DNMT3b 39179GT polymorphism and the risk of adenocarcinoma of the colon in Koreans

Systematic evaluation of cancer risk associated with DNMT3B polymorphisms

PURPOSE

The aim of our study is to provide a precise quantification for the association between DNA methyltransferase 3B (DNMT3B) variations (rs2424913 C/T, rs1569686 G/T, rs6087990 T/C and rs2424908 T/C) and the risk of cancer.

METHODS

We performed a systematic literature review and assessed the methodological quality of included case-control designed studies based on Newcastle-Ottawa Scale. Pooled odds ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were calculated to assess the strengths of the associations.

RESULTS

We identified 34 studies for pooled analyses. Overall, the results demonstrated that rs2424913 polymorphism was significantly associated with negative cancer risk in the African population (CT vs TT: OR 0.10, 95% CI 0.02-0.63, P = 0.01; CT+CC vs TT: OR 0.14, 95% CI 0.03-0.76, P = 0.02), and the rs1569686 polymorphism was significantly associated with a subtly decreased cancer risk (GT vs TT: OR 0.80, 95% CI 0.72-0.90, P < 0.01; GT+GG vs TT: OR 0.84, 95% CI 0.76-0.94, P < 0.01), particularly in the Asian population (GT vs TT: OR 0.79, 95% CI 0.66-0.96, P < 0.01) and in colorectal cancer subgroup (G vs T: OR 0.69, 95% CI 0.54-0.88, P < 0.01). In addition, the rs6087990 polymorphism was associated with decreased risk in Asian population (T vs C: OR 0.77, 95% CI 0.62-0.96, P = 0.02). Similarly, the rs2424908 polymorphism was observed as a protective factor for cancer in the Asian population (CT+CC vs TT: OR 0.79, 95% CI 0.66-0.95, P = 0.01).

CONCLUSIONS

DNMT3B polymorphisms might be associated with decreased cancer risk especially in the Asian population and for colorectal cancer. Further multicentric studies are still needed to confirm the results.

Genetic polymorphism of DNA methyltransferase 3B 149 C>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.

Association of the DNMT3B -579G>T polymorphism with risk of thymomas in patients with myasthenia gravis

Increasing evidence suggests a contribution of epigenetic processes in promoting cancer and autoimmunity. Myasthenia gravis (MG) is an autoimmune disease mediated, in approximately 80% of the patients, by antibodies against the nicotinic acetylcholine receptor (AChR+). Moreover, epithelial tumours (thymomas) are present in about 10-20% of the patients, and there is indication that changes in DNA methylation might contribute to the risk and progression of thymomas. However, the role of epigenetics in MG is still not completely clarified. In the present study we investigated if a common polymorphism (-579G>T: rs1569686) in the promoter of the DNMT3B gene coding for the DNA methyltransferase 3B, an enzyme that mediates DNA methylation, increases the risk to develop MG or MG-associated thymomas. The study polymorphism was selected based on recent reports and a literature meta-analysis suggesting association with increased risk of various types of cancer. We screened 324 AChR+ MG patients (140 males and 184 females, mean age 56.0 ± 16.5 years) and 735 healthy matched controls (294 males and 441 females, mean age 57.3 ± 15.6 years). 94 of the total MG patients had a thymoma. While there was no association with the whole cohort of MG patients, we found a statistically significant association of the DNMT3B-579T allele (OR = 1.51; 95% CI=1.1-2.1, P = 0.01) and the TT homozygous genotype (OR = 2.59; 95% CI=1.4-4.9, P = 0.006) with the risk of thymoma. No association was observed in MG patients without thymoma, even after stratification into clinical subtypes. Present results suggest that the DNMT3B-579T allele might contribute to the risk of developing thymoma in MG patients, particularly in homozygous TT subjects.

Association between DNA methyltransferases 3B gene polymorphisms and the susceptibility to acute myeloid leukemia in Chinese Han population

DNMT3B plays a crucial role in the generation of aberrant methylation during carcinogenesis. Polymorphisms in the DNMT3B gene may influence the DNA methylation enzymatic activity of DNMT3B, thereby modulating the susceptibility to AML. Thus, we investigated the association between SNPs in the DNMT3Bgene and their haplotypes with the risk of AML in the Chinese Han population. The DNMT3B genotype was determined by HRM in 317 de novo AML patients and 406 healthy control subjects matched for age and gender. Among the 5 SNPs investigated in this study, rs2424913 demonstrated no polymorphisms in the Chinese Han populations, rs1569686 and rs2424908 were significantly associated with AML risk. The GG genotype of rs1569686 was associated with increased AML risk (OR: 5.76; 95%CI: 2.60-12.73; P<0.01) compared with the TT genotype, and individuals with a G allele had a significantly increased risk (OR: 1.89; 95%CI: 1.41-2.52; P<0.01) for AML compared with those harboring a C allele, this polymorphism can predict the risk of AML in a minority of patients. While the CC genotype of rs2424908 appeared to reduce the AML risk (OR: 0.57; 95%CI: 0.36-0.91; P=0.01) compared with the TT genotype, individuals with a C allele were associated with a lower risk (OR: 0.79, 95%CI: 0.64-0.97, P=0.03) for developing AML compared with those harboring a T allele. The other 2 SNPs, rs6087990 and rs6119954, had no significant association with AML risk in the study population. The CGGT, CTAT, TGAT, and CGAT haplotypes of rs6087990, rs1569686, rs6119954, and rs2424908 appeared to significantly increase the AML risk, and the TTGC haplotype appeared to significantly reduce the risk. These results suggest that DNMT3B polymorphisms may contribute to the genetic susceptibility to AML; in particular, the G allele of rs1569686 serves as a risk factor for AML, whereas the C allele of rs2424908 represents a potential protective factor.

Promoter polymorphisms of DNA methyltransferase 3B and risk of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common solid tumors worldwide. Epigenetic changes in gene expression, including DNA methylation and histone modifications, may contribute to the development of HCC. Polymorphisms of the DNA methyltransferase 3B (DNMT3B) gene may affect the activity of this enzyme and increase the susceptibility to several types of cancer, including HCC. To confirm this hypothesis, we investigated the association between single-nucleotide polymorphisms-149C>T (rs2424913) and -579G>T (rs1569686) in the promoter region of DNMT3B and the risk of HCC. DNMT single-nucleotide polymorphisms (SNPs) were genotyped by polymerase chain reaction-restriction fragment length polymorphism in 108 HCC patients and 240 healthy controls matched for age, gender and ethnicity. The DNMT3B-149 TT genotype was not significantly associated with an increased risk of HCC. The frequency of DNMT3B-149C was 0.46% in HCC patients and 1.39% in healthy individuals, whereas the frequency of DNMT3B-579G was 8.33% in HCC patients and 10.42% in healthy individuals. No significant differences were observed in the genotype or allelic distribution between HCC patients and controls. In conclusion, DNMT3B-149C>T and -579G>T polymorphisms are not significantly associated with an increased risk of HCC. These results demonstrated that these particular SNPs may not be used as biomarkers to predict susceptibility to HCC.

The role of genetics in the establishment and maintenance of the epigenome

Epigenetic mechanisms play an important role in gene regulation during development. DNA methylation, which is probably the most important and best-studied epigenetic mechanism, can be abnormally regulated in common pathologies, but the origin of altered DNA methylation remains unknown. Recent research suggests that these epigenetic alterations could depend, at least in part, on genetic mutations or polymorphisms in DNA methyltransferases and certain genes encoding enzymes of the one-carbon metabolism pathway. Indeed, the de novo methyltransferase 3B (DNMT3B) has been recently found to be mutated in several types of cancer and in the immunodeficiency, centromeric region instability and facial anomalies syndrome (ICF), in which these mutations could be related to the loss of global DNA methylation. In addition, mutations in glycine-N-methyltransferase (GNMT) could be associated with a higher risk of hepatocellular carcinoma and liver disease due to an unbalanced S-adenosylmethionine (SAM)/S-adenosylhomocysteine (SAH) ratio, which leads to aberrant methylation reactions. Also, genetic variants of chromatin remodeling proteins and histone tail modifiers are involved in genetic disorders like α thalassemia X-linked mental retardation syndrome, CHARGE syndrome, Cockayne syndrome, Rett syndrome, systemic lupus erythematous, Rubinstein-Taybi syndrome, Coffin-Lowry syndrome, Sotos syndrome, and facioescapulohumeral syndrome, among others. Here, we review the potential genetic alterations with a possible role on epigenetic factors and discuss their contribution to human disease.

DNA methyltransferase 3B (DNMT3B -579G>T) promotor polymorphism and the susceptibility to pediatric immune thrombocytopenic purpura in Egypt

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disease 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. The present study aimed at exploring a novel molecular determinant that may influence the susceptibility and course of ITP in Egyptian children. To achieve our aim, genotyping of DNMT3B -579G>T promotor polymorphism by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assay. The current study was conducted on 140 ITP patients and 150 age and gender matched healthy controls. The results obtained revealed that DNMT3B -579 TT homotype was significantly higher in ITP patients and conferred almost three fold increased risk of ITP (OR=3.16, 95%CI=1.73-5.79). There was no statistically significant difference between ITP patients with wild or mutant genotypes as regards their clinical or laboratory data. Furthermore, there was no statistical difference in the distribution of DNMT3B -579G>T genotypes between acute and chronic ITP patients. In conclusion, DNMT3B -579G>T promotor polymorphism represents a novel genetic risk factor for ITP but not a predictor for tendency to chronicity in pediatric ITP in Egypt.

The -149C>T polymorphism of DNMT3B is not associated with colorectal cancer risk: Evidence from a meta-analysis based on case-control studies

The aim of this study was to examine the association between the −149C>T polymorphism of DNA methyltransferase 3B (DNMT3B) and colorectal cancer (CRC) susceptibility. A comprehensive search was conducted to identify all case-control studies of the −149C>T polymorphism of DNMT3B and CRC risk. Statistical analysis was performed with the software program Stata (version 12.0) and Review Manager (version 5.0). A total of seven eligible studies, including 2,666 cases and 4,022 controls, associating the DNMT3B polymorphism of −149C>T with the risk of CRC were identified. These studies suggested no significant associations between the −149C>T polymorphism of the DNMT3B gene and the risk of developing CRC in the recessive, dominant and co-dominant models [for CC vs. TT: odds ratio (OR), 0.90; 95% confidence interval (CI), 0.90–1.25; P=0.37; for the recessive model: OR, 0.54, 95% CI, 0.28–1.04; P<0.00001; for the dominant model: OR, 1.07; 95% CI, 0.93–1.23; P=0.83 and C allele vs. T allele: OR, 0.70; 95% CI, 0.43–1.13; P<0.00001]. In the subgroup analysis, no significant associations were found in the European populations (for CC vs. TT: OR, 1.09; 95% CI, 0.92–1.30; P=0.88; for the recessive model: OR, 1.00; 95% CI, 0.88–1.13; P=0.14; for the dominant model: OR, 1.50; 95% CI, 0.89–2.54; P<0.00001 and C allele vs. T allele: OR, 0.70; 95% CI, 0.38–1.28; P<0.00001). No significant association was found between the −149C>T polymorphism in DNMT3B and CRC susceptibility.

DNMT3B polymorphisms and cancer risk: a meta analysis of 24 case-control studies

The association between polymorphism of DNA methyltransferases 3B and cancer risk has been widely studied recently, and no consensus conclusion is available up to now. We perform a comprehensive search using the databases of Medline, ISI Web of Knowledge and Embase. The odds ratio (OR) and its 95% confidence interval (95% CI) are used to investigate the strength of the association. A total of 24 case-control studies with 15,647 individuals are included in this meta-analysis. For -149C > T (17 studies, 5229 cases and 6910 controls), no evidence indicate that individuals carrying the variant genotypes (CC + CT), relative to those carrying the wild homozygote TT genotype, have an increased risk of cancer (OR = 1.03; 95% CI = 0.84-1.26; P = 0.76). Similarly, no cancer risk is found in the subgroup analyses. For -579G > T (11 studies, 3513 cases and 3714 controls), significantly decreased risks of cancer are observed, and the ORs (95% CI) are 0.70 (0.56-0.87) for GT versus TT, 0.70 (0.57-0.85) for GG + GT versus TT and 0.76 (0.63-0.93) for G-allele versus T-allele, respectively. Subgroup analyses stratified by ethnicity and types of cancer are also performed, and results indicated that -579G > C polymorphism is associated with risk of cancer in Asians [0.68 (0.53-0.87) for GT vs. TT] but not in Europeans [0.82 (0.63-1.07) for GT vs. TT]. We also observe that the -579G is associated with decreased risk of colorectal cancer [0.49(0.38-0.62) for GT vs. TT]. More studies with larger sample size were needed to provide more precise evidence.

The DNMT3B -579 G>T promoter polymorphism and risk of lung cancer

The present study aimed to investigate the association of the -579 G>T polymorphism in the DNMT3B promoter with susceptibility to lung cancer. A total of 174 lung cancer patients and 135 healthy controls from the northern part of China were enrolled, and were matched for gender and age. All subjects were genotyped by polymerase chain reaction-restriction-fragment length polymorphism analysis and confirmed by DNA sequencing. Stratification analyses were used to study the subgroups of subjects by age and gender, and evaluate the association between the -579 G>T polymorphism and the genetic susceptibility to lung cancer. The results revealed that individuals with the DNMT3B -579 GT genotype had a significantly decreased risk of lung cancer [odds ratio (OR), 0.517; 95% confidence interval (CI), 0.273-0.981] compared with those with a -579 TT genotype in the studied population. However, the deviation was significant (OR, 0.138, 95% CI, 0.034-0.549) between the risk of lung cancer and the GT and GG genotype, when the smoking factor was considered. The data from this study indicate that the DNMT3B genetic polymorphism varies among various races, ethnic groups and geographical areas. The DNMT3B -579 G>T polymorphism may contribute to the genetic susceptibility to lung cancer.

Genetic variation in the promoter of DNMT3B is associated with the risk of colorectal cancer

PURPOSE

DNA methyltransferase-3B (DNMT3B) plays an important role in the generation of aberrant methylation in carcinogenesis. Polymorphisms of the DNMT3B gene may influence DNMT3B enzyme activity on DNA methylation, thereby modulating the susceptibility to colorectal cancer (CRC).

METHODS

The polymorphisms in the promoter region of the DNMT3B gene [-149C>T (rs2424913) and -579G>T (rs1569686)] were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and a total of 544 CRC patients and 533 age- and sex-matched healthy controls were enrolled in the case-control study.

RESULTS

The results showed that the -579G allele was associated with a significantly decreased risk of CRC (adjusted OR, 0.50; 95%CI, 0.35-0.72; P = 0.0002) when compared with the -579TT genotype. However, the DNMT3B-149CT genotype was not associated with the risk of CRC (adjusted OR, 0.48; 95%CI, 0.18-1.30; P = 0.151). In addition, stratification analysis revealed that the increased risk was predominant in both colon cancer and rectal cancer showing no effect of primary occurrence site.

CONCLUSION

Our research demonstrated the -579G allele was a potential protective factor for the occurrence of CRC.

Linking obesity to colorectal cancer: application of nutrigenomics

Diet is one of the most affective environmental factors in cancer development. Due to complicated nature of the diet, it has been very difficult to provide clear explanations for the role of dietary components in carcinogenesis. However, as high-throughput omics techniques became available, researchers are now able to analyze large sets of gene transcripts, proteins, and metabolites to identify molecules involved in disease development. Bioinformatics uses these data to perform network analyses and suggest possible interactions between metabolic processes and environmental factors. Obesity is known as one of the most closely related risk factors of colorectal cancer (CRC). Metabolic disturbances due to a positive energy balance may trigger and accelerate CRC development. In this review, we have summarized reports on genes, proteins and metabolites that are related to either obesity or CRC, and suggested candidate molecules linking obesity and CRC based on currently available literature. Possible application of bioinformatics for a large scale network analysis in studying cause-effect relationship between dietary components and CRC are suggested.

DNMT3B -579 G>T promoter polymorphism and risk of gallbladder carcinoma in North Indian population

AIM

Carcinoma of gallbladder (GBC) is a relatively rare but highly fatal disease. The DNA (cytosine-5-)-methyltransferase 3 beta (DNMT3B) -579 G>T promoter polymorphism (rs1569686) influences gene function and has been associated with various malignancies. Present population-based case-control study was undertaken to examine the potential association of DNMT3B -579 G>T variation with GBC in North Indian population.

METHODS

Genotypes and allelic frequencies of the DNMT3B -579 G>T polymorphism were determined for 212 GBC patients and 219 controls using PCR-RFLP. Odds ratio (OR) and 95% confidence interval (95% CI) were calculated for the association of DNMT3B polymorphism with GBC. Analysis of potential transcription factor binding sites was also identified in the region harboring the polymorphism.

RESULTS

The DNMT3B -579 G>T polymorphism was found to be non-significantly associated with an overall increased risk of GBC (OR = 1.10 and 1.56 for T/G and G/G genotypes, respectively, P (trend) = 0.227). The increased risk was predominant in both male and female cohorts and also non-significantly in GBC patients with gallstone status (OR = 1.44; P = 0.280, OR = 1.06; P = 0.804 and OR = 1.45; P = 0.143, respectively).

CONCLUSION

DNMT3B -579 G>T polymorphism may alter susceptibility to GBC although it may not play a major role in the pathoetiology of this disease in North Indian population.

DNMT3B promoter polymorphism and risk of gastric cancer

To investigate the association of single-nucleotide polymorphism (SNP) in DNA methyltransferase 3B (DNMT3B) gene and the risk of gastric cancer (GC), we detected -149C>T and -579G>T in the promoter region of the DNMT3B gene by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing analysis. The DNMT3B genotype was determined in 259 gastric cancer patients and 262 healthy controls that were frequency matched for age and gender. Results showed that individuals with at least one -579G allele were also at significantly decreased risk of gastric cancer [odds ratio (OR), 0.43; 95% confidence interval (CI) 0.26-0.72] compared with those having a -579TT genotype. The -149C>T genotype distribution was irrelevant to the risk of gastric cancer (OR, 1.49; 95% CI, 0.17-17.94) in the studied Chinese population. In addition, data suggested that DNMT3B genetic polymorphism varied among different races, ethnic groups, and geographic areas.

Association of the DNMT3B polymorphism with colorectal adenomatous polyps and adenocarcinoma

DNMT3B is an important enzyme to modulate the methylation status in mammalian cells. The aim of this study is to investigate the correlation of the DNMT3B G39179T polymorphism with the susceptibilities of colorectal adenomatous polyps and adenocarcinoma. This case-control study included 146 colorectal adenomatous polyps, 170 colorectal adenocarcinoma patients, and 157 normal controls. DNMT3B polymorphism was analyzed by polymerase chain reaction-restriction fragment length polymorphism analysis. Family history of colorectal cancer significantly increases the risk of developing colorectal adenomatous polyps and adenocarcinoma. The genotype frequency of DNMT3B polymorphism (T/T and G/T + G/G) in adenocarcinoma patients was significantly different from that in controls (P value = 0.01). Compared with DNMT3B T/T genotype, the G allelotype (G/T + G/G genotype) had lower risk to develop colorectal adenocarcinoma (OR = 0.50, 95% CI = 0.29-0.87); while there was no significant difference between the colorectal adenomatous polyps patients and controls (OR = 0.63, 95% CI = 0.37-1.09), although descending tendency could be found in this polyps group. In the stratification analysis, a significant association was confined to subgroups of age < 55 (OR = 0.31, 95% CI = 0.12-0.84) and males (OR = 0.35, 95% CI = 0.17-0.71). Meanwhile, combined G/T + G/G genotypes were found to have a lower risk in non-drinkers to develop both colorectal adenomatous polyps and adenocarcinoma (OR = 0.54, 95% CI = 0.31-0.96 and OR = 0.48, 95% CI = 0.27-0.84, respectively). This study also showed a distinct difference in the distribution of DNMT3B G39179T SNP in different ethnics. DNMT3B G39179T SNP may be a potential genetic susceptibility factor for adenocarcinoma of the colon, especially in younger Chinese Han non-drinker men.

Genetic variants of methyl metabolizing enzymes and epigenetic regulators: associations with promoter CpG island hypermethylation in colorectal cancer

Aberrant DNA methylation affects carcinogenesis of colorectal cancer. Folate metabolizing enzymes may influence the bioavailability of methyl groups, whereas DNA and histone methyltransferases are involved in epigenetic regulation of gene expression. We studied associations of genetic variants of folate metabolizing enzymes (MTHFR, MTR, and MTRR), DNA methyltransferase DNMT3b, and histone methyltransferases (EHMT1, EHMT2, and PRDM2), with colorectal cancers, with or without the CpG island methylator phenotype (CIMP), MLH1 hypermethylation, or microsatellite instability. Incidence rate ratios were calculated in case-cohort analyses, with common homozygotes as reference, among 659 cases and 1,736 subcohort members of the Netherlands Cohort Study on diet and cancer (n = 120,852). Men with the MTHFR 677TT genotype were at decreased colorectal cancer risk (incidence rate ratio, 0.49; P = 0.01), but the T allele was associated with increased risk in women (incidence rate ratio, 1.39; P = 0.02). The MTR 2756GG genotype was associated with increased colorectal cancer risk (incidence rate ratio, 1.58; P = 0.04), and inverse associations were observed among women carrying DNMT3b C-->T (rs406193; incidence rate ratio, 0.72; P = 0.04) or EHMT2 G-->A (rs535586; incidence rate ratio, 0.76; P = 0.05) polymorphisms. Although significantly correlated (P < 0.001), only 41.5% and 33.3% of CIMP tumors harbored MLH1 hypermethylation or microsatellite instability, respectively. We observed inverse associations between MTR A2756G and CIMP among men (incidence rate ratio, 0.58; P = 0.04), and between MTRR A66G and MLH1 hypermethylation among women (incidence rate ratio, 0.55; P = 0.02). In conclusion, MTHFR, MTR, DNMT3b, and EHMT2 polymorphisms are associated with colorectal cancer, and rare variants of MTR and MTRR may reduce promoter hypermethylation. The incomplete overlap between CIMP, MLH1 hypermethylation, and microsatellite instability indicates that these related "methylation phenotypes" may not be similar and should be investigated separately.

DNA methyltransferase 3B gene increases risk of early onset schizophrenia

OBJECTIVE

Consistent evidence indicated that aberrant DNA methylation may be involved in the development of schizophrenia. DNA methyltransferase 3B (DNMT3B) is the key methyltransferase in DNA methylation regulations. In this study, we investigated the association between DNMT3B polymorphisms and the susceptibility of early onset schizophrenia in Chinese Han population.

METHODS

Case-control (patients=381 and controls=472) and family based (trios=103) study was performed through genotyping two tag single nucleotide polymorphisms (rs2424908 and rs6119954) covering the whole DNMT3B gene. Single nucleotide polymorphism association and haplotype analysis were performed.

RESULTS

The frequency of G allele of rs6119954 was significantly higher in patients than that in controls (P=0.017). Genotype distribution of rs6119954 was significantly different between patients and controls (P=0.046). A haplotype-wise analysis revealed a higher frequency of the T-G (rs2424908-rs6119954) haplotype in patients than that in controls (P=0.033). In the transmission disequilibrium test analysis, G allele of rs6119954 was preferentially transmitted in the trios (P=0.030).

CONCLUSION

Our findings indicate that DNMT3B may be a candidate gene for susceptibility to early onset schizophrenia.

The MTHFR C677T and DeltaDNMT3B C-149T polymorphisms confer different risks for right- and left-sided colorectal cancer

Etiological risk factors for proximal (right-sided) colon cancers may be different to those of distal colon and rectal (left-sided) cancers if these tumors develop along distinct pathways. The CpG Island Methylator Phenotype (CIMP+) occurs in approximately 15% of colorectal cancers (CRC) and predominantly in the proximal colon. CIMP+ tumors have frequent methylation of gene promoter regions and increased tissue folate levels. The aim here was to determine whether polymorphisms in 2 genes involved in cellular methyl group metabolism were associated with different risks for right- and left-sided CRC. This population-based case-control study involved 859 incident cases of CRC and 973 sex and age-matched controls. Information on dietary folate and alcohol intake was obtained from food frequency questionnaires and information on the anatomical site of tumors from pathology reports. DNA was collected using FTA cards and genotyping performed for the MTHFR C677T and DeltaDNMT3B C-149T polymorphisms. The MTHFR 677 T allele was associated with increased risk for proximal colon cancer (adjusted odds ratio, AOR = 1.29) but decreased risk for distal cancers (AOR = 0.87). The increased risk for proximal cancers was especially pronounced in older individuals (AOR = 1.49) and those with a low folate diet (AOR = 1.67) or high alcohol consumption (AOR = 1.90). The DeltaDNMT3B-149 TT genotype was protective against proximal colon cancers (AOR = 0.65), but showed no association with the risk of distal colon and rectal cancers (AOR = 1.02). Epidemiological studies on dietary and genetic risk factors for CRC should take into account these may confer different risks for right- and left-sided tumors.

Polymorphisms of the DNMT3B gene and risk of squamous cell carcinoma of the head and neck: a case-control study

DNA-methyltransferase-3B (DNMT3B) may play an oncogenic role during tumorigenesis, and its genetic variants have been reportedly to be associated with risk of several cancers, but few studies have investigated their roles in squamous cell carcinoma of the head and neck cancer (SCCHN). Here we report a hospital-based case-control study with 832 SCCHN patients and 843 cancer-free controls of non-Hispanic whites that evaluated the association between two DNMT3B single nucleotide polymorphisms (SNPs) DNMT3B -149C>T (rs2424913) and DNMT3B -579G>T (rs2424909) in the promoter region and risk of SCCHN. We found that compared with C-allele carriers, the DNMT3B -149 TT genotype was statistically significantly associated with increased risk of SCCHN (adjusted OR, 1.35, 95% CI, 1.01-1.80, P=0.043), whereas the DNMT3B -579 TT genotype showed only a non-statistically significant risk compared with G-allele carriers. Further analysis of the effects of combined genotypes suggested that subjects with either DNMT3B -149 TT or DNMT3B -579 TT homozygous genotypes had statistically significantly increased risk of SCCHN (adjusted OR=1.36, 95% CI=1.07-1.73, P=0.013). Stratification analysis showed a more profound risk in the subgroups of the young (< or =57 years, the median age of the controls), males, current smokers, current drinkers, and patients with primary tumor sites of pharynx and larynx. This large study provides reliable risk estimates for associations between DNMT3B variants and SCCHN risk in non-Hispanic whites, and our findings are consistent with that of previously reported cancer case-control studies of other cancers. Further mechanistic studies are needed to unravel the underlying molecular mechanisms.

Promoter polymorphisms of DNMT3B and the risk of colorectal cancer in Chinese: a case-control study

BACKGROUND

DNA-methyltransferase-3B (DNMT3B), which plays a role in DNA methylation, is usually aberrant expression involved in carcinogenesis. Polymorphisms of the DNMT3B gene may influence DNMT3B activity on DNA methylation in several cancers, thereby modulating the susceptibility to cancer.

METHODS

DNMT3B -579G>T genotypes and -149C>T were determined by PCR-RFLP and sequencing in 137 colorectal cancer patients and 308 controls matched for age and sex, who did not receive radiotherapy or chemotherapy for newly diagnosed and histopathologically confirmed colorectal cancer. The association between two SNPs of the DNMT3B promoter and the risk of the development of colorectal cancer was analyzed in a population of Chinese.

RESULTS

The allele frequency of -149C >T among patients and controls was 0.73% versus 0.65%, respectively. The allele frequency of -597G>T for patients and controls was 6.57% versus 11.53%, respectively. Individuals with at least one -149C>T allele were no at a significantly increase risk of colorectal cancer compared with those having a -149TT genotype. However, Individuals with at least one 579G>T allele were decreased risk of colorectal cancer compared with those having a -579TT genotype.

CONCLUSION

The relative distribution of -149C>T DNMT3B SNPs among a Chinese population can not be used as a stratification marker to predict an individual's susceptibility to colorectal cancer. However, the DNMT3B -579G>T polymorphism may contribute to the genetic susceptibility to colorectal cancer.

DNMT3B 579 G>T promoter polymorphism and risk of esophagus carcinoma in Chinese

AIM

To investigate the relationship between 579 G>T polymorphisms in the DNMT3B gene, which is involved in de novo methylation and associated with the risk of esophagus cancer (EC) in Chinese.

METHODS

DNMT3B 579 G>T genotypes were determined by PCR-RFLP in 194 EC patients and 210 healthy controls matched for age and sex, who did not receive radiotherapy or chemotherapy for newly diagnosed and histopathologically confirmed EC.

RESULTS

In control subjects, the frequency of T/T and G/T genotypes, and T and G alleles was 81.4%, 18.1%, 90.05% and 9.55%, respectively. The distribution of genotypes and allelotypes in the EC patients was not significantly different from that in the controls. When stratified by sex and age, there was still no significant association between the risks of EC and GT and GG genotypes. This study also showed a distinct difference in the distribution of DNMT3B and single nucleotide polymorphism (SNP) between Chinese and Koreans.

CONCLUSION

DNMT3B 579 G>T polymorphism may not be a stratification marker to predict the susceptibility to EC, at least in Chinese. DNMT3B promoter SNP is diverse in ethnic populations.

DNA methyltransferase and alcohol dehydrogenase: gene-nutrient interactions in relation to risk of colorectal polyps

Disturbances in DNA methylation are a characteristic of colorectal carcinogenesis. Folate-mediated one-carbon metabolism is essential for providing one-carbon groups for DNA methylation via DNA methyltransferases (DNMTs). Alcohol, a folate antagonist, could adversely affect one-carbon metabolism. In a case-control study of colorectal polyps, we evaluated three single nucleotide polymorphisms (-149C>T, -283T>C, -579G>T) in the promoter region of the DNMT3b gene, and a functional polymorphism in the coding region of the alcohol dehydrogenase ADH1C gene, ADH1C *2. Cases had a first diagnosis of colorectal adenomatous (n = 530) or hyperplastic (n = 202) polyps at the time of colonoscopy, whereas controls were polyp-free (n = 649). Multivariate logistic regression analysis was used to estimate odds ratios (OR) and corresponding 95% confidence intervals (CI). There were no significant main associations between the DNMT3b or ADH1C polymorphisms and polyp risk. However, DNMT3b -149TT was associated with an increase in adenoma risk among individuals with low folate and methionine intake (OR, 2.00; 95% CI, 1.06-3.78, P interaction = 0.10). The ADH1C *2/*2 genotype was associated with a possibly elevated risk for adenomatous polyps among individuals who consumed >26 g of alcohol/d (OR, 1.95; 95% CI, 0.60-6.30), whereas individuals who were wild-type for ADH1C were not at increased risk of adenoma (P interaction = 0.01). These gene-diet interactions suggest that polymorphisms relevant to DNA methylation or alcohol metabolism may play a role in colorectal carcinogenesis in conjunction with a high-risk diet.