Lack of significant estrogenic or antiestrogenic activity of pyrethroid insecticides in three in vitro assays based on classic estrogen receptor alpha-mediated mechanisms.
Estrogenic and antiestrogenic activity of pyrethroid insecticides (d-trans-allethrin, cypermethrin, empenthrin, fenvalerate, imiprothrin, permethrin, d-phenothrin and prallethrin) was evaluated using a suite of three in vitro assays based on classic human estrogen receptor alpha (hER alpha)-mediated mechanisms. A mammalian cell-based luciferase reporter gene assay was developed for examining effects on hER alpha-mediated gene activation. hER alpha-independent effects on the gene activation were examined using control cells with constitutive luciferase activation by a herpes simplex virus thymidine kinase (HSV-TK) promoter for determining appropriate dose levels of test chemicals. Moreover, the test chemical-dependent interaction between hER alpha and a coactivator (transcriptional intermediary factor 2: TIF2) was analyzed by a yeast two-hybrid method, competitive binding to hER alpha being assayed by a fluorescence polarization method. Significant (p < 0.05) positive effects of estrogenic substances (E2/estradiol, diethylstilbestrol, and p-nonylphenol) were detected in all assays. An antiestrogen, 4-hydroxytamoxifen, significantly inhibited E2-mediated transactivation and interaction between hER alpha and TIF2 through hER alpha binding (p < 0.05). However, none of the pyrethroids tested showed significant (p < 0.05) estrogenic or antiestrogenic effects (100 nM-10 microM), indicating that they do not impact on the classic hER alpha-mediated activation pathway in vitro.
Saito
K
K
Environmental Health Science Laboratory, Sumitomo Chemical Company, Limited., 1-98, 3-Chome, Kasugade-Naka, Konohana-Ku, Osaka 554-8558, Japan. saitok5@sc.sumitomo-chem.co.jp
Tomigahara
Y
Y
Ohe
N
N
Isobe
N
N
Nakatsuka
I
I
Kaneko
H
H
D001667:Binding, Competitive / Q000187:drug effects; D004965:Estrogen Antagonists / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D004968:Estrogens, Non-Steroidal / Q000494:pharmacology*; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D006824:Hybridization, Genetic; D007306:Insecticides / Q000494:pharmacology*; D008156:Luciferases / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D011722:Pyrethrins / Q000494:pharmacology*; D011960:Receptors, Estrogen / Q000187:drug effects*; D015003:Yeasts / Q000235:genetics
D004965:Estrogen Antagonists; D047628:Estrogen Receptor alpha; D004968:Estrogens, Non-Steroidal; D007306:Insecticides; D011722:Pyrethrins; D011960:Receptors, Estrogen; D008156:Luciferases