MUC1 gene overexpressed in breast cancer: Structure and transcriptional activity of the MUC1 promoter and role of estrogen receptor alpha (ERα) in regulation of the MUC1 gene expression

Department of Cell Research and Immunology, Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel.
Molecular Cancer (Impact Factor: 4.26). 02/2006; 5(1):57. DOI: 10.1186/1476-4598-5-57
Source: PubMed


The MUC1 gene encodes a mucin glycoprotein(s) which is basally expressed in most epithelial cells. In breast adenocarcinoma and a variety of epithelial tumors its transcription is dramatically upregulated. Of particular relevance to breast cancer, steroid hormones also stimulate the expression of the MUC1 gene. The MUC1 gene directs expression of several protein isoforms, which participate in many crucial cell processes. Although the MUC1 gene plays a critical role in cell physiology and pathology, little is known about its promoter organization and transcriptional regulation. The goal of this study was to provide insight into the structure and transcriptional activity of the MUC1 promoter.
Using TRANSFAC and TSSG soft-ware programs the transcription factor binding sites of the MUC1 promoter were analyzed and a map of transcription cis-elements was constructed. The effect of different MUC1 promoter regions on MUC1 gene expression was monitored. Different regions of the MUC1 promoter were analyzed for their ability to control expression of specific MUC1 isoforms. Differences in the expression of human MUC1 gene transfected into mouse cells (heterologous artificial system) compared to human cells (homologous natural system) were observed. The role of estrogen on MUC1 isoform expression in human breast cancer cells, MCF-7 and T47D, was also analyzed. It was shown for the first time that synthesis of MUC1/SEC is dependent on estrogen whereas expression of MUC1/TM did not demonstrate such dependence. Moreover, the estrogen receptor alpha, ERalpha, could bind in vitro estrogen responsive cis-elements, EREs, that are present in the MUC1 promoter. The potential roles of different regions of the MUC1 promoter and ER in regulation of MUC1 gene expression are discussed.
Analysis of the structure and transcriptional activity of the MUC1 promoter performed in this study helps to better understand the mechanisms controlling transcription of the MUC1 gene. The role of different regions of the MUC1 promoter in expression of the MUC1 isoforms and possible function of ERalpha in this process has been established. The data obtained in this study may help in development of molecular modalities for controlled regulation of the MUC1 gene thus contributing to progress in breast cancer gene therapy.

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    • "Zaretsky and others discussed about the possible involvement of estrogen receptors in regulation of the MUC1 gene transcription. However, it is known that ER may regulate gene transcription also by interaction with other transcription factors (STAT, AP1, EGFR or NF-kB) without direct binding to estrogen receptors [21]. "
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    ABSTRACT: Mucin 1 (MUC1) is overexpressed in various cancer cells especially in breast cancer cells. There are known research works on the use of anti-MUC1 antibody with docetaxel in ovarian cancer, but there are no data about combined therapy platinum compounds with anti-MUC1 in breast cancer. The aim of the study was to evaluate the antiproliferative properties of a new dinuclear platinum(II) complex (Pt12) used with anti-MUC1 in human breast cancer cells. The dinuclear platinum(II) complex (Pt12) has been synthesized, and its cytotoxicity with anti-MUC1 has been tested in both MCF-7 and MDA-MB-231 breast cancer cells. In this study, the effects of Pt12 with anti-MUC1 on collagen and DNA biosynthesis in human breast cancer cells were compared to those evoked by cisplatin and cisplatin with anti-MUC1. The mechanism of action of Pt12 with anti-MUC1 was studied employing flow cytometry assessment of annexin V binding assay. It was found that Pt12 with anti-MUC1 was more active inhibitor of DNA and collagen synthesis as well more cytotoxic agent than Pt12 alone and cisplatin with anti-MUC1. Cytotoxicity of Pt12 with anti-MUC1 against breast cancer cells is due to apoptotic cell death as well as necrotic cell death. These results indicate that the use of Pt12 with anti-MUC1 may constitute a novel strategy in the chemotherapy of breast cancer tumors.
    Full-text · Article · Mar 2014 · Molecular and Cellular Biochemistry
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    • "In gastric cancer cells, MUC1 interacts with the H. pylori cytotoxin-associated gene A (cagA), a major bacterial virulence factor, upregulates Wnt-b-catenin signaling, and increases cyclin D1-dependent cell proliferation, all of which are known to contribute to gastric carcinogenesis [6]. While the MUC1 promoter contains putative binding sites for a variety of transcription factors [7], the role of altered transcriptional regulation in MUC1 overexpression and gastric tumorigenesis remains to be determined. Cytosine methylation of CpG dinucleotides regulates the expression of most eukaryotic genes [8]. "
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    ABSTRACT: Helicobacter pylori infection of the stomach is associated with the development of gastritis, peptic ulcers, and gastric adenocarcinomas, but the mechanisms are unknown. MUC1 is aberrantly overexpressed by more than 50% of stomach cancers, but its role in carcinogenesis remains to be defined. The current studies were undertaken to identify the genetic mechanisms regulating H. pylori-dependent MUC1 expression by gastric epithelial cells. Treatment of AGS cells with H. pylori increased MUC1 mRNA and protein levels, and augmented MUC1 gene promoter activity, compared with untreated cells. H. pylori increased binding of STAT3 and MUC1 itself to the MUC1 gene promoter within a region containing a STAT3 binding site, and decreased CpG methylation of the MUC1 promoter proximal to the STAT3 binding site, compared with untreated cells. These results suggest that H. pylori upregulates MUC1 expression in gastric cancer cells through STAT3 and CpG hypomethylation.
    Full-text · Article · Feb 2014 · Biochemical and Biophysical Research Communications
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    • "Approximately 20% of breast cancers belong to the Luminal B genetic subtype, typified by estrogen receptor positivity and a slow, steady rate of recurrence over time despite anti-estrogen therapy [1]. Estrogen is known to increase the expression of MUC1 [2], a well-characterized member of the mucin family of glycoproteins, and a correlation has been demonstrated between MUC1 expression, resistance to anti-estrogen therapy and metastatic behaviour [3]. We have been investigating the mechanism of cell migration in the Luminal B breast cancer cell lines MCF7 and T47D, and were the first to demonstrate that MUC1 mediates heterotypic cell-cell adhesion by binding ICAM-1 [4], which is expressed on peritumoral stromal and endothelial cells. "
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    ABSTRACT: The mucin MUC1, a type I transmembrane glycoprotein, is overexpressed in breast cancer and has been correlated with increased metastasis. We were the first to report binding between MUC1 and Intercellular adhesion molecule-1 (ICAM-1), which is expressed on stromal and endothelial cells throughout the migratory tract of a metastasizing breast cancer cell. Subsequently, we found that MUC1/ICAM-1 binding results in pro-migratory calcium oscillations, cytoskeletal reorganization, and simulated transendothelial migration. These events were found to involve Src kinase, a non-receptor tyrosine kinase also implicated in breast cancer initiation and progression. Here, we further investigated the mechanism of MUC1/ICAM-1 signalling, focusing on the role of MUC1 dimerization in Src recruitment and pro-metastatic signalling. To assay MUC1 dimerization, we used a chemical crosslinker which allowed for the detection of dimers on SDS-PAGE. We then generated MUC1 constructs containing an engineered domain which allowed for manipulation of dimerization status through the addition of ligands to the engineered domain. Following manipulation of dimerization, we immunoprecipitated MUC1 to investigate recruitment of Src, or assayed for our previously observed ICAM-1 binding induced events. To investigate the nature of MUC1 dimers, we used both non-reducing SDS-PAGE and generated a mutant construct lacking cysteine residues. We first demonstrate that the previously observed MUC1/ICAM-1 signalling events are dependent on the activity of Src kinase. We then report that MUC1 forms constitutive cytoplasmic domain dimers which are necessary for Src recruitment, ICAM-1 induced calcium oscillations and simulated transendothelial migration. The dimers are not covalently linked constitutively or following ICAM-1 binding. In contrast to previously published reports, we found that membrane proximal cysteine residues were not involved in dimerization or ICAM-1 induced signalling. Our data implicates non-cysteine linked MUC1 dimerization in cell signalling pathways required for cancer cell migration.
    Full-text · Article · Jul 2011 · Molecular Cancer
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