Abstract. The DNA methyltransferase (Dnmt) inhibitor and demethylating agent 5-aza-2'-deoxycytidine (5azadC) has been used to induce cellular differentiation and gene activation. It has been approved for treating several kinds of malignancies due to its ability to reactivate silenced tumor suppressor genes. Considering the potential effect of 5azadC on non-targeted genomic regions in normal cells, we investigated its effect on repetitive sequences and selected gene loci, Sall3, Per1, Clu, Dpep1 and Igf2r, including tissue-dependent and differentially methylated regions, by treating mouse NIH/3T3 fibroblast cells with concentrations of 5azadC ranging from 0.001 to 5 μM. Demethylation of minor satellite repeats and endogenous viruses was concentration dependent, and the demethylation was strong at 1 and 5 μM. In genic regions, the methylation level decreased only at 0.1 μM, but was minimally altered at concentrations lower or higher, regardless of the abundance of CpG sites. Thus, repeats are strongly demethylated, but genic regions are only demethylated at effective doses. Genes were activated by 5azadC treatment and were accompanied by a unique combination of histone modifications in genic regions, including an increased level of H3K9me3 and a decreased level of AcH3. Increase of H3K9me3 in genic regions was not observed in Dnmt knock out cells. We identified differential effects of 5azadC on repetitive sequences and genic regions and revealed the importance of choosing appropriate 5azadC doses to achieve targeted gene recovery. Key words: 5-aza-2'-deoxycytidine, Decitabine, DNA methylation, Epigenetics, Histone modification (J. Reprod. Dev. 56: [86][87][88][89][90][91][92][93] 2010) NA methylation is one of the epigenetic events associated with gene regulation and function. Hypermethylation of promoter regions of tumor suppressor genes causes silencing of the genes that lead to cancer [1][2][3]. Thus, reversing the methylation status of gene promoters to their prevalent methylation states has become a treatment option for certain cancer types. To date, there are many types of demethylating agents that have been shown to inhibit promoter methylation and reactivate silenced genes [4][5][6]. Some of these have been approved or are in clinical studies to be developed as cancer drugs [7].The cytosine analog 5-aza-2'-deoxycytidine (5azadC), also known as decitabine, has been widely used as a DNA methyltransferase (Dnmt) inhibitor to reverse aberrant hypermethylation [8,9]. It has been approved for hematological malignancies, showing favorable results with low dose treatment [10,11]. Known to have dual modes of action, 5azadC at low doses induces gene hypomethylation, whereas high doses of 5azadC induce cytotoxicity and cause severe side effects in patients [12,13].Nearly 40% of the mouse genome is composed of repetitive sequences including different classes of interspersed repeats, such as LINEs, SINEs, LTR elements and satellites, that are mainly found in heterochromatin regions [14]. Most repeats are densely m...
Epigenetics is fundamental to the development and maintenance of cellular phenotypes. Epigenetic status is inherited by the next cell generation and is changeable during the process of cellular differentiation. DNA methylation, in association with histone modifications and chromatin condensation, is a major epigenetic event that causes gene silencing. Every cell type or tissue has a unique DNA methylation profile comprising at least thousands of tissue-dependent differentially methylated regions (T-DMRs), suggesting that the epigenetic changes at T-DMRs underlie cellular differentiation. Genome-wide epigenetic information is called the epigenome. Disruption of the normal epigenome produces aberrant cells with prolonged abnormal phenotypes. Epimutation may be more common than previously thought considering there are numerous T-DMRs in the mammalian genome. Mutation and epimutation are inherited by the next cell generation, and both continue throughout life. However, epimutation is reversible, and drug treatment could potentially reverse the epigenetic status. Analysis of the epigenome will provide insight into novel advances in diagnosis and treatment of, as well as drug development for, complex chronic diseases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.