title: Certain styrene oligomers have proliferative activity on MCF-7 human breast tumor cells and binding affinity for human estrogen receptor.
abstract: To examine the estrogenic activities of styrene oligomers, we carried out cell proliferation assays with estrogen-sensitive MCF-7 cells and competitive binding assays to human estrogen receptor [alpha] (hER[alpha]). The styrene oligomers tested were 1,3-diphenyl propane (SD-1), 2,4-diphenyl-1-butene (SD-2), cis-1,2-diphenyl cyclobutane (SD-3), trans-1,2-diphenyl cyclobutane (SD-4), 2,4,6-triphenyl-1-hexene (ST-1), 1a-phenyl-4a-(1'-phenylethyl)tetralin (ST-2), 1a-phenyl-4e-(1'-phenylethyl)tetralin (ST-3), 1e-phenyl-4a-(1'-phenylethyl)tetralin (ST-4), 1e-phenyl-4e-(1'-phenylethyl)tetralin (ST-5), 1e,3e,5a-triphenylcyclohexane (ST-6), and 1e,3e,5e-triphenylcyclohexane (ST-7). In the MCF-7 cell proliferation assay, styrene trimers (ST-1, ST-3, ST-4, and ST-5) had the highest proliferative activities of the compounds tested. The relative potency of these chemicals was 0.0002-0.0015%, which was comparable with that of bisphenol A (0.0001-0.0025%), and their relative proliferative effect was 51-104%. Styrene dimers (SD-3 and SD-4) also significantly increased the cell yields. However, SD-1, SD-2, ST-2, ST-6, and ST-7 had insignificant proliferative activities. The competitive binding assay revealed the binding affinity of some styrene oligomers for hER[alpha]. The order of their binding potency for hER[alpha] was as follows: ST-4 > ST-2 > ST-3 > ST-5 > ST-1 > SD-3 > SD-4 > SD-2 > SD-1. ST-6 and ST-7 did not appear to bind to hER[alpha]. The present studies indicate that styrene dimers SD-3 and SD-4 and styrene trimers ST-1, ST-3, ST-4, and ST-5 have estrogenic activity on MCF-7 cells and binding affinity for hER[alpha]. These compounds might be endocrine disrupters.
authors.affiliation: Department of Environmental Health, Tokyo Metropolitan Research Laboratory of Public Health, 24-1, Hyakunincho 3 chome, Shinjuku-ku, Tokyo 169-0073, Japan. ohyama@tokyo-eiken.go.jp
authors.forename: K I
authors.initials: KI
authors.lastname: Ohyama
authors.forename: F
authors.initials: F
authors.lastname: Nagai
authors.forename: Y
authors.initials: Y
authors.lastname: Tsuchiya
mesh_terms: D001667:Binding, Competitive; D001943:Breast Neoplasms / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D047628:Estrogen Receptor alpha; D005260:Female; D006801:Humans; D011960:Receptors, Estrogen / Q000502:physiology*; D013343:Styrenes / Q000009:adverse effects*; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D047628:Estrogen Receptor alpha; D011960:Receptors, Estrogen; D013343:Styrenes