title: Effects of single and repeated in vitro exposure of three forms of parabens, methyl-, butyl- and propylparabens on the proliferation and estradiol secretion in MCF-7 and MCF-10A cells.
abstract: BACKGROUND
  Here, we analyzed the dose- (0.2, 2, 20, 200 nM or 2 μM) and time- (48, 96, 144 and 196 h) dependent activity of a single or repeated exposure of methyl-, butyl- and propylparaben on the proliferation of MCF-7 human breast cancer cells and MCF-10A human breast epithelial cells. Additionally, the effect on estradiol secretion, gene and protein expression of aromatase (CYP19A1) was investigated.
  
  
  METHODS
  Cell proliferation was determined by AlamarBlue assay, and estradiol secretion by ELISA kits. Gene and protein expression of CYP19A1 was measurement using real time PCR and western blot, respectively.
  
  
  RESULTS
  Stimulatory effect of a single exposure of all doses of tested parabens and time dependent effect of repeated exposure to methylparaben, propylparaben and butylparaben, the same as that of 17β-estradiol, on proliferation of MCF-7 cells was observed. Only at low doses methyl- and butylparabens increased MCF-10A cells proliferation after single exposure, but no effect of repeated exposure was noted. Exposure at low doses of all of the parabens significantly increased 17β-estradiol (E2) secretion in MCF-7 cells but had the opposite effect on MCF-10A cells. It was correlated with gene and protein expression of CYP19A1 in MCF-7 and MCF-10 cells.
  
  
  CONCLUSIONS
  In summary, present study indicates a different mechanism of proliferative action of parabens in investigated cell lines. In MCF-7 breast cancer cell line it is probably due to stimulatory action on estradiol secretion and aromatase activity. In MCF-10A by an unknown mechanism, independent on stimulatory action on estradiol section, which requires further investigation.
authors.affiliation: Department of Physiology and Toxicology of Reproduction, Jagiellonian University, Gronostajowa 9, PL 30-387 Kraków, Poland. ania.wrobel@uj.edu.pl
authors.forename: Anna
authors.initials: A
authors.lastname: Wróbel
authors.forename: Ewa Ł
authors.initials: EŁ
authors.lastname: Gregoraszczuk
mesh_terms: D001141:Aromatase / Q000235:genetics; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D061986:MCF-7 Cells; D010226:Parabens / Q000008:administration & dosage / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D010226:Parabens; C038091:butylparaben; D004958:Estradiol; C015358:methylparaben; D001141:Aromatase; C561410:CYP19A1 protein, human; C006068:propylparaben