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  • Title: The tamoxifen-responsive estrogen receptor alpha mutant D351Y shows reduced tamoxifen-dependent interaction with corepressor complexes.
    Author: Yamamoto Y, Wada O, Suzawa M, Yogiashi Y, Yano T, Kato S, Yanagisawa J.
    Journal: J Biol Chem; 2001 Nov 16; 276(46):42684-91. PubMed ID: 11553641.
    Abstract:
    The effects of estrogen and anti-estrogen are mediated through the estrogen receptors ERalpha and beta, which function as ligand-induced transcriptional factors. The nonsteroidal anti-estrogen tamoxifen is the most commonly used endocrine in the treatment of all stages of breast cancer in both pre- and postmenopausal women. Several lines of evidence have indicated that tamoxifen promotes association between ERalpha and corepressors N-CoR or silencing mediator for retinoid and thyroid hormone receptor (SMRT). Our results indicate that N-CoR/SMRT recognize and interact with helices H3 and H5 of the ERalpha ligand-binding domain in a 4-hydroxy tamoxifen-dependent manner. The mutant ERalpha(D351Y), derived from a tamoxifen-stimulated tumor and containing an amino acid substitution at position 351 within H3, showed reduced interaction with N-CoR/SMRT and high tamoxifen-induced activation function-1 (AF-1) activity. While the estradiol-dependent transcriptional activity of ERalpha(D351Y) was almost equal to that of wild-type ERalpha, the mutant exhibited higher levels of transcriptional activity in the presence of both E2 and 4-hydroxy tamoxifen compared with wild-type ERalpha. These results may explain the observation that the growth of tumor cells expressing ERalpha(D351Y) can be stimulated by tamoxifen, E2, or both.
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