PP2A activators in combination with the BCL2 inhibitor venetoclax exhibits synergistic antileukemic activity in AML cell lines in vitro and in vivo. Bar graphs show the reduction of venetoclax IC50 values (A) or A-1331852 (BCL-XL inhibitor) IC50 values (B) when combined with FTY720 in a panel of 14 AML cell lines (48 hours of treatment). (C) Heatmap representations of viability percentages and CI values along with cell viability curves of combined PP2A-activating drugs FTY720 or CM-1231 with venetoclax at increasing concentrations (48 hours of treatment). Dashed rectangles highlight data represented in the next graph. (D) After 24 hours of treatment, stained AML cells were injected into the yolk sac of dechorionated Casper zebrafish embryos (48 hours postfecundation). Proliferation and colonization analyses were performed at 72 hours postinjection (hpi). (E) Quantification of cell proliferation and colonization potential of AML cell lines injected into zebrafish embryos after drug exposure. All experiments were done in triplicate; the number of embryos used is indicated as “n.” Proliferation fold change (line graphs) was calculated as the difference between fluorescent readouts at 2 and 72 hpi. Statistical significance was determined by two-way ANOVA, followed by Tukey post hoc test for multiple comparisons. For analysis of colonization potential (bar graphs), zebrafish embryos were categorized into invasion or noninvasion groups. Data were analyzed by χ2 tests; ∗P < .05, ∗∗P < .01, ∗∗∗P < .001. ANOVA, analysis of variance; ns, not statistically different.
