Figure 5. Deletion of FoxO Transcription Factors Suppresses MLL-AF9-Induced Leukemia In Vivo.

(A) Experimental scheme used in Figures 5B–5H where MLL-AF9⁺FoxO1/3/4^floxed murine bone marrow (BM) cells recovered from a leukemic primary recipient mouse carrying the Mx1-Cre transgene (Cre⁺) or not (Cre⁻) were transplanted into recipient mice. Cre⁺ and Cre⁻ mice were administered saline or pI-pC and then all mice from each Cre condition were assessed for leukemic burden (day 29 for Cre⁻ and day 39 for Cre⁺).

(B) Mean spleen weight of Cre⁺ (pI-pC) versus Cre⁺ (saline) (p < 0.0001; n = 4). Data represented as the mean ± SEM.

(C) Gross anatomical view of spleens recovered from Cre⁺ mice administered pI-pC (right) or saline (left).

(D) WBC analysis of peripheral blood collected every 4–14 days post-transplant from Cre⁺ saline- and pI-pC-treated mice (n = 4).

(E and F) Kaplan-Meier survival curve analysis of mice transplanted and treated as described above (E: Cre⁻, p = 0.6899; n = 6 and F: Cre⁺, p = 0.0009; n = 10).

(G) Leukemic BM cells isolated from Cre⁺ mice administered saline or pI-pC 7 days earlier were analyzed for the mean proportion ±SEM of L-GMPs (lineage^low, Sca-1 ^–, cKit^high, CD34⁺, FcgRII/III⁺, p = 0.039; n = 3).

(H and I) Leukemic BM cells isolated from Cre⁺ mice administered saline (H) or pI-pC (I) 7 days earlier were transplanted into tertiary recipients at various cell numbers: 300 (n = 6), 3,000 (n = 6), 30,000 (n = 4), and 300,000 (n = 4). Kaplan-Meier analysis of animals that developed leukemia is shown. LIC frequencies were calculated using poisson statistics (H: LICfreq^+/+ = 1:5,314 and I: LICfreq^Δ/Δ = 1: 86,044).

See also Figure S5.