sphingosine-1-phosphate and Hematologic-Neoplasms

Allogeneic haemopoietic stem cell transplantation (HSCT) is increasingly used to treat haematological malignant diseases via the graft-versus-leukaemia (GvL) or graft-versus-tumour effects. Although improvements in infectious disease prophylaxis, immunosuppressive treatments, supportive care, and molecular based tissue typing have contributed to enhanced outcomes, acute graft-versus-host disease and other transplant related complications still contribute to high mortality and significantly limit the more widespread use of HSCT. Sphingosine 1-phosphate (S1P) is a zwitterionic lysophospholipid that has been implicated as a crucial signaling regulator in many physiological and pathophysiological processes including multiple cell types such as macrophages, dendritic cells, T cells, T regulatory cells and endothelial cells. Recent data suggested important roles for S1P signaling in engraftment, graft-versus-host disease (GvHD), GvL and other processes that occur during and after HSCT. Based on such data, pharmacological intervention via S1P modulation may have the potential to improve patient outcome by regulating GvHD and enhancing engraftment while permitting effective GvL.

Topics: Azetidines; Benzyl Compounds; Dendritic Cells; Endothelial Cells; Graft vs Host Disease; Graft vs Leukemia Effect; Hematologic Neoplasms; Hematopoietic Stem Cell Transplantation; Humans; Lysophospholipids; Macrophages; Organophosphates; Protein Isoforms; Receptors, Lysosphingolipid; Signal Transduction; Sphingosine; T-Lymphocytes, Regulatory; Transplantation, Homologous

Sphingosine 1-phosphate (S1P) is a sphingosine containing lipid intermediate obtained from ceramide. S1P is known to be an important signaling molecule and plays multiple roles in the context of immunity. This lysophospholipid binds and activates G-protein-coupled receptors (GPCRs) known as S1P receptors 1-5 (S1P1-5). Once activated, these GPCRs mediate signaling that can lead to alterations in cell proliferation, survival or migration, and can also have other effects such as promoting angiogenesis. In this review, we will present evidence demonstrating a role for S1P in lymphocyte migration, inflammation and infection, as well as in cancer. The therapeutic potential of targeting S1P receptors, kinases and lyase will also be discussed.

Topics: Animals; Chemotaxis, Leukocyte; Cytokines; Disease Models, Animal; Fingolimod Hydrochloride; Hematologic Neoplasms; Host-Pathogen Interactions; Humans; Immune System; Immunosuppressive Agents; Infections; Inflammation; Lymphocytes; Lysophospholipids; Signal Transduction; Sphingosine; Transcription Factors

Sphingolipids, such as ceramide, sphingosine and sphingosine 1-phosphate (S1P) are bioactive molecules that have important functions in a variety of cellular processes, which include proliferation, survival, differentiation and cellular responses to stress. Sphingolipids have a major impact on the determination of cell fate by contributing to either cell survival or death. Although ceramide and sphingosine are usually considered to induce cell death, S1P promotes survival of cells. Sphingosine kinases (SPHKs) are the enzymes that catalyze the conversion of sphingosine to S1P. There are two isoforms, SPHK1 and SPHK2, which are encoded by different genes. SPHK1 has recently been implicated in contributing to cell transformation, tumor angiogenesis and metastatic spread, as well as cancer cell multidrug-resistance. More recent findings suggest that SPHK2 also has a role in cancer progression. This review is an overview of our understanding of the role of SPHKs and S1P in hematopoietic malignancies and provides information on the current status of SPHK inhibitors with respect to their therapeutic potential in the treatment of hematological cancers.

Topics: Disease Progression; Hematologic Neoplasms; Humans; Lysophospholipids; Molecular Targeted Therapy; Phosphotransferases (Alcohol Group Acceptor); Protein Kinase Inhibitors; Sphingosine

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. This review provides an overview of the current state of knowledge of the SphKs and the bioactive lipid sphingosine 1-phosphate (S1P), the product of the reaction they catalyse. It then reviews the current literature regarding the roles of S1P and the SphKs in haemopoietic malignancies and discusses the compounds currently available that modulate sphingolipid metabolism and their potential and shortcomings as therapeutic agents for the treatment of haematological malignancies.

Topics: Antineoplastic Agents; Drug Design; Drug Resistance, Neoplasm; Enzyme Inhibitors; Hematologic Neoplasms; Hematopoiesis; Humans; Lysophospholipids; Phosphotransferases (Alcohol Group Acceptor); Sphingosine

Hypoxia, defined as reduced tissue oxygen concentration, is a characteristic of solid tumors and is an indicator of unfavorable diagnosis in patients. At the cellular level, the adaptation to hypoxia is under the control of two related transcription factors, HIF-1α and HIF-2α (Hypoxia-Inducible Factor), which activate expression of genes promoting angiogenesis, metastasis, increased tumor growth and resistance to treatments. A role for HIF-1α and HIF-2α is also emerging in hematologic malignancies such as lymphoma and l eukemia. Recent studies have identified the sphingosine kinase 1/sphingosine 1-phosphate (SphK1/S1P) signaling pathway - which elicits various cellular processes including cell proliferation, cell survival or angiogenesis - as a new regulator of HIF-1α or HIF-2α activity. This review will consider how targeting the SphK1/S1P signaling could represent an attractive strategy for therapeutic intervention in cancer.

Topics: Animals; Antineoplastic Agents; Basic Helix-Loop-Helix Transcription Factors; Hematologic Neoplasms; Humans; Hypoxia-Inducible Factor 1; Lysophospholipids; Phosphotransferases (Alcohol Group Acceptor); Signal Transduction; Sphingosine

Autophagy is an evolutionary conserved process by which cells recycle intracellular materials to maintain homeostasis in different cellular contexts. Under basal conditions it prevents accumulation of damaged proteins and organelles; during starvation, autophagy provides cells with sufficient nutrients to survive. Sphingolipids are a family of bioactive molecules modulating vital cellular functions such as apoptosis, cell cycle arrest or proliferation. Besides these functions, some sphingolipids like ceramide, sphingosine- 1-phosphate or gangliosides have been described to promote autophagy in several cancer cell lines. Current evidence supports the notion that induction of autophagic cell death can halt tumorigenesis. Of interest, some chemotherapeutic agents used for the treatment of hematological malignancies trigger the production of endogenous sphingolipids with pro-autophagic effects. In this review we describe the regulation and functions of the sphingolipid-induced autophagy and the tight relationship with the cancer cell response to current chemotherapeutic regimens.

Topics: Animals; Antineoplastic Agents; Autophagy; Ceramides; Hematologic Neoplasms; Humans; Lysophospholipids; Sphingolipids; Sphingosine

The sphingolipid sphingosine-1-phosphate (S1P) is an important regulator of immune cell functions in vivo. Besides recruiting lymphocytes to blood and lymph, it may promote immune cell survival and proliferation, but also interferes with their activation. Hereby, S1P may act as an intracellular second messenger or cofactor or, upon being secreted from cells, may bind to and activate a family of specific G-protein-coupled receptors (S1PR1-5). Extracellular versus intracellular S1P hereby might trigger synergistic/identical or fundamentally distinct responses. Furthermore, engagement of different S1PRs is connected to different functional outcome. This complexity is exemplified by the influence of S1P on the inflammatory potential of macrophages, shaping their role in inflammatory pathologies such as atherosclerosis and cancer. Here, we summarize the recent progress in understanding the impact of S1P signaling in macrophage biology, discuss its impact in solid as well as 'wet' tumors and elaborate potential options to interfere with S1P signaling in the context of cancer.

Topics: Animals; Hematologic Neoplasms; Humans; Inflammation; Lysophospholipids; Macrophages; Neoplasms; Signal Transduction; Sphingosine

Sphingosine-1-phosphate (S1P) is a pleiotropic bioactive lipid mediator that regulates several processes important for hematologic cancer progression. S1P is generated by two sphingosine kinases, SphK1 and SphK2, and is exported outside the cell, where it activates specific cell surface S1P G-protein coupled receptors in autocrine/paracrine manner, coined "inside-out signaling". In this review, we highlight the importance of SphK1 and inside-out signaling by S1P in hematologic malignancy. We also summarize the results of studies targeting the SphK1/S1P/S1P receptor axis and the effects of the S1P receptor modulator, FTY720, in hematologic malignancy.

Topics: Animals; Fingolimod Hydrochloride; Hematologic Neoplasms; Humans; Immunosuppressive Agents; Lysophospholipids; Phosphotransferases (Alcohol Group Acceptor); Propylene Glycols; Receptors, Lysosphingolipid; Sphingosine