Pten deletion in the hematopoietic stem cells (HSC) causes a myeloproliferative disorder, which may subsequently develop into a T-cell acute lymphoblastic leukemia (T-ALL). beta-catenin expression was dramatically increased in the c-Kit(mid)CD3(+)Lin(-) leukemia stem cells (LSC) and was critical for T-ALL development. Therefore, the inactivation of b-catenin in LSC may have a potential to eliminate the LSC. In this study, we investigated the mechanism of enhancement of the beta-catenin expression and subsequently used a drug to inactivate b-catenin expression in T-ALL. Western blot (WB) analysis revealed an increased level of beta-catenin in the leukemic cells, but not in the pre-leukemic cells. Furthermore, the WB analysis of the thymic cells from different stages of leukemia development showed that increased expression of beta-catenin was not via the pS9-GSK3 beta signaling, but was dependent on the pT308-Akt activation. Miltefosine (Hexadecylphosphocholine) is the first oral anti-Leishmania drug, which is a phospholipid agent and has been shown to inhibit the PI3K/Akt activity. Treatment of the Pten(Delta/Delta) leukemic mice with Miltefosine for different durations demonstrated that the pT308-Akt and the beta-catenin expressions were inhibited in the leukemia blast cells. Miltefosine treatment also suppressed the TGF beta 1/Smad3 signaling pathway. Analysis of TGFb1 in the sorted subpopulations of the blast cells showed that TGF beta 1 was secreted by the CD3(+)CD4(-) subpopulation and may exert effects on the subpopulations of both CD3(+)CD4(+) and CD3(+)CD4(-) leukemia blast cells. When a TGF beta R1 inhibitor, SB431542 was injected into the Pten(Delta/Delta) leukemic mice, the Smad3 and beta-catenin expressions were down-regulated. On the basis of the results, we conclude that Miltefosine can suppress leukemia by degrading beta-catenin through repression of the pT308-Akt and TGF beta 1/Smad3 signaling pathways. This study demonstrates a possibility to inhibit Pten loss-associated leukemia genesis via targeting Akt and Smad3. (C) 2020 Elsevier Inc. All rights reserved.