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      Azacitidine regulates DNA methylation of GADD45γ in myelodysplastic syndromes

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          Abstract

          Background

          Myelodysplastic syndrome (MDS) is a heterogeneous clonal disease originated from hematopoietic stem cells. Epigenetic studies had demonstrated that DNA methylation and histone acetylation were abnormal in MDS. Azacitidine is an effective drug in the treatment of demethylation.

          Methods

          RT‐PCR was performed to determine GADD45γ in 15 MDS clinical samples. Myelodysplastic syndrome cell lines SKM‐1 and HS‐5 were transfected with GADD45γ eukaryotic expression vector and/or GADD45γ shRNA interference plasmid, and treated with azacitidine. Proliferation and apoptosis were examined by CCK‐8 and Western blot analysis to confirm the function role of GADD45γ and azacitidine. The methylation level of GADD45γ gene was detected by bisulfite conversion and PCR.

          Results

          This study found that GADD45γ gene was down‐expressed in MDS patients' bone marrow and MDS cell lines, and the down‐regulation of GADD45γ in MDS could inhibit MDS cell apoptosis and promote proliferation. Azacitidine, a demethylation drug, could restore the expression of GADD45γ in MDS cells and inhibit the proliferation of MDS cells by inducing apoptosis, which was related to prognosis and transformation.

          Conclusion

          This study indicated that GADD45γ was expected to become a new target of MDS‐targeted therapy. The findings of this study provided a new direction for the research and development of new MDS clinical drugs, and gave a new idea for the development of MDS demethylation drug to realize precise treatment.

          Abstract

          Azacitidine Induce MDS cell apoptosis.

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          Most cited references37

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          DNA methylation: past, present and future directions.

          DNA methylation, or the covalent addition of a methyl group to cytosine within the context of the CpG dinucleotide, has profound effects on the mammalian genome. These effects include transcriptional repression via inhibition of transcription factor binding or the recruitment of methyl-binding proteins and their associated chromatin remodeling factors, X chromosome inactivation, imprinting and the suppression of parasitic DNA sequences. DNA methylation is also essential for proper embryonic development; however, its presence can add an additional burden to the genome. Normal methylation patterns are frequently disrupted in tumor cells with global hypomethylation accompanying region-specific hypermethylation. When these hypermethylation events occur within the promoter of a tumor suppressor gene they will silence the gene and provide the cell with a growth advantage in a manner akin to deletions or mutations. Recent work indicating that DNA methylation is an important player in both DNA repair and genome stability as well as the discovery of a new family of DNA methyltransferases makes now a very exciting period for the methylation field. This review will highlight the major findings in the methylation field over the past 20 years then summarize the most important and interesting future directions the field is likely to take in the next millennium.
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            Myelodysplastic syndromes: Contemporary review and how we treat.

            Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal stem cell disorders with an inherent tendency for leukemic transformation. Diagnosis is currently based on the presence of peripheral blood cytopenias, peripheral blood and bone marrow dysplasia/blasts, and clonal cytogenetic abnormalities. With the advent of next generation sequencing, recurrent somatic mutations in genes involved in epigenetic regulation (TET2, ASXL1, EZH2, DNMT3A, IDH1/2), RNA splicing (SF3B1, SRSF2, U2AF1, ZRSR2), DNA damage response (TP53), transcriptional regulation (RUNX1, BCOR, ETV6) and signal transduction (CBL, NRAS, JAK2) have been identified in MDS. Conventional prognostication is by the revised International prognostic scoring system (IPSS-R) with additional adverse prognosis conferred by presence of ASXL1, EZH2, or TP53 mutations. Currently Food and Drug administration (FDA)-approved drugs for the treatment of MDS are not curative and their effect on survival is limited; they include the hypomethylating agents (HMA) azacitidine and decitabine and lenalidomide for MDS with isolated del(5q). To date, allogeneic stem cell transplant (ASCT) remains the only treatment option for possible cure. Given the current lack of drugs with convincing evidence of favorable effect on survival, we consider ASCT as the treatment of choice for most patients with symptomatic disease, and especially for those with high-risk disease. For nontransplant candidates, participation in clinical trials is preferred over conventional therapy. There is not one right way of treatment for patients who are not candidates for either ASCT or clinical trials and palliative drugs of choice depend on the clinical problem, such as symptomatic anemia (ESAs, danazol, HMA), thrombocytopenia (HMA), or neutropenia (myeloid growth factors). Conversely, there is no controlled evidence to support the use of iron chelating agents in MDS. Going forward, we believe it is time to incorporate mutation information in clinically derived prognostic models in MDS and encourage development of novel drugs with disease-modifying activity.
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              The stress-responsive gene GADD45G is a functional tumor suppressor, with its response to environmental stresses frequently disrupted epigenetically in multiple tumors.

              The CpG island of GADD45G was identified as a target sequence during the identification of hypermethylated genes using methylation-sensitive representational difference analysis combined with 5-aza-2'-deoxycytidine demethylation. Located at the commonly deleted region 9q22, GADD45G is a member of the DNA damage-inducible gene family. In response to stress shock, GADD45G inhibits cell growth and induces apoptosis. Same as other GADD45 members, GADD45G is ubiquitously expressed in all normal adult and fetal tissues. However, its transcriptional silencing or down-regulation and promoter hypermethylation were frequently detected in tumor cell lines, including 11 of 13 (85%) non-Hodgkin's lymphoma, 3 of 6 (50%) Hodgkin's lymphoma, 8 of 11 (73%) nasopharyngeal carcinoma, 2 of 4 (50%) cervical carcinoma, 5 of 17 (29%) esophageal carcinoma, and 2 of 5 (40%) lung carcinoma and other cell lines but not in any immortalized normal epithelial cell line, normal tissue, or peripheral blood mononuclear cells. The silencing of GADD45G could be reversed by 5-aza-2'-deoxycytidine or genetic double knockout of DNMT1 and DNMT3B, indicating a direct epigenetic mechanism. Aberrant methylation was further frequently detected in primary lymphomas although less frequently in primary carcinomas. Only one single sequence change in the coding region was detected in 1 of 25 cell lines examined, indicating that genetic inactivation of GADD45G is very rare. GADD45G could be induced by heat shock or UV irradiation in unmethylated cell lines; however, this stress response was abolished when its promoter becomes hypermethylated. Ectopic expression of GADD45G strongly suppressed tumor cell growth and colony formation in silenced cell lines. These results show that GADD45G can act as a functional new-age tumor suppressor but being frequently inactivated epigenetically in multiple tumors.
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                Author and article information

                Contributors
                Listar1588@126.com
                Journal
                J Clin Lab Anal
                J Clin Lab Anal
                10.1002/(ISSN)1098-2825
                JCLA
                Journal of Clinical Laboratory Analysis
                John Wiley and Sons Inc. (Hoboken )
                0887-8013
                1098-2825
                20 October 2020
                February 2021
                : 35
                : 2 ( doiID: 10.1002/jcla.v35.2 )
                : e23597
                Affiliations
                [ 1 ] Department of Hematology The First Affiliated Hospital of Bengbu Medical College Bengbu City China
                [ 2 ] Department of Respiratory and Critical Care Medicine The First Affiliated Hospital of Bengbu Medical College Bengbu China
                Author notes
                [*] [* ] Correspondence

                Dianming Li, Department of respiratory and critical care medicine, The First Affiliated Hospital of Bengbu Medical College, Bengbu, China

                Email: Listar1588@ 123456126.com

                Author information
                https://orcid.org/0000-0002-1279-1319
                Article
                JCLA23597
                10.1002/jcla.23597
                7891504
                33080073
                46cfad0f-78f1-4c24-a277-e5259511475d
                © 2020 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC

                This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

                History
                : 15 May 2020
                : 30 August 2020
                : 04 September 2020
                Page count
                Figures: 5, Tables: 1, Pages: 9, Words: 5793
                Funding
                Funded by: Key Natural Science Research Projects of Anhui Education Department
                Award ID: KJ2019A0375
                Categories
                Research Article
                Research Articles
                Custom metadata
                2.0
                February 2021
                Converter:WILEY_ML3GV2_TO_JATSPMC version:5.9.7 mode:remove_FC converted:18.02.2021

                Clinical chemistry
                azacitidine,gadd45γ,mds
                Clinical chemistry
                azacitidine, gadd45γ, mds

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