title: Impact of low concentrations of phthalates on the effects of 17β-estradiol in MCF-7 breast cancer cells.
abstract: OBJECTIVE
  To explore whether lower concentrations of phthalates interfere with the effects of 17β-estradiol on the growth of MCF-7 breast cancer cells.
  
  
  METHODS
  MCF-7 cells were treated with 17β-estradiol (E2), phthalates, including butyl benzyl phthalate (BBP), di(n-butyl) phthalate (DBP), and di(20ethylhexyl) phthalate (DEHP), or with both E2and phthalates, all at 10nM. After incubation for 48 hours, the cells were harvested and extracted for MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The proteins involving proliferative and apoptotic pathway were then evaluated using Western blot analysis.
  
  
  RESULTS
  In MCF-7 cell cultures, the MTT assay revealed a significant increase in cell viability with E2and these three phthalates, and significantly more cell proliferation with the combination of E2and phthalates. Proliferating cell nuclear antigen, as well as phosphatidylinositide 3-kinase (PI3K) and p-Akt, were all substantially increased in cultures with E2, phthalates, and the two combined. An additive effect of phthalates on the obvious increase of Bcl-2 and ER α expression was also noted in the presence of E2.
  
  
  CONCLUSIONS
  The present study demonstrates that even at a very low concentration, BBP, DBP, and DEHP were not only still capable of displaying estrogenic activity, but also of inducing an additive proliferative effect through the PI3K/Akt signaling pathway and preventing apoptosis in the presence of E2. Therefore, the effects of current reference doses for phthalates defined by the government, especially for premenopausal women, should be further considered.
authors.affiliation: Department of Obstetrics and Gynecology, Keelung Chang Gung Memorial Hospital, Keelung, Taiwan; College of Medicine, Chang Gung University, Taiwan. Electronic address: fangping@cgmh.org.tw.
authors.forename: Fang-Ping
authors.initials: FP
authors.lastname: Chen
authors.affiliation: Department of Obstetrics and Gynecology, Keelung Chang Gung Memorial Hospital, Keelung, Taiwan; College of Medicine, Chang Gung University, Taiwan.
authors.forename: Mei-Hua
authors.initials: MH
authors.lastname: Chien
authors.affiliation: School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Ingrid Ying-Yu
authors.initials: IY
authors.lastname: Chern
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D049109:Cell Proliferation / Q000187:drug effects*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D010795:Phthalic Acids / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D010795:Phthalic Acids; D004958:Estradiol
keywords: MCF-7 breast cancer cells; PI3K/Akt signaling pathway; phthalates; proliferating cell nuclear antigen