Targeting SIRT1 sensitizes AML cell lines and primary AML patient cells to TKI treatment. (A) Cell proliferation assay of Molm-14 (black bars) and MV4-11 (white bars). Cells were treated with PKC412 (35 nM), TV-6 (2 and 1 µM, respectively), or a combination for 48 hours. Shown are mean values ± SD of 3 independent experiments. (B) Molm-14 and MV4-11 cells were treated with PKC412, TV-6 (top), or EX527 (bottom) or in combination, as indicated. The percentage of apoptotic cells was determined by Annexin V expression. Shown are mean values ± SD of 3 independent experiments. (C) Molm-14 (left) and MV4-11 (right) cells were transduced with lentiviral vectors expressing a doxycycline-inducible nonsilencing miR-shRNA (shScr) or a miR-shRNA targeting SIRT1 (shSIRT1-1 and shSIRT1-2), incubated with doxycycline for 72 hours, followed by PKC412 treatment, as indicated. The percentage of sub-G1 cells corresponding to apoptotic cells was determined by flow cytometry. Data represent mean values ± SD of 3 independent experiments. (E) Primary AML blasts were treated with PKC412, TV-6, and daunorubicin alone or in combination for 48 hours, as indicated. The percentage of apoptotic cells in blast gate was determined by Annexin V expression. Shown is the pooled analysis of apoptotic cell death in primary AML samples treated with PKC412 (n = 5) or daunorubicin (DNR; n = 3) with and without TV-6. *P < .05; **P < .01; ***P < .001; unpaired Student t test. (F) Kaplan-Meier survival curves of NSG mice transplanted with MV4-11 cells expressing either a doxycycline-inducible nonsilencing miR-shRNA or a miR-shRNA targeting SIRT1. Oral doxycycline treatment was initiated 10 days after transplantation, treatment with PKC412 (100 mg/kg per day) by oral gavage was started 15 days after transplantation. *P < .05, **P < .01, ***P < .001; log-rank test.