The Role of miR-206 in The Epidermal Growth Factor (EGF) Induced Repression of Estrogen Receptor-alpha (ER{alpha}) Signaling and a Luminal Phenotype in MCF-7 Breast Cancer Cells

Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3505, USA.
Molecular Endocrinology (Impact Factor: 4.02). 06/2009; 23(8):1215-30. DOI: 10.1210/me.2009-0062
Source: PubMed


Epidermal growth factor (EGF) receptor (EGFR)/MAPK signaling can induce a switch in MCF-7 breast cancer cells, from an estrogen receptor (ER)α-positive, Luminal-A phenotype, to an ERα-negative, Basal-like phenotype. Although mechanisms for this switch remain obscure, Basal-like cancers are typically high grade and confer a poorer clinical prognosis. We previously reported that miR-206 and ERαrepress each other's expression in MCF-7 cells in a double-negative feedback loop.Weshow herein that miR-206 coordinately targets mRNAs encoding the coactivator proteins steroid receptor coactivator (SRC)-1 and SRC-3, and the transcription factor GATA-3, all of which contribute to estrogenic signaling and a Luminal-A phenotype. Overexpression of miR-206 repressed estrogen-mediated responses in MCF-7 cells, even in the presence of ERα encoded by an mRNA lacking a 3′-untranslated region, suggesting miR-206 affects estrogen signaling by targeting mRNAs encoding ERα-associated coregulatory proteins. Furthermore, EGF treatments enhanced miR-206 levels in MCF-7 cells and ERα-negative, EGFR-positive MDA-MB-231 cells, whereas EGFR small interfering RNA, or PD153035, an EGFR inhibitor, or U0126, a MAPK kinase inhibitor, significantly reduced miR-206 levels in MDA-MB-231 cells. Blocking EGF-induced enhancement of miR-206 with antagomiR-206 abrogated the EGF-inhibitory effect on ERα, SRC-1, and SRC-3 levels, and on estrogen response element-luciferase activity, indicating that EGFR signaling represses estrogenic responses in MCF-7 cells by enhancing miR-206 activity. Elevated miR-206 levels in MCF-7 cells ultimately resulted in reduced cell proliferation, enhanced apoptosis, and reduced expression of multiple estrogen-responsive genes. In conclusion, miR-206 contributes to EGFRmediated abrogation of estrogenic responses in MCF-7 cells, contributes to a Luminal-A- to Basallike phenotypic switch, and may be a measure of EGFR response within Basal-like breast tumors.

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Available from: Brian D Adams, Jun 18, 2014
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    • "In contrast to these observations, cancers of the breast and lung have been characterized as exhibiting low miR-206 expression levels, suggesting a possible tumor suppressor function [9,10,12]. Changes in the expression of KLF4 also can be site specific, being upregulated in cancers of the breast, skin, and lung, but attenuated in colon and gastric tumors [14,15,19,31]. The prior investigation of high-abundance miRNAs in rat colon tumors highlighted a role for c-Myc, Oct-3/4, and Sox2 [24], whereas the present work has implicated a fourth ‘defined factor’ for pluripotency, namely KLF4[13]. "
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    ABSTRACT: Background MicroRNAs (miRNAs or miRs) are short non-coding RNAs that affect the expression of genes involved in normal physiology, but that also become dysregulated in cancer development. In the latter context, studies to date have focused on high-abundance miRNAs and their targets. We hypothesized that among the pool of low-abundance miRNAs are some with the potential to impact crucial oncogenic signaling networks in colon cancer. Results Unbiased screening of over 650 miRNAs identified miR-206, a low-abundance miRNA, as the most significantly altered miRNA in carcinogen-induced rat colon tumors. Computational modeling highlighted the stem-cell marker Krüppel-like factor 4 (KLF4) as a potential target of miR-206. In a panel of primary human colon cancers, target validation at the mRNA and protein level confirmed a significant inverse relationship between miR-206 and KLF4, which was further supported by miR-206 knockdown and ectopic upregulation in human colon cancer cells. Forced expression of miR-206 resulted in significantly increased cell proliferation kinetics, as revealed by real-time monitoring using HCT116 cells. Conclusions Evolutionarily conserved high-abundance miRNAs are becoming established as key players in the etiology of human cancers. However, low-abundance miRNAs, such as miR-206, are often among the most significantly upregulated miRNAs relative to their expression in normal non-transformed tissues. Low-abundance miRNAs are worthy of further investigation, because their targets include KLF4 and other pluripotency and cancer stem-cell factors.
    09/2012; 4(1). DOI:10.1186/1868-7083-4-16
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    • "miR-18a/b was clustered together with miR-17-92 [44,45] according to the similar expression profiles, which were induced by c-myc and reported to promote cell differentiation and proliferation. In pattern 6, such as miR-206 [46] and miR-1 [47], miRNA expressions dramatically increased in the lymph node metastasis. It indicated that these miRNAs may play an important role in the metastasis and may be a special biomarker for the lymph node metastasis. "
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    ABSTRACT: MicroRNAs (miRNAs) are small non-coding RNAs that participate in the spatiotemporal regulation of messenger RNA (mRNA) and protein synthesis. Recent studies have shown that some miRNAs are involved in the progression of nasopharyngeal carcinoma (NPC). However, the aberrant miRNAs implicated in different clinical stages of NPC remain unknown and their functions have not been systematically studied. In this study, miRNA microarray assay was performed on biopsies from different clinical stages of NPC. TargetScan was used to predict the target genes of the miRNAs. The target gene list was narrowed down by searching the data from the UniGene database to identify the nasopharyngeal-specific genes. The data reduction strategy was used to overlay with nasopharyngeal-specifically expressed miRNA target genes and complementary DNA (cDNA) expression data. The selected target genes were analyzed in the Gene Ontology (GO) biological process and Kyoto Encyclopedia of Genes and Genomes (KEGG) biological pathway. The microRNA-Gene-Network was build based on the interactions of miRNAs and target genes. miRNA promoters were analyzed for the transcription factor (TF) binding sites. UCSC Genome database was used to construct the TF-miRNAs interaction networks. Forty-eight miRNAs with significant change were obtained by Multi-Class Dif. The most enriched GO terms in the predicted target genes of miRNA were cell proliferation, cell migration and cell matrix adhesion. KEGG analysis showed that target genes were significantly involved in adherens junction, cell adhesion molecules, p53 signalling pathway et al. Comprehensive analysis of the coordinate expression of miRNAs and mRNAs reveals that miR-29a/c, miR-34b, miR-34c-3p, miR-34c-5p, miR-429, miR-203, miR-222, miR-1/206, miR-141, miR-18a/b, miR-544, miR-205 and miR-149 may play important roles on the development of NPC. We proposed an integrative strategy for identifying the miRNA-mRNA regulatory modules and TF-miRNA regulatory networks. TF including ETS2, MYB, Sp1, KLF6, NFE2, PCBP1 and TMEM54 exert regulatory functions on the miRNA expression. This study provides perspective on the microRNA expression during the development of NPC. It revealed the global trends in miRNA interactome in NPC. It concluded that miRNAs might play important regulatory roles through the target genes and transcription factors in the stepwise development of NPC.
    BMC Medical Genomics 01/2012; 5(1):3. DOI:10.1186/1755-8794-5-3 · 2.87 Impact Factor
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    • "Furthermore, introduction of miR-206 produced a dose-dependent decrease of mRNA expression of ERα-target genes, such as progesterone receptor, cyclin D1 and pS2. Adams and colleagues recently reported that miR-206 coordinately targeted mRNAs encoding the coactivator proteins SRC-1 and SRC-3, and the transcription factor GATA-3, all of which contribute to estrogenic signaling and a luminal A phenotype (Adams et al., 2009). Furthermore, they identified that miR-206 contributed to the epidermal growth factor (EGF) induced repression of ERα signaling in MCF-7 cells. "

    Breast Cancer - Carcinogenesis, Cell Growth and Signalling Pathways, 11/2011; , ISBN: 978-953-307-714-7
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