| Summary: | Epigenetic mechanisms are essential for normal cell development. Alteration in those normal processes leads to malignant cell transformation and with this to cancer development. Use of inhibitors that alter the epigenetics of DNA methylation and histone post translational modifications has lead to the exploration of the epigenetic mechanism involved in silencing of tumor suppressor genes in cancer, including acute myeloid leukemia (AML). Moreover, combinations of inhibitors that target various epigenetic enzymes have being recognized to be more effective in the re-activation of tumor suppressor genes than individual drug treatments. Here, we reported that p15, p21 and E-cadherin genes are more effectively re-expressed using a combination of DNA methyltransferase and histone methyltransferase inhibitors in AML cell lines. Re-expression of hypermethylated p15 and E-cadherin genes required reduced levels of promoter histone 3 lysine 9 (H3K9) methylation rather than inhibition of DNA methylation itself. Moreover, induction of p21 expression was associated with changes in promoter histone 3 lysine 9 methylation (H3K9Me) by achieving inhibition of the histone methyltransferase, SUV39H1, activity. Altogether, our results highlight the potential of combining epigenetic drugs in the re-activation of epigenetically silenced tumor suppressor genes and the need for evaluating histone methyltransferases as therapeutic targets for treatment of acute myeloid malignancies.
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