Signals mediated by FcgammaRIIA suppress the growth of B-lineage acute lymphoblastic leukemia cells

FCGR2B as a prognostic and immune microenvironmental marker for gliomas based on transcriptomic analysis

To explore the expression and prognosis of Fc fragment of IgG low affinity IIb receptor (FCGR2B) in glioma and its relationship with immune microenvironment, so as to provide potential molecular targets for the treatment of glioma. We analyzed the gene expression of FCGR2B using the Cancer Genome Atlas database, Chinese Glioma Genome Atlas, Gene Expression Omnibus database and other glioma related databases. Moreover, we generated survival receiver operating characteristic curve, carried out univariate and multivariate Cox analysis and nomograph construction, and analyzed the relationship between FCGR2B and prognosis. According to the median of FCGR2B gene expression value, the differential expression analysis was carried out by high and low grouping method, and the gene ontology, Kyoto encyclopedia of genes and genomes, and gene set enrichment analysis enrichment analysis were carried out to explore the possible mechanism. Then, the correlation between immune score of glioma and prognosis, World Health Organization grade and FCGR2B expression was analyzed. Finally, the correlation between FCGR2B expression and the proportion of tumor infiltrating immune cells, immune checkpoints, tumor mutation load and immune function was analyzed. The expression of FCGR2B in gliomas was higher than that in normal tissues and was associated with poor prognosis. Independent prognostic analysis showed that FCGR2B was an independent prognostic factor for glioma. The analysis of gene ontology and gene set enrichment analysis showed that FCGR2B was closely related to immune-related functions. The analysis of immune scores and prognosis, World Health Organization grade and FCGR2B expression in gliomas indicated that patients with high immune scores had significantly poorer overall survival and higher tumor pathological grade. In addition, immune scores were significantly positively correlated with the expression of FCGR2B. The analysis of tumor infiltrating immune cells suggested that the expression level of FCGR2B affected the immune activity of TME. In addition, the expression of FCGR2B was positively correlated with almost all immune checkpoint molecules including CD28, CD44, TNFSF14, PDCD1LG2, LAIR1, and CD48 and was significantly positively correlated with tumor mutation load. All immunobiological functions of the high expression group of FCGR2B were significantly inhibited. FCGR2B may play an important role in the occurrence, development and invasion of tumor by influencing the tumor microenvironment of immunosuppression. FCGR2B may be an important target for the treatment of glioma.

CD38 expression in early B-cell precursors contributes to extracellular signal-regulated kinase-mediated apoptosis

CD38 is a 45,000 molecular weight transmembrane protein that is expressed in immature and mature lymphocytes. However, the expression and function of CD38 during B-cell differentiation in mice is poorly understood. Here, we report that CD38 is expressed from the earliest stages of B-cell development. Pre-pro-B, pro-B, pre-B and immature B cells from murine bone marrow all stained positive for CD38. Interestingly, CD38 expression increases with B-cell maturation. To assess the role of CD38 during B-cell maturation, CD38-deficient mice were analysed. CD38(-/-) mice showed a significant increase in both the frequency of B-lineage cells and the absolute numbers of pre-pro-B cells in bone marrow; however, no other differences were observed at later stages. CD38 cross-linking in Ba/F3 cells promoted apoptosis and marked extracellular signal-regulated kinase (ERK) phosphorylation, and these effects were reduced by treatment with the mitogen-activated protein kinase/ERK kinase inhibitor PD98059, and similar effects were observed in B-cell precursors from bone marrow. These data demonstrate that B-cell precursors in mouse bone marrow express functional CD38 and implicate the early ligation of CD38 in the ERK-associated regulation of the B-lineage differentiation pathway.

Tetraspanins as therapeutic targets in hematological malignancy: a concise review

Tetraspanins belong to a family of transmembrane proteins which play a major role in the organization of the plasma membrane. While all immune cells express tetraspanins, most of these are present in a variety of other cell types. There are a select few, such as CD37 and CD53, which are restricted to hematopoietic lineages. Tetraspanins associate with numerous partners involved in a diverse set of biological processes, including cell activation, survival, proliferation, adhesion, and migration. The historical view has assigned them a scaffolding role, but recent discoveries suggest some tetraspanins can directly participate in signaling through interactions with cytoplasmic proteins. Given their potential roles in supporting tumor survival and immune evasion, an improved understanding of tetraspanin activity could prove clinically valuable. This review will focus on emerging data in the study of tetraspanins, advances in the clinical development of anti-CD37 therapeutics, and the future prospects of targeting tetraspanins in hematological malignancy.

Kinase activity profiling reveals active signal transduction pathways in pediatric acute lymphoblastic leukemia: a new approach for target discovery

Still about 20% of patients with acute lymphoblastic leukemia (ALL) struggle with relapse, despite intensive chemotherapy. We and others have shown that kinase activity profiling is able to give more insights in active signal transduction pathways and point out interesting signaling hubs as well as new potential druggable targets. With this technique the gap between newly designed drugs and ALL may be bridged. The aim of this study was to perform kinome profiling on 20 pediatric ALL samples (14 BCP-ALL and six T-ALL) to identify signaling proteins relevant to ALL. We defined 250 peptides commonly activated in both BCP-ALL and T-ALL representing major signal transduction pathways including MAPK, PI3K/Akt, and regulators of the cell cycle/p53 pathway. For 27 peptides, differentially phosphorylation between BCP-ALL and T-ALL was observed. Among these, ten peptides were more highly phosphorylated in BCP-ALL while 17 peptides showed increased phosphorylation in T-ALL. Furthermore we selected one lead of the list of commonly activated peptides (HGFR_Y1235) in order to test its efficacy as a potential target and provide proof of principle for this approach. In conclusion kinome profiling is an elegant approach to study active signaling and identify interesting potential druggable targets.

Bispecific and trispecific killer cell engagers directly activate human NK cells through CD16 signaling and induce cytotoxicity and cytokine production

This study evaluates the mechanism by which bispecific and trispecific killer cell engagers (BiKEs and TriKEs) act to trigger human natural killer (NK) cell effector function and investigates their ability to induce NK cell cytokine and chemokine production against human B-cell leukemia. We examined the ability of BiKEs and TriKEs to trigger NK cell activation through direct CD16 signaling, measuring intracellular Ca²⁺ mobilization, secretion of lytic granules, induction of target cell apoptosis, and production of cytokine and chemokines in response to the Raji cell line and primary leukemia targets. Resting NK cells triggered by the recombinant reagents led to intracellular Ca²⁺ mobilization through direct CD16 signaling. Coculture of reagent-treated resting NK cells with Raji targets resulted in significant increases in NK cell degranulation and target cell death. BiKEs and TriKEs effectively mediated NK cytotoxicity of Raji targets at high and low effector-to-target ratios and maintained functional stability after 24 and 48 hours of culture in human serum. NK cell production of IFN-γ, TNF-α, granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-8, macrophage inflammatory protein (MIP)-1α, and regulated and normal T cell expressed and secreted (RANTES) was differentially induced in the presence of recombinant reagents and Raji targets. Moreover, significant increases in NK cell degranulation and enhancement of IFN-γ production against primary acute lymphoblastic leukemia and chronic lymphocytic leukemia targets were induced with reagent treatment of resting NK cells. In conclusion, BiKEs and TriKEs directly trigger NK cell activation through CD16, significantly increasing NK cell cytolytic activity and cytokine production against tumor targets, showing their therapeutic potential for enhancing NK cell immunotherapies for leukemias and lymphomas.

New approaches to allergen immunotherapy

Allergic diseases are common problems affecting 20% to 30% of the US population. Mast cells and basophils are the primary effector cells mediating allergic inflammation through the triggering of membrane immunoglobulin E receptors (FceRI) with antigen. Allergen immunotherapy is used as one treatment for allergic disease and results in the inhibition of mast cell and basophil responses through unknown mechanisms. In this review, we examine potential mechanisms that could result in blunted human mast cell/basophil functional responses, strategies aimed at using these mechanisms to develop new immunologically based therapies, and recent findings that have broad implications toward our understanding of how mast cells/basophils become desensitized.

All-trans retinoic acid induces p62DOK1 and p56DOK2 expression which enhances induced differentiation and G0 arrest of HL-60 leukemia cells

p62(DOK1) (DOK1) and p56(DOK2) (DOK2) are sequence homologs that act as docking proteins downstream of receptor or nonreceptor tyrosine kinases. Originally identified in chronic myelogenous leukemia cells as a highly phosphorylated substrate for the chimeric p210(bcr-abl) protein, DOK1 was suspected to play a role in leukemogenesis. However, p62(DOK1-/-) fibroblast knockout cells were found to have enhanced MAPK signaling and proliferation due to growth factors, suggesting negative regulatory capabilities for DOK1. The role of DOK1 and DOK2 in leukemogeneis thus is enigmatic. The data in this report show that both the DOK1 and the DOK2 adaptor proteins are constitutively expressed in the myelomonoblastic leukemia cell line, HL-60, and that expression of both proteins is induced by the chemotherapeutic differentiation causing agents, all-trans retinoic acid (atRA) and 1,25-dihydroxyvitamin D3 (VD3). Ectopic expression of either protein enhances atRA- or VD3-induced growth arrest, differentiation, and G(0)/G(1) cell cycle arrest and results in increased ERK1/2 phosphorylation. DOK1 and DOK2 are similarly effective in these capabilities. The data provide evidence that DOK1 and DOK2 proteins have a similar role in regulating cell proliferation and differentiation and are positive regulators of the MAPK signaling pathway in this context.

Chimeric receptors with 4-1BB signaling capacity provoke potent cytotoxicity against acute lymphoblastic leukemia

To develop a therapy for drug-resistant B-lineage acute lymphoblastic leukemia (ALL), we transduced T lymphocytes with anti-CD19 chimeric receptors, consisting of an anti-CD19 single-chain variable domain (reactive with most ALL cases), the hinge and transmembrane domains of CD8alpha, and the signaling domain of CD3zeta. We compared the antileukemic activity mediated by a novel receptor ('anti-CD19-BB-zeta') containing the signaling domain of 4-1BB (CD137; a crucial molecule for T-cell antitumor activity) to that of a receptor lacking costimulatory molecules. Retroviral transduction produced efficient and durable receptor expression in human T cells. Lymphocytes expressing anti-CD19-BB-zeta receptors exerted powerful and specific cytotoxicity against ALL cells, which was superior to that of lymphocytes with receptors lacking 4-1BB. Anti-CD19-BB-zeta lymphocytes were remarkably effective in cocultures with bone marrow mesenchymal cells, and against leukemic cells from patients with drug-resistant ALL: as few as 1% anti-CD19-BB-zeta-transduced T cells eliminated most ALL cells within 5 days. These cells also expanded and produced interleukin-2 in response to ALL cells at much higher rates than those of lymphocytes expressing equivalent receptors lacking 4-1BB. We conclude that anti-CD19 chimeric receptors containing 4-1BB are a powerful new tool for T-cell therapy of B-lineage ALL and other CD19+ B-lymphoid malignancies.