scholarly journals DNA methylation prevents CTCF-mediated silencing of the oncogene BCL6 in B cell lymphomas

2010 ◽  
Vol 207 (9) ◽  
pp. 1939-1950 ◽  
Author(s):  
Anne Y. Lai ◽  
Mehrnaz Fatemi ◽  
Archana Dhasarathy ◽  
Christine Malone ◽  
Steve E. Sobol ◽  
...  
Keyword(s):  
Dna Methylation ◽  
B Cell ◽  
Transcriptional Activation ◽  
Messenger Rna ◽  
Plasma Cells ◽  
Cpg Islands ◽  
Dna Methyltransferases ◽  
B Cell Lymphomas ◽  
Aberrant Dna Methylation ◽  
Bcl6 Expression

Aberrant DNA methylation commonly occurs in cancer cells where it has been implicated in the epigenetic silencing of tumor suppressor genes. Additional roles for DNA methylation, such as transcriptional activation, have been predicted but have yet to be clearly demonstrated. The BCL6 oncogene is implicated in the pathogenesis of germinal center–derived B cell lymphomas. We demonstrate that the intragenic CpG islands within the first intron of the human BCL6 locus were hypermethylated in lymphoma cells that expressed high amounts of BCL6 messenger RNA (mRNA). Inhibition of DNA methyltransferases decreased BCL6 mRNA abundance, suggesting a role for these methylated CpGs in positively regulating BCL6 transcription. The enhancer-blocking transcription factor CTCF bound to this intronic region in a methylation-sensitive manner. Depletion of CTCF by short hairpin RNA in neoplastic plasma cells that do not express BCL6 resulted in up-regulation of BCL6 transcription. These data indicate that BCL6 expression is maintained during lymphomagenesis in part through DNA methylation that prevents CTCF-mediated silencing.

scholarly journals Neuroblastoma and the epigenome

2021 ◽  
Author(s):  
Irfete S. Fetahu ◽  
Sabine Taschner-Mandl
Keyword(s):  
Dna Methylation ◽  
Histone Modifications ◽  
Disease Diagnosis ◽  
Dna Methyltransferases ◽  
Epigenetic Alterations ◽  
Aberrant Expression ◽  
Tet Proteins ◽  
Relative Paucity ◽  
Underlying Causes ◽  
Aberrant Dna Methylation

AbstractNeuroblastoma (NB) is a pediatric cancer of the sympathetic nervous system and one of the most common solid tumors in infancy. Amplification of MYCN, copy number alterations, numerical and segmental chromosomal aberrations, mutations, and rearrangements on a handful of genes, such as ALK, ATRX, TP53, RAS/MAPK pathway genes, and TERT, are attributed as underlying causes that give rise to NB. However, the heterogeneous nature of the disease—along with the relative paucity of recurrent somatic mutations—reinforces the need to understand the interplay of genetic factors and epigenetic alterations in the context of NB. Epigenetic mechanisms tightly control gene expression, embryogenesis, imprinting, chromosomal stability, and tumorigenesis, thereby playing a pivotal role in physio- and pathological settings. The main epigenetic alterations include aberrant DNA methylation, disrupted patterns of posttranslational histone modifications, alterations in chromatin composition and/or architecture, and aberrant expression of non-coding RNAs. DNA methylation and demethylation are mediated by DNA methyltransferases (DNMTs) and ten-eleven translocation (TET) proteins, respectively, while histone modifications are coordinated by histone acetyltransferases and deacetylases (HATs, HDACs), and histone methyltransferases and demethylases (HMTs, HDMs). This article focuses predominately on the crosstalk between the epigenome and NB, and the implications it has on disease diagnosis and treatment.

DNA methylation-based classification of small B-cell lymphomas: a proof-of-principle study

2021 ◽  
Author(s):  
Daniel Xia ◽  
Alberto Jose Leon ◽  
Jiong Yan ◽  
Anjali Silva ◽  
Mehran Bakhtiari ◽  
...  
Keyword(s):  
Dna Methylation ◽  
B Cell ◽  
B Cell Lymphomas ◽  
Proof Of Principle

scholarly journals Distinct DNA methylation targets by aging and chronic inflammation: a pilot study using gastric mucosa infected with Helicobacter pylori

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Satoshi Yamashita ◽  
Sohachi Nanjo ◽  
Emil Rehnberg ◽  
Naoko Iida ◽  
Hideyuki Takeshima ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Helicobacter Pylori ◽  
Gastric Mucosa ◽  
Chronic Inflammation ◽  
Cpg Islands ◽  
Human Gastric Mucosa ◽  
Driver Genes ◽  
Age Related ◽  
A Genome ◽  
Aberrant Dna Methylation

Abstract Background Aberrant DNA methylation is induced by aging and chronic inflammation in normal tissues. The induction by inflammation is widely recognized as acceleration of age-related methylation. However, few studies addressed target genomic regions and the responsible factors in a genome-wide manner. Here, we analyzed methylation targets by aging and inflammation, taking advantage of the potent methylation induction in human gastric mucosa by Helicobacter pylori infection-triggered inflammation. Results DNA methylation microarray analysis of 482,421 CpG probes, grouped into 270,249 genomic blocks, revealed that high levels of methylation were induced in 44,461 (16.5%) genomic blocks by inflammation, even after correction of the influence of leukocyte infiltration. A total of 61.8% of the hypermethylation was acceleration of age-related methylation while 21.6% was specific to inflammation. Regions with H3K27me3 were frequently hypermethylated both by aging and inflammation. Basal methylation levels were essential for age-related hypermethylation while even regions with little basal methylation were hypermethylated by inflammation. When limited to promoter CpG islands, being a microRNA gene and high basal methylation levels strongly enhanced hypermethylation while H3K27me3 strongly enhanced inflammation-induced hypermethylation. Inflammation was capable of overriding active transcription. In young gastric mucosae, genes with high expression and frequent mutations in gastric cancers were more frequently methylated than in old ones. Conclusions Methylation by inflammation was not simple acceleration of age-related methylation. Targets of aberrant DNA methylation were different between young and old gastric mucosae, and driver genes were preferentially methylated in young gastric mucosa.

Identification of two DNA methylation subtypes of Waldenström's macroglobulinemia with plasma and memory B cell features

Blood ◽  
2020 ◽  
Author(s):  
Damien Roos-Weil ◽  
Brian Giacopelli ◽  
Marine Armand ◽  
Véronique Della Valle ◽  
Hussein Ghamlouch ◽  
...  
Keyword(s):  
Dna Methylation ◽  
B Cell ◽  
Plasma Cells ◽  
Surface Expression ◽  
B Cell Differentiation ◽  
Waldenström’S Macroglobulinemia ◽  
Waldenstrom's Macroglobulinemia ◽  
Waldenstrom’S Macroglobulinemia ◽  
B Cell Subsets ◽  
Waldenström's Macroglobulinemia

Epigenetic changes during B cell differentiation generates distinct DNA methylation signatures specific for B cell subsets, including memory B cells (MBCs) and plasma cells (PCs). Waldenström's macroglobulinemia (WM) is a complex B cell malignancy uniquely comprised of a mixture of lymphocytic and plasmacytic phenotypes. Here we integrated genome-wide DNA methylation, transcriptome, mutation and other phenotypic features of tumor cells from 35 MYD88-mutated WM patients in relation to normal plasma and B cell subsets. We discovered that WM patients naturally segregate into two groups according to DNA methylation patterns, related to normal MBC and PC profiles, and reminiscent of other memory and plasma cell-derived malignancies. Concurrent analysis of DNA methylation changes in normal and WM development were used to capture tumor-specific events, highlighting a selective reprogramming of enhancer regions in MBC-like WM and repressed and heterochromatic regions in PC-like WM. MBC-like WM hypomethylation was enriched in motifs belonging to PU.1, TCF3 and OCT2 transcription factors and involved elevated MYD88/TLR pathway activity. PC-like WM displayed marked global hypomethylation and selective overexpression of histone genes. Finally, WM subtypes exhibited differential genetic, phenotypic and clinical features. MBC-like WM harbored significantly more clonal CXCR4 mutations (P=0.015), deletion 13q (P=0.006), splenomegaly (P=0.02) and thrombocytopenia (P=0.004), while PC-like WM harbored more deletion 6q (P=0.012), gain 6p (P=0.033), had increased frequencies of IGHV3 genes (P=0.002), CD38 surface expression (P=4.1e-5), and plasmacytic differentiation features (P=0.008). Together our findings illustrate a novel approach to subclassify WM patients using patterns of DNA methylation and reveal divergent molecular signatures among WM patients.

scholarly journals Marginal zone B cell lymphomas with extensive plasmacytic differentiation are neoplasms of precursor plasma cells

2010 ◽  
Vol 80B (2) ◽  
pp. 71-82 ◽  
Author(s):  
Howard J. Meyerson ◽  
Jeffrey Bailey ◽  
John Miedler ◽  
Felix Olobatuyi
Keyword(s):  
B Cell ◽  
Marginal Zone ◽  
Plasma Cells ◽  
B Cell Lymphomas ◽  
Plasmacytic Differentiation

scholarly journals Effect of Disease-Associated Germline Mutations on Structure Function Relationship of DNA Methyltransferases

Genes ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 369 ◽  
Author(s):  
Allison B. Norvil ◽  
Debapriya Saha ◽  
Mohd Saleem Dar ◽  
Humaira Gowher
Keyword(s):  
Dna Methylation ◽  
Association Studies ◽  
Large Body ◽  
Genetic Alterations ◽  
Dna Methyltransferases ◽  
Neurological Dysfunction ◽  
Genome Association ◽  
Hereditary Disorders ◽  
Aberrant Dna Methylation ◽  
Function Relationship

Despite a large body of evidence supporting the role of aberrant DNA methylation in etiology of several human diseases, the fundamental mechanisms that regulate the activity of mammalian DNA methyltransferases (DNMTs) are not fully understood. Recent advances in whole genome association studies have helped identify mutations and genetic alterations of DNMTs in various diseases that have a potential to affect the biological function and activity of these enzymes. Several of these mutations are germline-transmitted and associated with a number of hereditary disorders, which are potentially caused by aberrant DNA methylation patterns in the regulatory compartments of the genome. These hereditary disorders usually cause neurological dysfunction, growth defects, and inherited cancers. Biochemical and biological characterization of DNMT variants can reveal the molecular mechanism of these enzymes and give insights on their specific functions. In this review, we introduce roles and regulation of DNA methylation and DNMTs. We discuss DNMT mutations that are associated with rare diseases, the characterized effects of these mutations on enzyme activity and provide insights on their potential effects based on the known crystal structure of these proteins.

scholarly journals Differential DNA Methylation of Gene Promoters in Small B-Cell Lymphomas

2005 ◽  
Vol 124 (3) ◽  
pp. 430-439 ◽  
Author(s):  
Juyuan Guo ◽  
Matthias Burger ◽  
Inko Nimmrich ◽  
Sabine Maier ◽  
Evelyne Becker ◽  
...  
Keyword(s):  
Dna Methylation ◽  
B Cell ◽  
Gene Promoters ◽  
B Cell Lymphomas

Aberrant DNA Methylation of the Src Tyrosine Kinase Hck Is a Frequent Event in Human Leukemia and May Predict for Poor Prognosis in Adult Acute Lymphocytic Leukemia (ALL).

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1542-1542
Author(s):  
Koyu Hoshino ◽  
Hui Yang ◽  
Claritsa Santos-Malave ◽  
Blanca Sanchez-Gonzalez ◽  
Guillermo Garcia-Manero
Keyword(s):  
Dna Methylation ◽  
Protein Expression ◽  
B Cell ◽  
Cell Lines ◽  
Leukemia Cell ◽  
Myelogenous Leukemia ◽  
Human Leukemia ◽  
Expression Levels ◽  
Leukemia Cell Lines ◽  
Aberrant Dna Methylation

Abstract Aberrant DNA methylation of promoter-associated CpG islands is a frequent phenomenon in human leukemias, and in particular in adult ALL. Hck is a member of the Src family of tyrosine kinases, and functionally is located downstream of BCR-ABL signaling in chronic myelogenous leukemia (CML). Hck expression is limitedly to myeloid cells and B cell lymphocytes. Although some evidence indicates that Hck is required for malignant transformation and apoptosis, its role in leukemia is not fully understood. Here we analyze the role of aberrant DNA methylation of Hck in leukemia cell lines and patients. Using BLAT, we first identified the presence of a canonical CpG island in the near proximity of the transcription start site of HcK. To detect and measure DNA methylation, we designed a combined bisulfite restriction PCR assay. Using this assay, we found that Hck was methylated in 13 out of 23 hematopoietic and 8 out of 10 non-hematopoietic cell lines, but not in the bone marrow from 6 healthy individuals. We subsequently studied Hck expression by real-time PCR using GAPDH expression as an internal control. Hck expression was lower (dCT = −14.2± 3.6) in 7 Hck methylated cell lines than in 8 Hck unmethylated ones (dCT= −9.0± 3.5), p=0.017. All the cell lines studied were of myeloid or B cell origin. We then treated the Raji cell line with the hypomethylating agent 5-aza-2-deoxycytidine (DAC). DAC treatment resulted in partial hypomethylation of Hck and in an increment of Hck expression (dCT: −19.37 to −8.47). Subsequently, the effects of DAC treatment on Hck protein expression levels were analyzed using Western blot. These experiments showed a strong correlation between hypomethylation, gene re-expression and protein expression levels. These data therefore indicates that DNA methylation is an important aberrant regulator of Hck expression in leukemia cell lines. Based on the relevance of these findings, we then analyzed the frequency of Hck methylation in patients with leukemia. Using a cut-off of 10%, Hck was found to be methylated in 15 out of 44 (34%) patients with ALL, 9 out 23 pts (39%) with CML, and 3 out 10 pts (30%) with AML. Of importance, the density of Hck methylation was significantly higher in patients with ALL (mean 11.3%; range 0–76) compared to those with CML(5.2%; range 0–12) or AML ( 7.5%, range 0–14), p=0.02. Hck methylation was not associated with a B cell phenotype or the presence of the Philadelphia chromosome in patients with ALL. Nine ALL pts out of 15 with Hck methylation had died compared to 7 out 29 unmethylated (total ALL group n=34). Median survival had not been reached for the group of patients with no Hck methylation (n=29) compared to 116 weeks for those with Hck methylation (n=15) (p=0.08). All pts had been treated with hyperCVAD based chemotherapy. These data indicates that Hck methylation is a frequent phenomenon in human leukemia that maybe associated with a worse prognosis in ALL and suggests that Hck has a tumor suppressor like function in these disorders.

Activation of the Endoplasmic Reticulum (ER) Unfolded Protein Response (UPR) in Aggressive B-Cell Lymphomas.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2038-2038
Author(s):  
Olga Balague ◽  
Luis Colomo ◽  
Armando Lopez-Guillermo ◽  
Elias Campo ◽  
Antonio Martinez
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcription Factors ◽  
Western Blot ◽  
Er Stress ◽  
B Cell ◽  
Cell Lines ◽  
Plasma Cell ◽  
Plasma Cells ◽  
Lymphoid Tissues ◽  
B Cell Lymphomas

Abstract BACKGROUND The UPR is a prosurvival pathway activated in cells under ER stress induced by the accumulation of unfolded proteins. UPR activation in B cells normally occurs during the differentiation to antibody secreting plasma cells and requires XBP1activation. XBP-1 is a member of the TREB family of transcription factors that exists in the endoplasmic reticulum (ER) as a 33kDa protein, and in the nucleus as an active 50kDa transcription factor. The UPR stimulates two different ER proteins, ATF-6 and Ire-1, to increase XBP-1 transcription and XBP-1 mRNA splicing resulting in the accumulation of the active 50kDa nuclear protein. Moreover XBP1 is a target of proteosome inhibitors and is related to the aggressive behaviour of some carcinomas. The role of the activation of XBP-1 in lymphomas is still unknown. DESIGN: Reactive lymphoid tissues and 25 neoplastic human B-cell lines representing different stages of B-cell development were studied for XBP-1 expression by western blot and XBP-1, PAX-5, Blimp-1/prdm1, MUM-1/IRF-4 and ICSBP1/IRF-8 by immunohistochemistry. XBP-1 activation was assessed in 225 B-cell lymphomas from the archives of the laboratory of pathology by western blot, RT-PCR and immunohistochemistry . To further evaluate whether XBP-1 activation was related to the plasmacytic program or to ER stress signals we analyzed the cell lines by Western blot for XBP-1 and ATF-6 expression. RESULTS We characterize XBP-1 expression in reactive lymphoid tissues, 25 human cell lines and 225 B-cell tumors. In nearly all tonsillar lymphoid cells XBP-1 was detected as a cytoplasmic protein with a paranuclear dot pattern. Nuclear positivity was observed only in scattered centrocytes in the light zone of the germinal centers and in plasma cells, always coexpressed with plasma cell related transcription factors as MUM-1/IRF-4 and Blimp1/prdm1. Active p50XBP-1 was found in 24/25 cell lines by western blot regardless ATF-6 expression and confirmed by immunohistochemistry . Moreover p50XBP1 was found in 27/31(87%) plasmacytomas, 36/64(56%) DLBCL-ABC and in 3/10(30%) DLBCL-GCB and 22/43(51%) plasmablastic lymphomas. Intriguingly, p50XBP1 was detected also in 2/11(18%)BL and 4/25(16%)MCL with blastic features. CONCLUSIONS.XBP-1 is activated in a subset of follicular centre cells committed to plasma cell differentiation and in plasma cells.UPR prosurvival pathways in the neoplastic cell lines are activated independently of the extent of the ATF-6 activation.p50XBP1 is mostly activated in aggressive B-cell lymphomas regardless to the plasmacytic differentiation of the tumours. Thus, p50XBP-1 may be a new molecular target in the treatment of aggressive B-cell malignancies.

Sign in / Sign up

Export Citation Format

Share Document