MBD2

Gene Summary

Gene:MBD2; methyl-CpG binding domain protein 2
Aliases: DMTase, NY-CO-41
Location:18q21.2
Summary:DNA methylation is the major modification of eukaryotic genomes and plays an essential role in mammalian development. Human proteins MECP2, MBD1, MBD2, MBD3, and MBD4 comprise a family of nuclear proteins related by the presence in each of a methyl-CpG binding domain (MBD). Each of these proteins, with the exception of MBD3, is capable of binding specifically to methylated DNA. MECP2, MBD1 and MBD2 can also repress transcription from methylated gene promoters. The protein encoded by this gene may function as a mediator of the biological consequences of the methylation signal. It is also reported that the this protein functions as a demethylase to activate transcription, as DNA methylation causes gene silencing. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Feb 2011]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:methyl-CpG-binding domain protein 2
Source:NCBIAccessed: 11 March, 2017

Ontology:

What does this gene/protein do?
Show (19)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Upstream Stimulatory Factors
  • Transcription Factors
  • Prostate Cancer
  • Molecular Sequence Data
  • Chromatin Immunoprecipitation
  • Uterine Cancer
  • Messenger RNA
  • Breast Cancer
  • Cancer DNA
  • VEGFA
  • Base Sequence
  • Enzyme Inhibitors
  • Transcriptional Activation
  • Tumor Suppressor Protein p14ARF
  • Epigenetics
  • CpG Islands
  • Stomach Cancer
  • Polymerase Chain Reaction
  • Histones
  • RTPCR
  • Cancer Gene Expression Regulation
  • Chromosome 18
  • MicroRNAs
  • Methyl-CpG-Binding Protein 2
  • DNA-Binding Proteins
  • Serologic Tests
  • DNA (Cytosine-5-)-Methyltransferase
  • Hydroxamic Acids
  • Lung Cancer
  • Histone Deacetylase Inhibitors
  • Chromosomal Proteins, Non-Histone
  • Cancer RNA
  • Bladder Cancer
  • Chromatin
  • Azacitidine
  • Acetylation
  • Promoter Regions
  • Tumor Suppressor Proteins
  • Gene Silencing
  • Down-Regulation
  • DNA Methylation
Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: MBD2 (cancer-related)

Cheng X, Waghulde H, Mell B, et al.
Pleiotropic Effect of a High Resolution Mapped Blood Pressure QTL on Tumorigenesis.
PLoS One. 2016; 11(4):e0153519 [PubMed] Free Access to Full Article Related Publications
This study is focused on a translationally significant, genome-wide-association-study (GWAS) locus for cardiovascular disease (QT-interval) on human chromosome 17. We have previously validated and high resolution mapped the homologous genomic segment of this human locus to <42.5 kb on rat chromosome 10. This <42.5 kb segment in rats regulates both QT-interval and blood pressure and contains a single protein-coding gene, rififylin (Rffl). The expression of Rffl in the hearts and kidneys is differential between Dahl S and S.LEW congenic rats, which are the strains used for mapping this locus. Our previous study points to altered rate of endocytic recycling as the underlying mechanism, through which Rffl operates to control both QT-interval and blood pressure. Interestingly, Rffl also contributes to tumorigenesis by repressing caspases and tumor suppressor genes. Moreover, the expression of Methyl-CpG Binding Domain Protein 2 (Mbd2) in the hearts and kidneys is also higher in the S.LEW congenic strain than the background (control) Dahl S strain. Mbd2 can repress methylated tumor suppressor genes. These data suggest that the S.LEW congenic strain could be more susceptible to tumorigenesis. To test this hypothesis, the S and S.LEW strains were compared for susceptibility to azoxymethane-induced colon tumors. The number of colon tumors was significantly higher in the S.LEW congenic strain compared with the S rat. Transcriptomic analysis confirmed that the chemical carcinogenesis pathway was significantly up-regulated in the congenic strain. These studies provide evidence for a GWAS-validated genomic segment on rat chromosome 10 as being important for the regulation of cardiovascular function and tumorigenesis.

He S, Lai R, Chen D, et al.
Downregulation of miR-221 Inhibits Cell Migration and Invasion through Targeting Methyl-CpG Binding Domain Protein 2 in Human Oral Squamous Cell Carcinoma Cells.
Biomed Res Int. 2015; 2015:751672 [PubMed] Free Access to Full Article Related Publications
Oral squamous cell carcinoma (OSCC), the most frequent of all oral cancers, is a type of highly malignant tumors with a high capacity to invade locally and form distant metastases. An increasing number of studies have shown that microRNAs (miRNAs) play an important role in regulating cancer metastasis and invasion. In the present study, we detected the expression of miR-221 in two highly metastatic OSCC cell lines and two OSCC cell lines that are less metastatic using quantitative real-time PCR analysis (qRT-PCR). The qRT-PCR results indicate that miR-221 is upregulated in highly metastatic OSCC cell lines. Then, miR-221 expression was knocked down by transfection with miR-221 inhibitor, and UM1 cell migration and invasion were assessed using transwell migration and invasion assays. The results indicate that inhibition of miR-221 suppressed migration and invasion of UM1 cells. Furthermore, methyl-CpG binding domain protein 2 (MBD2) was identified as a direct target gene of miR-221. Additionally, MBD2 silencing could partly reverse the effect of miR-221 on cell migration and invasion. In conclusion, downregulation of miR-221 inhibits cell migration and invasion at least partially through targeting MBD2 in the human OSCC cell line UM1.

Nagoshi H, Taki T, Chinen Y, et al.
Transcriptional dysregulation of the deleted in colorectal carcinoma gene in multiple myeloma and monoclonal gammopathy of undetermined significance.
Genes Chromosomes Cancer. 2015; 54(12):788-95 [PubMed] Related Publications
The deleted in colorectal carcinoma (DCC) gene at 18q21 encodes a netrin-1 receptor, a tumor suppressor that prevents cell growth. While allele loss or decreased expression of DCC has been associated with the progression of solid tumors and hematologic malignancies, including leukemias and malignant lymphomas, its involvement has not been evaluated in multiple myeloma (MM), a plasma cell malignancy characterized by complex and heterogenous molecular abnormalities. We here show that 10 of 11 human myeloma-derived cell lines (HMCLs) expressed non-translated aberrant DCC transcriptional variants, in which exon 2 fuses with intron 1 instead of exon 1 (mt.DCC). Among them, two co-expressed wild type transcripts (wt.DCC), while eight co-expressed the splicing variant (sv.DCC) lacking exon 1. The remaining HMCL expressed only sv.DCC. In addition, analyses revealed that there were two types of mt.DCC that differed in their fusion of intron 1 with exon 2. In patient-derived samples from 30 MM and 8 monoclonal gammopathy of undetermined significance (MGUS) patients, wt.DCC was expressed in 53% of MM, but not in MGUS, while 23% of MM and 75% of MGUS expressed only sv.DCC. Considering that 25% of MGUS, 57% of MM, and 91% HMCLs expressed mt.DCC, our results suggest that the acquisition of mt.DCC might be a secondary genetic change in plasma cell dyscrasia.

Devailly G, Grandin M, Perriaud L, et al.
Dynamics of MBD2 deposition across methylated DNA regions during malignant transformation of human mammary epithelial cells.
Nucleic Acids Res. 2015; 43(12):5838-54 [PubMed] Free Access to Full Article Related Publications
DNA methylation is thought to induce transcriptional silencing through the combination of two mechanisms: the repulsion of transcriptional activators unable to bind their target sites when methylated, and the recruitment of transcriptional repressors with specific affinity for methylated DNA. The Methyl CpG Binding Domain proteins MeCP2, MBD1 and MBD2 belong to the latter category. Here, we present MBD2 ChIPseq data obtained from the endogenous MBD2 in an isogenic cellular model of oncogenic transformation of human mammary cells. In immortalized (HMEC-hTERT) or transformed (HMLER) cells, MBD2 was found in a large proportion of methylated regions and associated with transcriptional silencing. A redistribution of MBD2 on methylated DNA occurred during oncogenic transformation, frequently independently of local DNA methylation changes. Genes downregulated during HMEC-hTERT transformation preferentially gained MBD2 on their promoter. Furthermore, depletion of MBD2 induced an upregulation of MBD2-bound genes methylated at their promoter regions, in HMLER cells. Among the 3,160 genes downregulated in transformed cells, 380 genes were methylated at their promoter regions in both cell lines, specifically associated by MBD2 in HMLER cells, and upregulated upon MBD2 depletion in HMLER. The transcriptional MBD2-dependent downregulation occurring during oncogenic transformation was also observed in two additional models of mammary cell transformation. Thus, the dynamics of MBD2 deposition across methylated DNA regions was associated with the oncogenic transformation of human mammary cells.

Du Q, Luu PL, Stirzaker C, Clark SJ
Methyl-CpG-binding domain proteins: readers of the epigenome.
Epigenomics. 2015; 7(6):1051-73 [PubMed] Related Publications
How DNA methylation is interpreted and influences genome regulation remains largely unknown. Proteins of the methyl-CpG-binding domain (MBD) family are primary candidates for the readout of DNA methylation as they recruit chromatin remodelers, histone deacetylases and methylases to methylated DNA associated with gene repression. MBD protein binding requires both functional MBD domains and methyl-CpGs; however, some MBD proteins also bind unmethylated DNA and active regulatory regions via alternative regulatory domains or interaction with the nucleosome remodeling deacetylase (NuRD/Mi-2) complex members. Mutations within MBD domains occur in many diseases, including neurological disorders and cancers, leading to loss of MBD binding specificity to methylated sites and gene deregulation. Here, we summarize the current state of knowledge about MBD proteins and their role as readers of the epigenome.

Yang Y, Li D, Yang Y, Jiang G
An integrated analysis of the effects of microRNA and mRNA on esophageal squamous cell carcinoma.
Mol Med Rep. 2015; 12(1):945-52 [PubMed] Free Access to Full Article Related Publications
Esophageal squamous cell cancer (ESCC) is an aggressive type of cancer with poor prognosis and leading to decreased quality of life. The identification of patients at increased risk of esophageal squamous cell cancer may improve current understanding of the role of micro (mi)RNA in tumorigenesis, since the miRNA pattern of these patients may be associated with tumorigenesis. In the present study, the miRNA and mRNA expression profiles of ESCC tissue samples and adjacent normal control tissue samples were obtained from two dependent GEO series. Bioinformatics analyses, including the use of the Gene Oncology and Kyoto Encyclopedia of Genes and Genomes databases, were used to identify genes and pathways, which were specifically associated with miRNA-associated ESCC oncology. A total of 17 miRNAs and 1,670 probes were differentially expressed in the two groups, and the differentially expressed miRNA and target interactions were analyzed. The mRNA of miRNA target genes were found to be involve 49 GO terms and 14 pathways. Of the genes differentially expressed between the two groups, miRNA-181a, miRNA-202, miRNA-155, FNDC3B, BNC2 and MBD2 were the most significantly altered and may be important in the regulatory network. In the present study, a novel pattern of differential miRNA-target expression was constructed, which with further investigation, may provide novel targets for diagnosing and understanding the mechanism of ESCC.

Khor TO, Fuentes F, Shu L, et al.
Epigenetic DNA methylation of antioxidative stress regulator NRF2 in human prostate cancer.
Cancer Prev Res (Phila). 2014; 7(12):1186-97 [PubMed] Free Access to Full Article Related Publications
Epigenetic control of NRF2, a master regulator of many critical antioxidative stress defense genes in human prostate cancer (CaP), is unknown. Our previous animal study found decreased Nrf2 expression through promoter CpG methylation/histone modifications during prostate cancer progression in TRAMP mice. In this study, we evaluated CpG methylation of human NRF2 promoter in 27 clinical prostate cancer samples and in LNCaP cells using MAQMA analysis and bisulfite genomic DNA sequencing. Prostate cancer tissue microarray (TMA) containing normal and prostate cancer tissues was studied by immunohistochemistry. Luciferase reporter assay using specific human NRF2 DNA promoter segments and chromatin immunoprecipitation (ChIP) assay against histone modifying proteins were performed in LNCaP cells. Three specific CpG sites in the NRF2 promoter were found to be hypermethylated in clinical prostate cancer samples (BPH

Cheishvili D, Chik F, Li CC, et al.
Synergistic effects of combined DNA methyltransferase inhibition and MBD2 depletion on breast cancer cells; MBD2 depletion blocks 5-aza-2'-deoxycytidine-triggered invasiveness.
Carcinogenesis. 2014; 35(11):2436-46 [PubMed] Free Access to Full Article Related Publications
5-Aza-2'-deoxycytidine (5-azaCdR) not only inhibits growth of non-invasive breast cancer cells but also increases their invasiveness through induction of pro-metastatic genes. Methylated DNA binding protein 2 (MBD2) is involved in silencing methylated tumor suppressor genes as well as activation of pro-metastatic genes. In this study, we show that a combination of MBD2 depletion and DNA methyltransferases (DNMT) inhibition in breast cancer cells results in a combined effect in vitro and in vivo, enhancing tumor growth arrest on one hand, while inhibiting invasiveness triggered by 5-azaCdR on the other hand. The combined treatment of MBD2 depletion and 5-azaCdR suppresses and augments distinct gene networks that are induced by DNMT inhibition alone. These data point to a potential new approach in targeting the DNA methylation machinery by combination of MBD2 and DNMT inhibitors.

Menafra R, Brinkman AB, Matarese F, et al.
Genome-wide binding of MBD2 reveals strong preference for highly methylated loci.
PLoS One. 2014; 9(6):e99603 [PubMed] Free Access to Full Article Related Publications
MBD2 is a subunit of the NuRD complex that is postulated to mediate gene repression via recruitment of the complex to methylated DNA. In this study we adopted an MBD2 tagging-approach to study its genome wide binding characteristics. We show that in vivo MBD2 is mainly recruited to CpG island promoters that are highly methylated. Interestingly, MBD2 binds around 1 kb downstream of the transcription start site of a subset of ∼ 400 CpG island promoters that are characterized by the presence of active histone marks, RNA polymerase II (Pol2) and low to medium gene expression levels and H3K36me3 deposition. These tagged-MBD2 binding sites in MCF-7 show increased methylation in a cohort of primary breast cancers but not in normal breast samples, suggesting a putative role for MBD2 in breast cancer.

Pontes TB, Chen ES, Gigek CO, et al.
Reduced mRNA expression levels of MBD2 and MBD3 in gastric carcinogenesis.
Tumour Biol. 2014; 35(4):3447-53 [PubMed] Related Publications
Aberrant methylation has been reported in several neoplasias, including gastric cancer. The methyl-CpG-binding domain (MBD) family proteins have been implicated in the chromatin remodeling process, leading to the modulation of gene expression. To evaluate the role of MBD2 and MBD3 in gastric carcinogenesis and the possible association with clinicopathological characteristics, we assessed the mRNA levels and promoter methylation patterns in gastric tissues. In this study, MBD2 and MBD3 mRNA levels were determined by RT-qPCR in 28 neoplastic and adjacent nonneoplastic and 27 gastritis and non-gastritis samples. The promoter methylation status was determined by bisulfite sequencing, and we found reduced MBD2 and MBD3 levels in the neoplastic samples compared with the other groups. Moreover, a strong correlation between the MBD2 and MBD3 expression levels was observed in each set of paired samples. Our data also showed that the neoplastic tissues exhibited higher MBD2 promoter methylation than the other groups. Interestingly, the non-gastritis group was the only one with positive methylation in the MBD3 promoter region. Furthermore, a weak correlation between gene expression and methylation was observed. Therefore, our data suggest that DNA methylation plays a minor role in the regulation of MBD2 and MBD3 expression, and the presence of methylation at CpGs that interact with transcription factor complexes might also be involved in the modulation of these genes. Moreover, reduced mRNA expression of MBD2 and MBD3 is implicated in gastric carcinogenesis, and thus, further investigations about these genes should be conducted for a better understanding of the role of abnormal methylation involved in this neoplasia.

Alvarado S, Wyglinski J, Suderman M, et al.
Methylated DNA binding domain protein 2 (MBD2) coordinately silences gene expression through activation of the microRNA hsa-mir-496 promoter in breast cancer cell line.
PLoS One. 2013; 8(10):e74009 [PubMed] Free Access to Full Article Related Publications
Methylated DNA binding protein 2 (MBD2) binds methylated promoters and suppresses transcription in cis through recruitment of a chromatin modification repressor complex. We show here a new mechanism of action for MBD2: suppression of gene expression indirectly through activation of microRNA hsa-mir-496. Overexpression of MBD2 in breast epithelial cell line MCF-10A results in induced expression and demethylation of hsa-mir-496 while depletion of MBD2 in a human breast cancer cell lines MCF-7 and MDA-MB231 results in suppression of hsa-mir-496. Activation of hsa-mir-496 by MBD2 is associated with silencing of several of its target genes while depletion of MBD2 leads to induction of hsa-mir-496 target genes. Depletion of hsa-mir-496 by locked nucleic acid (LNA) antisense oligonucleotide leads to activation of these target genes in MBD2 overexpressing cells supporting that hsa-mir-496 is mediating in part the effects of MBD2 on gene expression. We demonstrate that MBD2 binds the promoter of hsa-mir-496 in MCF-10A, MCF-7 and MDA-MB-231 cells and that it activates an in vitro methylated hsa-mir-496 promoter driving a CG-less luciferase reporter in a transient transfection assay. The activation of hsa-mir-496 is associated with reduced methylation of the promoter. Taken together these results describe a novel cascade for gene regulation by DNA methylation whereby activation of a methylated microRNA by MBD2 that is associated with loss of methylation triggers repression of downstream targets.

Wang LS, Kuo CT, Huang TH, et al.
Black raspberries protectively regulate methylation of Wnt pathway genes in precancerous colon tissue.
Cancer Prev Res (Phila). 2013; 6(12):1317-27 [PubMed] Free Access to Full Article Related Publications
Ulcerative colitis is frequently an intermediate step to colon cancer. The interleukin-10 knockout mouse is a genetic model of this progression. We report that knockout mice fed 5% black raspberries (BRB) had significantly less colonic ulceration as compared with knockout mice that consumed the control diet. Dysfunction of the Wnt signaling pathway is a key event in ulcerative colitis-associated colon carcinogenesis. Therefore, we investigated the effects of BRBs on the Wnt pathway and found that the BRB-fed knockout mice exhibited a significantly lower level of β-catenin nuclear translocation. We followed-up this observation by evaluating the effect of BRBs on selected Wnt pathway antagonists. The mRNA expression levels of wif1, sox17, and qki were diminished in the knockout mice, whereas they were expressed at normal levels in knockout mice that were fed BRBs. The lower mRNA expression of these genes in the colon from the knockout mice correlated with hypermethylation of their promoter regions; BRBs decreased their promoter methylation and increased mRNA expression of these genes. This hypomethylation was associated with elevated protein expression of key proteins/enzymes that augment methylation, for example, dnmt3b, hdac1, hdac2, and mbd2 in the knockout mice; in addition, BRBs decreased the protein expression of these proteins/enzymes. The knockout mouse model recapitulates what occurs in human ulcerative colitis. Promoter methylation of CDH1 and SFRP1 was significantly higher in human ulcerative colitis tissues compared with their adjacent normal tissues. In conclusion, our results suggest that BRBs inhibit colonic ulceration and, ultimately, colon cancer partly through inhibiting aberrant epigenetic events that dysregulate Wnt signaling.

Stefanska B, Suderman M, Machnes Z, et al.
Transcription onset of genes critical in liver carcinogenesis is epigenetically regulated by methylated DNA-binding protein MBD2.
Carcinogenesis. 2013; 34(12):2738-49 [PubMed] Related Publications
We previously delineated genes whose promoters are hypomethylated and induced in hepatocellular carcinoma (HCC) patients. The purpose of this study was to establish the players that regulate these genes in liver cancer cells. We performed chromatin immunoprecipitation with methyl-CpG-binding domain protein 2 (MBD2), RNA polymerase II (RNA pol II), CCAAT/enhancer-binding protein alpha (CEBPA) antibodies and methylated DNA immunoprecipitation in HepG2 liver cancer cells treated with scrambled small interfering RNA (siRNA) and siRNA to MBD2 or CEBPA. We then hybridized DNA to microarrays spanning the entire coding sequences, introns and regulatory regions of several hundred HCC-hypomethylated genes. These analyses reveal that MBD2 binds a significant fraction of the hypomethylated genes, determines RNA pol II binding and DNA methylation state. MBD2 binding can result in promoter activation and hypomethylation or in repression. In activated target genes, MBD2 colocalizes with the transcription factor CEBPA, and MBD2 binding at these positions is reduced upon CEBPA depletion. Significant fraction of MBD2 effects on DNA methylation and transcription appears to be indirect since changes occur upon MBD2 depletion in genes where no MBD2 binding was detected. Our study delineates the rules governing the interaction of MBD2 with its targets and the consequences to RNA pol II binding and DNA methylation states. This has important implications for understanding the role of DNA methylation in cancer and targeting DNA methylation proteins in cancer therapy.

Li Q, Lan Q, Zhang Y, et al.
Role of one-carbon metabolizing pathway genes and gene-nutrient interaction in the risk of non-Hodgkin lymphoma.
Cancer Causes Control. 2013; 24(10):1875-84 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Genetic polymorphisms in one-carbon metabolizing pathway genes have been associated with risk of malignant lymphoma. However, the results have been inconsistent. The objectives of this study were to examine the potential relationship between gene-nutrient interactions and the risk of non-Hodgkin lymphoma (NHL).
METHODS: We examined 25 polymorphisms in 16 one-carbon metabolism genes for their main effect and gene-nutrient interactions in relation to NHL risk among 518 incident cases and 597 population-based controls of Connecticut women enrolled between 1996 and 2000.
RESULTS: A significantly reduced risk of NHL was associated with the homozygous TT genotype in CBS (rs234706, Ex9+33C>T) (OR = 0.51, 95 % CI 0.31-0.84), the homozygous CC genotype in MBD2 (rs603097, -2176C>T) (OR = 0.37, 95 % CI 0.17-0.79), the heterozygote AG genotype in FTHFD (rs1127717, Ex21+31A>G) (OR = 0.73, 95 % CI 0.55-0.98), and a borderline significantly reduced risk of NHL was observed for the homozygous CC genotype in MTRR (rs161870, Ex5+136T>C) (OR = 0.23, 95 % CI 0.05-1.04). The reduced risk of NHL associated with these genotypes was predominately in those with higher dietary vitamin B6 and methionine intakes, as well as with higher dietary folate intake although results were less stable. A borderline significantly increased risk of NHL was also observed for CBS (rs1801181, Ex13+41C>T), FTHFD (rs2305230, Ex10-40G>T), SHMT1 (rs1979277, Ex12+138C>T), and SHMT1 (rs1979276, Ex12+236T>C), and these associations appeared to be contingent on dietary nutrient intakes.
CONCLUSION: Our results suggest that variation in several one-carbon metabolizing pathway genes may influence the risk of NHL through gene-nutrient interactions involving dietary nutrient intakes.

Imai S, Kikuchi R, Tsuruya Y, et al.
Epigenetic regulation of organic anion transporting polypeptide 1B3 in cancer cell lines.
Pharm Res. 2013; 30(11):2880-90 [PubMed] Related Publications
PURPOSE: The expression of a multispecific organic anion transporter, OATP1B3/SLCO1B3, is associated with clinical prognosis and survival of cancer cells. The aims of present study were to investigate the involvement of epigenetic regulation in mRNA expression of a cancer-type variant of OATP1B3 (Ct-OATP1B3) in cancer cell lines.
METHODS: The membrane localization and transport functions of Ct-OATP1B3 were investigated in HEK293 cells transiently expressing Ct-OATP1B3. DNA methylation profiles around the transcriptional start site of Ct-OATP1B3 in cancer cell lines were determined. The effects of a DNA methyltransferase inhibitor and siRNA knockdown of methyl-DNA binding proteins (MBDs) on the expression of Ct-OATP1B3 mRNA were investigated.
RESULTS: 5'-RACE identified the TSS of Ct-OATP1B3 in PK-8 cells. Ct-OATP1B3 was localized on the plasma membrane, and showed the transport activities of E217βG, fluvastatin, rifampicin, and Gd-EOB-DTPA. The CpG dinucleotides were hypomethylated in Ct-OATP1B3-positive cell lines (DLD-1, TFK-1, PK-8, and PK-45P) but were hypermethylated in Ct-OATP1B3-negative cell lines (HepG2 and Caco-2). Treatment with a DNA methyltransferase inhibitor and siRNA knockdown of MBD2 significantly increased the expression of Ct-OATP1B3 mRNA in HepG2 and Caco-2.
CONCLUSIONS: Ct-OATP1B3 is capable of transporting its substrates into cancer cells. Its mRNA expression is regulated by DNA methylation-dependent gene silencing involving MBD2.

Huang RL, Gu F, Kirma NB, et al.
Comprehensive methylome analysis of ovarian tumors reveals hedgehog signaling pathway regulators as prognostic DNA methylation biomarkers.
Epigenetics. 2013; 8(6):624-34 [PubMed] Free Access to Full Article Related Publications
Women with advanced stage ovarian cancer (OC) have a five-year survival rate of less than 25%. OC progression is associated with accumulation of epigenetic alterations and aberrant DNA methylation in gene promoters acts as an inactivating "hit" during OC initiation and progression. Abnormal DNA methylation in OC has been used to predict disease outcome and therapy response. To globally examine DNA methylation in OC, we used next-generation sequencing technology, MethylCap-sequencing, to screen 75 malignant and 26 normal or benign ovarian tissues. Differential DNA methylation regions (DMRs) were identified, and the Kaplan-Meier method and Cox proportional hazard model were used to correlate methylation with clinical endpoints. Functional role of specific genes identified by MethylCap-sequencing was examined in in vitro assays. We identified 577 DMRs that distinguished (p < 0.001) malignant from non-malignant ovarian tissues; of these, 63 DMRs correlated (p < 0.001) with poor progression free survival (PFS). Concordant hypermethylation and corresponding gene silencing of sonic hedgehog pathway members ZIC1 and ZIC4 in OC tumors was confirmed in a panel of OC cell lines, and ZIC1 and ZIC4 repression correlated with increased proliferation, migration and invasion. ZIC1 promoter hypermethylation correlated (p < 0.01) with poor PFS. In summary, we identified functional DNA methylation biomarkers significantly associated with clinical outcome in OC and suggest our comprehensive methylome analysis has significant translational potential for guiding the design of future clinical investigations targeting the OC epigenome. Methylation of ZIC1, a putative tumor suppressor, may be a novel determinant of OC outcome.

Yuan K, Xie K, Fox J, et al.
Decreased levels of miR-224 and the passenger strand of miR-221 increase MBD2, suppressing maspin and promoting colorectal tumor growth and metastasis in mice.
Gastroenterology. 2013; 145(4):853-64.e9 [PubMed] Free Access to Full Article Related Publications
BACKGROUND & AIMS: Little is known about functions of microRNA (miR) passenger strands (miR*) or their roles in tumor development or progression. We screened for miRs and miR* with levels that were altered in metastatic colorectal cancer (CRC) cells and human tumor samples and investigated their targets and effects on cell function and tumor progression in mice.
METHODS: We performed array-based profile analysis to identify miRs with levels that were increased more than 2-fold in metastatic (SW620) CRC cells compared with nonmetastatic (SW480) cells. Quantitative polymerase chain reaction and in situ hybridization analyses were used to measure miRNA levels in CRC cell lines and human tumor samples. We used miRNA duplex mimics or inhibitors to increase and decrease levels of miRNA in CRC cells and assessed their activities and ability to form metastatic xenograft tumors in nude mice.
RESULTS: Levels of miR-221* and miR-224 were reduced in metastatic compared with nonmetastatic CRC cells; levels in human tumor samples correlated inversely with tumor stage and metastasis to lymph nodes as well as patient survival times. SW480 cells transfected with miR-221* or miR-224 inhibitors had increased motility in vitro compared with SW480 control cells and formed larger, more metastatic tumors when injected into mice. SW620 cells transfected with miR-221* or miR-224 mimics had reduced migration and motility in vitro and formed smaller tumors with fewer metastases in mice compared with control SW620 cells. We identified the 3' untranslated region of MBD2 messenger RNA as a target of miR-221* and miR-224. MBD2 silences the gene encoding maspin, a suppressor of metastasis. In CRC cells, we found that miR-221* and miR-224 increase the expression of maspin through MBD2 down-regulation.
CONCLUSIONS: In metastatic CRC cells, reduced levels of miR-221* and miR-224 increase levels of MBD2, thereby decreasing expression of the metastasis suppressor maspin. Increased activities of miR-221* and miR-224 reduce growth and metastasis of CRC xenograft tumors in mice; these miRs might be developed as therapeutic reagents or biomarkers of CRC progression.

Sapkota Y, Mackey JR, Lai R, et al.
Assessing SNP-SNP interactions among DNA repair, modification and metabolism related pathway genes in breast cancer susceptibility.
PLoS One. 2014; 8(6):e64896 [PubMed] Free Access to Full Article Related Publications
Genome-wide association studies (GWASs) have identified low-penetrance common variants (i.e., single nucleotide polymorphisms, SNPs) associated with breast cancer susceptibility. Although GWASs are primarily focused on single-locus effects, gene-gene interactions (i.e., epistasis) are also assumed to contribute to the genetic risks for complex diseases including breast cancer. While it has been hypothesized that moderately ranked (P value based) weak single-locus effects in GWASs could potentially harbor valuable information for evaluating epistasis, we lack systematic efforts to investigate SNPs showing consistent associations with weak statistical significance across independent discovery and replication stages. The objectives of this study were i) to select SNPs showing single-locus effects with weak statistical significance for breast cancer in a GWAS and/or candidate-gene studies; ii) to replicate these SNPs in an independent set of breast cancer cases and controls; and iii) to explore their potential SNP-SNP interactions contributing to breast cancer susceptibility. A total of 17 SNPs related to DNA repair, modification and metabolism pathway genes were selected since these pathways offer a priori knowledge for potential epistatic interactions and an overall role in breast carcinogenesis. The study design included predominantly Caucasian women (2,795 cases and 4,505 controls) from Alberta, Canada. We observed two two-way SNP-SNP interactions (APEX1-rs1130409 and RPAP1-rs2297381; MLH1-rs1799977 and MDM2-rs769412) in logistic regression that conferred elevated risks for breast cancer (P(interaction)<7.3 × 10(-3)). Logic regression identified an interaction involving four SNPs (MBD2-rs4041245, MLH1-rs1799977, MDM2-rs769412, BRCA2-rs1799943) (P(permutation) = 2.4 × 10(-3)). SNPs involved in SNP-SNP interactions also showed single-locus effects with weak statistical significance, while BRCA2-rs1799943 showed stronger statistical significance (P(correlation/trend) = 3.2 × 10(-4)) than the others. These single-locus effects were independent of body mass index. Our results provide a framework for evaluating SNPs showing statistically weak but reproducible single-locus effects for epistatic effects contributing to disease susceptibility.

Aryee MJ, Liu W, Engelmann JC, et al.
DNA methylation alterations exhibit intraindividual stability and interindividual heterogeneity in prostate cancer metastases.
Sci Transl Med. 2013; 5(169):169ra10 [PubMed] Free Access to Full Article Related Publications
Human cancers almost ubiquitously harbor epigenetic alterations. Although such alterations in epigenetic marks, including DNA methylation, are potentially heritable, they can also be dynamically altered. Given this potential for plasticity, the degree to which epigenetic changes can be subject to selection and act as drivers of neoplasia has been questioned. We carried out genome-scale analyses of DNA methylation alterations in lethal metastatic prostate cancer and created DNA methylation "cityscape" plots to visualize these complex data. We show that somatic DNA methylation alterations, despite showing marked interindividual heterogeneity among men with lethal metastatic prostate cancer, were maintained across all metastases within the same individual. The overall extent of maintenance in DNA methylation changes was comparable to that of genetic copy number alterations. Regions that were frequently hypermethylated across individuals were markedly enriched for cancer- and development/differentiation-related genes. Additionally, regions exhibiting high consistency of hypermethylation across metastases within individuals, even if variably hypermethylated across individuals, showed enrichment for cancer-related genes. Whereas some regions showed intraindividual metastatic tumor heterogeneity in promoter methylation, such methylation alterations were generally not correlated with gene expression. This was despite a general tendency for promoter methylation patterns to be strongly correlated with gene expression, particularly at regions that were variably methylated across individuals. These findings suggest that DNA methylation alterations have the potential for producing selectable driver events in carcinogenesis and disease progression and highlight the possibility of targeting such epigenome alterations for development of longitudinal markers and therapeutic strategies.

Gopisetty G, Xu J, Sampath D, et al.
Epigenetic regulation of CD133/PROM1 expression in glioma stem cells by Sp1/myc and promoter methylation.
Oncogene. 2013; 32(26):3119-29 [PubMed] Free Access to Full Article Related Publications
Tumor stem cells, postulated to be the source cells for malignancies, have been identified in several cancers using cell-surface expression of markers including CD133, a pentaspan membrane protein. CD133+ve cells form neurospheres, exhibit self-renewal and differentiation, and are tumorigenic. However, despite its association with stem cells, a causal relationship of CD133 to tumorigenesis remains to be defined. Hypothesizing that specific epigenetic and transcription factors implicated in driving the stem cell state may concurrently regulate CD133 expression in stem cells, we analyzed the structure and regulation of CD133 promoter in glioma stem cells and glioma cell lines. Initially, a minimal promoter region was identified by analyzing the activity of CD133 promoter-driven luciferase-expressing 5'-and 3'-deletion-constructs upstream of the transcription start site. This region contained a CpG island that was hypermethylated in CD133-ve glioma stem cells (GSC) and glioma cells but unmethylated in CD133+ve ones. Of several predicted TF-binding sites in this region, the role of tandem Sp1 (-242 and -221) and two Myc (-541 and -25)-binding sites were examined. Overexpression of Sp1 or Myc increased CD133 minimal promoter-driven luciferase activity and CD133 levels in GSC and in glioma cell line. Mithramycin, a Sp1 inhibitor, decreased minimal promoter activity and downregulated CD133 levels in GSC. Gel-shift assays demonstrated direct binding of Sp1 to their predicted sites that was competitively inhibited by oligonucleotide-binding-site sequences and supershifted by anti-Sp1 confirming the interaction. Sp1 and Myc-antibody chromatin immunoprecipitation (ChIP) analysis in GSC showed enrichment of regions with Sp1 and Myc-binding sites. In CD133-ve cells, ChIP analysis showed binding of the methyl-DNA-binding proteins, MBD1, MBD2 and MeCP2 to the methylated CpG island and repression of transcription. These results demonstrate that Sp1 and Myc regulate CD133 transcription in GSC and that promoter methylation and methyl-DNA-binding proteins cause repression of CD133 by excluding transcription-factor binding.

Chen YJ, Luo J, Yang GY, et al.
Mutual regulation between microRNA-373 and methyl-CpG-binding domain protein 2 in hilar cholangiocarcinoma.
World J Gastroenterol. 2012; 18(29):3849-61 [PubMed] Free Access to Full Article Related Publications
AIM: To investigate the reciprocal modulation between microRNA (miRNA) and DNA methylation via exploring the correlation between miR-373 and methyl-CpG-binding domain protein (MBD)2.
METHODS: MiR-373 expression was examined using the TaqMan miRNA assay. Methylation of miR-373 was investigated using methylation-specific polymerase chain reaction, and recruitment of methyl binding proteins was studied using the chromatin immunoprecipitation assay. Mutation analysis was conducted using the QuikChange™ Site-Directed Mutagenesis kit. The activity of miR-373 gene promoter constructs and targeting at MBD2-three prime untranslated region (3'UTR) by miR-373 were evaluated by a dual-luciferase reporter gene assay.
RESULTS: In hilar cholangiocarcinoma, miR-373 decreased and was closely associated with poor cell differentiation, advanced clinical stage, and shorter survival. The promoter-associated CpG island of miR-373 gene was hypermethylated and inhibited expression of miR-373. MBD2 was up-regulated and enriched at the promoter-associated CpG island of miR-373. Methylation-mediated suppression of miR-373 required MBD2 enrichment at the promoter-associated CpG island, and miR-373 negatively regulated MBD2 expression through targeting the 3'UTR.
CONCLUSION: MiR-373 behaves as a direct transcriptional target and negative regulator of MBD2 activity through a feedback loop of CpG island methylation.

Liu D, Zhou P, Zhang L, et al.
HPV16 activates the promoter of Oct4 gene by sequestering HDAC1 from repressor complex to target it to proteasomal degradation.
Med Hypotheses. 2012; 79(4):531-4 [PubMed] Related Publications
Human papillomavirus 16 (HPV16) is the key factor to initiate cervical carcinogenesis and development. Octamer-binding transcription factor 4 (Oct4) is an important transcriptional factor which is up-regulated in some cancer cells. Our study showed that the expression of Oct4 might be activated by HPV16 infection. Both the levels of histone deacetylase 1 (HDAC1) and DNA methyltransferase 3A (DNMT3A) were negatively correlated with the level of Oct4 in cervical cancer cells. Moreover, HDAC1 and DNMT3A proteins were in the same complex, the level of which was higher in the presence of HPV16. The treatment with HDAC1 inhibitor reduced the level of this complex, followed by the upregulation of Oct4 expression. Based on these findings and previous reports, we hypothesize that a repressor complex containing methyl CpG-binding domain protein 2 (MBD2), DNMT3A and HDAC1 binds to the hyper-methylated regulatory regions of Oct4 gene to facilitate forming a close chromatin which results in the suppression of Oct4 transcription in cervical cells. The oncoproteins of HPV16 synergistically sequester HDAC1 protein from repressor complex, and target it to ubiquitin mediated proteasome degradation. The repressor complex is thus destroyed and the close chromatin is relaxed, which eventually lead to the upregulation of Oct4 expression.

Yan P, Frankhouser D, Murphy M, et al.
Genome-wide methylation profiling in decitabine-treated patients with acute myeloid leukemia.
Blood. 2012; 120(12):2466-74 [PubMed] Free Access to Full Article Related Publications
The outcome of older (≥ 60 years) acute myeloid leukemia (AML) patients is poor, and novel treatments are needed. In a phase 2 trial for older AML patients, low-dose (20 mg/m(2) per day for 10 days) decitabine, a DNA hypomethylating azanucleoside, produced 47% complete response rate with an excellent toxicity profile. To assess the genome-wide activity of decitabine, we profiled pretreatment and post treatment (day 25/course 1) methylomes of marrow samples from patients (n = 16) participating in the trial using deep-sequencing analysis of methylated DNA captured by methyl-binding protein (MBD2). Decitabine significantly reduced global methylation compared with pretreatment baseline (P = .001). Percent marrow blasts did not correlate with global methylation levels, suggesting that hypomethylation was related to the activity of decitabine rather than to a mere decrease in leukemia burden. Hypomethylation occurred predominantly in CpG islands and CpG island-associated regions (P ranged from .03 to .04) A significant concentration (P < .001) of the hypomehtylated CpG islands was found in chromosome subtelomeric regions, suggesting a differential activity of decitabine in distinct chromosome regions. Hypermethylation occurred much less frequently than hypomethylation and was associated with low CpG content regions. Decitabine-related methylation changes were concordant with those previously reported in distinct genes. In summary, our study supports the feasibility of methylome analyses as a pharmacodynamic endpoint for hypomethylating therapies.

Du J, Zhou N, Liu H, et al.
Arsenic induces functional re-expression of estrogen receptor α by demethylation of DNA in estrogen receptor-negative human breast cancer.
PLoS One. 2012; 7(4):e35957 [PubMed] Free Access to Full Article Related Publications
Estrogen receptor α (ERα) is a marker predictive for response of breast cancers to endocrine therapy. About 30% of breast cancers, however, are hormone- independent because of lack of ERα expression. New strategies are needed for re-expression of ERα and sensitization of ER-negative breast cancer cells to selective ER modulators. The present report shows that arsenic trioxide induces reactivated ERα, providing a target for therapy with ER antagonists. Exposure of ER-negative breast cancer cells to arsenic trioxide leads to re-expression of ERα mRNA and functional ERα protein in in vitro and in vivo. Luciferase reporter gene assays and 3-(4,5-dimethylthiazol-2-yl)- 5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assays show that, upon exposure to arsenic trioxide, formerly unresponsive, ER-negative MDA-MB-231 breast cancer cells become responsive to ER antagonists, 4-hydroxytamoxifen and ICI 182,780. Furthermore, methylation- specific PCR and bisulfite-sequencing PCR assays show that arsenic trioxide induces partial demethylation of the ERα promoter. A methyl donor, S-adenosylmethionine (SAM), reduces the degree of arsenic trioxide-induced re-expression of ERα and demethylation. Moreover, Western blot and ChIP assays show that arsenic trioxide represses expression of DNMT1 and DNMT3a along with partial dissociation of DNMT1 from the ERα promoter. Thus, arsenic trioxide exhibits a previously undefined function which induces re-expression ERα in ER-negative breast cancer cells through demethylation of the ERα promoter. These findings could provide important information regarding the application of therapeutic agents targeting epigenetic changes in breast cancers and potential implication of arsenic trioxide as a new drug for the treatment of ER-negative human breast cancer.

Ping SY, Shen KH, Yu DS
Epigenetic regulation of vascular endothelial growth factor a dynamic expression in transitional cell carcinoma.
Mol Carcinog. 2013; 52(7):568-79 [PubMed] Related Publications
Vascular endothelial growth factor A (VEGF-A) is a key mediator in the neovascularization of cancers. We have found that VEGF-A was expressed at significantly higher levels in high-grade transitional cell carcinoma (TCC) cells than low-grade TCC cells in our previous study. In the present study, promoter methylation pattern was assessed and quantified by bisulfite genomic sequencing (BGS) and specific VEGF-A CpG sites in low-grade, but not in high-grade, TCC cells were observed. Reporter assays indicated that hypermethylation of nine CpG sites can inhibit the transcriptional activity of the VEGF-A gene. Subsequent chromatin immunoprecipitation (ChIP) assay revealed down-regulation of transcription activity of VEGF-A with increasing binding of methyl-CpG-binding protein 2 (MBD2) and trimethyl-histone H3 (Lys9) proteins to these CpG sites in low-grade TCC cells during hypermethylation. Furthermore, treatment of low-grade TCC cells with DNA methyltransferase inhibitor and histone deacetylase inhibitor can restore the expression of VEGF-A and promote the invasive ability of low-grade TCC cells. Hypermethylation with lower expression levels of VEGF-A in low-grade TCC tumors than high-grade TCC tumors was also confirmed in clinical specimens by reverse transcriptase-PCR and pyrosequencing analyses. Our findings are the first results indicating that VEGF-A expression is suppressed in low-grade TCC tumors by promoter hypermethylation. This offers a new perspective on the role of VEGF-A in TCC tumor behavior.

Papoutsis AJ, Borg JL, Selmin OI, Romagnolo DF
BRCA-1 promoter hypermethylation and silencing induced by the aromatic hydrocarbon receptor-ligand TCDD are prevented by resveratrol in MCF-7 cells.
J Nutr Biochem. 2012; 23(10):1324-32 [PubMed] Related Publications
Epigenetic mechanisms may contribute to reduced expression of the tumor suppressor gene BRCA-1 in sporadic breast cancers. Through environmental exposure and diet, humans are exposed to xenobiotics and food compounds that bind the aromatic hydrocarbon receptor (AhR). AhR-ligands include the dioxin-like and tumor promoter 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD). The activated AhR regulates transcription through binding to xenobiotic response elements (XREs=GCGTG) and interactions with transcription cofactors. Previously, we reported on the presence of several XREs in the proximal BRCA-1 promoter and that the expression of endogenous AhR was required for silencing of BRCA-1 expression by TCDD. Here, we document that in estrogen receptor-α-positive and BRCA-1 wild-type MCF-7 breast cancer cells, the treatment with TCDD attenuated 17β-estradiol-dependent stimulation of BRCA-1 protein and induced hypermethylation of a CpG island spanning the BRCA-1 transcriptional start site of exon-1a. Additionally, we found that TCDD enhanced the association of the AhR; DNA methyl transferase (DNMT)1, DNMT3a and DNMT3b; methyl binding protein (MBD)2; and trimethylated H3K9 (H3K9me3) with the BRCA-1 promoter. Conversely, the phytoalexin resveratrol, selected as a prototype dietary AhR antagonist, antagonized at physiologically relevant doses (1 μmol/L) the TCDD-induced repression of BRCA-1 protein, BRCA-1 promoter methylation and the recruitment of the AhR, MBD2, H3K9me3 and DNMTs (1, 3a and 3b). Taken together, these observations provide mechanistic evidence for AhR agonists in the establishment of BRCA-1 promoter hypermethylation and the basis for the development of prevention strategies based on AhR antagonists.

Stefanska B, Huang J, Bhattacharyya B, et al.
Definition of the landscape of promoter DNA hypomethylation in liver cancer.
Cancer Res. 2011; 71(17):5891-903 [PubMed] Related Publications
We use hepatic cellular carcinoma (HCC), one of the most common human cancers, as a model to delineate the landscape of promoter hypomethylation in cancer. Using a combination of methylated DNA immunoprecipitation and hybridization with comprehensive promoter arrays, we have identified approximately 3,700 promoters that are hypomethylated in tumor samples. The hypomethylated promoters appeared in clusters across the genome suggesting that a high-level organization underlies the epigenomic changes in cancer. In normal liver, most hypomethylated promoters showed an intermediate level of methylation and expression, however, high-CpG dense promoters showed the most profound increase in gene expression. The demethylated genes are mainly involved in cell growth, cell adhesion and communication, signal transduction, mobility, and invasion; functions that are essential for cancer progression and metastasis. The DNA methylation inhibitor, 5-aza-2'-deoxycytidine, activated several of the genes that are demethylated and induced in tumors, supporting a causal role for demethylation in activation of these genes. Previous studies suggested that MBD2 was involved in demethylation of specific human breast and prostate cancer genes. Whereas MBD2 depletion in normal liver cells had little or no effect, we found that its depletion in human HCC and adenocarcinoma cells resulted in suppression of cell growth, anchorage-independent growth and invasiveness as well as an increase in promoter methylation and silencing of several of the genes that are hypomethylated in tumors. Taken together, the findings define the potential functional role of hypomethylation in cancer.

Lai AY, Wade PA
Cancer biology and NuRD: a multifaceted chromatin remodelling complex.
Nat Rev Cancer. 2011; 11(8):588-96 [PubMed] Free Access to Full Article Related Publications
The nucleosome remodelling and histone deacetylase (NuRD; also known as Mi-2) complex regulates gene expression at the level of chromatin. The NuRD complex has been identified - using both genetic and molecular analyses - as a key determinant of differentiation in mouse embryonic stem cells and during development in various model systems. Similar to other chromatin remodellers, such as SWI/SNF and Polycomb complexes, NuRD has also been implicated in the regulation of transcriptional events that are integral to oncogenesis and cancer progression. Emerging molecular details regarding the recruitment of NuRD to specific loci during development, and the modulation of these events in cancer, are used to illustrate how the inappropriate localization of the complex could contribute to tumour biology.

Zhu D, Hunter SB, Vertino PM, Van Meir EG
Overexpression of MBD2 in glioblastoma maintains epigenetic silencing and inhibits the antiangiogenic function of the tumor suppressor gene BAI1.
Cancer Res. 2011; 71(17):5859-70 [PubMed] Free Access to Full Article Related Publications
Brain angiogenesis inhibitor 1 (BAI1) is a putative G protein-coupled receptor with potent antiangiogenic and antitumorigenic properties that is mutated in certain cancers. BAI1 is expressed in normal human brain, but it is frequently silenced in glioblastoma multiforme. In this study, we show that this silencing event is regulated by overexpression of methyl-CpG-binding domain protein 2 (MBD2), a key mediator of epigenetic gene regulation, which binds to the hypermethylated BAI1 gene promoter. In glioma cells, treatment with the DNA demethylating agent 5-aza-2'-deoxycytidine (5-Aza-dC) was sufficient to reactivate BAI1 expression. Chromatin immunoprecipitation showed that MBD2 was enriched at the promoter of silenced BAI1 in glioma cells and that MBD2 binding was released by 5-Aza-dC treatment. RNA interference-mediated knockdown of MBD2 expression led to reactivation of BAI1 gene expression and restoration of BAI1 functional activity, as indicated by increased antiangiogenic activity in vitro and in vivo. Taken together, our results suggest that MBD2 overexpression during gliomagenesis may drive tumor growth by suppressing the antiangiogenic activity of a key tumor suppressor. These findings have therapeutic implications because inhibiting MBD2 could offer a strategy to reactivate BAI1 and suppress glioma pathobiology.

Mian OY, Wang SZ, Zhu SZ, et al.
Methyl-binding domain protein 2-dependent proliferation and survival of breast cancer cells.
Mol Cancer Res. 2011; 9(8):1152-62 [PubMed] Free Access to Full Article Related Publications
Methyl cytosine binding domain protein 2 (MBD2) has been shown to bind to and mediate repression of methylated tumor suppressor genes in cancer cells, where repatterning of CpG methylation and associated gene silencing is common. We have investigated the role of MBD2 in breast cancer cell growth and tumor suppressor gene expression. We show that stable short hairpin RNA (shRNA)-mediated knockdown of MBD2 leads to growth suppression of cultured human mammary epithelial cancer lines, SK-BR-3, MDA-MB-231, and MDA-MB-435. The peak antiproliferative occurs only after sustained, stable MBD2 knockdown. Once established, the growth inhibition persists over time and leads to a markedly decreased propensity for aggressive breast cancer cell lines to form in vivo xenograft tumors in Bagg Albino (BALB)/C nu/nu mice. The growth effects of MBD2 knockdown are accompanied by derepression of tumor suppressor genes, including DAPK1 and KLK10. Chromatin immunoprecipitation assays and bisulfite sequencing show MBD2 binding directly to the hyper methylated and CpG-rich promoters of both DAPK1 and KLK10. Remarkably, the promoter CpG island-associated methylation of these genes remained stable despite robust transcriptional activation in MBD2 knockdown cells. Expression of a shRNA-resistant MBD2 protein resulted in restoration of growth and resilencing of the MBD2-dependent tumor suppressor genes. Our data suggest that uncoupling CpG methylation from repressive chromatin remodeling and histone modifications by removing MBD2 is sufficient to initiate and maintain tumor suppressor gene transcription and suppress neoplastic cell growth. These results show a role for MBD2 in cancer progression and provide support for the prospect of targeting MBD2 therapeutically in aggressive breast cancers.

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