Selective and Titratable Effects On AML Genome Wide Methylation Patterning, Transcription and Clonogenicity Using Very Low Concentrations of 5-Aza-2'deoxycytidine.

Abstract 2385

Poster Board II-362

5-Aza-2'deoxycytidine (5AzadC) has significantly contributed to the treatment of myelodysplatic syndromes (MDS) and acute myeloid leukemia (AML). But while the cytotoxic effects of 5AzadC have been well characterized, its influence on methylation-induced cellular reprogramming remains poorly understood. We have treated several AML cell lines at extremely low concentrations of 5AzadC (0 nM to 1.0 nM) over the course of three days, followed by the determination of genome wide methylation changes, alterations in transcription profiles as well as cell viability, proliferation, apoptosis and changes in clonogenicity. The results demonstrate titratable responses on both genomic methylation and transcriptional patterns as well as a selective effect on clonogenicity compared to cytotoxicity. An alternative chemotherapeutic cytosine analog, cytosine arabinofuranoside (AraC), does not show the same selective depletion of clonogenic cells, suggesting that 5AzadC's effects are likely due to altered epigenetic changes associated with cellular reprogramming rather than a direct cytotoxic effect. We are currently evaluating 5AzadC and AraC effects on this population using immunophenotyping methods as well as xenograft models of tumorigenicity. These findings describe a potential role for very low concentrations of 5AzadC in treating acute myeloid leukemia through a selective affect on genome wide methylation patterns leading to altered transcription that differentially effects the clonogenic, leukemic stem cell compartment.