pi103 and Leukemia--Myeloid--Acute

Based on indole scaffold, a potent and selective phosphoinositide 3-kinase delta (PI3Kδ) inhibitor, namely FD223, was developed by the bioisosteric replacement drug discovery approach and studied for the treatment of acute myeloid leukemia (AML). In vitro studies revealed that FD223 displays high potency (IC

Topics: Animals; Binding Sites; Cell Line, Tumor; Cell Proliferation; Class I Phosphatidylinositol 3-Kinases; Drug Design; G1 Phase Cell Cycle Checkpoints; Half-Life; Humans; Indoles; Leukemia, Myeloid, Acute; Mice; Mice, Nude; Molecular Docking Simulation; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Structure-Activity Relationship; Transplantation, Heterologous

To date, acute myeloid leukemia (AML) shows very poor outcome for conventional chemotherapy. Leukemia stem cells (LSCs) are insensitive to conventional chemotherapeutic drugs and play a central role in the pathogenesis of AML. Failure to effectively ablate these cells may lead to AML relapse following chemotherapy. Phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway is constructively activated in LSCs. This pathway can be inhibited by PI-103, a novel synthesized molecule of the pyridofuropyrimidine class, resulting in the apoptosis of LSCs. Therefore, we investigate the influences of PI-103 in combination with daunorubicin (DNR) on the LSCs. Our data indicate that PI-103 synergistically sensitizes LSCs to DNR-induced cytotoxicity. In addition, the PI-103/DNR co-treatment can induce significant apoptosis in LSCs, but sparing hematopoietic stem cells. The synergistic effect and the LSCs-specific apoptosis mechanism may be associated with the inhibition of PI3K/Akt/mTOR signaling pathway. Our results suggest that PI-103 in combination with DNR may be a potent and less toxic therapy for targeting LSCs and deserve further preclinical and clinical studies in the treatment of AML.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Blotting, Western; Cell Survival; Cells, Cultured; Daunorubicin; Female; Flow Cytometry; Furans; Humans; Leukemia, Myeloid, Acute; Male; Middle Aged; Neoplastic Stem Cells; Pyridines; Pyrimidines; Signal Transduction; Young Adult

Although dramatic clinical success has been achieved in acute promyelocytic leukemia (APL), the success of differentiating agents has not been reproduced in non-APL leukemia. A key barrier to the clinical success of arsenic is that it is not potent enough to achieve a clinical benefit at physiologically tolerable concentrations by targeting the leukemia cell differentiation pathway alone. We explored a novel combination approach to enhance the eradication of leukemia stem cells (LSCs) by arsenic in non-APL leukemia. In the present study, phosphatidylinositol 3-kinase /AKT/mammalian target of rapamycin (mTOR) phosphorylation was strengthened after As(2)S(2) exposure in leukemia cell lines and stem/progenitor cells, but not in cord blood mononuclear cells (CBMCs). propidium iodide-103, the dual PI3K/mTOR inhibitor, effectively inhibited the transient activation of the PI3K/AKT/mTOR pathway by As(2)S(2). The synergistic killing and differentiation induction effects on non-APL leukemia cells were examined both in vitro and in vivo. Eradication of non-APL LSCs was determined using the nonobese diabetic/severe combined immunodeficiency mouse model. We found that a combined As(2)S(2)/PI-103 treatment synergized strongly to kill non-APL leukemia cells and promote their differentiation in vitro. Furthermore, the combined As(2)S(2)/PI-103 treatment effectively reduced leukemia cell repopulation and eradicated non-APL LSCs partially via induction of differentiation while sparing normal hematopoietic stem cells. Taken together, these findings suggest that induction of the PI3K/AKT/mTOR pathway could provide a protective response to offset the antitumor efficacy of As(2)S(2). Targeting the PI3K/AKT/mTOR pathway in combination with As(2)S(2) could be exploited as a novel strategy to enhance the differentiation and killing of non-APL LSCs.

Topics: Animals; Apoptosis; Arsenicals; Blotting, Western; Cell Differentiation; Cell Line, Tumor; Drug Synergism; Furans; Humans; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukemia, Myeloid, Acute; Mice; Mice, Inbred NOD; Mice, SCID; Neoplastic Stem Cells; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Pyridines; Pyrimidines; Sulfides; TOR Serine-Threonine Kinases

Activation of the phosphatidylinositol-3 kinase/Akt/mammalian target of the rapamycin (PI3K/Akt/mTOR) pathway and inactivation of wild-type p53 by murine double minute 2 homologue (Mdm2) overexpression are frequent molecular events in acute myeloid leukemia (AML). We investigated the interaction of PI3K/Akt/mTOR and p53 pathways after their simultaneous blockade using the dual PI3K/mTOR inhibitor PI-103 and the Mdm2 inhibitor Nutlin-3. We found that PI-103, which itself has modest apoptogenic activity, acts synergistically with Nutlin-3 to induce apoptosis in a wild-type p53-dependent fashion. PI-103 synergized with Nutlin-3 to induce Bax conformational change and caspase-3 activation, despite its inhibitory effect on p53 induction. The PI-103/Nutlin-3 combination caused profound dephosphorylation of 4E-BP1 and decreased expression of many proteins including Mdm2, p21, Noxa, Bcl-2 and survivin, which can affect mitochondrial stability. We suggest that PI-103 actively enhances downstream p53 signaling and that a combination strategy aimed at inhibiting PI3K/Akt/mTOR signaling and activating p53 signaling is potentially effective in AML, where TP53 mutations are rare and downstream p53 signaling is intact.

Topics: Apoptosis; Drug Synergism; Furans; Gene Expression Regulation; Humans; Imidazoles; Leukemia, Myeloid, Acute; Mitochondrial Proteins; Phosphoinositide-3 Kinase Inhibitors; Piperazines; Protein Kinase Inhibitors; Protein Kinases; Proto-Oncogene Proteins c-mdm2; Pyridines; Pyrimidines; TOR Serine-Threonine Kinases; Tumor Cells, Cultured; Tumor Suppressor Protein p53

The phosphatidylinositol 3-kinase (PI3K)/Akt and mammalian target of rapamycin complex 1 (mTORC1) signaling pathways are frequently activated in acute myelogenous leukemia (AML). mTORC1 inhibition with RAD001 induces PI3K/Akt activation and both pathways are activated independently, providing a rationale for dual inhibition of both pathways. PI-103 is a new potent PI3K/Akt and mTOR inhibitor. In human leukemic cell lines and in primary blast cells from AML patients, PI-103 inhibited constitutive and growth factor-induced PI3K/Akt and mTORC1 activation. PI-103 was essentially cytostatic for cell lines and induced cell cycle arrest in the G1 phase. In blast cells, PI-103 inhibited leukemic proliferation, the clonogenicity of leukemic progenitors and induced mitochondrial apoptosis, especially in the compartment containing leukemic stem cells. In contrast, apoptosis was not induced with RAD001 and IC87114 association, which specifically inhibits mTORC1 and p110delta activity, respectively. PI-103 had additive proapoptotic effects with etoposide in blast cells and in immature leukemic cells. Interestingly, PI-103 did not induce apoptosis in normal CD34(+) cells and had moderate effects on their clonogenic and proliferative properties. Here, we demonstrate that multitargeted therapy against PI3K/Akt and mTOR with PI-103 may be of therapeutic value in AML.

Topics: Antineoplastic Agents; Apoptosis; Bone Marrow Cells; Furans; Hematopoietic Stem Cells; Humans; Leukemia, Myeloid, Acute; Neoplastic Stem Cells; Phosphoinositide-3 Kinase Inhibitors; Protein Kinase Inhibitors; Protein Kinases; Pyridines; Pyrimidines; TOR Serine-Threonine Kinases; Tumor Cells, Cultured