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Ken-ichi Ohyama,¹ Fumiko Nagai,¹ and Yoshiteru Tsuchiya²

¹Department of Environmental Health, Tokyo Metropolitan Research Laboratory of Public Health, Tokyo, Japan; ²Department of Applied Chemistry, Kogakuin University, Tokyo, Japan

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 (hER) . 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. The order of their binding potency for hER 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. 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. These compounds might be endocrine disrupters. Key words: binding affinities, cell proliferative activities, estrogenic activities, human estrogen receptor , MCF-7 cells, styrene oligomers. Environ Health Perspect 109:699-703 (2001) . [Online 29 June 2001*]

http://ehpnet1.niehs.nih.gov/docs/2001/109p699-703ohyama/ abstract.html

Address correspondence to K. Ohyama, Department of Environmental Health, Tokyo Metropolitan Research Laboratory of Public Health, 24-1, Hyakunincho 3 chome, Shinjuku-ku, Tokyo 169-0073, Japan. Telephone: 81-3-3363-3231. Fax: 81-3-3368-4060. E-mail: ohyama@tokyo-eiken.go.jp

We thank A. Hamaoka and T. Yamamoto for technical assistance.

Received 6 December 2000 ; accepted 5 February 2001.

*Erratum. Figure 3 was changed on 18 June 2002. The erratum was published in EHP vol 110:7, page A 386.