Figure 2

Inhibition of FLT-3 results in downregulation of mTOR signaling, accompanied by decreased survival of AML cells harboring mutated FLT-3. A. Pharmacologic inhibition by the FLT3-specific inhibitor GTP14564 resulted in a concentration-dependent downregulation of downstream mTOR mediators in the FLT3-mutated AML cell lines MV4-11, and MOLM13, with no effect on the Wt-FLT3 U937 cell line, 48 hours after treatment. However, note that pAKT is minimally affected in all three cell lines. B. Treatment of homozygously mutated-FLT3 MV4-11 cells with increasing concentrations of GTP14564 (up to 5 uM) resulted in dose-dependent decrease in cell proliferation, up to 33%, and apoptotic cell death was increased, up to 15%. Concentrations up to 1 uM had no significant effect on survival and the proliferation of the heterozygously FLT3-mutated MOLM13 cells. However, after treatment with 5 uM GTP14564, the proliferation of MOLM13 cells was decreased, up to 44%, and apoptotic cell death was increased, up to 19%. GTP14564 had no significant antitumor activity against Wt-FLT3 U937 cells (p < 0.05). C. Pharmacologic inhibition of FLT-3 by increasing concentrations of GTP14564 (up to 5 uM) resulted in a concentration-dependent decrease of cell viability, up to 31% (after 72 hours) (left panel, p < 0.05), accompanied by downregulation of mTOR signaling, as shown by Western blot analysis (right panel) in FLT3-mutated primary AML cells.