Decitabine Induces Cell Differentiation and Growth Inhibition that Accompanies Up-regulation of microRNA-143 and MS4A3 in MDS-derived leukemic cell line, MDS-L.. Decitabine Induces Cell Differentiation and Growth Inhibition that Accompanies Up-regulation of microRNA-143 and MS4A3 in MDS-derived leukemic cell line, MDS-L.

Myelodysplastic syndromes (MDS) are a group of clonal myeloid neoplasms characterized by ineffective hematopoiesis and cytopenia. Hypomethylating agents (HMAs) play a central role in the treatment of high-risk MDS, but their mechanisms of action are diverse and not fully understood. To investigate the molecular mechanisms of HMA, an MDS cell line (MDS-L) was cultured with a non-toxic concentration of decitabine for 6 months and drug sensitivity, cell differentiation, and DNA methylation profiles were evaluated. Cells with long-term exposure to decitabine (MDS-L-DAC) were morphologically mature with nuclear lobulation and cytoplasmic granulation, accompanied by decreased expression of the CD34 surface antigen. MDS-L-DAC cells exhibited decreased WT1 expression and intense induction of apoptosis by DAC. DNA methylation array analysis revealed the demethylation of the membrane spanning 4-domains A3 (MS4A3) genes and microRNA-143 (MIR143) in MDS-L-DAC cells. MIR143 functions as a tumor suppressor through the MAPK/ERK pathway, and in MDS-L-DAC cells, decreased expression of KRAS and β-catenin was observed in response to the increased expression of MIR143. The differentiation of MDS cells and decreased expression of WT1 induced by long-term incubation with DAC may involve the restoration of function via demethylation of the MIR143 and MS4A3 gene promoters, which may contribute to eliminating the malignant phenotype through reductions in KRAS and β-catenin expression. Overall design: We investigated the mechanisms of DAC-induced demethylation and expression restoration of tumor suppressor genes via studies in the MDS-derived leukemic cell line MDS-L. Long-term culture with DAC was conducted for downstream methylation array analysis and the identification of factors involved in cell differentiation and cell death. When DAC was applied at a low concentration, the intracellularly converted active metabolite 5-aza-dCTP was subsequently incorporated into DNA, resulting in the inhibition of DNA synthesis and the consequent induction of apoptosis. Our results may indicate the mechanism underlying HMA-induced expression restoration and differentiation in MDS-L cells. Submitters state that output from Illumina's GenomeStudio (HM450_Report_191-1.txt) is provided as raw data since IDAT files are unavailable.