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Vallet A, El Ezzy M, Diennet M, Haidar S, Bouvier M, Mader S. The AF-2 cofactor binding region is key for the selective SUMOylation of estrogen receptor alpha by antiestrogens. J Biol Chem 2022; 299:102757. [PMID: 36460099 PMCID: PMC9823126 DOI: 10.1016/j.jbc.2022.102757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/19/2022] [Accepted: 11/21/2022] [Indexed: 12/03/2022] Open
Abstract
Antiestrogens (AEs) are used to treat all stages of estrogen receptor (ER)-positive breast cancer. Selective estrogen receptor modulators such as tamoxifen have tissue-specific partial agonist activity, while selective estrogen receptor downregulators such as fulvestrant (ICI182,780) display a more complete antiestrogenic profile. We have previously observed that fulvestrant-induced ERα SUMOylation contributes to transcriptional suppression, but whether this effect is seen with other AEs and is specific to ERα is unclear. Here we show that several AEs induce SUMOylation of ERα, but not ERβ, at different levels. Swapping domains between ERα and ERβ indicates that the ERα identity of the ligand-binding domain helices 3 and 4 (H3-H4 region), which contribute to the static part of the activation function-2 (AF-2) cofactor binding groove, is sufficient to confer fulvestrant-induced SUMOylation to ERβ. This region does not contain lysine residues unique to ERα, suggesting that ERα-specific residues in H3-H4 determine the capacity of the AE-bound ERα ligand-binding domain to recruit the SUMOylation machinery. We also show that the SUMO E3 ligase protein inhibitor of activated STAT 1 increases SUMOylation of ERα and of ERβ containing the H3-H4 region of ERα, but not of ERβ. Together, these results shed new light on the molecular basis for the differential capacity of selective estrogen receptor modulators and selective estrogen receptor downregulators to suppress transcription by ERα.
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Affiliation(s)
- Amandine Vallet
- Institut de Recherche en Immunologie et Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Mohamed El Ezzy
- Institut de Recherche en Immunologie et Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Marine Diennet
- Institut de Recherche en Immunologie et Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Salwa Haidar
- Institut de Recherche en Immunologie et Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada
| | - Michel Bouvier
- Institut de Recherche en Immunologie et Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada,Département de Biochimie et Biologie Moléculaire, Université de Montréal, Montréal, Québec, Canada
| | - Sylvie Mader
- Institut de Recherche en Immunologie et Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada,Département de Biochimie et Biologie Moléculaire, Université de Montréal, Montréal, Québec, Canada,For correspondence: Sylvie Mader
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Traboulsi T, El Ezzy M, Dumeaux V, Audemard E, Mader S. Role of SUMOylation in differential ERα transcriptional repression by tamoxifen and fulvestrant in breast cancer cells. Oncogene 2018; 38:1019-1037. [PMID: 30190545 PMCID: PMC6514857 DOI: 10.1038/s41388-018-0468-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 07/15/2018] [Accepted: 07/20/2018] [Indexed: 01/19/2023]
Abstract
Antiestrogens (AEs) are widely used for treatment of estrogen receptor alpha (ERα)-positive breast cancer, but display variable degrees of partial agonism in estrogen target tissues and breast cancer (BC) cells. The fact that BC cells resistant to selective ER modulators (SERMs) like tamoxifen (Tam) can still be sensitive to pure AEs, also called selective ER downregulators, suggests different mechanisms of action, some of which may contribute to the more complete suppression of estrogen target genes by pure AEs. We report herein that pure AEs such as fulvestrant induce transient binding of ERα to DNA, followed by rapid release after 30–40 min without loss of nuclear localization. Loss of DNA binding preceded receptor degradation and was not prevented by proteasome inhibition. Chromatin was less accessible in the presence of fulvestrant than with estradiol or Tam as early as 20 min following treatment, suggesting that chromatin remodeling by pure AEs at ERα target regions prevents transcription in spite of receptor binding. SUMO2/3 marks were detected on chromatin at the peak of ERα binding in cells treated with pure AEs, but not SERMs. Furthermore, decreasing SUMOylation by overexpressing the deSUMOylase SENP1 significantly delayed receptor release from DNA and de-repressed expression of estrogen target genes in the presence of fulvestrant, both in ERα-expressing MCF-7 cells and in transiently transfected ER-negative SK-BR-3 cells. Finally, mutation V534E, identified in a breast metastasis resistant to hormonal therapies, prevented ERα modification and resulted in increased transcriptional activity of estrogen target genes in the presence of fulvestrant in SK-BR-3 cells. Together, our results establish a role for SUMOylation in achieving a more complete transcriptional shut-off of estrogen target genes by pure AEs vs. SERMs in BC cells.
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Affiliation(s)
- Tatiana Traboulsi
- Institute for Research in Immunology and Cancer, Montréal, QC, H3C 3J7, Canada.,Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Mohamed El Ezzy
- Institute for Research in Immunology and Cancer, Montréal, QC, H3C 3J7, Canada
| | - Vanessa Dumeaux
- Institute for Research in Immunology and Cancer, Montréal, QC, H3C 3J7, Canada.,PERFORM Centre, Concordia University, Montréal, QC, H4B 1R6, Canada
| | - Eric Audemard
- Institute for Research in Immunology and Cancer, Montréal, QC, H3C 3J7, Canada
| | - Sylvie Mader
- Institute for Research in Immunology and Cancer, Montréal, QC, H3C 3J7, Canada. .,Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC, H3C 3J7, Canada.
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