Decitabine priming enhances selinexor antileukemic effects in vitro. (A) CI plots of decitabine (DAC) with selinexor. The effect of the combinations was assessed by WST-1 assay after initial priming with DAC (24 hours) followed by selinexor treatment for 24 hours. The doses for both drugs were chosen according to their individual IC₅₀ (twofold dilutions), which were determined by using the WST-1 assay (supplemental Table 1). Because DAC was given for 48 hours, we determined the DAC IC₅₀ at 48 hours. The IC₅₀ for selinexor was determined at 24 hours because the treatment with this drug was shorter. The effects of the combinations were calculated by using CalcuSyn software, where CI < 1 indicates synergy, CI = 1 is additive, and CI > 1 is antagonistic. (B) Schematic illustrating the hypothesis. (C) Fold change in CDKN1A and FOXO3a messenger RNA (mRNA) expression by real-time polymerase chain reaction (PCR) (24 hours) and western blot (48 hours) of the same to show change in protein expression. (D) WST-1 assay of cell lines treated with control or lentiviral vector expressing CDKN1A (p21) followed by selinexor treatment. (E) WST-1 assay of cell lines treated with control or lentiviral vector expressing FOXO3A followed by selinexor treatment. Selinexor was introduced to cell culture 24 hours after transfection. Assays were performed at indicated time points.