Figure 6.

Jak1/2 inhibition synergizes in vitro and in vivo with LSD1 inhibition. (A) Number of colonies formed by SET-2 cells, treated either with DMSO, IMG-7289 (25 nM, 50 nM) or ruxolitinib (175 nM) alone or both drugs in combination, as indicated (n = 3 independent experiments). (B) Quantification of apoptosis in SET-2 cells, treated as indicated, detected with FACS for either Annexin V (left) or Annexin V and PI staining (right) (n = 2 independent experiments, each in duplicate). (C) Hematological parameters in peripheral blood of Jak2^V617F mice treated either with vehicle, IMG-7289, ruxolitinib, or IMG-7289 and ruxolitinib (n = 6–9 mice per group). White blood cell (WBC, top left) count, platelet counts (PLT, top right), RBC count (bottom left), and reticulocytes (bottom right). Gray bars depict the normal range for each parameter (except for RBCs, where the normal range is below 10⁷/μL). (D) BM cells were stained with antibodies against a cocktail of lineage markers as well as against c-kit, Sca-1, CD34, Fc-γR, and Flt3/Flk2. Hematopoietic cell populations, defined as previously described,^51,52,55 are depicted as a percentage of total BM cells. Lineage⁻, c-kit⁺, Sca-1⁺ (LSK) cells (left), long-term hematopoietic stem cell (LT-HSC, second to left), short-term hematopoietic stem cell (ST-HSC, second to right) and multipotent progenitor (MPP, right). n = 6 to 8, as indicated. (E) Colony formation of BM from treated Jak2^V617F mice. Colony-forming unit (CFU) granulocyte, erythrocyte, monocyte, megakaryocyte (GEMM, left), burst-forming unit erythrocyte (BFU-E, middle), and CFU granulocyte, monocyte (CFU-GM, right). n = 2 to 3 (each in duplicate). (F) Spleen weight of treated Jak2^V617F mice. n = 6 to 7, as indicated. (A–F) Mean and standard error of mean are shown. Statistical analysis was conducted using Student t tests with Welch correction. ^∗P < 0.05, ^∗∗P < 0.01, ^∗∗∗P < 0.001, and ^∗∗∗∗P < 0.0001. BM = bone marrow, RBC = red blood cell.