Overexpression of Rasgrf1, a Guanine Nucleotide Exchange Factor in Chronic Lymphocytic Leukemia.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1253-1253
Author(s):  
Sanjai Sharma
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Microarray Analysis ◽  
Peripheral Blood ◽  
Conflicts Of Interest ◽  
Mapk Pathway ◽  
Lymphocytic Leukemia ◽  
Ras Signaling ◽  
Guanine Nucleotide ◽  
Normal Peripheral Blood

Abstract 1253 Poster Board I-275 We performed microarray expression analysis to identify genes which are differentially expressed in chronic lymphocytic leukemia (CLL) cells. A number of genes from the cohort of maximally upregulated genes were members of the Ras superfamily of proteins function which function as switches between active GTP-complexed and inactive GDP-complexed states. One of the genes upregulated on the microarray analysis in all the CLL cells as compared to normal B cells was RASGRF1. This ras protein specific guanine nucleotide release factor stimulates the dissociation of GDP and activates Ras signaling pathway. To confirm our microarray analysis results, we performed real time PCR analysis on 35 CLL specimens and observed a 10-50 fold upregulation of rasgrf1 RNA as compared to human peripheral blood B cells. This high expression is consistently observed in all CLL specimens regardless of stage indicating that this upregulation is an early important event in the pathogenesis of CLL. Rasgrf1 protein expression was also higher in CLL cells as compared to normal B cells by western blot analysis. Interestingly the rasgrf1 gene is genomically imprinted during development in certain tissues and the expression is downregulated. Demethylation of normal peripheral blood B cells by treatment with azacytidine resulted in increased expression of rasgrf1 with no change in expression of rasgrf1 in CLL cells implying imprinting in normal B cells. Thus malignant transformation of B cells to CLL cells results in a loss of genomic imprinting and an aberrant upregulation of rasgrf1 in CLL cells. One important downstream effect of rasgrf1 upregulation is ERK activation via Ras-MAPK pathway. B cell receptor signaling in CLL results in activation of a number of pro-survival pathways including ERK which is more active in poor prognosis, unmutated immunoglobulin heavy chain CLL. Our results indicate that ERK phosphorylation is also increased in CLL specimens with rasgrf1 overexpression. Disclosures No relevant conflicts of interest to declare.

scholarly journals Immunoglobulin secretory function of B cells from untreated patients with chronic lymphocytic leukemia and hypogammaglobulinemia: role of T cells

Blood ◽  
1983 ◽  
Vol 62 (4) ◽  
pp. 767-774 ◽  
Author(s):  
LA Fernandez ◽  
JM MacSween ◽  
GR Langley
Keyword(s):  
T Cells ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
B Lymphocytes ◽  
Peripheral Blood ◽  
Cell Function ◽  
Lymphocytic Leukemia ◽  
Suppressor Activity ◽  
Normal Peripheral Blood

Abstract The mechanism of the hypogammaglobulinemia in patients with chronic lymphocytic leukemia (CLL) was studied by determining the generation of specific immunoglobulin-secreting cells in response to mitogen and antigen stimulation in culture. Normal peripheral blood B lymphocytes from 18 normal subjects cocultured with equal numbers of autologous T cells generated cells secreting 2,542 +/- 695 IgG, 2,153 +/- 615 IgA, and 2,918 +/- 945 IgM. Normal B lymphocytes cocultured with normal allogeneic T cells generated similar numbers. However, B lymphocytes from patients with chronic lymphocytic leukemia cocultured with T cells from the same patient generated only 0.5% as many cells secreting IgG and 11% and 23% as many secreting IgA and IgM, respectively. The reason for this markedly defective generation of immunoglobulin-secreting cells was investigated by evaluating T-helper, T-suppressor, and B-cell function using B cells from tonsil and T and B cells from peripheral blood of normal and leukemic individuals. T cells from patients with chronic lymphocytic leukemia provided somewhat greater help than did normal T cells to normal peripheral blood B cells and normal help to tonsil B cells, whether stimulated with mitogen or antigen. T cells from patients with chronic lymphocytic leukemia did not demonstrate increased suppressor function compared to normals with B cells from normal peripheral blood. The hypogammaglobulinemia in these patients therefore was associated with a markedly defective generation of immunoglobulin secreting cells, and as there was normal or increased T- cell helper activity without excessive suppressor activity, it seems likely that this was due to an intrinsic B-cell defect.

scholarly journals Immunoglobulin secretory function of B cells from untreated patients with chronic lymphocytic leukemia and hypogammaglobulinemia: role of T cells

Blood ◽  
1983 ◽  
Vol 62 (4) ◽  
pp. 767-774 ◽  
Author(s):  
LA Fernandez ◽  
JM MacSween ◽  
GR Langley
Keyword(s):  
T Cells ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
B Lymphocytes ◽  
Peripheral Blood ◽  
Cell Function ◽  
Lymphocytic Leukemia ◽  
Suppressor Activity ◽  
Normal Peripheral Blood

The mechanism of the hypogammaglobulinemia in patients with chronic lymphocytic leukemia (CLL) was studied by determining the generation of specific immunoglobulin-secreting cells in response to mitogen and antigen stimulation in culture. Normal peripheral blood B lymphocytes from 18 normal subjects cocultured with equal numbers of autologous T cells generated cells secreting 2,542 +/- 695 IgG, 2,153 +/- 615 IgA, and 2,918 +/- 945 IgM. Normal B lymphocytes cocultured with normal allogeneic T cells generated similar numbers. However, B lymphocytes from patients with chronic lymphocytic leukemia cocultured with T cells from the same patient generated only 0.5% as many cells secreting IgG and 11% and 23% as many secreting IgA and IgM, respectively. The reason for this markedly defective generation of immunoglobulin-secreting cells was investigated by evaluating T-helper, T-suppressor, and B-cell function using B cells from tonsil and T and B cells from peripheral blood of normal and leukemic individuals. T cells from patients with chronic lymphocytic leukemia provided somewhat greater help than did normal T cells to normal peripheral blood B cells and normal help to tonsil B cells, whether stimulated with mitogen or antigen. T cells from patients with chronic lymphocytic leukemia did not demonstrate increased suppressor function compared to normals with B cells from normal peripheral blood. The hypogammaglobulinemia in these patients therefore was associated with a markedly defective generation of immunoglobulin secreting cells, and as there was normal or increased T- cell helper activity without excessive suppressor activity, it seems likely that this was due to an intrinsic B-cell defect.

CD8 Expression on B Cells in Chronic Lymphocytic Leukemia

2000 ◽  
Vol 124 (9) ◽  
pp. 1361-1363
Author(s):  
Anwarul Islam ◽  
Adrian O. Vladutiu ◽  
Theresa Donahue ◽  
Selina Akhter ◽  
Amy M. Sands ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Tract Infection ◽  
Respiratory Tract ◽  
Respiratory Tract Infection ◽  
Peripheral Blood ◽  
Lymphocytic Leukemia ◽  
Cell Antigen

Abstract The expression of CD8, a restricted T-cell antigen, on B cells in B chronic lymphocytic leukemia is rare, and its significance, if any, remains unknown. We report herein a patient with B chronic lymphocytic leukemia in whom CD8 was strongly expressed on all B cells, both in the bone marrow and peripheral blood. The patient required no therapy for 6 years after being diagnosed as having B chronic lymphocytic leukemia. Then, when the disease progressed, he was treated with conventional doses of fludarabine phosphate (25 mg/m2 daily for 5 days), but unlike other patients with B chronic lymphocytic leukemia he tolerated this therapy poorly. He received a total of only 4 series of fludarabine therapy, and following each course of treatment, he developed considerable myelosuppression. After the fourth course of therapy, his bone marrow failed to show any evidence of regeneration, and he died as a result of intercurrent respiratory tract infection 1 month after his last dose of fludarabine was given.

scholarly journals Increased Proportion of Complement-Receptor Lymphocytes in the Peripheral Blood of Patients With Chronic Lymphocytic Leukemia

Blood ◽  
1972 ◽  
Vol 40 (3) ◽  
pp. 303-310 ◽  
Author(s):  
Seth Pincus ◽  
Celso Bianco ◽  
Victor Nussenzweig
Keyword(s):  
Lymph Node ◽  
Chronic Lymphocytic Leukemia ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Peripheral Blood Lymphocytes ◽  
Lymphocytic Leukemia ◽  
Complement Receptor ◽  
Normal Peripheral Blood ◽  
Present Evidence ◽  
Normal Individuals

Abstract In the present study we present evidence that the proportion of complement-receptor lymphocytes (CRL) is greatly increased in the circulation in most cases of chronic lymphocytic leukemia (CLL). Lymphocytes (> 99% pure, 70% recovery) were obtained from the peripheral blood of normal individuals by separation of the mononuclear cells from the leukocyte-enriched plasma by differential flotation in Hypaque-Ficoll and incubation of the mononuclear cells with iron-containing particles followed by removal of the phagocytes with a magnet. Complement - receptor lymphocytes were detected by incubating lymphocytes with sheep erythrocytes coated with antibody and mouse complement (EAC) and counting the EAC—CRL rosettes under the microscope. 7.1 ± 3.8% of normal peripheral blood lymphocytes, 31.0 ± 6.9% of lymph node, and 59.6 ± 13.2% of tonsil lymphocytes bind EAC. The binding was C3-dependent since it could be inhibited specifically by papain fragments of rabbit antibodies to mouse C3. Among lymphocytes from the peripheral blood of patients with CLL, 50.7 ± 25.0% bear the complement receptor. These results suggest that CLL preferentially affects B cells.

Comprehensive Analysis of BAFF Binding Receptor Profiles and Receptor Occupancy in B Cell Chronic Lymphocytic Leukemia: Identification of Discrete Phenotypic Subgroups.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1135-1135
Author(s):  
Renee C. Tschumper ◽  
Jaime R. Darce ◽  
Xiaosheng Wu ◽  
Stephen A. Mihalcik ◽  
Diane F. Jelinek
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Cell Activation ◽  
Receptor Occupancy ◽  
Lymphocytic Leukemia ◽  
B Cell Activation ◽  
Normal Peripheral Blood ◽  
Fold Induction ◽  
Cell Chronic Lymphocytic Leukemia

Abstract B cell-activating factor (BAFF) is known to regulate normal B cell development and homeostasis primarily by signaling through the high affinity receptor, BAFF-R, one of three BAFF binding receptors (BBRs). BAFF also binds two other receptors, BCMA and TACI with lesser affinity. We have recently shown that normal peripheral blood (PB) B cells express high levels of prebound soluble BAFF, which is lost upon B cell activation. Because of BAFF’s activity on normal B cells, we have been interested in the roles of BAFF and BBRs in B cell chronic lymphocytic leukemia (B-CLL). We and others have demonstrated that BAFF promotes primary CLL B cell survival and that serum BAFF levels are elevated in some patients. Although CLL B cells are known to express BBRs, a comprehensive and quantitative analysis of BBR levels and CLL B cell capacity to bind BAFF has not yet been done. We began this study by characterizing the level of soluble BAFF bound to freshly isolated CLL B cells, measured by both western blot analysis and flow cytometry. To assess receptor occupancy, cells were incubated with or without exogenous BAFF before assessing anti-BAFF reactivity and changes in median fluorescence intensity (ΔMFI; defined by dividing the MFI of the anti-BAFF antibody by the MFI of the isotype matched control antibody) were calculated. Normal B cells have higher detectable levels of bound BAFF with a ΔMFI ranging from 16 to 35 (mean=22.2). Upon addition of exogenous BAFF, the ΔMFI range increased to 27–96.6 (mean=49.1; n=8). Thus, despite evidence of prebound BAFF, clearly not all BBRs were occupied on normal PB B cells. By contrast, the levels of prebound BAFF on CLL B cells were significantly lower with a ΔMFI ranging from 1 to 13.1 (mean=2.7; n=36). Of note, 10/36 patients did not exhibit increased anti-BAFF reactivity upon incubation with exogenous BAFF (mean fold induction=0.8) whereas 26/36 patients displayed a mean fold induction of anti-BAFF reactivity of 3.5. These observations prompted us to next quantitate CLL B cell BBR expression. All patient CLL B cells expressed BAFF-R but at significantly lower levels than observed in normal B cells (p=0.0009). When CLL patients were categorized into IGHV mutated (M; n=22) and unmutated (UM; n=24), UM patients were observed to express higher levels of BAFF-R (ΔMFI =8.9) than M patients (ΔMFI =5.24). Regarding TACI, we previously demonstrated that normal memory B cells uniformly express TACI (ΔMFI =12.7; n=10) and there is a small population of activated naïve B cells that express TACI at lower levels (ΔMFI =8.3; n=10). In our CLL cohort, 14/22 M patients were TACI+ (ΔMFI =7.0) and 19/24 UM patients were TACI+ (ΔMFI =4.7). Finally, whereas normal PB B cells completely lack BCMA expression, 7/22 M and 4/22 UM patients expressed BCMA. Thus, using the BBR profile and analysis of expression levels relative to normal PB B cells, the following subgroups of B-CLL can be defined: BAFF-R+; BAFF-R/TACI+; BAFF-R/BCMA+; BAFF-R/TACI/BCMA+. It remains to be determined if these BBR profiles correlate with aspects of clinical disease. In addition, given the putative importance of BAFF in this disease, it is interesting to note that in general, CLL B cells display overall lower levels of prebound BAFF. Current studies are focused on determining whether this reflects CLL B cell activation status, increased competition for BAFF, and/or reduced levels of BBR expression.

Increased Expression of PD-1 on CD4+ T Cells from Patients with Chronic Lymphocytic Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4154-4154
Author(s):  
Mary M Sartor ◽  
David J Gottlieb
Keyword(s):  
T Cells ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Nk Cells ◽  
Cd4 T Cells ◽  
Mononuclear Cells ◽  
Lymphocytic Leukemia ◽  
Effector Memory ◽  
Cd4 Cells ◽  
Normal Peripheral Blood

Abstract Although the predominant finding in patients with chronic lymphocytic leukemia (CLL) is an expansion of monoclonal B lymphocytes, a polyclonal expansion of T cells co-exists in CLL patients. Allogenic stem cell transplants for CLL suggest that a significant graft versus leukaemia effect mediated through recognition of minor MHC or leukaemia specific antigens can be achieved. Since it appears that the immune system and probably T cells recognise CLL cells, it is possible that one or more T cell defects might contribute to the initiation or maintenance of a clone of CLL lymphocytes. PD-1 is a coinhibitory molecule that is expressed on T cells in patients with chronic viral infections. It has been suggested that PD-1 expression might be a marker of cell exhaustion due to antigenic overstimulation. We examined the expression of PD-1 and its naturally occurring ligands PD-L1 and PD-L2 on both B and T cells in patients with CLL and compared this with expression on normal peripheral blood mononuclear cells. We found that PD-1 was expressed on over 10% of CD4+ T cells in 7 of 9 cases of CLL (mean 22±16%) but not on CD4+ T cells in any of 9 normal donors (mean 0±0%), p=0.0009. There was no difference in PD-1 expression on CD8+ or CD14+ PBMCs from CLL patients and normal donors (for CD8+ 24±21% and 19±16% for CLL and normals; for CD14+ 58±16% and 71±31% for CLL and normals). More than 10% of CD5+/19+ CLL cells expressed PD-1 in 7 of 10 cases (mean 18±18%) while more than 10% of normal B cells from 6 of 7 donors also expressed PD-1 (mean 49±30%). We examined the expression of PD-1 on naïve, central memory, effector memory and terminally differentiated subsets of CD4+ cells (CD62L+CD45RA+, CD62L+CD45RA−, CD62L−CD45RA− and CD62L−CD45RA+ respectively) from CLL patients and normal donors. The expression of PD-1 was higher on CD4+ cells from CLL patients in all subsets. The effect was most prominent in the effector memory subset (mean 54±4% for CLL patients versus 26±17% for normal donors, p=0.02). We looked for expression of PD-L1 and PD-L2 on T cells, B cells, monocytes and NK cells from CLL patients and normal donors. PD-L1 was only expressed on monocytes (mean 30±23%) and NK cells (mean 14±19%) from CLL patients and on monocytes from normal donors (mean 35±26%). There was no expression of PD-L2 on any cell type in either CLL patients or normal donors. We conclude that there is increased expression of the co-inhibitory molecule PD-1 on CD4+ T cells in patients with CLL. Ligation of PD-1 by PD-L1 expressed on monocytes or NK cells could inhibit immune responses to tumor and infectious antigens leading to persistence of clonally expanded cells and predisposition to opportunistic pathogens.

Dysregulation of TNFα-Induced Necroptotic Signaling In Chronic Lymphocytic Leukemia: Suppression of CYLD Gene by LEF1

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 377-377 ◽  
Author(s):  
Peng Liu ◽  
Bei Xu ◽  
Jianyong Li
Keyword(s):  
Cell Death ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Molecular Mechanisms ◽  
Conflicts Of Interest ◽  
Death Receptors ◽  
Lymphocytic Leukemia ◽  
Ros Production ◽  
A Genome ◽  
Stimulation Of

Abstract Abstract 377 Impaired cell death program has been noted as one of the hallmarks of Chronic lymphocytic leukemia (CLL) and contributes to its accumulation of malignant monoclonal B cells as well as to chemotherapy resistance. A cell can die through apoptosis or necrosis pathway. While apoptosis is known as a regulated cellular program, necrosis is known as an accidental event caused by overwhelming stress. However, accumulating evidence suggests that necrosis can also be executed by regulated mechanisms, especially in apoptotic-deficient conditions. Recently, the term necroptosis has been used to designate one particular form of programmed necrosis induced by stimulating death receptors with agonists such as TNFα, FasL, and TRAIL. Apoptosis suppression by caspase inhibitors such as zVAD may switch apoptotic response to necroptosis or enhance necroptosis. In contrast to well-characterized apoptotic pathway, the detailed molecular mechanisms underlying necroptosis are still not fully understood. A genome wide siRNA screen revealed two members of the receptor interacting protein (RIP) kinase family, RIP1 and RIP3P, to be essential for necroptosis. Upon stimulation of death receptors, RIP3 is recruited to RIP1 to form a necroptosis-inducing complex which is essential for cell death execution. The deubiquitinase cylindromatosis (CYLD) is recruited to TNFα receptor upon its activation and directly regulates RIP1 ubiquitination. In addition, by activating key enzymes of metabolic pathways, RIP3 regulates TNFα-inducing mitochondrial reactive oxygen species (ROS) production, which partly accounts for its ability to potentiate necroptosis. Until now, much less is known about the significance of necroptosis in malignant disease. Here we demonstrate that primary CLL cells failed to undergo necroptosis upon stimulation of TNFα combined with pan-caspase inhibitor zVAD. Upon TNFα+zVAD stimulation, normal CD19+ B cells increased ROS production > 8 fold, while same treatment only resulted in ∼ 2 fold induction in ROS generation in CLL samples. Two core components of necroptotic machine, RIP3 and CYLD, are markedly down-regulated in CLL compared with normal B cells, at both protein and transcription levels. Moreover, we identified LEF1, a downstream effector of Wnt/β-catenin pathway, as a transcription repressor of CYLD in CLL. LEF1 is highly expressed in CLL cells, whereas normal B cells have very low levels of LEF1 expression. Attenuation of LEF1 expression through RNAi technology resulted in a dramatic increase in CYLD levels in CLL cells, as determined by western blot and real time RT-PCR analysis. Dual-luciferase assays showed that forced expression of LEF1 markedly decreased CYLD promoter activity compared with controls. Mutation of LEF1 responsive elements (LERs) on CYLD promoter significantly abolished transcriptional repression of CYLD by LEF1. Chromatin immunoprecipitation assays showed that LEF1 is recruited to LER region within the CYLD promoter in CLL cells. Additionally, Knocking down LEF1 sensitizes CLL cells to TNFα-induced necroptosis. The present investigation provides the first evidence that CLL cells have defects not only in apoptotic program but also in necroptotic signaling. Targeting the key regulators of necroptotic machine such as LEF1 to restore this pathway may represent a novel approach for CLL treatment. Disclosures: No relevant conflicts of interest to declare.

CCR4:CCL17 Interaction Influences TLR-9 Mediated Cell Survival and Proliferation In Chronic Lymphocytic Leukemia

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3593-3593
Author(s):  
Sonal C. Temburni ◽  
Ryon M. Andersen ◽  
Luke Janson ◽  
Xiao-Jie Yan ◽  
Barbara Sherry ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
B Cell ◽  
Conflicts Of Interest ◽  
Dose Range ◽  
Serum Levels ◽  
Lymphocytic Leukemia ◽  
Novel Therapy

Abstract Abstract 3593 Unlike other hematologic disorders, chronic lymphocytic leukemia(CLL) exhibits remarkable heterogeneity in the rates of disease progression among cases. CLL cells survive by receiving signals from the microenvironment via various receptors: B-cell antigen receptor (BCR), Toll-like receptors (TLRs) and cytokine and chemokine receptors. We previously reported that CLL clones with somatically mutated IGHVs and high (≥30%) percentage of CD38 expressing cells have the highest percentage of CCR4-expressing cells. To further explore the functional contribution of the CCR4:CCL17 axis in CLL, we studied CCL17-induced chemotactic behavior in 16 CLL cases. In transwell cultures we observed a bimodal migratory response to CCL17 at 2 doses in a dose range of 0.78– 25ng/ml, in ~60% of cases; the remaining cases showed maximal migration at a single dose (1.56 or 3.12ng/ml). A comparison of phenotypes of the migrated and non-migrated cell populations was undertaken in 10 cases, analyzing CXCR3, CXCR4, CCR4 and CCR7 that are involved in homing of cells to sites favoring growth, and CD31, CD38 and CD69, activation related molecules. The migrated cells consistently showed significantly higher percentages and densities of CD38 expression than the non-migrated cells suggesting a role for CD38 in the CCR4-mediated downstream pathway. CCR4 ligand, CCL17, is constitutively expressed in the thymus and is produced by dendritic cells, endothelial cells, keratinocytes and fibroblasts, whereas CCL22 is produced by tumor cells and the tumor microenvironment. Serum levels of both these ligands in untreated patients were quantified by ELISA. CCL17 levels ranged between 45-1, 229 pg/ml in U-CLL cases (n=23) and between 43-1, 418 pg/ml in M-CLL cases (n=30). CCL22 levels ranged between 121-5, 497 pg/ml in U-CLL cases (n=23) and 409-5, 502 pg/ml in M-CLL cases (n=30). The percentages of CCR4- expressing B cells directly correlated with percentages of T cells expressing CCR4 in individual cases, whereas they inversely correlated with both, serum levels of CCL17 (p< 0.01) and CCL22 (p< 0.05). CCL17 produced by DCs in peripheral organs may exert an accessory role in BCR- and TLR-9-mediated immune responses in B cells. We therefore tested if CCL17 supported BCR- and TLR-mediated proliferative responses in a cohort of 31 (16 U-CLL and 15M-CLL) CLL cases. CCL17 augmented BCR-mediated B-cell proliferation in 9/16 (56%) U-CLL cases, but only in 3/15 (20%) M-CLL cases. On the other hand, CCL17 showed an additive effect in promoting TLR-9-mediated cell proliferation in 13/15 (87%) M-CLL cases at a dose of 2ng/nl (approximating that detected in serum); it also augmented TLR-9 mediated B cell proliferation in 6/16 U-CLL cases but at a 5-fold or higher dose (10-25 ng/ml). In a subset of this cohort (8 cases) CCL17-induced modulation of molecules involved in the apoptotic process was studied. We found upregulation of anti-apoptotic proteins Mcl-1 and Bcl2 and down-regulation of pro-apoptotic molecules Bim, PUMA, and Bid in 5 of these cases. The pro-survival effects of CCL17 were partially abrogated by the blocking anti-CCR4 mAb (1G1). Taken together, these findings suggest that CCL17 plays a role in modulating TLR-9-mediated signaling and migration in CLL. Therefore, inhibition of CCR4:CCL17 interaction in vivo represents a novel therapy by preventing migration of CLL cells towards an environment that promotes their survival. Disclosures: No relevant conflicts of interest to declare.

Reduced c-FOS Is Associated with Poor Prognosis and Clinical Course in Chronic Lymphocytic Leukemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2433-2433
Author(s):  
Christopher C Oakes ◽  
Rainer Claus ◽  
Christopher Schmidt ◽  
Yoon Jung Park ◽  
Michael Boutros ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
Gene Family ◽  
Conflicts Of Interest ◽  
Mapk Pathway ◽  
Substantial Reduction ◽  
Lymphocytic Leukemia ◽  
Prognostic Indicators ◽  
Autologous Serum ◽  
Isolated Cells

Abstract Abstract 2433 We have previously shown that silencing of the tumor suppressor gene, DAPK1, by genetic and epigenetic mechanisms is associated with the pathogenesis of CLL. To elucidate genes and pathways involved in DAPK1 transcriptional regulation, genome-wide siRNA screens were performed using a novel transgene reporter system involving a stably-integrated BAC construct expressing luciferase under the control of the DAPK1 locus. c-FOS and other members of the FOS gene family were identified as positive regulators, implicating the AP-1 pathway in DAPK1 transcription. A subsequent comprehensive examination of the FOS, JUN and ATF gene families in CLL and healthy B cells was performed. As the expression of the AP-1 gene family is highly subject to fluctuations in stress and mitogenic stimuli, freshly isolated cells were cultured using autologous serum conditions, allowing for a uniform establishment of baseline gene expression. This work reveals an alteration of the relative composition of AP-1 transcription factors in CLL, demarked by a substantial reduction in c-FOS gene expression. We find that the inducibility of c-FOS in CLL following MAPK activation by TPA (ERK-MAPK) is impaired 7.0-fold relative to healthy B cells and is completely abrogated following anisomycin (p38-MAPK) stimulation. The level of c-FOS induction following TPA activation can be used to clearly segregate CLL patients into two non-overlapping groups, those with low (mean=4.0-fold reduced expression; range=3.0–7.2; n=9) and very low (mean=21.7-fold reduced expression; range=17.6–36.7; n=8) following one hour induction versus healthy B cells. The very low c-FOS induction cases are characterized by poor prognostic indicators (IGHV unmutated (0/9 in low vs. 5/8 in very low); 17p, 6q deletion (0/9 in low vs. 3/8 in very low); and a substantially shorter time to progression (102.7±40.4 months in low vs. 10.8±8.6 in very low). Patients with very low c-FOS induction also demonstrate elevated c-MYC induction following activation. TPA-dependent ERK phosphorylation and activation of other immediate early genes, such as EGR1 and c-JUN, is intact in both CLL groups, absolving MAPK pathway dysfunction as a relevant c-FOS silencing mechanism. Reduced c-FOS expression can be partially explained, in the majority of very low c-FOS inducible cases, by elevated levels of miR-155 and miR-221 targeting the c-FOS transcript. Reduced expression of c-FOS and the resulting reconfiguration of AP-1 transcription factor composition may be involved in the pathogenesis of CLL and the subsequent silencing of DAPK1. Disclosures: No relevant conflicts of interest to declare.

Increased CD39 Expression on CD4+ T-Lymphocytes Has Clinical and Prognostic Significance in Chronic Lymphocytic Leukemia,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3895-3895
Author(s):  
Yair Herishanu ◽  
Inbal Hazan-Hallevi ◽  
Sigi Kay ◽  
Varda Deutsch ◽  
Aaron Polliack ◽  
...  
Keyword(s):  
T Cells ◽  
Chronic Lymphocytic Leukemia ◽  
T Lymphocytes ◽  
Peripheral Blood ◽  
Conflicts Of Interest ◽  
Prognostic Significance ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Anti Inflammatory

Abstract Abstract 3895 Chronic lymphocytic leukemia (CLL) cells depend on their microenvironment for proliferation and survival. Ectonucleotidase CD39 has anti-inflammatory properties as it hydrolyzes pro-inflammatory extra-cellular ATP, generates anti-inflammatory adenosine and also protects regulatory T cells from ATP-induced cell death. In this study we investigated the clinical significance of CD39 expression on CD4+T-cells in 45 patients with CLL as well as its compartmental regulation and explored the possible mechanisms for its induction. Compared to healthy individuals, CD4+CD39+ lymphocytes were increased in the peripheral blood of patients with CLL (4.6%±2.28 vs. 17.3%±12.49, respectively, p=0.004), and correlated with advanced stage of disease (9.72%±5.76, 18.15%±12.03 and 25.90%±16.34, of CD4+ lymphocytes, in patients with Rai stages 0, 1+2 and 3+4, respectively, p=0.019). CD4+CD39+ cells were also higher in patients with CLL who needed therapeutic intervention (untreated; 12.99%±10.63 vs treated; 22.21%±12.88, p=0.01) and in those who were ZAP70+ or had b2-microglobulin levels>3g/L. There were more CD4+CD39+ lymphocytes in the bone marrow compartment (22.25%±16.16) than in the peripheral blood (16.60%±15.84, p=0.009). In-vitro studies showed that CD39 can be induced on CD4+cells by exposure to ATP or indirectly, following B-cell receptor (BCR) engagement (CD4+CD39+ lymphocytes increased by 1.56 fold, in the BCR engaged samples compared to their paired controls; 20.27%±11.3 vs. 13%±9.42, respectively, p=0.0006). Conclusions: Increased CD39 expression on CD4+ T-lymphocytes in CLL associates with an aggressive disease. This may reflect the ability of the leukemic cells to suppress the surrounding immune environment, and contribute to a poorer prognosis. CD39+ may also serve as a future target for the development of novel therapies with immune modulating anti–tumor agents in CLL. Disclosures: No relevant conflicts of interest to declare.

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