Activation of Expression of p15, p73 and E-Cadherin in Leukemic Cells by Different Concentrations of 5-Aza-2’-Deoxycytidine (Decitabine)

Abstract

Background: Inactivation of genes that suppress neoplasia by aberrant DNA methylation is a key event that occurs during the development of leukemia. The inhibitor of DNA methylation, 5-aza-2’-deoxycytidine (5AZA), which can re-activate these genes, is under clinical investigation for therapy of leukemia. The objective of this study was to determine the concentrations of 5AZA that will re-activate target silent genes in human leukemic cell lines. Materials and Methods: RT-PCR was used to evaluate the effect of concentrations of 1 to 100 ng/ml of 5AZA on the reactivation of p15 and p73 in KG1a myeloid leukemic cells and Ecadherin in HL-60 myeloid leukemic cells. The effect of 5AZA on inhibition of growth, DNA synthesis and colony formation in these cell lines was also investigated. Results: The extent of activation of the target genes was dependent on the concentration of 5AZA. For p15, pronounced activation was observed at 10 ng/ml or greater. For p73 and E-cadherin significant activation was observed at 100 ng/ml of 5AZA. Maximal inhibition of growth, DNA synthesis and colony formation occurred at 100 ng/ml. Conclusion: The in vitro antineoplastic and gene re-activation activity of 5AZA is dependent on the concentration of this analog. These data may be helpful in the design of the optimal dose-schedule of 5AZA for the clinical therapy of leukemia.