Reactivation of the tumour suppressor RASSF1A in breast cancer by simultaneous targeting of DNA and E2F1 methylation.

<h4>Background</h4>Tumour suppressor genes are often transcriptionally silenced by promoter hypermethylation, and recent research has implicated alterations in chromatin structure as the mechanistic basis for this repression. In addition to DNA methylation, other epigenetic post-translat...

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Autores principales:	María F Montenegro, Magali Sáez-Ayala, Antonio Piñero-Madrona, Juan Cabezas-Herrera, José Neptuno Rodríguez-López
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2012
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/17eabdbfda8d4ce0be8e713fa74c05ba
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spelling	oai:doaj.org-article:17eabdbfda8d4ce0be8e713fa74c05ba2021-11-18T08:05:00ZReactivation of the tumour suppressor RASSF1A in breast cancer by simultaneous targeting of DNA and E2F1 methylation.1932-620310.1371/journal.pone.0052231https://doaj.org/article/17eabdbfda8d4ce0be8e713fa74c05ba2012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23251702/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>Tumour suppressor genes are often transcriptionally silenced by promoter hypermethylation, and recent research has implicated alterations in chromatin structure as the mechanistic basis for this repression. In addition to DNA methylation, other epigenetic post-translational modifications that modulate the stability and binding of specific transcription factors to gene promoters have emerged as important mechanisms for controlling gene expression. The aim of this study was to analyse the implications of these mechanisms and their molecular connections in the reactivation of RASSF1A in breast cancer.<h4>Methods</h4>Compounds that modulate the intracellular concentration of adenosine, such as dipyridamole (DIPY), greatly increase the antiproliferative effects of 3-O-(3,4,5-trimethoxybenzoyl)-(-)-catechin (TMCG), a synthetic antifolate derived from the structure of tea catechins. Quantitative real-time PCR arrays and MALDI-TOF mass spectrometry indicated that this combination (TMCG/DIPY) induced apoptosis in breast cancer cells by modulating the methylation levels of DNA and proteins (such as E2F1), respectively. Chromatin immunoprecipitation (ChIP) assays were employed to confirm that this combination induced chromatin remodelling of the RASSF1A promoter and increased the occupancy of E2F1 at the promoter of this tumour suppressor gene.<h4>Results</h4>The TMCG/DIPY combination acted as an epigenetic treatment that reactivated RASSF1A expression and induced apoptosis in breast cancer cells. In addition to modulating DNA methylation and chromatin remodelling, this combination also induced demethylation of the E2F1 transcription factor. The ChIP assay showed enhancement of E2F1 occupancy at the unmethylated RASSF1A promoter after TMCG/DIPY treatment. Interestingly, inhibition of E2F1 demethylation using an irreversible inhibitor of lysine-specific demethylase 1 reduced both TMCG/DIPY-mediated RASSF1A expression and apoptosis in MDA-MB-231 cells, suggesting that DNA and protein demethylation may act together to control these molecular and cellular processes.<h4>Conclusions/significance</h4>This study demonstrates that simultaneous targeting of DNA and E2F1 methylation is an effective epigenetic treatment that reactivates RASSF1A expression and induces apoptosis in breast cancer cells.María F MontenegroMagali Sáez-AyalaAntonio Piñero-MadronaJuan Cabezas-HerreraJuan Cabezas-HerreraJosé Neptuno Rodríguez-LópezPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 7, Iss 12, p e52231 (2012)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q María F Montenegro Magali Sáez-Ayala Antonio Piñero-Madrona Juan Cabezas-Herrera Juan Cabezas-Herrera José Neptuno Rodríguez-López Reactivation of the tumour suppressor RASSF1A in breast cancer by simultaneous targeting of DNA and E2F1 methylation.
description	<h4>Background</h4>Tumour suppressor genes are often transcriptionally silenced by promoter hypermethylation, and recent research has implicated alterations in chromatin structure as the mechanistic basis for this repression. In addition to DNA methylation, other epigenetic post-translational modifications that modulate the stability and binding of specific transcription factors to gene promoters have emerged as important mechanisms for controlling gene expression. The aim of this study was to analyse the implications of these mechanisms and their molecular connections in the reactivation of RASSF1A in breast cancer.<h4>Methods</h4>Compounds that modulate the intracellular concentration of adenosine, such as dipyridamole (DIPY), greatly increase the antiproliferative effects of 3-O-(3,4,5-trimethoxybenzoyl)-(-)-catechin (TMCG), a synthetic antifolate derived from the structure of tea catechins. Quantitative real-time PCR arrays and MALDI-TOF mass spectrometry indicated that this combination (TMCG/DIPY) induced apoptosis in breast cancer cells by modulating the methylation levels of DNA and proteins (such as E2F1), respectively. Chromatin immunoprecipitation (ChIP) assays were employed to confirm that this combination induced chromatin remodelling of the RASSF1A promoter and increased the occupancy of E2F1 at the promoter of this tumour suppressor gene.<h4>Results</h4>The TMCG/DIPY combination acted as an epigenetic treatment that reactivated RASSF1A expression and induced apoptosis in breast cancer cells. In addition to modulating DNA methylation and chromatin remodelling, this combination also induced demethylation of the E2F1 transcription factor. The ChIP assay showed enhancement of E2F1 occupancy at the unmethylated RASSF1A promoter after TMCG/DIPY treatment. Interestingly, inhibition of E2F1 demethylation using an irreversible inhibitor of lysine-specific demethylase 1 reduced both TMCG/DIPY-mediated RASSF1A expression and apoptosis in MDA-MB-231 cells, suggesting that DNA and protein demethylation may act together to control these molecular and cellular processes.<h4>Conclusions/significance</h4>This study demonstrates that simultaneous targeting of DNA and E2F1 methylation is an effective epigenetic treatment that reactivates RASSF1A expression and induces apoptosis in breast cancer cells.
format	article
author	María F Montenegro Magali Sáez-Ayala Antonio Piñero-Madrona Juan Cabezas-Herrera Juan Cabezas-Herrera José Neptuno Rodríguez-López
author_facet	María F Montenegro Magali Sáez-Ayala Antonio Piñero-Madrona Juan Cabezas-Herrera Juan Cabezas-Herrera José Neptuno Rodríguez-López
author_sort	María F Montenegro
title	Reactivation of the tumour suppressor RASSF1A in breast cancer by simultaneous targeting of DNA and E2F1 methylation.
title_short	Reactivation of the tumour suppressor RASSF1A in breast cancer by simultaneous targeting of DNA and E2F1 methylation.
title_full	Reactivation of the tumour suppressor RASSF1A in breast cancer by simultaneous targeting of DNA and E2F1 methylation.
title_fullStr	Reactivation of the tumour suppressor RASSF1A in breast cancer by simultaneous targeting of DNA and E2F1 methylation.
title_full_unstemmed	Reactivation of the tumour suppressor RASSF1A in breast cancer by simultaneous targeting of DNA and E2F1 methylation.
title_sort	reactivation of the tumour suppressor rassf1a in breast cancer by simultaneous targeting of dna and e2f1 methylation.
publisher	Public Library of Science (PLoS)
publishDate	2012
url	https://doaj.org/article/17eabdbfda8d4ce0be8e713fa74c05ba
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Reactivation of the tumour suppressor RASSF1A in breast cancer by simultaneous targeting of DNA and E2F1 methylation.

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