Sphingosine kinase 2 supports the development of BCR/ABL-independent acute lymphoblastic leukemia in mice.

Background: Sphingosine kinase (SphK) 2 has been implicated in the development of a range of cancers and inhibitors of this enzyme are currently in clinical trial. We have previously demonstrated a role for SphK2 in the development of acute lymphoblastic leukemia (ALL).

Methods: In this and our previous study we use mouse models: in the previous study the disease was driven by the proto-oncogene BCR/ABL1, while in this study cancer risk was elevated by deletion of the tumor suppressor ARF.

Regulation of the bone marrow microenvironment by G-CSF: Effects of G-CSF on acute lymphoblastic leukaemia.

It has been suggested that disruption of the lymphoid niche by G-CSF may be of therapeutic benefit to patients with acute lymphoblastic leukaemia. We used a xenograft model to determine the effect of G-CSF on ALL progression in a minimal residual disease setting. Consistent with the effects on normal murine B cell progenitors, G-CSF slowed disease in the majority of ALL xenografts tested, suggesting that G-CSF may provide benefits beyond neutrophil recovery for ALL patients.

Bone Marrow Graft-Versus-Host Disease in Major Histocompatibility Complex-Matched Murine Reduced-Intensity Allogeneic Hemopoietic Cell Transplantation.

Background: Most clinical allogeneic hemopoietic cell transplants (alloHCT) are now performed using reduced-intensity conditioning (RIC) instead of myeloablative conditioning (MAC); however, the biology underlying this treatment remains incompletely understood.

Methods: We investigated a murine model of major histocompatibility complex-matched multiple minor histocompatibility antigen-mismatched alloHCT using bone marrow (BM) cells and splenocytes from B6 (H-2) donor mice transplanted into BALB.B (H-2) recipients after RIC with fludarabine of 100 mg/kg per day for 5 days, cyclophosphamide of 60 mg/kg per day for 2 days, and total body irradiation (TBI).

Extracellular molecules in hematopoietic stem cell mobilisation.

Hematopoietic stem cells are a remarkable resource currently used for the life saving treatment, hematopoietic stem cell transplantation. Today, hematopoietic stem cells are primarily obtained from mobilized peripheral blood following treatment of the donor with the cytokine G-CSF, and in some settings, chemotherapy and/or the CXCR4 antagonist plerixafor. The collection of hematopoietic stem cells is contingent on adequate and timely mobilization of these cells into the peripheral blood.

Temporal Tracking of Cell Cycle Progression Using Flow Cytometry without the Need for Synchronization.

This protocol describes a method to permit the tracking of cells through the cell cycle without requiring the cells to be synchronized. Achieving cell synchronization can be difficult for many cell systems. Standard practice is to block cell cycle progression at a specific stage and then release the accumulated cells producing a wave of cells progressing through the cycle in unison.

A Phase I/II Study of the mTOR Inhibitor Everolimus in Combination with HyperCVAD Chemotherapy in Patients with Relapsed/Refractory Acute Lymphoblastic Leukemia.

Purpose: Previous studies suggest a potential therapeutic role for mTOR inhibition in lymphoid malignancies. This single-center phase I/II study was designed to test the safety and efficacy of the mTOR inhibitor everolimus in combination with HyperCVAD chemotherapy in relapsed/refractory acute lymphoblastic leukemia (ALL).

Experimental Design: Twenty-four patients were treated; 15 received everolimus 5 mg/day and 9 received 10 mg/day with HyperCVAD.

Efficacy of dual PI-3K and mTOR inhibitors in vitro and in vivo in acute lymphoblastic leukemia.

The major regulators of human acute lymphoblastic leukemia (ALL) cell growth and survival mediate their effects through the phosphoinositide 3-kinase (PI-3K)/mammalian target of rapamycin (mTOR) pathway. We have shown that the mTOR inhibitor everolimus extended survival in a non-obese diabetic/severe combined immune-deficient (NOD/SCID) mouse xenograft model of human ALL. Since PI-3K has mTOR dependent and independent functions we examined the effect of the dual PI-3K/mTOR inhibitors BEZ235 and BGT226.

G-CSF: From granulopoietic stimulant to bone marrow stem cell mobilizing agent.

G-CSF was among the first cytokines to be identified and rapidly transitioned into clinical medicine. Initially used to promote the production of neutrophils in patients with chemotherapy-induced neutropenia it helped to revolutionize the delivery of cancer therapy. Its ability to mobilize hematopoietic stem cells from the bone marrow into the blood was subsequently exploited, changing the face of hematopoietic stem cell transplantation.

Silencer of death domains controls cell death through tumour necrosis factor-receptor 1 and caspase-10 in acute lymphoblastic leukemia.

Resistance to apoptosis remains a significant problem in drug resistance and treatment failure in malignant disease. NO-aspirin is a novel drug that has efficacy against a number of solid tumours, and can inhibit Wnt signaling, and although we have shown Wnt signaling to be important for acute lymphoblastic leukemia (ALL) cell proliferation and survival inhibition of Wnt signaling does not appear to be involved in the induction of ALL cell death. Treatment of B lineage ALL cell lines and patient ALL cells with NO-aspirin induced rapid apoptotic cell death mediated via the extrinsic death pathway.

mTOR inhibition by everolimus in childhood acute lymphoblastic leukemia induces caspase-independent cell death.

Increasingly, anti-cancer medications are being reported to induce cell death mechanisms other than apoptosis. Activating alternate death mechanisms introduces the potential to kill cells that have defects in their apoptotic machinery, as is commonly observed in cancer cells, including in hematological malignancies. We, and others, have previously reported that the mTOR inhibitor everolimus has pre-clinical efficacy and induces caspase-independent cell death in acute lymphoblastic leukemia cells.

Sphingosine kinase 2 promotes acute lymphoblastic leukemia by enhancing MYC expression.

Sphingosine kinase 2 (SK2) may have utility as a prognostic marker in inflammatory diseases such as cancer in which it has been rationalized as a candidate therapeutic target. Here, we show that SK2 has an oncogenic role in acute lymphoblastic leukemia (ALL) by influencing expression of MYC. Genetic ablation of SK2 impaired leukemia development in a mouse model of ALL and pharmacologic inhibition extended survival in mouse xenograft models of human disease.

Oncogenic properties of sphingosine kinases in haematological malignancies.

The sphingosine kinases (SphKs) have relatively recently been implicated in contributing to malignant cellular processes with particular interest in the oncogenic properties of SPHK1. Whilst SPHK1 has received considerable attention as a putative oncoprotein, SPHK2 has been much more difficult to study, with often conflicting data surrounding its role in cancer. Initial studies focused on non-haemopoietic malignancies, however a growing body of literature on the role of sphingolipid metabolism in haemopoietic malignancies is now emerging.

Role of sphingosine 1-phosphate in trafficking and mobilization of hematopoietic stem cells.

Purpose Of Review: The 'mobilization' of hematopoietic stem cells (HSCs) out of the bone marrow and into the peripheral blood is used clinically to obtain HSCs for transplantation. Although generally successful, mobilization protocols remain imperfect and the mechanisms involved are not fully understood. This review discusses the latest findings in respect to the mechanisms involved in the egress of HSCs from the bone marrow into the circulation and the potential for these recent developments to improve mobilization procedures.

Plerixafor (AMD3100) induces prolonged mobilization of acute lymphoblastic leukemia cells and increases the proportion of cycling cells in the blood in mice.

The CXCR4 antagonist Plerixafor (AMD3100) induces the rapid mobilization of hematopoietic stem and progenitor cells into the blood in mice and humans. AMD3100 similarly induces the mobilization of human acute lymphoblastic leukemia (ALL) cells into the blood in mice. In this study, the temporal response of pre-B ALL cells to AMD3100 was compared with that of normal hematopoietic progenitor cells (HPC) using an NOD/SCID xenograft model of ALL and BALB/c mice, respectively.

Guidelines for the use and interpretation of assays for monitoring autophagy.

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding.

B-lymphopoiesis is stopped by mobilizing doses of G-CSF and is rescued by overexpression of the anti-apoptotic protein Bcl2.

Osteoblasts are necessary to B lymphopoiesis and mobilizing doses of G-CSF or cyclophosphamide inhibit osteoblasts, whereas AMD3100/Plerixafor does not. However, the effect of these mobilizing agents on B lymphopoiesis has not been reported. Mice (wild-type, knocked-out for TNF-α and TRAIL, or over-expressing Bcl-2) were mobilized with G-CSF, cyclophosphamide, or AMD3100.

Disparate in vivo efficacy of FTY720 in xenograft models of Philadelphia positive and negative B-lineage acute lymphoblastic leukemia.

Most patients with acute lymphoblastic leukemia (ALL) respond well to standard chemotherapy-based treatments. However a significant proportion of patients, particularly adult patients, relapse with the majority dying of leukemia. FTY720 is an immunosuppressive drug that was recently approved for the treatment of multiple sclerosis and is currently under pre-clinical investigation as a therapy for a number of hematological malignancies.

Para-NO-aspirin inhibits NF-κB and induces apoptosis in B-cell progenitor acute lymphoblastic leukemia.

Although patients with acute lymphoblastic leukemia (ALL) usually achieve complete remission, disease relapse is common and difficult to treat. Para-NO-aspirin (para-NO-ASA) is a novel drug with demonstrated efficacy against a number of solid tumors and most recently chronic lymphocytic leukemia. In this study, we used ALL cell lines to assess the effects on cell viability by flow cytometry and investigated the mechanism of cell death using chemical inhibitors of key molecules and assessed the effects by flow cytometry, electrophoretic mobility shift assay, Western blotting, and quantitative reverse transcription polymerase chain reaction.

Sphingosine-1-phosphate facilitates trafficking of hematopoietic stem cells and their mobilization by CXCR4 antagonists in mice.

CXCL12 and VCAM1 retain hematopoietic stem cells (HSCs) in the BM, but the factors mediating HSC egress from the BM to the blood are not known. The sphingosine-1-phosphate receptor 1 (S1P(1)) is expressed on HSCs, and S1P facilitates the egress of committed hematopoietic progenitors from the BM into the blood. In the present study, we show that both the S1P gradient between the BM and the blood and the expression of S1P(1) are essential for optimal HSC mobilization by CXCR4 antagonists, including AMD3100, and for the trafficking of HSCs during steady-state hematopoiesis.

Mobilisation strategies for normal and malignant cells.

This review evaluates the latest information on the mobilisation of haemopoietic stem cells for transplantation, with the focus on what is the current best practice and how new understanding of the bone marrow stem cell niche provides new insights into optimising mobilisation regimens. The review then looks at the mobilisation of mesenchymal stromal cells, immune cells as well as malignant cells and what clinical implications there are.

Variation in immunophenotype of lactating mice.

Immunological factors have been shown to play a crucial role in mammary remodelling in rodent models of lactation, particularly at the stage of mammary involution. However, the relationship between immunological factors and the ability of normal mammary gland to produce milk, as well as the genetic components contributing to lactation performance remain largely unknown. In this study, we assessed the lactation and immunological phenotypes of 11 inbred mouse strains, namely 129X1/SvJ (129), A/J, AKR, C3H/HeJ (C3H), CBA/CaH (CBA), C57BL/6J (C57), DBA/1J, DBA/2J, FVB/N (FVB), QSi5 and SJL/J (SJL) to identify potential links.

FTY720 produces caspase-independent cell death of acute lymphoblastic leukemia cells.

Acute lymphoblastic leukemia (ALL), the most common form of childhood cancer, usually responds to chemotherapy but patients who develop disease relapse have a poor prognosis. New agents to treat ALL are urgently required. FTY720 is an immunosuppressive drug that has promising in vitro activity in a number of malignancies, with the proposed mechanism being the reactivation of the protein serine/threonine phosphatase, PP2A.

The mammalian target of rapamycin inhibitor RAD001 (everolimus) synergizes with chemotherapeutic agents, ionizing radiation and proteasome inhibitors in pre-B acute lymphocytic leukemia.

Background: Despite incremental improvements in outcomes for patients with acute lymphoblastic leukemia, significant numbers of patients still die from this disease. Mammalian target of rapamycin inhibitors have shown potential in vitro and in vivo as therapeutic agents against a range of tumors including acute lymphoblastic leukemia.

Design And Methods: Flow cytometry was used to evaluate drug-induced cell death in acute lymphoblastic leukemia cell lines and patients' samples.