Epigenetic effects of decitabine on acute lymphoblastic and acute promyelocytic leukemia cells

Background: Decitabine (5-aza-2'-deoxycytidine, DAC) is a deoxycytidine analog currently used as an effective drug against myelodysplastic syndromes and acute myeloid leukemia. Although various studies have pointed out the epigenetic effects of this drug, its epigenetic mechanisms in different leukemic cell lines are not specified. In this lab trial study, possible epigenetic effects of decitabine on leukemia cell lines Hl-60 (acute promyelocytic leukemia) and Nalm-6 (acute pre-B cell lymphoblastic leukemia) vs. normal peripheral blood mononuclear cells (PBMCs) are compared. Materias and Methods: At the logarithmic phase of growth, the cultured cells Hl-60 and Nalm-6 obtained from Tehran Pasteur Institute, Iran, were treated for 24 hr with 1 μM of decitabine, a dose selected from literature and the MTT viability assay. Normal PBMCs were obtained from a pool of 3 healthy adult volunteer males, and cultured simultaneously in the same manner. The gene expressions of epigenetic enzymes DNA methyltransferases (DNMTs) were assessed with the real-time PCR technique before and after treatment. The GAPDH gene expression served as the calibrator, while normal PBMCs were used for comparison. Results: The expressions of DNMT1 and DNMT3B in lymphoblasts were significantly (p=0.0017 and p=0.0489, respectively) decreased after treatment with decitabine, while the expression of DNMT3A was significantly (p=0.0022) increased. In leukemic promyelocytes the expressions of DNMT1 and DNMT3B in lymphoblasts were significantly (p=0.0222 and p=0.0452, respectively) decreased after treatment with decitabine, while the expression of DNMT3A was significantly (p=0.0013) increased. Conclusion: One of the mechanisms by decitabine to inhibit the proliferation of both myeloid and lymphoid acute leukemia cells maybe by altering the gene expression of DNMTs.