title: Comparison of possible carcinogenic estradiol metabolites: effects on proliferation, apoptosis and metastasis of human breast cancer cells.
abstract: OBJECTIVE
  Certain estradiol metabolites may play a pivotal role in breast carcinogenesis. Of special interest are the metabolites 2-hydroxyestradiol (2-OHE2), which can react anti-carcinogenically, and 4-hydroxyestradiol (4-OHE1) and 16a-hydroxyestrone (16-OHE1), which may have procarcinogenic potential. In the present study, we have compared for the first time the effect of these metabolites and their parent substance 17beta-estradiol (E2) on proliferation, apoptosis, apoptosis markers and markers of metastatic property of human breast cancer cells.
  
  
  METHODS
  MCF-7 cells (human estrogen-receptor positive metastatic breast cancer cell line) were incubated with the estrogens at concentrations of 0.1-100 nM. Cell proliferation rate was measured by the ATP-assay. Apoptosis was measured by cell death assay and the apoptosis markers cytochrome C, Bcl-2, Fasl and p53 were determined in cell lysates by ELISAs. The markers of metastatic property of the cell line, VEGF and MCP-1 were measured in the cell supernatant by ELISAs.
  
  
  RESULTS
  The estrogens E2, 4-OHE2 and 16-OHE1 display a proliferative effect on MCF-7 cells which is accompanied by a down-regulation of apoptosis. Various markers of apoptosis such as Bcl-2, cytochrome C and p53 appear to be involved. No significant effect was found for the metabolite 2-OHE2. VEGF and MCP-1 were up-regulated by E2 and 16-OHE1, whereas 2-OHE2 and 4-OHE2 did not show any effect.
  
  
  CONCLUSIONS
  The most potent estrogen regarding proliferation, apoptosis and metastasis of breast cancer cells seems to be estradiol. However, the estradiol metabolites 4-OHE2 and 16-OHE1 elicit similar properties on cell proliferation, apoptosis and metastasis as compared to estradiol but only at higher concentrations. In contrast 2-OHE2 did not show any significant effect on these parameters. Thus, intracellular estradiol metabolism may determine an individual's risk for breast carcinogenesis.
authors.affiliation: Section of Endocrinology and Menopause, University Women's Hospital, Calwerstrasse 7, 72076 Tuebingen, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Seeger
authors.forename: Diethelm
authors.initials: D
authors.lastname: Wallwiener
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Kraemer
authors.forename: Alfred O
authors.initials: AO
authors.lastname: Mueck
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D045304:Cytochromes c / Q000187:drug effects / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D004964:Estriol / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D002393:Estrogens, Catechol; D053222:Fas Ligand Protein; D005260:Female; D006801:Humans; D008562:Membrane Glycoproteins / Q000187:drug effects / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism; D048069:Tumor Necrosis Factors / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D014408:Biomarkers, Tumor; D004967:Estrogens; D002393:Estrogens, Catechol; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D019253:Proto-Oncogene Proteins c-bcl-2; D048069:Tumor Necrosis Factors; D016159:Tumor Suppressor Protein p53; D004958:Estradiol; D045304:Cytochromes c; C001390:2-hydroxyestradiol; C014036:4-hydroxyestradiol; D004964:Estriol