Epigenetic reactivation of GLI3 increases sensitivity to the SMO antagonist PF-04449913 in AML. (A-B) Treatment with the demethylating agent DAC increases GLI3R protein levels in AML cell lines. K562 and KG1a cells (low basal GLI3 levels) were cultured in the presence of DAC (1 nM) for 5 days with the drug replaced daily, and cell lysates were subjected to immunoblotting for GLI3 levels. Glyceraldehyde-3-phosphate dehydrogenase was used as loading control. (C-D) K562 and KG1a cells were treated with DAC (1 nM) for 5 days followed by PF-04449913 (100 nM) treatment for 2 days. Cell proliferation was measured by using trypan blue assay. *P < .05. (E-J) Primary AML blasts were treated ex vivo with DAC and PF-04449913. DAC sensitizes AML blasts to PF-04449913 by reducing cell viability and downregulating GLI1 expression. *P < .05. (K) Kaplan-Meier survival curve of mice transplanted with K562 cells and treated with vehicle (n = 6), PF-04449913 (n = 5), DAC alone (n = 6), and a combination of PF-04449913 and DAC (n = 6).