fa قلب Heart پژوهشي Research <div><strong>Background: </strong>6-thioguanine (6-TG) is one of the thiopurine drugs with successful use in oncology, especially for acute lymphoblastic leukemia (ALL). 6-TG is proposed to act as an epigenetic drug affecting DNA methylation. The aim of this study was to clarify the effect of 6-TG on the proliferation, viability and expression of genes coding for the enzymes DNA methyltransferase 3A and DNA methyltransferase 3B (DNMTs) as well as histone deacetylase 3 (HDAC3) in the human B cell-ALL cell line Nalm6.<br> <strong>Materials and Methods: </strong>In this experimental study, Nalm6 cells and also normal peripheral blood mononuclear cells (PBMCs) were grown in RPMI 1640 medium containing 10% fetal bovine serum. They were then treated with 6-TG at their exponential growth phase. Cell viability was monitored using the Cell Counting Kit-8 assay with an enzyme-linked immunosorbent assay (ELISA) reader. The expressions of the above-mentioned 3 genes were quantified using real-time PCR.<br> <strong>Results: </strong>6-TG could inhibit the proliferation of Nalm6 cells and decrease their viability. In Nalm6 cells, as compared to normal PBMCs, 6-TG significantly decreased HDAC3 (p = 0.008) as well as DNMT3B (p = 0.003) gene expressions, but increased the expression of DNMT3A gene (p = 0.02) after normalization to GAPDH, as the housekeeping gene.<br> <strong>Conclusion: </strong>These findings suggested that the altered expression of DNMT3A, DNMT3B and HDAC3 genes was responsible for at least part of the antitumoral properties of 6-TG, providing an insight into mechanism of its action as an epigenetic drug.<br> &nbsp;</div> DNA methyltransferase, Histone deacetylase, Leukemia, Thioguanine, Thiopurine 28 37 http://ijpho.ssu.ac.ir/browse.php?a_code=A-10-722-2&slc_lang=fa&sid=1 Tohid Rostamian No Department of Biochemistry and Molecular Biology, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Shahid Sadoughi University of Medical Sciences Fatemeh Pourrajab 0000-0002-1724-5392 No Department of Biochemistry and Molecular Biology, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Shahid Sadoughi University of Medical Sciences Seyedhossein Hekmatimoghaddam 0000-0001-9859-375 Yes Hematology & Oncology Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Shahid Sadoughi University of Medical Sciences