Abstract 191: Azacitidine induces differentiation of acute myeloid leukemia cell lines along the granulocytic/monocytic lineage

Abstract

Acute myeloid leukemia (AML) is characterized by blast cells that are unable to mature into functional, terminally-differentiated hematopoietic cells. Inducing leukemic cells to differentiate restores a natural cell death program and inhibits proliferation. Azacitidine (AZA; 5-azacytidine; Vidaza) is a cytidine nucleoside analog used clinically for the treatment of myelodysplastic syndromes (MDS) and AML. AZA therapy was recently shown to significantly increase median overall survival in higher-risk MDS and World Health Organization AML (20-30% bone marrow blasts) patients compared with conventional care regimens, and a phase III clinical trial of AZA in patients with more advanced AML has been activated. We have shown previously that AZA induces dose-dependent cytotoxicity to AML cell lines; however, at sub-micromolar AZA concentrations, complete cell kill is not achieved. To explore an additional anti-leukemic mechanism of AZA in AML, we assessed the effect of AZA on induction of AML cell differentiation in vitro. AML cell lines, encompassing several FAB classifications, were evaluated, using all-trans retinoic acid (ATRA) and 1,25-dihydroxyvitamin D3 (VD3), two potent inducers of AML cell differentiation, as control compounds. Differentiation along the granulocytic/monocytic lineage was assayed by CD11b expression (antigen detection by flow cytometry and mRNA by Luminex) and nitroblue tetrazolium (NBT) reduction. ATRA, VD3, and AZA induced CD11b RNA and protein expression and NBT reduction in HL-60 and AML-193 cell lines. Gene expression profiles (GEPs) in HL-60 and AML-193 cells revealed significant overlap in the genes regulated by AZA-treatment vs. VD3- or ATRA-treatment. GEPs of HL-60 and AML-193 cells treated with AZA strongly correlated with publicly-available gene sets representing differentiated eosinophils, neutrophils, and monocytes, but negatively correlated with those of differentiated erythrocytes and megakaryocytes. Similar studies in primary AML cells are ongoing. Our results demonstrate that AZA can induce cellular differentiation of AML cell lines along the granulocytic/monocytic lineage in vitro, and suggest that cellular differentiation may contribute as one of multiple mechanisms of AZA's anti-leukemic activity in vivo. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 191.

Synergistic Antioncogenic Activity of Azacitidine and Curcumin in Myeloid Leukemia Cell Lines and Patient Samples

“…Azacitidine (AZA) is a hypomethylating agent that inhibits DNA methyltransferase at sufficiently low doses to avoid cytotoxicity, and can reverse the transcriptional silence of tumor-suppressor genes. It has also been observed, in leukemic cell assays, that restoration of methylation by AZA inhibits growth, induces apoptosis, alters cell cycle and promotes differentiation (2)(3)(4). The use of AZA is currently approved by the Food and Drug Administration and European Medicines Agency for use in MDS and in older patients (≥65 years) with newly diagnosed AML.…”