Figure 4. SerpinB2 modulates LSC activity in vivo.

(A) Primary blast crisis leukemia was generated using HSC-enriched bone marrow cells from either wild type or SerpinB2 knockout mice by co-expression of BCR-ABL and NUP98-HOXA9 as previously described. (B–C) Bone marrow from primary leukemic animals was analyzed for engraftment of cells expressing both BCR-ABL and NUP98-HOXA9, or BCR-ABL alone, using flow cytometry (*** p<0.001). (D) Primary leukemia bone marrow from wild type and SerpinB2 KO backgrounds were harvested, mixed at equal ratios, and transplanted into secondary recipient animals. Nine days post-transplant leukemic bone marrow was analyzed for engraftment of donor leukemia cells using flow cytometry and compared to time zero (T=0) (Top) (*** p<0.001). (E) Kaplan-Meier survival analysis of recipient mice transplanted with 1000 total leukemia cells from either wild type or SerpinB2 knockout primary leukemia (* p<0.01). (F) Limiting dilution results for LSC frequency between wild type and SerpinB2 knockout leukemias determined by L-CALC (Stem Cell Technologies), n=10. (G) Colony-forming ability of primary wild type or SeprinB2 KO bcCML (GFP+/YFP+) and CML(GFP+) cells (* p<0.01). (H) Percentage of apoptotic wild type or SeprinB2 KO leukemia cells analyzed by Annexin V staining (*** p<0.001). (I) Cell cycle analysis performed on primary wild type or SerpinB2 KO leukemia, n=10. See also Figure S4.