance,Electron Spin Resonance,Paramagnetic Resonance, Electron,Resonance, Electron Paramagnetic,Resonance, Electron Spin,Resonance, Paramagnetic
D004817	Epidermis	The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of EPITHELIUM: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis).
D005609	Free Radicals	Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. Free radicals include reactive oxygen and nitrogen species (RONS). They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.	Free Radical
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man