title: Oestrogenic activity of benzylparaben.
abstract: Previous work has demonstrated that the alkyl esters of p-hydroxybenzoic acid (parabens) possess oestrogenic activity, which increases with length of alkyl chain from methylparaben to n-butylparaben and with branching in the alkyl chain from n-butylparaben to isobutylparaben. This study reports on the oestrogenic activity of benzylparaben in a variety of assays in vitro and in vivo. Benzylparaben was able to displace [(3)H]oestradiol from cytosolic oestrogen receptor (ER) of MCF7 human breast cancer cells by 22% at 1000-fold molar excess, by 40% at 10,000-fold molar excess, by 57% at 100 000-fold molar excess and by 100% at 1,000,000-fold molar excess. It was able to increase expression of a stably transfected oestrogen responsive reporter gene (ERE-CAT) in MCF7 cells after 24 h at 10(-5)M/10(-4)M and after 7 days at 10(-6)M/10(-5)M/10(-4)M. Proliferation of MCF7 cells could be increased by 10(-6)M/10(-5)M benzylparaben and this could be inhibited by 10(-7)M pure anti-oestrogen ICI 182,780, indicating that growth effects were ER mediated. Further evidence for ER-mediation was provided from the ability of benzylparaben to increase the growth of a second oestrogen-dependent human breast cancer cell line ZR-75-1, but not the oestrogen-insensitive MDA-MB-231 cell line. When tested in the presence of 10(-10)M 17beta-oestradiol, benzylparaben gave no antagonist response on the growth of either MCF7 or ZR-75-1 cells. Finally, benzylparaben could increase uterine weight in the immature mouse following topical application of three daily doses of 33 mg to dorsal skin. These results demonstrate that the oestrogenicity of methylparaben can be increased by the addition of an aryl group as well as by lengthening or branching the alkyl grouping.
authors.affiliation: Division of Cell and Molecular Biology, School of Animal and Microbial Sciences, University of Reading, Reading, RG6 6AJ, UK. p.d.darbe@reading.ac.uk
authors.forename: P D
authors.initials: PD
authors.lastname: Darbre
authors.forename: J R
authors.initials: JR
authors.lastname: Byford
authors.forename: L E
authors.initials: LE
authors.lastname: Shaw
authors.forename: S
authors.initials: S
authors.lastname: Hall
authors.forename: N G
authors.initials: NG
authors.lastname: Coldham
authors.forename: G S
authors.initials: GS
authors.lastname: Pope
authors.forename: M J
authors.initials: MJ
authors.lastname: Sauer
mesh_terms: D000287:Administration, Topical; D000818:Animals; D001667:Binding, Competitive; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004958:Estradiol / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology*; D004968:Estrogens, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D000077267:Fulvestrant; D015870:Gene Expression; D017930:Genes, Reporter; D006801:Humans; D051379:Mice; D008815:Mice, Inbred Strains; D009929:Organ Size / Q000187:drug effects; D010226:Parabens / Q000494:pharmacology*; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014599:Uterus / Q000187:drug effects / Q000473:pathology
chemical_list: D004338:Drug Combinations; D004965:Estrogen Antagonists; D020847:Estrogen Receptor Modulators; D004968:Estrogens, Non-Steroidal; D010226:Parabens; D011960:Receptors, Estrogen; D000077267:Fulvestrant; D004958:Estradiol; C057775:benzylparaben