title: Indole-3-carbinol is a negative regulator of estrogen.
abstract: Studies increasingly indicate that dietary indole-3-carbinol (I3C) prevents the development of estrogen-enhanced cancers including breast, endometrial and cervical cancers. Epidemiological, laboratory, animal and translational studies support the efficacy of I3C. Whereas estrogen increases the growth and survival of tumors, I3C causes growth arrest and increased apoptosis and ameliorates the effects of estrogen. Our long-range goal is to best use I3C together with other nutrients to achieve maximum benefits for cancer prevention. This study examines the possibility that induction of growth arrest in response to DNA damage (GADD) in genes by diindolylmethane (DIM), which is the acid-catalyzed condensation product of I3C, promotes metabolically stressed cancer cells to undergo apoptosis. We evaluated whether genistein, which is the major isoflavonoid in soy, would alter the ability of I3C/DIM to cause apoptosis and decrease expression driven by the estrogen receptor (ER)-alpha. Expression of GADD was evaluated by real-time reverse transcription-polymerase chain reaction. Proliferation and apoptosis were measured by a mitochondrial function assay and by fluorescence-activated cell sorting analysis. The luciferase reporter assay was used to specifically evaluate expression driven by ER-alpha. The estrogen-sensitive MCF-7 breast cancer cell line was used for these studies. We show a synergistic effect of I3C and genistein for induction of GADD expression, thus increasing apoptosis, and for decrease of expression driven by ER-alpha. Because of the synergistic effect of I3C and genistein, the potential exists for prophylactic or therapeutic efficacy of lower concentrations of each phytochemical when used in combination.
authors.affiliation: North Shore-Long Island Jewish Research Institute, Manhasset, NY 11030, USA. kauborn@nshs.edu
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Auborn
authors.forename: Saijun
authors.initials: S
authors.lastname: Fan
authors.forename: Eliot M
authors.initials: EM
authors.lastname: Rosen
authors.forename: Leslie
authors.initials: L
authors.lastname: Goodwin
authors.forename: Alamelu
authors.initials: A
authors.lastname: Chandraskaren
authors.forename: David E
authors.initials: DE
authors.lastname: Williams
authors.forename: DaZhi
authors.initials: D
authors.lastname: Chen
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Carter
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D001943:Breast Neoplasms / Q000188:drug therapy / Q000209:etiology; D004357:Drug Synergism; D004965:Estrogen Antagonists / Q000494:pharmacology / Q000627:therapeutic use; D004967:Estrogens / Q000009:adverse effects*; D005260:Female; D019833:Genistein / Q000627:therapeutic use*; D006801:Humans; D007211:Indoles / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D014407:Tumor Cells, Cultured / Q000187:drug effects; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy / Q000209:etiology
chemical_list: D000970:Antineoplastic Agents; D004965:Estrogen Antagonists; D004967:Estrogens; D007211:Indoles; C016517:indole-3-carbinol; D019833:Genistein