title: 4-Hydroxyestradiol induces oxidative stress and apoptosis in human mammary epithelial cells: possible protection by NF-kappaB and ERK/MAPK.
abstract: Catechol estrogens, the hydroxylated metabolites of 17beta-estradiol (E2), have been considered to be implicated in estrogen-induced carcinogenesis. 4-Hydroxyestradiol (4-OHE2), an oxidized metabolite of E2 formed preferentially by cytochrome P450 1B1, reacts with DNA to form depurinating adducts thereby exerting genotoxicity and carcinogenicity. 4-OHE2 undergoes 2-electron oxidation to quinone via semiquinone, and during this process, reactive oxygen species (ROS) can be generated to cause DNA damage and cell death. In the present study, 4-OHE2 was found to elicit cytotoxicity in cultured human mammary epithelial (MCF-10A) cells, which was blocked by the antioxidant trolox. MCF-10A cells treated with 4-OHE2 exhibited increased intracellular ROS accumulation and 8-oxo-7,8-dihydroxy-2'-deoxyguanosine formation, and underwent apoptosis as determined by poly(ADP-ribose)polymerase cleavage and disruption of mitochondrial transmembrane potential. The redox-sensitive transcription factor nuclear factor kappaB (NF-kappaB) was transiently activated by 4-OHE2 treatment. Cotreatment of MCF-10A cells with the NF-kappaB inhibitor, L-1-tosylamido-2-phenylethyl chloromethyl ketone, exacerbated 4-OHE2-induced cell death. 4-OHE2 also caused transient activation of extracellular signal-regulated protein kinases (ERK) involved in transmitting cell survival or death signals. A pharmacological inhibitor of ERK aggravated the 4-OHE2-induced cytotoxicity, supporting the pivotal role of ERK in protecting against catechol estrogen-induced oxidative cell death.
authors.affiliation: National Research Laboratory of Molecular Carcinogenesis and Chemoprevention, College of Pharmacy, Seoul National University, Shinlim-dong, Kwanak-ku, Seoul 151-742, South Korea.
authors.forename: Zhi-Hua
authors.initials: ZH
authors.lastname: Chen
authors.forename: Hye-Kyung
authors.initials: HK
authors.lastname: Na
authors.forename: Yeon-Jin
authors.initials: YJ
authors.lastname: Hurh
authors.forename: Young-Joon
authors.initials: YJ
authors.lastname: Surh
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001665:Binding Sites / Q000235:genetics; D002417:Cattle; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D002839:Chromans / Q000494:pharmacology; D019327:Copper Sulfate / Q000494:pharmacology; D004247:DNA / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D002393:Estrogens, Catechol; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D042361:Mammary Glands, Human / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D011485:Protein Binding / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014108:Tosylphenylalanyl Chloromethyl Ketone / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection
chemical_list: D002614:Chelating Agents; D002839:Chromans; D002393:Estrogens, Catechol; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D014108:Tosylphenylalanyl Chloromethyl Ketone; D004958:Estradiol; D000080242:8-Hydroxy-2'-Deoxyguanosine; D004247:DNA; C014036:4-hydroxyestradiol; D008156:Luciferases; D048049:Extracellular Signal-Regulated MAP Kinases; D003849:Deoxyguanosine; D019327:Copper Sulfate; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid