scholarly journals De novo DNA methyltransferase activity in colorectal cancer is directed towards H3K36me3 marked CpG islands

2019 ◽  
Author(s):  
Roza H. Ali Masalmeh ◽  
Cristina Rubio-Ramon ◽  
Francesca Taglini ◽  
Jonathan Higham ◽  
Hazel Davidson-Smith ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Dna Methyltransferase ◽  
De Novo ◽  
Cpg Islands ◽  
Dna Methyltransferases ◽  
Transcriptional Elongation ◽  
Normal Tissues ◽  
Colorectal Cancer Cells ◽  
Low Levels ◽  
Colorectal Tumours

AbstractThe aberrant gain of DNA methylation at CpG islands (CGIs) is frequently observed in colorectal tumours and may silence the expression of tumour suppressors such as MLH1. Current models propose that these CGIs are targeted by de novo DNA methyltransferases (DNMTs) in a sequence-specific manner but this has not been tested. Using ectopically integrated CGIs, we find that aberrantly methylated CGIs are subject to low levels of de novo DNMT activity in colorectal cancer cells. By delineating DNMT targets, we find that instead de novo DNMT activity is targeted primarily to CGIs marked by the histone modification H3K36me3, a mark associated with transcriptional elongation. These H3K36me3 marked CGIs are heavily methylated in colorectal tumours and the normal colon suggesting that de novo DNMT activity at CGIs in colorectal cancer is focused on similar targets to normal tissues and not greatly remodelled by tumourigenesis.

scholarly journals De novo DNA methyltransferase activity in colorectal cancer is directed towards H3K36me3 marked CpG islands

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Roza H. Ali Masalmeh ◽  
Francesca Taglini ◽  
Cristina Rubio-Ramon ◽  
Kamila I. Musialik ◽  
Jonathan Higham ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Dna Methylation ◽  
Dna Methyltransferase ◽  
De Novo ◽  
Cpg Islands ◽  
Dna Methyltransferases ◽  
Transcriptional Elongation ◽  
Methyltransferase Activity ◽  
Methylation Activity ◽  
Colorectal Tumours

AbstractThe aberrant gain of DNA methylation at CpG islands is frequently observed in colorectal tumours and may silence the expression of tumour suppressors such as MLH1. Current models propose that these CpG islands are targeted by de novo DNA methyltransferases in a sequence-specific manner, but this has not been tested. Using ectopically integrated CpG islands, here we find that aberrantly methylated CpG islands are subject to low levels of de novo DNA methylation activity in colorectal cancer cells. By delineating DNA methyltransferase targets, we find that instead de novo DNA methylation activity is targeted primarily to CpG islands marked by the histone modification H3K36me3, a mark associated with transcriptional elongation. These H3K36me3 marked CpG islands are heavily methylated in colorectal tumours and the normal colon suggesting that de novo DNA methyltransferase activity at CpG islands in colorectal cancer is focused on similar targets to normal tissues and not greatly remodelled by tumourigenesis.

scholarly journals Structural insights into CpG-specific DNA methylation by human DNA methyltransferase 3B

2020 ◽  
Vol 48 (7) ◽  
pp. 3949-3961 ◽  
Author(s):  
Chien-Chu Lin ◽  
Yi-Ping Chen ◽  
Wei-Zen Yang ◽  
James C K Shen ◽  
Hanna S Yuan
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
Cytosine Methylation ◽  
Catalytic Domain ◽  
De Novo ◽  
Water Channel ◽  
Dna Methyltransferases ◽  
Structural Basis ◽  
Cpg Sites ◽  
Methylation Patterns

Abstract DNA methyltransferases are primary enzymes for cytosine methylation at CpG sites of epigenetic gene regulation in mammals. De novo methyltransferases DNMT3A and DNMT3B create DNA methylation patterns during development, but how they differentially implement genomic DNA methylation patterns is poorly understood. Here, we report crystal structures of the catalytic domain of human DNMT3B–3L complex, noncovalently bound with and without DNA of different sequences. Human DNMT3B uses two flexible loops to enclose DNA and employs its catalytic loop to flip out the cytosine base. As opposed to DNMT3A, DNMT3B specifically recognizes DNA with CpGpG sites via residues Asn779 and Lys777 in its more stable and well-ordered target recognition domain loop to facilitate processive methylation of tandemly repeated CpG sites. We also identify a proton wire water channel for the final deprotonation step, revealing the complete working mechanism for cytosine methylation by DNMT3B and providing the structural basis for DNMT3B mutation-induced hypomethylation in immunodeficiency, centromere instability and facial anomalies syndrome.

scholarly journals Landscape Of HOXA Genes Methylation in Colorectal Cancer

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Muhiddin Ishak ◽  
Rashidah Baharudin ◽  
Loh Teng-Hern Tan ◽  
Learn-Han Lee ◽  
Nurul-Syakima Ab Mutalib
Keyword(s):  
Colorectal Cancer ◽  
Cancer Susceptibility ◽  
Cpg Islands ◽  
Methylation Pattern ◽  
Gene Promoters ◽  
Normal Tissues ◽  
Genes Encoding ◽  
Hoxa Genes ◽  
A Minor ◽  
Hoxa Gene

Colorectal cancer (CRC) is among the most common cancers worldwide and the second leading cause of cancer-related death in Malaysia. The HOXA gene cluster is a family of Homeobox A genes encoding transcriptional regulators that play vital roles in cancer susceptibility and progression. Dysregulated HOXA expression influences various aspects of carcinogenesis processes. Therefore, this study aims to elucidate the methylation landscape of HOXA genes in CRC. Twelve pairs of CRC — adjacent normal tissues were subjected to Infinium DNA MethyEPIC array. Differentially methylatedregions were identified using the ChAMP Bioconductor and methylation levels of HOXA genes were manually curated. We identified 100 significantly differentially methylated probes annotated to HOXA genes. HOXA3 has the highest number of differentially methylated probes (n=27), followed by HOXA2 (n=20) and HOXA4 (n=14). The majority (43%) of the probes were located at the transcription start site (TSS) 200, which is one of the gene promoters. In respect to CpG islands (CGI), the probes were equally located in the island and shore regions (47% each) while a minor percentage was in the shelf (6%). Our work gave a comprehensive assessment of the DNA methylation pattern of HOXA genes and provide the first evidence of HOXA2, HOXA3 and HOXA4 differential methylation in Malaysian CRC. The new knowledge from this study can be utilized to further increase our understanding of CRC methylomics, particularly on the homeobox A genes. The prognostic and diagnostic roles of the differentially methylated HOXA genes warrant future investigations.

scholarly journals Primary DNA sequence determines sites of maintenance and de novo methylation by mammalian DNA methyltransferases.

1986 ◽  
Vol 6 (4) ◽  
pp. 1135-1140 ◽  
Author(s):  
A H Bolden ◽  
C M Nalin ◽  
C A Ward ◽  
M S Poonian ◽  
A Weissbach
Keyword(s):  
Dna Sequence ◽  
Dna Methyltransferase ◽  
De Novo ◽  
Dna Methyltransferases ◽  
Methylation Pattern ◽  
Complementary Strand ◽  
Target Strand ◽  
Enzymatic Methylation ◽  
Maintenance Methylation ◽  
De Novo Methylation

Analysis of the enzymatic methylation of oligodeoxynucleotides containing multiple C-G groups showed that hemimethylated sites in duplex oligomers are not significantly methylated by human or murine DNA methyltransferase unless those sites are capable of being methylated de novo in the single- or double-stranded oligomers. Thus, the primary sequence of the target strand, rather than the methylation pattern of the complementary strand, determines maintenance methylation. This suggests that de novo and maintenance methylation are the same process catalyzed by the same enzyme. In addition, the study revealed that complementary strands of oligodeoxynucleotides are methylated at different rates and in different patterns. Both primary DNA sequence and the spacing between C-G groups seem important since in one case studied, maximal methylation required a specific spacing of 13 to 17 nucleotides between C-G pairs.

scholarly journals Transcriptional overlap links DNA hypomethylation with DNA hypermethylation at adjacent promoters in cancer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jean S. Fain ◽  
Axelle Loriot ◽  
Anna Diacofotaki ◽  
Aurélie Van Tongelen ◽  
Charles De Smet
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
De Novo ◽  
Tumor Development ◽  
Transcriptional Elongation ◽  
Dna Hypomethylation ◽  
Dna Hypermethylation ◽  
Bioinformatics Analyses ◽  
Genomic Regions ◽  
Methylation Patterns

AbstractTumor development involves alterations in DNA methylation patterns, which include both gains (hypermethylation) and losses (hypomethylation) in different genomic regions. The mechanisms underlying these two opposite, yet co-existing, alterations in tumors remain unclear. While studying the human MAGEA6/GABRA3 gene locus, we observed that DNA hypomethylation in tumor cells can lead to the activation of a long transcript (CT-GABRA3) that overlaps downstream promoters (GABRQ and GABRA3) and triggers their hypermethylation. Overlapped promoters displayed increases in H3K36me3, a histone mark deposited during transcriptional elongation and known to stimulate de novo DNA methylation. Consistent with such a processive mechanism, increases in H3K36me3 and DNA methylation were observed over the entire region covered by the CT-GABRA3 overlapping transcript. Importantly, experimental induction of CT-GABRA3 by depletion of DNMT1 DNA methyltransferase, resulted in a similar pattern of regional DNA hypermethylation. Bioinformatics analyses in lung cancer datasets identified other genomic loci displaying this process of coupled DNA hypo/hypermethylation, and some of these included tumor suppressor genes, e.g. RERG and PTPRO. Together, our work reveals that focal DNA hypomethylation in tumors can indirectly contribute to hypermethylation of nearby promoters through activation of overlapping transcription, and establishes therefore an unsuspected connection between these two opposite epigenetic alterations.

Some characteristics of cancer-testis gene expression regulation in colorectal cancer.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e14233-e14233
Author(s):  
Kristina I. Soldatova ◽  
Oleg Ivanovich Kit ◽  
Roman E. Tolmakh ◽  
Denis S. Kutilin
Keyword(s):  
Colorectal Cancer ◽  
Cluster Analysis ◽  
Copy Number ◽  
Dna Methyltransferase ◽  
Gene Expression Regulation ◽  
Strong Positive Correlation ◽  
Aberrant Expression ◽  
Normal Tissues ◽  
Tumor Tissues ◽  
Cancer Testis

e14233 Background: Cancer-testis antigens (CTA) can be used in immunotherapy and for early detection of cancer. Despite numerous studies of the CTA expression in different tumors, their transcriptional activity and its regulation in colorectal cancer (CRC) remain poorly understood. The purpose of the study was to analyze the expression of cancer-testis genes (CT-genes) and mechanisms of its regulation in CRC. Methods: Tumor and intact tissues of the colon were studied in 60 patients. RNAs were isolated using the method described by Chomczynski and Sacchi (2006). The REVERTA-L reagent kit was used for the cDNA synthesis. Expression of 16 CT-genes (MAGE-A1, -A2, -A3, -A4, MAGE-B1, -B2, GAGE-1, -3, -4, MAGEC1, BAGE, XAGE3, NYESO1, SSX2, SCP1, PRAME1) and expression and copy number of 3 DNA methyltransferase genes (DNMT1, DNMT3A, DNMT3B) were determined by Real-Time qPCR (GAPDH and GUSB - reference genes). For the cluster analysis, we used our R scripts. Differences were assessed by the Mann-Whitney test, and correlations – by the Spearman's rank correlation coefficient (r). Results: The expression of 2 CT genes, SSX2 and PRAME1, was increased (p < 0.05) by 1.8 and 2.9 times, respectively, and the BAGE expression was decreased by 2.4 times in tumor tissues, compared to the normal tissues. The expression and copy number of DNMT3A in tumor tissues was 1.5 and 2 times higher (p < 0.05), and that of DNMT3B – 2 times lower (p < 0.005), compared to normal tissues. The copy number and expression of the DNMT1 gene did not change. A strong positive correlation (r = 0.996) between the expression and copy number of DNA methyltransferase genes was observed. Using cluster analysis (Hierarchical Clustering, Euclidean distance), we detected two clusters of CRC samples different in the expression of CT-genes and methyltransferases. Cluster 1 showed increased expression of DNMT1, DNMT3A and DNMT3B and decreased expression of BAGE, SSX2 and PRAME1; cluster 2 – decreased expression of DNMT1, DNMT3A and DNMT3B and increased expression of BAGE, SSX2 and PRAME1. Conclusions: The detected aberrant expression of the CT-genes BAGE, SSX2, PRAME1 in CRC depends on the expression of DNMT1, DNMT3A, DNMT3B, which in its turn depends on the copy number of the corresponding DNA methyltransferase genes.

scholarly journals Paradoxical interaction between cancer and long-term postsepsis disorder: impairment of de novo carcinogenesis versus favoring the growth of established tumors

2020 ◽  
Vol 8 (1) ◽  
pp. e000129
Author(s):  
Caio Abner Leite ◽  
Jose Mauricio Mota ◽  
Kalil Alves de Lima ◽  
Carlos Wagner Wanderley ◽  
Leticia Almeida Nascimento ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
T Regulatory Cells ◽  
De Novo ◽  
Tumor Development ◽  
Dependent Manner ◽  
Colorectal Cancer Cells ◽  
Tumor Load ◽  
Early Carcinogenesis

BackgroundPrevious data have reported that the growth of established tumors may be facilitated by postsepsis disorder through changes in the microenvironment and immune dysfunction. However, the influence of postsepsis disorder in initial carcinogenesis remains elusive.MethodsIn the present work, the effect of postsepsis on inflammation-induced early carcinogenesis was evaluated in an experimental model of colitis-associated colorectal cancer (CAC). We also analyzed the frequency and role of intestinal T regulatory cells (Treg) in CAC carcinogenesis.ResultsThe colitis grade and the tumor development rate were evaluated postmortem or in vivo through serial colonoscopies. Sepsis-surviving mice (SSM) presented with a lower colonic DNA damage, polyp incidence, reduced tumor load, and milder colitis than their sham-operated counterparts. Ablating Treg led to restoration of the ability to develop colitis and tumor polyps in the SSM, in a similar fashion to that in the sham-operated mice. On the other hand, the growth of subcutaneously inoculated MC38luc colorectal cancer cells or previously established chemical CAC tumors was increased in SSM.ConclusionOur results provide evidence that postsepsis disorder has a dual effect in cancer development, inhibiting inflammation-induced early carcinogenesis in a Treg-dependent manner, while increasing the growth of previously established tumors.

scholarly journals miR-20a regulates sensitivity of colorectal cancer cells to NK cells by targeting MICA

2019 ◽  
Vol 39 (7) ◽  
Author(s):  
Siwen Tang ◽  
Hongyu Fu ◽  
Qihua Xu ◽  
Ying Zhou
Keyword(s):  
Colorectal Cancer ◽  
Nk Cells ◽  
Luciferase Reporter ◽  
Normal Tissues ◽  
Histocompatibility Complex ◽  
Colorectal Cancer Cells ◽  
Reporter Assays ◽  
Direct Target ◽  
Causes Of Deaths

Abstract Colorectal cancer (CRC) is one of the leading cancer-related causes of deaths in the world. Recently, microRNAs have been reported to regulate the tumor growth, invasion and the immunosuppression. In the present study, we found that miR-20a was increased in human CRC specimens compared with the healthy normal tissues. However, miR-20a overexpression and knockdown did not impair the CRC cell growth in vitro. Our results indicated that CD107a+ NK cells are increased in CRC group. Furthermore, cytotoxicity assays demonstrated that miR-20a knockdown promoted the CRC cells sensitive to NK cells, whereas miR-20a overexpression showed the opposite results. Our results suggest that the regulation of NK cells by miR-20a depends on NKG2D. Luciferase reporter assays revealed that the NKG2D ligand Major Histocompatibility Complex (MHC) class I-related chain genes A (MICA) is the direct target of miR-20a. Flow cytometry showed the MICA protein level is significantly reduced in miR-20a-overexpressing CRC cells and increased in miR-20a knockdown CRC cells. Taken together, our results suggest that miR-20a regulates sensitivity of CRC cells to NK cells by targeting MICA.

scholarly journals Epigenetic Inactivation of Protocadherin 10 by Methylation in Colorectal Cancer

2020 ◽  
Author(s):  
Mohammad Amin Kerachian ◽  
Sahar Tavakolian ◽  
Matineh Barati Bagherabad ◽  
Dor Mohammad Kordi-Tamandani ◽  
Mohammad Reza Abbaszadegan
Keyword(s):  
Colorectal Cancer ◽  
Tumor Suppressor ◽  
Promoter Methylation ◽  
Methylation Status ◽  
Cpg Islands ◽  
High Specificity ◽  
Suppressor Gene ◽  
Potential Candidate ◽  
Critical Function ◽  
Normal Tissues

Aberrant promoter methylation of CpG islands of tumor-suppressor genes has been recognized as one of the important tumor markers for cancer detection. The aim of this study was to investigate the promoter methylation status of protocadherin 10 (PCDH10), a tumor suppressor gene, in Iranian colorectal cancer (CRC) patients. Cancerous and the adjacent normal tissues obtained from 38 CRC patients were used to assess the methylation status of PCDH10 with Methylation Specific PCR, in addition, to study the expression level of this gene by quantitative PCR. The relationship between hypermethylation and the demographic characteristics of these patients was analyzed. The promoter methylation level of PCDH10 was statistically different between tumoral and normal tissues in CRC patients. Twenty-seven out of 38 patients showed hypermethylation with a sensitivity of 73% and a specificity of 97%. PCDH10 expression decreased in 15 cases (46%) as 16 cases (50 %) showed overexpression and 1 case (4%) had no changes. Not a significant association was reported between PCDH10 hypermethylation and the clinicopathological characteristics (P>0.05). Our results indicated that PCDH10 methylation has a critical function in CRC, with a nearly elevated sensitivity and a high specificity in the Iranian population, qualify it as a potential candidate biomarker. © 2019 Tehran University of Medical Sciences. All rights reserved. Acta Med Iran 2019;57(8):472-477.

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