HMGA1 silencing enhances responses to the JAK/STAT inhibitor ruxolitinib (Rux), delaying leukemia engraftment and prolonging survival. (A) Dose response curve with 50% inhibitory concentration in DAMI cells, with or without HMGA1 silencing. (B) Leukemia cell engraftment by flow cytometry (mean ± standard deviation [SD]) in BM from NSG mice injected with DAMI cells, including DAMI controls with control chow, DAMI controls with Rux chow, DAMI cells with HMGA1 silencing and control chow, and DAMI cells with HMGA1 silencing and Rux chow (n = 3 or 4 per group). Representative flow cytometry plots from each group are shown. (C) BM (hematoxylin and eosin stain) from each group described above. Scale bar, 200 μm. (D) Survival curves (Kaplan-Meier plots) of NSG mice injected with DAMI cells and treated as follows: DAMI controls with control chow (median survival, 24 days), DAMI controls with Rux chow (median survival, 47.5 days), DAMI cells with HMGA1 silencing and control chow (median survival, 31.5 days), and DAMI cells with HMGA1 silencing and Rux chow (median survival 68 days; n = 6 per group). (E) MF scores based on reticulin staining (mean ± SD) in spleen (scale 0-2) and BM (scale 0-3) from JAK2^V617F/V617F mice with control chow or rux chow and JAK2^V617F/V617F/Hmga1^+/− mice with control chow or rux chow mice were assessed. (F) Representative images of spleen (upper panels) and BM (lower panels) from femurs of JAK2^V617F/V617F mice with control or rux chow and JAK2^V617F/V617F/Hmga1^+/− mice with control or rux chow (reticulin stain). Scale bar, 100 μm. *P < .01, **P < .01, ***P < .001, 1-way ANOVA, followed by Tukey’s multiple-comparison test (B,E), log-rank (Mantel-Cox) test, followed by Bonferroni correction (D), 2-way ANOVA (F).