Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo.

Hormone replacement therapy associated risks, and the concomitant reluctance of usage, has instigated the search for new generations of estrogen analogues that would maintain estrogen benefits without associated risks. Furthermore, if these analogues display chemo-preventative properties in breast a...

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Autores principales:	Koch Visser, Morné Mortimer, Ann Louw
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/4d6e1e49cb684491a6dd90125d888b2a
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spelling	oai:doaj.org-article:4d6e1e49cb684491a6dd90125d888b2a2021-11-18T08:48:29ZCyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo.1932-620310.1371/journal.pone.0079223https://doaj.org/article/4d6e1e49cb684491a6dd90125d888b2a2013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24223909/?tool=EBIhttps://doaj.org/toc/1932-6203Hormone replacement therapy associated risks, and the concomitant reluctance of usage, has instigated the search for new generations of estrogen analogues that would maintain estrogen benefits without associated risks. Furthermore, if these analogues display chemo-preventative properties in breast and endometrial tissues it would be of great value. Both the selective estrogen receptor modulators as well as the selective estrogen receptor subtype modulators have been proposed as estrogen analogues with improved risk profiles. Phytoestrogen containing extracts of Cyclopia, an indigenous South African fynbos plant used to prepare Honeybush tea may serve as a source of new estrogen analogues. In this study three extracts, P104, SM6Met, and cup-of-tea, from two species of Cyclopia, C. genistoides and C. subternata, were evaluated for ER subtype specific agonism and antagonism both in transactivation and transrepression. For transactivation, the Cyclopia extracts displayed ERα antagonism and ERβ agonism when ER subtypes were expressed separately, however, when co-expressed only agonism was uniformly observed. In contrast, for transrepression, this uniform behavior was lost, with some extracts (P104) displaying uniform agonism, while others (SM6Met) displayed antagonism when subtypes were expressed separately and agonism when co-expressed. In addition, breast cancer cell proliferation assays indicate that extracts antagonize cell proliferation in the presence of estrogen at lower concentrations than that required for proliferation. Furthermore, lack of uterine growth and delayed vaginal opening in an immature rat uterotrophic model validates the ERα antagonism of extracts observed in vitro and supports the potential of the Cyclopia extracts as a source of estrogen analogues with a reduced risk profile.Koch VisserMorné MortimerAnn LouwPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 8, Iss 11, p e79223 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Koch Visser Morné Mortimer Ann Louw Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo.
description	Hormone replacement therapy associated risks, and the concomitant reluctance of usage, has instigated the search for new generations of estrogen analogues that would maintain estrogen benefits without associated risks. Furthermore, if these analogues display chemo-preventative properties in breast and endometrial tissues it would be of great value. Both the selective estrogen receptor modulators as well as the selective estrogen receptor subtype modulators have been proposed as estrogen analogues with improved risk profiles. Phytoestrogen containing extracts of Cyclopia, an indigenous South African fynbos plant used to prepare Honeybush tea may serve as a source of new estrogen analogues. In this study three extracts, P104, SM6Met, and cup-of-tea, from two species of Cyclopia, C. genistoides and C. subternata, were evaluated for ER subtype specific agonism and antagonism both in transactivation and transrepression. For transactivation, the Cyclopia extracts displayed ERα antagonism and ERβ agonism when ER subtypes were expressed separately, however, when co-expressed only agonism was uniformly observed. In contrast, for transrepression, this uniform behavior was lost, with some extracts (P104) displaying uniform agonism, while others (SM6Met) displayed antagonism when subtypes were expressed separately and agonism when co-expressed. In addition, breast cancer cell proliferation assays indicate that extracts antagonize cell proliferation in the presence of estrogen at lower concentrations than that required for proliferation. Furthermore, lack of uterine growth and delayed vaginal opening in an immature rat uterotrophic model validates the ERα antagonism of extracts observed in vitro and supports the potential of the Cyclopia extracts as a source of estrogen analogues with a reduced risk profile.
format	article
author	Koch Visser Morné Mortimer Ann Louw
author_facet	Koch Visser Morné Mortimer Ann Louw
author_sort	Koch Visser
title	Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo.
title_short	Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo.
title_full	Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo.
title_fullStr	Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo.
title_full_unstemmed	Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo.
title_sort	cyclopia extracts act as erα antagonists and erβ agonists, in vitro and in vivo.
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/4d6e1e49cb684491a6dd90125d888b2a
work_keys_str_mv	AT kochvisser cyclopiaextractsactaseraantagonistsanderbagonistsinvitroandinvivo AT mornemortimer cyclopiaextractsactaseraantagonistsanderbagonistsinvitroandinvivo AT annlouw cyclopiaextractsactaseraantagonistsanderbagonistsinvitroandinvivo
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Cyclopia extracts act as ERα antagonists and ERβ agonists, in vitro and in vivo.

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