background: high-grade astrocytoma (grade 4) or glioblastoma multiforme (gbm) are deadly brain tumors. new therapies attempt to increase lifetime and quality of life in patients with malignant astrocytoma. o6-methylguanine-dna methyltransferase (mgmt) enzyme expression may be effective in prognosis and response to treatment of these patients. the aim of this study was assessment of mgmt enzyme ...

Objective DNA methylation is one the epigenetic mechanisms, which is critically involved in gene expression. This phenomenon is mediated by DNA methyl-transferases and is affected by environmental stress, including in vitro maturation (IVM) of oocytes. Melatonin, as an antioxidant, may theoretically be involved in epigenetic regulation via reductions of reactive oxygen species. This study was p...

aim :  to evaluate the association of dnmt1 and mgmt amino acid substitution polymorphisms and colorectal cancer in iranian population. background : the mgmt and dnmt1 are two important methyltransferase enzymes. amino acid substitution polymorphisms in mgmt and dnmt1 genes may be associated with the genetic susceptibility to sporadic colorectal cancer. patients and methods : we assessed eight ...

Background Genomic imprinting is a heritable and developmentally essential phenomenon by which gene expression occurs in an allele-specific manner1. While the imprinted alleles are primarily silenced by DNA methylation, it remains largely unknown how methylation is targeted to imprinting control region (ICR), also called differentially methylated region (DMR), and maintained. Here we show that ...

OBJECTIVES Previous studies found higher expression levels of DNA methyltransferase 1 in liver samples from smokers compared to those from non-smokers. In contrast, expression levels of DNA methyltransferase 3a and DNA methyltransferase 3b were similar in smokers and non-smokers. This study extends these studies to establish a causal linkage to cigarette smoke exposure by examining whether DNA ...

We have used a combination of genetics and pharmacology to assess the effects of reduced DNA methyltransferase activity on ApcMin-induced intestinal neoplasia in mice. A reduction in the DNA methyltransferase activity in Min mice due to heterozygosity of the DNA methyltransferase gene, in conjunction with a weekly dose of the DNA methyltransferase inhibitor 5-aza-deoxycytidine, reduced the aver...

DNA methyltransferase 1, 3a, and 3b affect DNA methylation, and it is thought that they play an important role in the malignant transformation of various cancers. The current study was designed to analyze DNA methyltransferase expression by immunohistochemistry in a series of 94 Tunisian sporadic breast carcinomas. Results were correlated to clinicopathologic parameters and promoter methylation...

The molecular basis of aberrant hypermethylation of CpG islands observed in a subset of human colorectal tumors is unknown. One potential mechanism is the up-regulation of DNA (cytosine-5)-methyltransferases. Recently, two new mammalian DNA methyltransferase genes have been identified, which are referred to as DNMT3A and DNMT3B. The encoded proteins differ from the predominant mammalian DNA met...

The molecular basis of aberrant hypermethylation of CpG islands observed in a subset of human colorectal tumors is unknown. One potential mechanism is the up-regulation of DNA (cytosine-5)-methyltransferases. Recently, two new mammalian DNA methyltransferase genes have been identified, which are referred to as DNMT3A and DNMT3B. The encoded proteins differ from the predominant mammalian DNA met...