DNA Methyltransferase 3B Gene Research Articles

Downregulating DNA methyltransferase 3B by suppressing the PI3K/Akt signaling pathway enhances the chemosensitivity of glioblastoma to temozolomide.

Glioblastoma (GBM) is the most common malignant brain tumor and has the poorest prognosis attributed to its chemoresistance to temozolomide (TMZ), the first-line drug for treating GBM. TMZ resistance represents a significant obstacle to successful GBM treatment, necessitating the development of new strategies to overcome this resistance and augment the chemosensitivity of GBM cells to TMZ. This study established a TMZ-resistant U251 (U251-TMZ) cell line by exposing it to increasing doses of TMZ in vitro. We focused on the DNA methyltransferase 3B (DNMT3B) gene, phosphorylated Akt (p-Akt), total Akt (t-Akt), phosphorylated PI3K (p-PI3K), and total PI3K (t-PI3K) protein expression. Results showed that the DNMT3B gene was significantly upregulated in the U251-TMZ cell line. The p-Akt and p-PI3K protein expression in U251-TMZ cells was also significantly elevated. Moreover, we found that DNMT3B downregulation was correlated with the increased chemosensitivity of GBM cells to TMZ. LY294002 suppressed the PI3K/Akt signaling pathway, leading to a notable inhibition of PI3K phosphorylation and a significant decrease in DNMT3B expression in U251-TMZ cells. Given that DNMT3B expression is mediated by the PI3K/Akt signaling pathway, its downregulation further increased the chemosensitivity of GBM cells to TMZ and therefore is a promising therapeutic for GBM treatment. Our results suggested that DNMT3B downregulation can inhibit the proliferation of GBM cells and induce GBM cell apoptosis in vitro. In addition,the PI3K/Akt signaling pathway plays an important role in the chemosensitivity of GBM cells to TMZ by regulating DNMT3B expression.

The interaction of RELN-DNMT genes involving in neurotrophin signaling pathway contributes to schizophrenia susceptibility.

Schizophrenia belongs to a severe mental illness with complicated clinical presentations, an ill-defined pathogenesis, and no known cause. Many genetic studies imply that polygenic interaction is important in the development of schizophrenia. The main mechanism of the RELN-BDNF-CREB-DNMT signaling pathway in neurodevelopment involves RELN, brain-derived neurotrophic factor (BDNF), transcription factor cyclic adenosine monophosphate response element binding protein (CREB), DNA methyltransferase 1 (DNMT1), as well as DNA methyltransferase 3B (DNMT3B). An early case-control research on 15 polymorphisms in the RELN, CREB, BDNF, DNMT1, and DNMT3B genes was done. A single gene variation has little effect on the pathogenesis of schizophrenia, but the combination of intergenic variation loci has a bigger impact because schizophrenia is a complex polygenic disorder. The objective of the current study sought to explore the impact of genetic interactions between RELN, BDNF, CREB, DNMT1, and DNMT3B on schizophrenia in order to further highlight the genetic factors influencing the risk of schizophrenia. Taking the case-control study design, with the Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition (DSM-5) to be the evaluation norm, 134 individuals suffering from schizophrenia hospitalized in the Third People's Hospital of Zhongshan City within January 2018 to April 2020 (case group) were selected, and 64 healthy individuals (control group) from the same geographical area had been chosen as well. MassArray identified DNMT1 gene single nucleotide polymorphisms (rs2114724 and rs2228611) and DNMT3B gene SNPs (rs2424932, rs1569686, rs6119954, and rs2424908). Using the generalized multifactor dimensionality reduction (GMDR), the RELN-BDNF-CREB-DNMT pathway's gene interactions were examined for their impact on schizophrenia. GMDR analysis showed that the three-order interaction model RELN (rs2073559, rs2229864)-DNMT3B (rs2424908) was the optimal model (p = 0.001), with the consistency of cross-validation of 10/10 and the test accuracy of 0.8711. The interaction between the RELN (rs2073559, rs2229864)-DNMT3B (rs2424908) may be related to schizophrenia, and large sample sizes should be verified in different population.

Investigation of the DNMT3B -579 G>T Promoter Polymorphism in Patients with Colorectal Cancer in an Azerbaijani Population.

Objective:The main aim of the present study was to determine the clinical significance of the DNA methyltransferase 3B (DNMT3B) gene –579 G>T polymorphism in colorectal cancer (CRC) patients. Methods:A total of 140 patients with CRC and 164 healthy individuals were included in the study. According to the manufacturer’s instructions, DNA was isolated from blood, and genotypes were determined on agarose gel by the PCR-RFLP method. Genotype confirmation was performed using Sanger sequencing in randomly selected samples. Results:When comparing the case and control groups, heterozygous GT (OR=0.53; 95% CI=0.32–0.88), under the dominant model (OR=0.53; 95% CI=0.33–0.87), and the mutant T allele (OR=0.71; 95% CI=0.51–0.98) were statistically associated with a reduced risk of CRC. However, when the age, pathological tumor grade and stage, smoking habit, and alcohol consumption were compared, no significant relationship was determined (P>0.05). Furthermore, among males, heterozygous GT was associated with a reduced risk of CRC (OR=0.40; 95% CI=0.19–0.84). Conclusion:Our study highlighted that the –579 G>T polymorphism of the DNMT3B gene plays a protective role against CRC development.

T060 Association of DNA methyl transferase 3B gene polymorphism with coronary artery disease

T060 Association of DNA methyl transferase 3B gene polymorphism with coronary artery disease

DNMT3B Oncogenic Activity in Human Intestinal Cancer Is Not Linked to CIMP or BRAFV600E Mutation.

SummaryApproximately 10% of human colorectal cancer (CRC) are associated with activated BRAFV600E mutation, typically in absence of APC mutation and often associated with a CpG island methylator (CIMP) phenotype. To protect from cancer, normal intestinal epithelial cells respond to oncogenic BRAFV600E by activation of intrinsic p53 and p16-dependent tumor suppressor mechanisms, such as cellular senescence. Conversely, CIMP is thought to contribute to bypass of these tumor suppressor mechanisms, e.g. via epigenetic silencing of tumor suppressor genes, such as p16. It has been repeatedly proposed that DNMT3B is responsible for BRAFV600E-induced CIMP in human CRC. Here we set out to test this by in silico, in vitro, and in vivo approaches. We conclude that although both BRAFV600E and DNMT3B harbor oncogenic potential in vitro and in vivo and show some evidence of cooperation in tumor promotion, they do not frequently cooperate to promote CIMP and human intestinal cancer.

Single-nucleotide polymorphisms in DNMT3B gene and DNMT3B mRNA expression in association with prostate cancer mortality.

Germline variants in DNA methyltransferase 3B (DNMT3B) may influence DNMT3B enzymatic activity, which, in turn, may affect cancer aggressiveness by altering DNA methylation. The study involves two Italian cohorts (NTAT cohort, n = 157, and 1980s biopsy cohort, n = 182) and two U.S. cohorts (Health Professionals Follow-Up Study, n = 214, and Physicians' Health Study, n = 298) of prostate cancer (PCa) patients, and a case-control study of lethal (n = 113) vs indolent (n = 290) PCa with DNMT3B mRNA expression data nested in the U.S. cohorts. We evaluated the association between: three selected DNMT3B variants and global DNA methylation using linear regression in the NTAT cohort, the three DNMT3B variants and PCa mortality using Cox proportional hazards regression in all cohorts, and DNMT3B expression and lethal PCa using logistic regression, with replication in publicly available databases (TCGA, n = 492 and MSKCC, n = 140). The TT genotype of rs1569686 was associated with LINE-1 hypomethylation in tumor tissue (β = -2.71, 95% CI: -5.41, -0.05). There was no evidence of association between DNMT3B variants and PCa mortality. DNMT3B expression was consistently associated with lethal PCa in the two U.S. cohorts (3rd vs 1st tertile, combined cohorts: OR = 2.04, 95% CI: 1.13, 3.76); the association was replicated in TCGA and MSKCC data (3rd vs 1st tertile, TCGA: HR = 3.00, 95% CI: 1.78, 5.06; MSKCC: HR = 2.22, 95% CI: 1.01, 4.86). Although there was no consistent evidence of an association between DNMT3B variants and PCa mortality, the TT genotype of rs1569686 was associated with LINE-1 hypomethylation in tumor tissue and DNMT3B mRNA expression was associated with an increased risk of lethal PCa.

A Single Nucleotide Polymorphism of DNA methyltransferase 3B gene is a risk factor for recurrent spontaneous abortion.

Aberrant DNA methylation has been suggested as a potential cause of recurrent spontaneous abortion (RSA). Considering the growing evidence on the important roles of DNA methylation in gametogenesis and early pregnancy, we investigated the potential association of DNA methyltransferase gene polymorphisms (DNMT1 rs2228611, DNMT3A rs1550117, DNMT3B rs1569686) with RSA in Slovenian reproductive couples. A total of 146 couples with ≥3 consecutive spontaneous abortions and 149 control women and men with ≥2 normal pregnancies were included. Genotyping was performed using PCR-RFLP methods. We found a statistically significant higher frequency of the DNMT3B rs1569686 GG genotype (X2 =7.37;P=.025) and G allele (X2 =6.33;P=.012) in RSA women compared with controls. Moreover, the odds for RSA in women were increased under the recessive genetic model (GGvsTG+TT: OR=1.92; 95% CI=1.18-3.09; P=.008). DNMT3B rs1569686 gene polymorphism in women might be a genetic marker for the susceptibility to RSA.

Meta-analysis Reveals No Association of DNMT3B -149 C>T Gene Polymorphism With Overall Cancer Risk.

Background: DNA methyltransferase-3B (DNMT3B) plays a key role in establishment and maintenance of genomic methylation patterns. Polymorphism in promoter region -149 C>T (C46359T) of DNMT3B gene may alter DNMT3B activity which leads to increased susceptibility to cancer. Inconsistent results regarding this have been reported in a number of studies.Objective: To carry out a meta-analysis of the studies reported to assess the precise relationship between the DNMT3B -149 C>T polymorphism and the overall cancer risk.Method: PubMed (MEDLINE) web database was searched for the studies concerning DNMT3B -149 C>T polymorphism and its association with cancer risk. The pooled odds ratios (ORs) along with 95% confidence intervals (95% CIs) were calculated for all the genetic models, from the selected case-control studies, by meta-analysis.Results: Overall eighteen studies containing 5583 cancer cases and 7618 controls were analyzed. No significant risk was observed overall for T allele carrier (T vs. C: p=0.303; OR=1.032, 95% CI=0.972-1.097), homozygous (TT vs. CC: p=0.336; OR=1.063, 95% CI=0.939–1.204), heterozygous (CT vs. CC: p=0.802; OR=1.022, 95% CI=0.860-1.216), dominant (TT vs. CC+CT: p=0.298; OR=1.101, 95% CI=0.919-1.319) and recessive (TT+CT vs. CC: p=0.656; OR=1.021, 95% CI=0.931-1.121) genetic models. Subgroup analysis of Asian and Caucasian populations also did not demonstrate any cancer risk in all the genetic models studied.Conclusion: Our meta-analysis proposes that the DNMT3B -149 C>T polymorphism may not be an independent predisposing factor for the risk of cancer. However, larger sample size and expression studies are required to confirm the observation.

MiR-339 and especially miR-766 reactivate the expression of tumor suppressor genes in colorectal cancer cell lines through DNA methyltransferase 3B gene inhibition

ABSTRACTIt is observed that upregulation of DNMT3B enzyme in some cancers, including colon cancer, could lead to silencing of tumor suppressor genes. MiR-339 and miR-766 have been predicted to target 3′UTR of DNMT3B gene. Luciferase reporter assay validated that individual and co-transfection of miR-766 and miR-339 into the HEK293T cell reduced luciferase activity to 26% ± 0.41%, 43% ± 0.42 and 64% ± 0.52%, respectively, compared to the control (P < 0.05). Furthermore, transduction of miR-339 and miR-766 expressing viruses into colon cancer cell lines (SW480 and HCT116) decreased DNMT3B expression (1.5, 3-fold) and (3, 4-fold), respectively. In addition, DNA methylation of some tumor suppressor genes decreased. Expression of these genes such as SFRP1 (2 and 1.6-fold), SFRP2 (0.07 and 4-fold), WIF1 (0.05 and 4-fold), and DKK2 (2 and 4-fold) increased in SW-339 and SW-766 cell lines; besides, expression increments for these genes in HCT-339 and HCT-766 cell lines were (2.8, 4-fold), (0.005, 1.5-fold), (1.7 and 3-fold) and (0.04, 1.7-fold), respectively. Also, while in SW-766, cell proliferation reduced to 2.8% and 21.7% after 24 and 48 hours, respectively, SW-339 showed no reduced proliferation. Meanwhile, HCT-766 and HCT-339 showed (3.5%, 12.8%) and (18.8%, 33.9%) reduced proliferation after 24 and 48 hours, respectively. Finally, targeting DNMT3B by these miRs, decreased methylation of tumor suppressor genes such as SFRP1, SFRP2, WIF1 and DKK2 in the mentioned cell lines, and returned the expression of these tumor suppressor genes which can contribute to lethal effect on colon cancer cells and reducing tumorigenicity of these cells.

DNA methyltransferase 3B gene promotor and interleukin-1 receptor antagonist polymorphisms in Egyptian children with immune thrombocytopenic purpura

Background and objectives Idiopathic thrombocytopenic purpura (ITP) is an autoimmune condition characterized by increased platelet destruction. Although the etiology of ITP remains unclear, it is accepted that both environmental and genetic factors play an important role in the development of the disease. Many gene polymorphisms have been reported to be closely associated with the susceptibility to ITP. Aim of the work The current study aimed to investigate the association between the DNA methyltransferase DNMT3B-46359 C/T promoter and IL-1Ra polymorphism and the risk for acquisition of pediatric ITP in a cohort of Egyptian children. Patients and methods Genotyping of the studied genes using PCR-RFLP assays was conducted on 40 children with ITP and 20 age-matched and sex-matched normal controls. Results Our results revealed that DNMT3B-46359 C/T heterotype was higher in patients than in controls but did not reach statistical significance and conferred 2.2-fold increased risk for ITP (odds ratio=2.2, confidence interval = 1.4–2.6). There was no statistically significant difference between ITP patients and controls as regards allele frequency. Moreover, there was no statistically significant difference in the clinical and laboratory data between ITP patients with wild or mutant genotypes. Moreover, there was no statistically significant difference in the distribution of DNMT3B-46359 . C/T genotypes between acute and chronic ITP patients. Conclusion This genetic polymorphism cannot be considered as a molecular marker for ITP risk among Egyptian children. Moreover, it is not a molecular predictor for chronicity.

DNA methyltransferase 3b silencing affects locus-specific DNA methylation and inhibits proliferation, migration and invasion in human hepatocellular carcinoma SMMC-7721and BEL-7402cells.

DNA methylation is an important regulator of gene transcription, and its role in carcinogenesis has been a topic of considerable interest in previous years. The present study examined the influence of DNA methyltransferase 3b (DNMT3b) on cell proliferation, migration and invasion, and the methylation status of identified tumor suppressor genes in hepatoma SMMC-7721 and BEL-7402 cells. DNMT3b was silenced by small interfering RNA (siRNA) in human hepatocellular carcinoma cell lines. Transfection efficiency was verified using a fluorescent imaging system, reverse transcription polymerase chain reaction (RT-PCR) and western blotting. A cell proliferation assay was performed to evaluate cell viability. Cell cycle distribution and apoptosis were analyzed by flow cytometry. The migratory and invasive ability of cells was measured using a Transwell assay. Methylation-specific PCR (MSP) was performed to assess methylation in the promoter region of genes. The present data revealed that DNMT3b siRNA successfully inhibited expression of the DNMT3b gene in these two liver cancer cell lines and therefore inhibited the proliferation of the transfected cells, stimulated apoptosis in the cells, led to an accumulation of cells in the G2/M phase and decreased cell migration and invasion. It was also found that silencing DNMT3b expression results in hypomethylation of specific sets of gene promoters and increases the expression of distinct set of genes in HCC cell lines. The present study is therefore useful for assessing the specificity of emerging action based on the altered expression of associated regulatory genes, particularly in methylation-silenced genes.

Maternal risk for down syndrome and polymorphisms in the promoter region of the DNMT3B gene: a case-control study.

Epigenetic changes leading to improper methylation of the pericentromeric region of chromosome 21 may contribute to the nondisjunction of this chromosome. Polymorphisms in the DNA Methyltransferase 3B (DNMT3B) gene, one of the crucial gene of the folate metabolism, affects the activity of the enzyme and increases the susceptibility of nondisjunction in mothers of Down syndrome children (MDS). Considering this hypothesis we investigated the association of single nucleotide polymorphisms in the promoter region of the DNMT3B gene (rs1569686 -579G>T; rs2424913 -149C>T) with a predisposition of mothers to deliver a Down syndrome (DS) child. The study was performed on DNA samples from 150 MDS and 172 control mothers. Transmission disequilibrium tests were performed on 103 DS trio families. Genotyping was done using a polymerase chain reaction-restriction fragment length polymorphism method. With respect to the single nucleotide polymorphisms studied, no significant difference was observed in the genotypes and alleles frequency distributions between MDS and control mothers. The frequency of the DNMT3B-579G allele was, respectively, 0.34 in MDS and 0.33 in control mothers whereas the frequency of the DNMT3B-149C allele was respectively 0.31 in MDS and 0.26 in control mothers. No significant deviation in genotypic combinations as well as in transmission disequilibrium tests analysis was observed. However, a strong linkage disequilibrium was observed with significant differences in the distribution of G-T and G-C haplotypes among case and control mothers. Although the above studied polymorphisms of DNMT3B may not be an independent risk factor it might be possible that certain allelic combinations (G-T) are. This finding suggests that DNMT3B might be a maternal risk factor for DS in our Indian cohort. Replication studies are required to confirm these findings.

Immunodeficiency, Centromeric Instability, Facial Anomalies Syndrome Type 2 (ICF2): Combined Immunodeficiency, Autoimmune Phenomena, and Intellectual Disability

Introduction: The immunodeficiency, centromeric instability, facial anomalies syndrome (ICF) is a rare autosomal recessive disease defined by immunodeficiency, developmental delay, and facial abnormalities. Centromeric instability results in chromosomal rearrangements and genomic methylation is due to a defect. ICF1 and 2 are caused by biallelic mutations in the DNA methyltransferase 3B gene DNMT3B and the zinc finger and BTB domain-containing 24 gene ZBTB24, respectively. Patients without immunodeficiency but only with facial dysmorphism and intellectual deficit exist.

Genetic polymorphism of DNA methyltransferase 3B 149 C&gt;T and risk of colorectal cancer: a meta-analysis

Numerous studies have investigated the risk of colorectal cancer (CRC) associated with the polymorphism of DNA methyltransferase 3B (DNMT3B) 149 C>T, but results have been inconsistent. We performed this meta-analysis to drive a more precise estimation of the association between this polymorphism and risk of CRC. A comprehensive search was conducted to identify all case-control studies of the -149C>T polymorphism of DNMT3B and CRC risk. A total of seven eligible studies, including 2,666 cases and 4,022 controls, relating the DNMT3B polymorphism of -149C>T to the risk of CRC were identified. It suggested no significant associations between -149C>T polymorphism of DNMT3B gene and the risk of developing CRC in the recessive, dominant, and co-dominant models (for CC versus TT: OR = 0.90, 95% CI = 0.90-1.25, P heterogeneity = 0.37; for recessive model: OR = 0.54, 95% CI = 0.28-1.04, P heterogeneity = 0.00001; for dominant model: OR = 1.07, 95% CI = 0.93-1.23, P heterogeneity = 0.83; and for C allele versus T allele: OR = 0.70, 95% CI = 0.43-1.13, P heterogeneity = 0.00001). In the subgroup analysis, there is no significant associations were also found in European populations (for CC versus TT: OR = 1.09, 95% CI = 0.92-1.30, P heterogeneity = 0.88; for recessive model: OR = 1.00, 95% CI = 0.88-1.13, P heterogeneity = 0.14; for dominant model: OR = 1.50, 95% CI = 0.89-2.54, P heterogeneity = 0.00001; and for C allele versus T allele: OR = 0.70, 95% CI = 0.38-1.28, P heterogeneity = 0.00001). In conclusion, no significant association was found between the -149C>T polymorphisms in DNMT3B and CRC susceptibility.

Correlation between polymorphism in the promoter of DNA methyltransferase-3B gene and susceptibility of colorectal cancer

Objective To observe and analyze the correlation between the DNA methyltransferase-3B (DNMT3B) gene single nucleotide polymorphisms (SNP) rs 1569686 and the susceptibility to colorectal cancer (CRC) in Tianjin Han population.Methods A case-control study was performed.89 CRC patients and 94 normal controls were examined,and Sequenom MassArray system was applied to detect the genotype of rs1569686 in DNMT3B gene polymorphisms.The association results were analyzed of the SNP and CRC.Results The frequencies of genotypes TT,GT and GG at SNP rs1569686 were 74.2％,24.7％ and 1.1％ in CRC patients respectively,which there were no significant differences from that in controls(73.4％,23.4％ and 3.2％; P＞0.05).Conclusion It suggests that the SNP rs1569686 of DNMT3B gene may not be related to susceptibility of CRC in Tianjin Han population. Key words: Colon neoplasms; Rectal neoplasms; DNA methyltransferase 3B; Single nucleotide polymorphism

DNMT3B promoter polymorphism and risk of immune thrombocytopenic purpura in pediatric Egyptians

Idiopathic (immune) thrombocytopenic purpura (ITP) is a heterogeneous clinical disorder characterized by immune-mediated platelet destruction. Epigenetic changes in gene expression, including DNA methylation and histone modifications, might contribute to autoimmunity. Polymorphisms of the DNA methyltransferase 3B (DNMT3B) gene may influence DNMT3B activity on DNA methylation and increase the susceptibility to several diseases. The current study investigated the association between a single nucleotide polymorphism (SNP) in the promoter of DNMT3B gene and the risk for ITP in pediatric Egyptians. DNMT3B SNP was genotyped by PCR-restriction fragment length polymorphism in 71 pediatric ITP patients and 82 healthy controls matched for age and sex. The C/C wild genotype was not detected in ITP patients or in the controls. The frequencies of the T/T and C/T genotypes were 93.9 and 6.1% in the controls and 91.5 and 6.1% in ITP patients, respectively. There was no significant difference in either genotypes or allelic distribution between ITP patients and the controls. In conclusion, this polymorphism was almost equally distributed between ITP patients and the controls. These results demonstrated that this SNP may not be used as a stratification marker to predict the susceptibility to childhood ITP in Egypt.

DNA methyltransferase 3b (DNMT3b), tumor tissue DNA methylation, Gleason score, and prostate cancer mortality: investigating causal relationships

Aberrant DNA methylation plays a role in prostate cancer progression. We studied the relationships among DNA methyltransferase (DNMT) genotype, DNA methylation, Gleason score, and mortality in two cohorts of prostate cancer patients, previously reported with associations between DNA methylation in GSTP1, APC, and RUNX3 and prostate cancer mortality. Herein, we considered possible causal relationships between the studied variables, assuming that (1) DNMT activity affects tumor tissue methylation, (2) methylation status affects tumor morphology, and thus the Gleason score, and (3) DNA methylation affects mortality via Gleason score. The cohorts comprised 438 patients diagnosed at one Italian pathology ward before 1997, with DNA obtained from paraffin-embedded tumor tissues. The polymorphism rs406193 in the DNMT3b gene was assessed by allele discrimination in real-time PCR. According to the assumed causal model, we analyzed the effects of rs406193 (T carriers vs others) on the Gleason score without adjusting for gene methylation, and the effects of rs406193 on gene methylation and prostate cancer mortality without adjusting for Gleason score. We found no evidence of association between T carriers and the number of methylated genes. However, T carriers had reduced risk of a Gleason score 8+ (odds ratio=0.57, 95% CI 0.39-0.85), and a hazard ratio of 0.81 (0.61-1.09) of dying from prostate cancer, which would have been erroneously estimated of 0.93 if adjusted for Gleason score. These findings provide clues on the role of a DNMT3b SNP in prostate cancer progression and illustrate the importance of considering possible causal relationships in the analyses.

New DNA methylation markers associated with oral cancer (OC) development (dvlpt).

5524 Background: We have reported that DNA methyltransferase-3B (DNMT3B) gene expression is a strong predictor of OC dvlpt. Using high-throughput DNA methylation profiles of oral preneoplastic lesions (OPL), we identified 86 candidate genes that were hypermethylated in patients (pts) developing OC and suggested that a CpG island methylation phenotype may occur early during OC dvlpt. Our aim was to validate some of the candidate genes and to study the value of LINE1 repetitive element methylation, a surrogate of global DNA methylation, as biomarkers of risk to develop OC. Methods: Validation cohort included 40 pts with a median follow-up of 4.2 years, including 14 pts who developed OC. None of them were used in the discovery phase. Frozen OPL were collected prospectively and subject to DNA extraction. We performed a quantitative analysis of the degree of methylation of LINE1, and AGTR1, FOXI2, PENK, and HOXA9 promoters CpG sites using pyrosequencing. Results: The degree of methylation of AGTR1 (Mann-Whitney P&lt;0.0001), FOXI2 (P=0.0002), PENK (P&lt;0.0001), but not HOXA9 (P=0.0714) was significantly higher in pts who developed OC. On the contrary, LINE1 methylation was significantly lower in pts who developed OC (P&lt;0.0001). The median percent of methylation was used to dichotomize the pts into high versus low methylation levels. Oral cancer-free survival (OCFS) was significantly worse in pts with high levels of AGTR1 (Log-rank P=0.0229), FOXI2 (P=0.0170), and PENK (P=0.0142) promoter methylation. No significant difference was found with HOXA9. A Methylation Index (MI) was developed by averaging the percent of methylation of AGTR1, FOXI2, and PENK promoters; pts with a high MI had a worse OCFS (P=0.0031). On the other hand, pts with low levels of LINE1 methylation had a significantly worse OCFS (P=0.0118). Finally, in 26 pts, a positive correlation was observed between DNMT3B gene expression levels and the MI (rho=0.65, P=0.0003); surprisingly, there was a negative correlation with LINE1 methylation (rho=-0.74, P&lt;0.0001). Conclusions: AGTR1, FOXI2 and PENK promoter methylation may be associated with increased OC risk in pts with OPL and correlate with DNMT3B expression. Global DNA hypomethylation is an early event in OC dvlpt.

DNA replication is altered in Immunodeficiency Centromeric instability Facial anomalies (ICF) cells carrying DNMT3B mutations

ICF syndrome is a rare autosomal recessive disorder that is characterized by Immunodeficiency, Centromeric instability, and Facial anomalies. In all, 60% of ICF patients have mutations in the DNMT3B (DNA methyltransferase 3B) gene, encoding a de novo DNA methyltransferase. In ICF cells, constitutive heterochromatin is hypomethylated and decondensed, metaphase chromosomes undergo rearrangements (mainly involving juxtacentromeric regions), and more than 700 genes are aberrantly expressed. This work shows that DNA replication is also altered in ICF cells: (i) heterochromatic genes replicate earlier in the S-phase; (ii) global replication fork speed is higher; and (iii) S-phase is shorter. These replication defects may result from chromatin changes that modify DNA accessibility to the replication machinery and/or from changes in the expression level of genes involved in DNA replication. This work highlights the interest of using ICF cells as a model to investigate how DNA methylation regulates DNA replication in humans.

DNA Methyltransferase 3B Gene Promoter and Interleukin-1 Receptor Antagonist Polymorphisms in Childhood Immune Thrombocytopenia

Primary immune thrombocytopenia (ITP) is one of the most common blood diseases as well as the commonest acquired bleeding disorder in childhood. Although the etiology of ITP is unclear, in the pathogenesis of the disease, both environmental and genetic factors including polymorphisms of TNF-a, IL-10, and IL-4 genes have been suggested to be involved. In this study, we investigated the rs2424913 single-nucleotide polymorphism (SNP) (C46359T) in DNA methyltransferase 3B (DNMT3B) gene promoter and the VNTR polymorphism of IL-1 receptor antagonist (IL-1 Ra) intron-2 in 32 children (17 boys) with the diagnosis of ITP and 64 healthy individuals. No significant differences were found in the genotype distribution of DNMT3B polymorphism between the children with ITP and the control group, whereas the frequency of allele T appeared significantly increased in children with ITP (P = 0.03, OR = 2, 95% CI: 1.06–3.94). In case of IL-1 Ra polymorphism, children with ITP had a significantly higher frequency of genotype I/II, compared to control group (P = 0.043, OR = 2.60, 95% CI: 1.02–6.50). Moreover, genotype I/I as well as allele I was overrepresented in the control group, suggesting that allele I may have a decreased risk for development of ITP. Our findings suggest that rs2424913 DNMT3B SNP as well as IL-1 Ra VNTR polymorphism may contribute to the susceptibility to ITP.