Figure 3: Sustained MSI2 overexpression transforms MDS to a lethal AML.

(a) Experimental scheme for MSI2 overexpression in the NHD13 transplant model. (b) Peripheral blood analysis 5 months posttransplantation, including WBC. (c) Red blood cell count (RBC). (d) Mean corpuscular volume (MCV). Data in b–d, (C; n=8, NHD13; n=13, NHD13/MSI2; n=25). (e) Chimerism (CD45.2) in the peripheral blood 5 months posttransplantation, (C; n=8, NHD13; n=11, NHD13/MSI2; n=21). (f) Representative Mac1, Gr1, and c-Kit staining of peripheral blood from the bone marrow. Mice were analysed 5 months posttransplant and gated on CD45.2⁺ cells. (g) Immunophenotyping of peripheral blood 5 months posttransplant. Samples gated as in e, data in f and g, (C; n=8, NHD13; n=11, NHD13/MSI2; n=17). (h) Survival curves of NHD13 with MSI2 overexpression combined from two independent transplants mice (C; n=8, NHD13; n=15, NHD13/MSI2^Dox; n=18). (i) Spleen and (j) liver weights from healthy mice analysed at the end point or moribund mice, (C; n=5, NHD13; n=10, NHD13/MSI2; n=17). (k) Survival analysis of serially transplanted myeloid disease in the NHD13/MSI2^Dox mice (primary donor; n=8, secondary; n=4 and tertiary transplants; n=10; transplanted from two independent donors). (l) Experimental scheme for testing MSI2 dependence of NHD13/MSI2 AML. The bone marrow from moribund primary NHD13/MSI2 transplanted animals was secondarily transplanted into congenic mice and treated accordingly. (m) Survival analysis for doxycycline on/off secondary transplants, (Dox^ON; n=8 and Dox^OFF; n=8 from two independent donors and transplants), Arrows 1, 2 and 3 indicate three representative mice that are described in n and o. (n) Intracellular MSI2 staining by flow cytometry in fixed bone marrows of representative moribund mice described in m. (o) Representative CD45.1/2 staining of mice at different points in the survival curve from m. (p) Survival analysis of doxycycline treated NHD13/MSI2 secondary transplants relative to transplants whose recipients had a 2-week delay in doxycycline treatment posttransplant, Dox^ON; n=9 and Dox^OFF; n=10 from two independent transplants). Data in b–k, are represented two independent transplants *P<0.05, **P<0.01, ***P<0.001, b–e, g,i and j are Student’s t-test and horizontal line is the mean±s.e.m and h,k,m and p, P values assessed by log-rank.