title: Disruption of estrogen-regulated gene expression by dioxin: downregulation of a gene associated with the onset of non-insulin-dependent diabetes mellitus (type 2 diabetes).
abstract: Expression of an estrogen-regulated reporter gene, growth of MCF-7 cells in the presence of 17beta-estradiol (E2) or E2 plus TCDD, and DNA microarray plus real time quantitative PCR analyses of gene expression in MCF-7 cells were used to evaluate the effects of TCDD, a known E2 antagonist, on E2-regulated gene expression in human cells. TCDD added simultaneously with E2 exhibited significantly decreased E2-associated upregulation of reporter gene expression compared with cells treated with E2 alone, and decreased E2 enhancement of mitosis in MCF-7 cells. MCF-7 cells treated with E2 or E2 plus TCDD and DNA microarray-evaluated to determine patterns of gene expression, showed substantial differences in gene expression in TCDD-treated cells compared with E2-treated cells. Of the 2400 genes on the Perkin Elmer global array microchip utilized for this analysis, a minimum of 317 were significantly upregulated and 488 were significantly downregulated. Of these, the gene encoding insulin receptor substrate-1 (IRS-1), the protein product of which has been previously reported to be decreased, missing, altered, or defective in persons with type 2 diabetes mellitus, was evaluated by real time quantitative PCR to corroborate the array data. An evaluation of the potential consequences of TCDD-altered IRS-1 downregulation is presented.
authors.affiliation: Department of Anatomy and Public Health, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Regina
authors.initials: R
authors.lastname: Hokanson
authors.forename: Susan
authors.initials: S
authors.lastname: Miller
authors.forename: Maxine
authors.initials: M
authors.lastname: Hennessey
authors.forename: Mark
authors.initials: M
authors.lastname: Flesher
authors.forename: William
authors.initials: W
authors.lastname: Hanneman
authors.forename: David
authors.initials: D
authors.lastname: Busbee
mesh_terms: D000818:Animals; D002460:Cell Line; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D055504:Insulin Receptor Substrate Proteins; D008938:Mitosis / Q000187:drug effects; D020411:Oligonucleotide Array Sequence Analysis; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics*; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D004965:Estrogen Antagonists; C526292:IRS1 protein, human; D055504:Insulin Receptor Substrate Proteins; D010750:Phosphoproteins; D000072317:Polychlorinated Dibenzodioxins; D004958:Estradiol