ZAP-70 Expression in Chronic Lymphocytic Leukemia Is Associated with Altered Signal Transduction.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4702-4702
Author(s):  
Kristy L. Wolniak ◽  
James Marvin ◽  
Charles Goolsby
Keyword(s):  
Signal Transduction ◽  
Chronic Lymphocytic Leukemia ◽  
Tyrosine Kinase ◽  
B Cell ◽  
Kinase Inhibitors ◽  
Cell Receptor ◽  
Prognostic Indicator ◽  
Lymphocytic Leukemia ◽  
Prognostic Information

Abstract B-cell chronic lymphocytic leukemia (CLL) is a malignancy of mature B-cells with a variable clinical course. Given the heterogeneity of disease course, identification of prognostic factors is imperative. One recently identified negative prognostic indicator in CLL is the T-cell tyrosine kinase ZAP70. ZAP70 is analogous to, and can functionally substitute for, the B-cell tyrosine kinase Syk and is activated following B cell receptor (BCR) crosslinking in CLL cells. However, the role of ZAP70 expression in CLL remains elusive. Utilizing flow cytometric analyses of signal transduction molecules, this study examined if ZAP70 expression affects signal transduction in CLL. Peripheral blood samples from ZAP70+ and ZAP70− CLL patients were analyzed. The levels of phosphorylated ERK, STAT5, and S6 (p-ERK, p-STAT5, p-S6) were measured by flow cytometry with and without BCR stimulation. Kinase inhibitors were used to verify the measured phosphorlyated protein levels. Increased constitutive levels of p-ERK, p-STAT5, and p-S6 were seen in ZAP70+ CLL cells as compared to ZAP70− CLL cells. BCR crosslinking gave variable responses in both ZAP70+ and ZAP70− CLL. The majority of ZAP70− cases showed no significant activation or a predominant activation of ERK with rare p-S6 activation. ZAP70+ cells showed activation of either, or both, ERK and S6 pathways and fewer showing no activation. In summary, though the role of ZAP70 in B cell signaling is poorly understood, expression of ZAP70 in CLL correlates with a constitutively active phenotype. Additionally, differential response in ZAP70+ versus ZAP70− cases following BCR crosslinking suggests a possible modulatory role of the BCR pathway. Current studies are underway to determine if these measures carry prognostic information and if the varying signal responses to BCR stimulation correlate with reported differences in apoptotic versus proliferative response.

Nurture versus Nature: The Microenvironment in Chronic Lymphocytic Leukemia

Hematology ◽  
2011 ◽  
Vol 2011 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Jan A. Burger
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Tyrosine Kinase ◽  
B Cell ◽  
Disease Progression ◽  
Drug Testing ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
In Vivo Models

Abstract Intrinsic factors such as genetic lesions, anti-apoptotic proteins, and aberrant signaling networks within leukemia cells have long been the main focus of chronic lymphocytic leukemia (CLL) research. However, over the past decade, it became increasingly clear that external signals from the leukemia microenvironment make pivotal contributions to disease progression in CLL and other B-cell malignancies. Consequently, increasing emphasis is now placed on exploring and targeting the CLL microenvironment. This review highlights critical cellular and molecular pathways of CLL-microenvironment cross-talk. In vitro and in vivo models for studying the CLL microenvironment are discussed, along with their use in searching for therapeutic targets and in drug testing. Clinically, CXCR4 antagonists and small-molecule antagonists of B cell receptor (BCR)-associated kinases (spleen tyrosine kinase [Syk], Bruton's tyrosine kinase [Btk], and PI3Kδ) are the most advanced drugs for targeting specific interactions between CLL cells and the miocroenvironment. Preclinical and first clinical evidence suggests that high-risk CLL patients can particularly benefit from these alternative agents. These findings indicate that interplay between leukemia-inherent and environmental factors, nature and nurture determines disease progression in CLL.

scholarly journals Emerging role of kinase-targeted strategies in chronic lymphocytic leukemia

Hematology ◽  
2012 ◽  
Vol 2012 (1) ◽  
pp. 88-96 ◽  
Author(s):  
Adrian Wiestner
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Absolute Lymphocyte Count ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Cell Trafficking

Abstract Chronic lymphocytic leukemia (CLL) is a malignancy of mature B cells that depend on host factors in the tissue microenvironment for survival and proliferation. In vitro, CLL cells rapidly undergo apoptosis unless microenvironmental factors are provided that support their survival. Signaling pathways activated in the microenvironment in vivo include the B-cell receptor (BCR) and NF-κB pathways. Thus, CLL is a disease “addicted to the host” and is dependent on pathways that promote normal B-cell development, expansion, and survival; this is particularly true in the case of the BCR signaling cascade. Small-molecule inhibitors of kinases that are essential for BCR signal transduction abrogate the stimulating effects of the microenvironment on CLL cells. The orally administered tyrosine kinase inhibitors fostamatinib and ibrutinib and the phosphatidylinositol 3-kinase inhibitor GS-1101 have induced impressive responses in relapsed and refractory CLL patients, mostly with moderate side effects. Reductions in lymphadenopathy and splenomegaly are seen within weeks and are frequently accompanied by a transient rise in absolute lymphocyte count that is asymptomatic and probably the result of changes in CLL cell trafficking. This review discusses the biologic basis for kinase inhibitors as targeted therapy of CLL and summarizes the exciting early clinical experience with these agents.

scholarly journals Emerging role of kinase-targeted strategies in chronic lymphocytic leukemia

Blood ◽  
2012 ◽  
Vol 120 (24) ◽  
pp. 4684-4691 ◽  
Author(s):  
Adrian Wiestner
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Absolute Lymphocyte Count ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Cell Trafficking

AbstractChronic lymphocytic leukemia (CLL) is a malignancy of mature B cells that depend on host factors in the tissue microenvironment for survival and proliferation. In vitro, CLL cells rapidly undergo apoptosis unless microenvironmental factors are provided that support their survival. Signaling pathways activated in the microenvironment in vivo include the B-cell receptor (BCR) and NF-κB pathways. Thus, CLL is a disease “addicted to the host” and is dependent on pathways that promote normal B-cell development, expansion, and survival; this is particularly true in the case of the BCR signaling cascade. Small-molecule inhibitors of kinases that are essential for BCR signal transduction abrogate the stimulating effects of the microenvironment on CLL cells. The orally administered tyrosine kinase inhibitors fostamatinib and ibrutinib and the phosphatidylinositol 3-kinase inhibitor GS-1101 have induced impressive responses in relapsed and refractory CLL patients, mostly with moderate side effects. Reductions in lymphadenopathy and splenomegaly are seen within weeks and are frequently accompanied by a transient rise in absolute lymphocyte count that is asymptomatic and probably the result of changes in CLL cell trafficking. This review discusses the biologic basis for kinase inhibitors as targeted therapy of CLL and summarizes the exciting early clinical experience with these agents.

scholarly journals Bruton tyrosine kinase inhibitors for the frontline treatment of chronic lymphocytic leukemia

2020 ◽  
Vol 27 (6) ◽  
Author(s):  
V. Banerji ◽  
A. Aw ◽  
S. Robinson ◽  
S. Doucette ◽  
A. Christofides ◽  
...  
Keyword(s):  
High Risk ◽  
Chronic Lymphocytic Leukemia ◽  
Tyrosine Kinase ◽  
Kinase Inhibitors ◽  
Variable Region ◽  
Tp53 Gene ◽  
Cell Receptor ◽  
Response To Therapy ◽  
Lymphocytic Leukemia ◽  
Btk Inhibitors

Chronic lymphocytic leukemia (CLL) is the most commonly diagnosed adult leukemia in Canada. Biologic heterogeneity of CLL can be observed between patients which results in variable disease trajectory and response to therapy. Notably, patients with high-risk features such as the presence of deletions in chromosome 17p, aberrations in the TP53 gene, or unmutated immunoglobulin heavy chain variable region genes have inferior outcomes and response to standard chemoimmunotherapy compared to patients without these features. Novel agents which target the B cell receptor signalling pathway, such as Bruton’s tyrosine kinase (BTK) inhibitors have demonstrated clinical efficacy and safety in patients with treatment-naïve CLL, particularly in those with high-risk features. However, due to the current lack of head-to-head trials comparing BTK inhibitors, selection of the optimal BTK inhibitor for patients with CLL is unclear and requires the consideration of multiple factors. This review focuses on the efficacy, safety, and pharmacological features of the BTK inhibitors that are approved or are under clinical development and discusses the practical considerations for the use of these agents in the Canadian treatment landscape.

CLL Biology and Prognosis

Hematology ◽  
2005 ◽  
Vol 2005 (1) ◽  
pp. 278-284 ◽  
Author(s):  
Guillaume Dighiero
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
B Lymphocyte ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Staging Systems ◽  
Cellular Markers ◽  
Major Progress

Abstract Chronic lymphocytic leukemia (CLL) follows an extremely variable course with survival ranging from months to decades. Recently, there has been major progress in the identification of molecular and cellular markers that may predict the tendency for disease progression in CLL patients. In particular, the mutational profile of Ig genes and some cytogenetic abnormalities have been found to be important predictors of prognosis in CLL. However, this progress has raised new questions about the biology and prognosis of the disease, some of which are addressed here. Such questions include: 1) What is the role of the B-cell receptor (BCR) in CLL pathogenesis? 2) Is CLL one disease? 3) Is CLL an accumulative disease? 4) What is the normal counterpart of the CLL B lymphocyte? 5) Have the Rai and Binet staging systems become obsolete? 6) Which is the best surrogate for Ig mutational profiles?

Leukemic B Cells from Patients with Chronic Lymphocytic Leukemia Show Anomalous Lyn Tyrosine Kinase which Contributes to Defective Apoptosis.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1917-1917
Author(s):  
Livio Trentin ◽  
Anna Maria Brunati ◽  
Antonella Contri ◽  
Anna Cabrelle ◽  
Marta Miorin ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Tyrosine Kinase ◽  
Cyclosporin A ◽  
B Cell ◽  
B Lymphocytes ◽  
Protein Level ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells

Abstract B-cell chronic lymphocytic leukemia (B-CLL) is the most common leukemia in adults and is characterized by the accumulation of mature B lymphocytes in the G0/G1 phase of the cell cycle, expressing B-cell related (i.e. CD19, surface immunoglobulins) and unrelated molecules (CD5 and CD23). The signal transduction pathways underlying the abnormalities of these leukemic cells are poorly understood and no data are available on deregulated cell signalling in B-CLL. Since Lyn activation plays a pivotal role in the signaling cascade triggered by BCR engagement, we investigated whether this kinase may be involved in CLL pathogenesis. In this study, we investigated freshly isolated and purified malignant B cells obtained from 40 CLL patients and we observed that the Src-kinase Lyn, the switch molecule coupling B-cell-receptor to downstream signaling, displays anomalous properties. Western blot and confocal analyses demonstrated that Lyn is overexpressed at the protein level in leukemic cells as compared to normal B-lymphocytes with a substantial aliquot of the kinase anomalously present in the cytosol of leukemic cells. While in normal B lymphocytes Lyn activation is triggered by B-cell-receptor engagement with anti-IgM antibodies, in freshly isolated leukemic cells this kinase is constitutively active and accounts for high basal protein tyrosine-phosphorylation and low responsiveness to IgM-ligation. To address the question of whether the upregulation of Lyn protein and activity plays a role in the defective apoptosis of leukemic cells, we investigated the relationship between Lyn and the cell survival of malignant lymphocytes in the presence of either dexamethazone and cyclosporin A, which are known to induce apoptosis of human lymphocytes, or PP2 and SU6656, which are selective inhibitors of Lyn. When leukemic cells were cultured in the presence of cyclosporin A or dexamethazone, a marked increase in apoptosis was observed as compared to cells cultured in medium alone, and this effect correlated with a great decrease in both basal activity and protein level of Lyn. The exposure of the leukemic cells to PP2 and SU6656 caused both the inhibition of the overexpressed Lyn activity and marked cell apoptosis. These findings suggest a direct correlation between high basal Lyn activity and defects in the induction of apoptosis in leukemic cells. They also support a critical role for Lyn in B-CLL pathogenesis and identify this tyrosine kinase as a potential therapeutic target for drugs capable of inducing apoptosis in B-CLL leukemic cells.

Role of the STAT1 pathway in apoptosis induced by fludarabine and JAK kinase inhibitors in B-cell chronic lymphocytic leukemia

2005 ◽  
Vol 46 (3) ◽  
pp. 435-442 ◽  
Author(s):  
Luis Martinez-Lostao ◽  
Javier Briones ◽  
Ignasi Forné ◽  
Monica Martinez-Gallo ◽  
Beatriz Ferrer ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Kinase Inhibitors ◽  
Lymphocytic Leukemia ◽  
Jak Kinase ◽  
Cell Chronic Lymphocytic Leukemia

scholarly journals Aspartic Aminopeptidase Is a Novel Biomarker of Aggressive Chronic Lymphocytic Leukemia

Cancers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1876
Author(s):  
Pramath Kakodkar ◽  
Sanket More ◽  
Kinga András ◽  
Nikos Papakonstantinou ◽  
Sharon Kelly ◽  
...  
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Phosphatidyl Inositol ◽  
Cell Types ◽  
Cell Receptor ◽  
Gene Signature ◽  
Lymphocytic Leukemia ◽  
Bcr Signaling

Treatment of chronic lymphocytic leukemia has advanced substantially as our understanding of the kinase signal transduction pathways driven by the B cell receptor (BcR) has developed. Particularly, understanding the role of Bruton tyrosine kinase and phosphatidyl inositol 3 kinase delta in driving prosurvival signal transduction in chronic lymphocytic leukemia (CLL) cells and their targeting with pharmacological inhibitors (ibrutinib and idelalisib, respectively) has improved patient outcomes significantly. The kinase signaling pathway induced by the BcR is highly complex and has multiple interconnecting branches mediated by tyrosine and serine/threonine kinases activated downstream of the BcR. There is a high level of redundancy in the biological responses, with several BcR-signaling kinases driving nuclear factor kappa B activation or inducing antiapoptotic Bcl-2 genes. Accordingly, common gene targets of BcR-signaling kinases may serve as biomarkers indicating enhanced BCR-signaling and aggressive disease progression. This study used a gene expression correlation analysis of malignant B cell lines and primary CLL cells to identify genes whose expression correlated with BCR-signaling kinases overexpressed and/or overactivated in CLL, namely: AKT1, AKT2, BTK, MAPK1, MAPK3, PI3KCD and ZAP70. The analysis identified a 32-gene signature with a strong prognostic potential and DNPEP, the gene coding for aspartic aminopeptidase, as a predictor of aggressive CLL. DNPEP gene expression correlated with MAPK3, PI3KCD, and ZAP70 expression and, in the primary CLL test dataset, showed a strong prognostic potential. The inhibition of DNPEP with a pharmacological inhibitor enhanced the cytotoxic potential of idelalisib and ibrutinib, indicating a biological functionality of DNPEP in CLL. DNPEP, as an aminopeptidase, contributes to the maintenance of the free amino acid pool in CLL cells found to be an essential process for the survival of many cancer cell types, and thus, these results warrant further research into the exploitation of aminopeptidase inhibitors in the treatment of drug-resistant CLL.

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