TY - JOUR
T1 - Global identification of genes regulated by estrogen signaling and demethylation in MCF-7 breast cancer cells
AU - Putnik, Milica
AU - Zhao, Chunyan
AU - Gustafsson, Jan Åke
AU - Dahlman-Wright, Karin
N1 - Funding Information:
The study was supported by Cancerfonden, Karolinska Institute’s faculty funds for partial financing of doctoral students (KID), Karolinska Institute’s Center for Biosciences and the EU integrated project CRESCENDO. We are grateful to the Bioinformatic and Expression Analysis core facility at the Karolinska Institute (BEA, www.bea.ki.se ) for performing the microarray assay.
Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2012/9/14
Y1 - 2012/9/14
N2 - Estrogen signaling and epigenetic modifications, in particular DNA methylation, are involved in regulation of gene expression in breast cancers. Here we investigated a potential regulatory cross-talk between these two pathways by identifying their common target genes and exploring underlying molecular mechanisms in human MCF-7 breast cancer cells. Gene expression profiling revealed that the expression of approximately 140 genes was influenced by both 17β-estradiol (E2) and a demethylating agent 5-aza-2'-deoxycytidine (DAC). Gene ontology (GO) analysis suggests that these genes are involved in intracellular signaling cascades, regulation of cell proliferation and apoptosis. Based on previously reported association with breast cancer, estrogen signaling and/or DNA methylation, CpG island prediction and GO analysis, we selected six genes (BTG3, FHL2, PMAIP1, BTG2, CDKN1A and TGFB2) for further analysis. Tamoxifen reverses the effect of E2 on the expression of all selected genes, suggesting that they are direct targets of estrogen receptor. Furthermore, DAC treatment reactivates the expression of all selected genes in a dose-dependent manner. Promoter CpG island methylation status analysis revealed that only the promoters of BTG3 and FHL2 genes are methylated, with DAC inducing demethylation, suggesting DNA methylation directs repression of these genes in MCF-7 cells. In a further analysis of the potential interplay between estrogen signaling and DNA methylation, E2 treatment showed no effect on the methylation status of these promoters. Additionally, we show that the ERα recruitment occurs at the FHL2 promoter in an E2- and DAC-independent fashion. In conclusion, we identified a set of genes regulated by both estrogen signaling and DNA methylation. However, our data does not support a direct molecular interplay of mediators of estrogen and epigenetic signaling at promoters of regulated genes.
AB - Estrogen signaling and epigenetic modifications, in particular DNA methylation, are involved in regulation of gene expression in breast cancers. Here we investigated a potential regulatory cross-talk between these two pathways by identifying their common target genes and exploring underlying molecular mechanisms in human MCF-7 breast cancer cells. Gene expression profiling revealed that the expression of approximately 140 genes was influenced by both 17β-estradiol (E2) and a demethylating agent 5-aza-2'-deoxycytidine (DAC). Gene ontology (GO) analysis suggests that these genes are involved in intracellular signaling cascades, regulation of cell proliferation and apoptosis. Based on previously reported association with breast cancer, estrogen signaling and/or DNA methylation, CpG island prediction and GO analysis, we selected six genes (BTG3, FHL2, PMAIP1, BTG2, CDKN1A and TGFB2) for further analysis. Tamoxifen reverses the effect of E2 on the expression of all selected genes, suggesting that they are direct targets of estrogen receptor. Furthermore, DAC treatment reactivates the expression of all selected genes in a dose-dependent manner. Promoter CpG island methylation status analysis revealed that only the promoters of BTG3 and FHL2 genes are methylated, with DAC inducing demethylation, suggesting DNA methylation directs repression of these genes in MCF-7 cells. In a further analysis of the potential interplay between estrogen signaling and DNA methylation, E2 treatment showed no effect on the methylation status of these promoters. Additionally, we show that the ERα recruitment occurs at the FHL2 promoter in an E2- and DAC-independent fashion. In conclusion, we identified a set of genes regulated by both estrogen signaling and DNA methylation. However, our data does not support a direct molecular interplay of mediators of estrogen and epigenetic signaling at promoters of regulated genes.
KW - 5-Aza-2'-deoxycytidine
KW - Breast cancer
KW - DNA methylation
KW - Estrogen
KW - Estrogen receptor
KW - Microarray
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U2 - 10.1016/j.bbrc.2012.08.007
DO - 10.1016/j.bbrc.2012.08.007
M3 - Article
C2 - 22902638
AN - SCOPUS:84866320302
VL - 426
SP - 26
EP - 32
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
SN - 0006-291X
IS - 1
ER -