Elevated FANCA Expression Marks a Worse Prognosis in Chronic Lymphocytic Leukemia. Evidence of a New Role of FANCA in the Stability of p53 By a Neddylation-Related Mechanism

Abstract Background: Chronic lymphocytic leukemia (CLL) is the most common hematological malignancy in western countries. It is characterized by a failure in the mechanisms of apoptosis that leads to an accumulation of mature B cells in peripheral blood, bone marrow and lymphoid organs. With exceptions, CLL is considered incurable and some patients show a worse prognosis related to the expression of certain cytogenetic or molecular markers such as p53 dysfunction (17p13 deletion or TP53 inactivation), 11q23 deletion, unmutated IgVH and the presence of a complex karyotype. FANC proteins have been related to chromosomal instability and alterations in the mechanisms of p53 activation, control of cell cycle and apoptosis. Germline mutations in any of the 20 FANC genes known so far generates Fanconi Anemia, a syndrome characterized by a extraordinary proneness to cell apoptosis leading to a progressive bone marrow aplasia and pancytopenia. Some FANCA proteins aggregate in response to DNA damage forming the FANCcore complex that mediates the monoubiquitination of FANCD2 and FANCI, thus activating the mechanism to repair stalled replication forks. In addition, individual FANC proteins have been involved in functions out of the FANCcore. This is the case of FANCA, that has recently been involved in the neddylation of CXCR5 and beta-2-microglobulin, processes reported to be altered in CLL. Hypothesis: Given the fragmentary information connecting FANC proteins with cellular processes altered in CLL, like apoptosis, cell cycle or neddylation, we hypothesize a role of these proteins in the diagnosis or prognosis of CLL. Methods: We analyzed the expression of 5 FANC genes in a cohort of 160 patients of CLL by quantitative RT-PCR. Statistical analysis were carried out to establish relations between FANC genes deregulation and clinical manifestations. We also investigated the role of the FANCA gene in primary circulating B-lymphocytes from CLL patients by either gain- or loss-of-function approaches. Results: Our data identified a group of CLL patients with high expression of FANCA in peripheral B-CLL cells, and we stablished its relationship with the deletion of 11q23 and a worse prognosis. When we investigated the molecular mechanisms of this bad prognosis, we observed a reduction in the mRNA expression of two p53 target genes, p21 and ∆Np73, in CLL primary cells transfected with FANCA. Luciferase studies demonstrated an impairment of p53 function by FANCA. Moreover, we obtained evidence of a cooperation between FANCA and the NEDD8-interacting protein NUB1L in the destabilization of p53. Conclusion: These results point to FANCA as a bad prognosis marker in CLL and unveils a new role of this protein aside from its role in the FA-BRCA DNA repair pathway. Disclosures No relevant conflicts of interest to declare.

Download Full-text

miR-15b/16-2 deletion promotes B-cell malignancies

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1514954112 ◽

2015 ◽

Vol 112 (37) ◽

pp. 11636-11641 ◽

Cited By ~ 60

Author(s):

Francesca Lovat ◽

Matteo Fassan ◽

Pierluigi Gasparini ◽

Lara Rizzotto ◽

Luciano Cascione ◽

...

Keyword(s):

Chronic Lymphocytic Leukemia ◽

B Cell ◽

Knockout Mice ◽

Molecular Mechanisms ◽

Target Genes ◽

Flow Cytometric Analysis ◽

Lymphocytic Leukemia ◽

White Pulp ◽

Cell Chronic Lymphocytic Leukemia

The central role of the microRNA (miR) 15a/16-1 cluster in B-cell oncogenesis has been extensively demonstrated, with over two-thirds of B-cell chronic lymphocytic leukemia characterized by the deletion of the miR-15a/16-1 locus at 13q14. Despite the well-established understanding of the molecular mechanisms occurring during miR-15a/16-1 dysregulation, the oncogenic role of other miR-15/16 family members, such as the miR-15b/16-2 cluster (3q25), is still far from being elucidated. Whereas miR-15a is highly similar to miR-15b, miR-16-1 is identical to miR-16-2; thus, it could be speculated that both clusters control a similar set of target genes and may have overlapping functions. However, the biological role of miR-15b/16-2 is still controversial. We generated miR-15b/16-2 knockout mice to better understand the cluster’s role in vivo. These mice developed B-cell malignancy by age 15–18 mo with a penetrance of 60%. At this stage, mice showed significantly enlarged spleens with abnormal B cell-derived white pulp enlargement. Flow cytometric analysis demonstrated an expanded CD19+ CD5+ population in the spleen of 40% knockout mice, a characteristic of the chronic lymphocytic leukemia-associated phenotype found in humans. Of note, miR-15b/16-2 modulates the CCND2 (Cyclin D2), CCND1 (Cyclin D1), and IGF1R (insulin-like growth factor 1 receptor) genes involved in proliferation and antiapoptotic pathways in mouse B cells. These results are the first, to our knowledge, to suggest an important role of miR-15b/16-2 loss in the pathogenesis of B-cell chronic lymphocytic leukemia.

Download Full-text

Reconstitution of PTEN activity by CK2 inhibitors and interference with the PI3-K/Akt cascade counteract the antiapoptotic effect of human stromal cells in chronic lymphocytic leukemia

Blood ◽

10.1182/blood-2009-10-248054 ◽

2010 ◽

Vol 116 (14) ◽

pp. 2513-2521 ◽

Cited By ~ 78

Author(s):

Medhat Shehata ◽

Susanne Schnabl ◽

Dita Demirtas ◽

Martin Hilgarth ◽

Rainer Hubmann ◽

...

Keyword(s):

Bone Marrow ◽

Chronic Lymphocytic Leukemia ◽

Stromal Cells ◽

Molecular Mechanisms ◽

Mononuclear Cells ◽

Lymphocytic Leukemia ◽

Therapeutic Concept ◽

Antiapoptotic Effect ◽

Human Stromal Cells ◽

Ck2 Inhibitors

Abstract Evidence suggests that tumor microenvironment is critically involved in supporting survival of chronic lymphocytic leukemia (CLL) cells. However, the molecular mechanisms of this effect and the clinical significance are not fully understood. We applied a microenvironment model to explore the interaction between CLL cells and stromal cells and to elucidate the role of phosphatidylinositol 3 kinase (PI3-K)/Akt/phosphatase and tensin homolog detected on chromosome 10 (PTEN) cascade in this process and its in vivo relevance. Primary human stromal cells from bone marrow, lymph nodes, and spleen significantly inhibited spontaneous apoptosis of CLL cells. Pan–PI3-K inhibitors (LY294002, wortmannin, PI-103), isotype-specific inhibitors of p110α, p110β, p110γ, and small interfering RNA against PI3-K and Akt1 counteracted the antiapoptotic effect of the stromal cells. Induction of apoptosis was associated with a decrease in phosphatidylinositol-3,4,5-triphosphate, PI3-K–p85, and dephosphorylation of phosphatidylinositol-dependent kinase-1 (PDK-1), Akt1, and PTEN. Freshly isolated peripheral blood mononuclear cells from patients with CLL (n = 44) showed significantly higher levels of phosphorylated Akt1, PDK-1, PTEN, and CK2 than healthy persons (n = 8). CK2 inhibitors (4,5,6,7-tetrabromo-1H-benzotriazole, apigenin, and 5,6-dichloro-1-β-D-ribofuranosylbenzimidazol) decreased phosphorylation of PTEN and Akt, induced apoptosis in CLL cells, and enhanced the response to fludarabine. In conclusion, bone marrow microenvironment modulates the PI3-K/Akt/PTEN cascade and prevents apoptosis of CLL cells. Combined inhibition of PI3-K/Akt and recovery of PTEN activity may represent a novel therapeutic concept for CLL.

Download Full-text

Chronic Lymphocytic Leukemia (CLL) Cells Require Microenvironmental Stimuli to Resist Apoptosis through Activation of STAT3 Mediated by VEGF.

Blood ◽

10.1182/blood.v112.11.1069.1069 ◽

2008 ◽

Vol 112 (11) ◽

pp. 1069-1069

Author(s):

Iris Gehrke ◽

Julian Paesler ◽

Rajesh Kumar Gandhirajan ◽

Regina Razavi ◽

Alexandra Filipovich ◽

...

Keyword(s):

Bone Marrow ◽

B Cells ◽

Chronic Lymphocytic Leukemia ◽

Cell Survival ◽

Lymphocytic Leukemia ◽

Vegf Receptor ◽

Mrna Levels ◽

Activated State ◽

Survival Effect

Abstract B-cell chronic lymphocytic leukemia (CLL) is characterized by an accumulation of mature, but incompetent B-cells due to a decrease of apoptosis rather than an increase in proliferation. Vascular endothelial growth factor (VEGF) has been suggested to play an important role in this so called apoptotic block. However, so far little is understood whether VEGF is acting mainly as a microenvironmental stimulus and/or whether CLL cells themselves contribute to the enhanced apoptotic resistance by maintaining an autocrine VEGF loop. Moreover, it is unknown by which mechanisms VEGF prevents apoptosis and whether this can be circumvented by inhibition of VEGF signaling. By quantitative real time PCR we found no significant difference in mRNA VEGF levels in B-cells from CLL patients and healthy donors after isolation from blood. In contrast, ELISA revealed clearly increased levels of secreted VEGF in plasma of CLL patients and in the supernatant under culture conditions compared to healthy individuals. In addition, we found the VEGF receptor 2 (VEGFR2), which is existent in CLL and healthy B-cells, in a phosphorylated, hence activated state, to a significantly higher extent in CLL cells as assessed by intracellular phospho flow cytometry. In conclusion, despite its expression in healthy B-cells VEGF does not seem to be secreted and therefore, no VEGF receptor phosphorylation takes place. Whereas CLL cells exhibit a long life span in vivo, they die rapidly in vitro, suggesting major survival factors being existent in the CLL cells microenvironment. We found levels of secreted VEGF in supernatant decreasing with time in culture, going along with decreasing levels of phosphorylated VEGFR2 and increasing cell death as assessed by Annexin V-FITC/PI staining. This further supports the role of VEGF in CLL cell survival. Coculturing primary CLL cells with the bone marrow stromal derived cell line HS5 dramatically increased VEGF transcription and secretion and improved cell survival. Hence, VEGF expression in CLL cells is not only mediated by autocrine, but also paracrine stimuli involving bone marrow stromal. Knocking down VEGF in HS5 cells and subsequent coculture with CLL cells might prove the major role of VEGF in this survival supporting coculture setting. Besides coculturing also supplement of culture medium with recombinant human VEGF (rhVEGF) increased survival, but to a lesser extent than coculture, indicating a direct cell-cell interaction as advantageous. Furthermore, we found a downregulation of anti apoptotic proteins, such as X-linked inhibitor of apoptosis protein (XIAP), myeloid cell leukemia 1 (MCL1) and BclXL upon VEGF stimulation. Also cyclinD1 was upregulated as seen by immunoblotting. We further tried to discover the underlying mechanism of how VEGF mediates its pro survival effect and found STAT3 to become phosphorylated on tyrosine 705 upon VEGF stimulation. In CLL STAT3 is known to be constitutively phosphorylated on serine 727. This phosphorylation is not sufficient to induce target gene expression though. We could show that Y705 phosphorylation of STAT3 is responsible for upregulation of anti apoptotic BCLXL and cyclinD1. A PCR array detecting mRNA levels of 84 transcription factors in untreated and VEGF stimulated CLL cells shall provide more information about mechanistical details how VEGF mediates it pro survival effect. Since VEGF seems to be a major player in CLL cell survival it might be a suitable target to overcome the apoptotic block. In first experiments we found an induction of apoptosis after neutralization of VEGF or inhibition of the VEGF receptor. This additionally highlights the severe importance of VEGF in the apoptotic block in CLL cells. Therefore, VEGF might serve as an excellent therapeutic target in CLL.

Download Full-text

Abnormal Free Light Chain Ratios in Chronic Lymphocytic Leukemia: A New Prognostic Factor?.

Blood ◽

10.1182/blood.v114.22.1237.1237 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1237-1237 ◽

Cited By ~ 2

Author(s):

Johannes Matschke ◽

Lewin Eisele ◽

Ludger Sellmann ◽

Ulrich Duehrsen ◽

Jan Duerig ◽

...

Keyword(s):

Prognostic Factor ◽

Chronic Lymphocytic Leukemia ◽

Conflicts Of Interest ◽

Prognostic Significance ◽

Risk Groups ◽

Typical Feature ◽

Lymphocytic Leukemia ◽

Al Amyloidosis ◽

Abnormal Ratio

Abstract Abstract 1237 Poster Board I-259 Introduction Free light chains (FLC) have prognostic significance in monoclonal gammopathy of undetermined significance, solitary plasmocytoma of bone, smouldering myeloma, multiple myeloma, Waldenstroms macroglobulinaemia and AL amyloidosis. Although monoclonal protein secretion is a typical feature of plasma cell dyscrasias, it can also be detected in other B cell malignancies including chronic lymphocytic leukemia (CLL). Recent data suggest a significant correlation between abnormal ratio of FLC and outcome. Therefore, we investigated FLC in a large cohort of 120 patients in order to assess the role of FLC in CLL. Methods and Results Plasma samples which had been previously cryopreserved and collected at the time before the initiation of therapy or six months after finishing therapy were used. The levels of FLC were assessed using nephelometric immunoassays (The Binding Site) and quantified nephelometrically with the BNII analyser. A normal FLC range (κlγ) was defined as 0.26-1.65. Moreover, in all cases we evaluated the M band on immunofixation (IF). Abnormal FLC ratios were found in 71 patients (59%) whereas the IF was positive in only 32 cases (27%). In 48 cases the FLC ratio was positive while IF was negative and in only 9 cases the IF was positive while the FLC ratio was normal. In total, 23 patients had both a positive IF and an abnormal FLC ratio. Patients with an abnormal FLC ratio for γ had a significantly shorter treatment-free survival (TFS) than patients with an abnormal ratio for κ or with a normal FLC ratio (median TFS: 34 versus 78 versus 109 months, p=0.042). Evaluation of several disease characteristics in association with FLC of the patients' B-CLL cells showed no significant differences for FLC in the different risk groups (ZAP-70 status, CD38 status, cytogenetics and Binet stage) suggesting no correlation of the FLC with these already established adverse prognostic factors. Conclusion FLC can be detected in a substantial fraction of patients with CLL and the FLC technique improves detection of M-proteins. Moreover, an abnormal FLC ratio is associated with worse outcome, particularly those with a low abnormal FLC ratio. Evaluation of the prognostic significance of abnormal FLC in a larger cohort is currently under way. This data will be presented at the meeting. Future studies are warranted to elucidate the role of FLC as biomarkers of disease and as a prognostic factor for response. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Erythroid Differentiation Regulator 1 (ERDR1) From Nurse-Like Cells Promotes the Survival of Chronic Lymphocytic Leukemia Cells

Blood ◽

10.1182/blood.v116.21.1372.1372 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1372-1372

Author(s):

Hendrik W. Van Deventer ◽

Robert Mango ◽

Jonathan Serody

Keyword(s):

Bone Marrow ◽

Chronic Lymphocytic Leukemia ◽

Stromal Cells ◽

Stromal Cell ◽

Conflicts Of Interest ◽

Erythroid Differentiation ◽

Mesenchymal Cells ◽

Lymphocytic Leukemia ◽

Leukemia Cells ◽

Wild Type

Abstract Abstract 1372 Background: Chemotherapy resistance in chronic lymphocytic leukemia (CLL) can be mediated by anti-apoptotic signals produced by stromal or nurse-like cells. Developing strategies to overcome this resistance is hindered by the lack of suitable “stromal” targets responsible for these signals. We have discovered that erythroid differentiation regulator 1 (ERDR1) may be a candidate target for such a strategy. In this study, we show Erdr1 is generated by several stromal cell types including bone marrow stromal cells, fibrocytes, and nurse-like cells. Furthermore, inhibition of stroma-generated Erdr1 results in increased apoptosis of co-cultured CLL cells. Methods/Results: We initially identified Erdr1 on an Affymetrix array that compared the gene expression of wild type and CCR5-/- mice with pulmonary metastasis. The increased expression of Erdr1 in the wild type mice was particularly pronounced in the pulmonary mesenchymal cells. Therefore, these cells were transfected with one of two shRNAs (shRNA #9 or shRNA#11) and the survival of these cells was compared with mesenchymal cells transfected with a non-targeted control vector. After 15 days in culture, the control cells expanded normally; however, no significant expansion was seen in either the shRNA#9 or shRNA#11 transfected cells. These differences in cellular expansion were associated with differences in apoptosis. 21.4+1.6% of the Erdr1 knockdown cells were annexin V+ compared to 11.2+1.9% of the non-targeted control (p<0.03). Using GFP as a marker for transfection, we were also able to show that knockdown of Erdr1 increased the apoptosis of surrounding non-transfected mesenchymal cells. Thus, Erdr1 is a critical protein for the survival of stromal cells. Further analysis of the mesenchymal cell subpopulations revealed the greatest expression of Erdr1 in the CD45+, thy1.1+/− fibrocytes. When compared to CD45- fibroblasts, the fibrocytes expressed CCR5 and increased Erdr1 expression by 14.2+/−2.9 fold when treated with the CCR5 ligand CCL4. Given the similarities between fibrocytes and nurse-like cells, we went on to measure the effect of Erdr1 inhibition on CLL cells. In these experiments, stable Erdr1 knockdown and control clones were selected after the transfection of the bone marrow stromal cell line M2-10B4. These clones were then co-cultured with primary CLL cells. At 96 hours, leukemia cells co-cultured with the control lines had expanded by 1.33 + 0.9 compared to 0.74 + 0.22 fold in the knock-down lines (p<0.03). As before, the lack of cellular expansion was associated with an increase in apoptosis. To further show the relevance of these findings to CLL, we demonstrated that human fibrocytes and nurse-like cells expressed mRNA and protein for ERDR1 in all patient samples tested. Implications for the treatment of human disease: Our data demonstrate that ERDR1 is a critically important protein for the survival of nurse-like cells. These data suggest that targeting ERDR1 or the upstream pathway through CCR5 might be a novel approach for the treatment of CLL. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

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

Blood ◽

10.1182/blood.v116.21.377.377 ◽

2010 ◽

Vol 116 (21) ◽

pp. 377-377 ◽

Cited By ~ 2

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.

Download Full-text

Heat-Shock Protein Signature Is Associated with Refractory Chronic Lymphocytic Leukemia Cells From Different In Vivo Microenvironments,

Blood ◽

10.1182/blood.v118.21.3866.3866 ◽

2011 ◽

Vol 118 (21) ◽

pp. 3866-3866

Author(s):

Payal Gupta ◽

Amit K. Mittal ◽

Dennis D Weisenburger ◽

Philip Bierman ◽

Shantaram S Joshi

Keyword(s):

Bone Marrow ◽

Heat Shock ◽

Chronic Lymphocytic Leukemia ◽

Heat Shock Protein ◽

Peripheral Blood ◽

Treatment Cycle ◽

Conflicts Of Interest ◽

Lymphocytic Leukemia ◽

Activation Markers ◽

Protein Signature

Abstract Abstract 3866 Chronic Lymphocytic Leukemia (CLL) is a monoclonal B-cell disorder with accumulation of leukemic cells in peripheral blood, bone marrow and lymphoid organs. It presents with a heterogeneous clinical course. Many patients survive long periods of time without any need for treatment, whereas other patients show resistance to treatment or relapse soon after administration of therapy. Although some prognostic markers such as mutational status of immunoglobulin variable heavy chain, chromosomal abnormalities, CD38 levels, or ZAP-70 expression may help predict at initial diagnosis which patients will have more aggressive disease, the exact factors that can determine chances of remission in CLL are still not clear, making treatment challenging. Furthermore, CLL remains an incurable disease, necessitating a way for controlling its progression. Identifying novel molecular signatures associated with refractory CLL disease may help devise targeted treatment strategies and thus may prolong survival times and prevent the progression of CLL in relapsed patients. Considering this, we performed gene expression profiling (GEP) on peripheral blood (PB), bone marrow (BM) and lymph node (LN) samples collected at the time of diagnosis. We divided CLL samples into 3 groups based on their response to treatment; i) Stable CLL group: asymptomatic patients requiring no treatment, ii) Treated but stable CLL group: patients required treatment but had stable disease for at least one year after the end of the treatment cycle, and iii) Relapsed CLL: patients who relapsed within a year of end of the treatment cycle. Significance analysis of microarray (SAM) revealed that the heat-shock protein (HSP) signature (HSJ2, HSP70, HSP90, HSP60, HSP10, HSP 105, HSP40, HSP27, HSPA2, HSJ1, HSF4, HSPCA), BCR signaling pathway (JUN, NFATC4, NFKBIE, PPP3CB, TRAF3, CD81, CCT4), activation markers (CD81, CD83) and MMPs (MMP3, MMP9) were overexpressed in relapsed PB-CLL (n=3) compared to stable PB-CLL (n=6) and treated but stable PB-CLL (n=10). Overexpression of heat-shock protein signature genes were further observed in additional relapsed PB-CLL (n=6) group compared to other two PB-CLL (n=22) group. Interestingly, the HSP signature was consistently overexpressed in relapsed BM-CLL (n=6) and LN-CLL (n=12) compared to stable and treated but stable BM-CLL (n=11) and LN-CLL (n=3) groups. HSPs are considered chaperones of tumorigenesis and known to enhance survival, migration, and proliferation of tumor cells which may contribute to relapse in patients. Furthermore, the HSPs genes (HSP90 and HSP70) were significantly overexpressed in LN-CLL as compared to PB-CLL which implies important role of the microenviroment in rendering CLL refractory. To investigate the link between the expression of the individual genes with the aggressiveness of the disease, Kaplan-Meier log-rank tests were performed. We found that the higher expression of HSP90A, HSP90B, HSJ, and MMP9 were significantly (p<0.05) associated with shorter time to treatment. In summary, our study suggests that HSP genes are overexpressed in refractory CLL patients and thus are promising targets to improve clinical outcome. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

CD1d Expression Is Higher In Chronic Lymphocytic Leukemia Patients With Unfavorable Prognosis

Blood ◽

10.1182/blood.v122.21.5278.5278 ◽

2013 ◽

Vol 122 (21) ◽

pp. 5278-5278

Author(s):

Agnieszka Bojarska-Junak ◽

Iwona Hus ◽

Anna Dmoszynska ◽

Jacek Rolinski

Keyword(s):

B Cells ◽

Chronic Lymphocytic Leukemia ◽

Disease Progression ◽

Conflicts Of Interest ◽

Staining Intensity ◽

Lymphocytic Leukemia ◽

Disease Stage ◽

Inkt Cells ◽

Cd38 Expression

Abstract Chronic lymphocytic leukemia (CLL) is characterized by a very heterogeneous clinical course, which is slow and indolent in most of the patients, however some patient experience rapid disease progression and anticancer therapy is required shortly after the diagnosis. Many issues in CLL development and progression are still unclear. The functional consequences of CD1d expression on tumour cells are not well understood. However, increasing evidence suggests that they may affect iNKT cells.The role of CD1d expression in CLL immunopathogenesis remains undefined. In this study, we investigated the potential role of CD1d in CLL by analyzing the level of CD1d expression on leukemic B cells in peripheral blood of120 patients and assessed its correlation with prognostic markers such as ZAP-70 and CD38 expression, Rai stages and unfavourable cytogenetic changes.Measuring CD1d expression by flow cytometry and qRT-PCR, we showed lower CD1d molecule and CD1d mRNA expression in B cells of CLL patients than of healthy controls. The frequency of CD1d+/CD19+ cells, CD1d staining intensity and CD1d transcript levels increased with the disease stage. CD1d expression was positively associated with ZAP-70 and CD38 expressions as well as with unfavourable cytogenetic changes (17p deletion, 11q deletio),. We established the relationship between high CD1d expression and shorter time to treatment and overall survival. The percentage of CD1d+/CD19+cells inversely correlated with the percentage of iNKT cells. iNKT cells ζ-chain expression was downregulated in the high-CD1d group.These results suggest that high CD1d expression is associated with poor prognosis of CLL and might be involved in disease progression. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Serum IgM Activates BCR Signaling Pathways and Increases Survival of Chronic Lymphocytic Leukemia B Cells

Blood ◽

10.1182/blood.v126.23.4131.4131 ◽

2015 ◽

Vol 126 (23) ◽

pp. 4131-4131

Author(s):

Stefania Gobessi ◽

Binu K Sasi ◽

Luca Laurenti ◽

Dimitar G Efremov

Keyword(s):

B Cells ◽

Chronic Lymphocytic Leukemia ◽

Signaling Pathways ◽

Target Genes ◽

Conflicts Of Interest ◽

Direct Interaction ◽

Leukemic Cell ◽

Fold Increase ◽

Lymphocytic Leukemia ◽

Bcr Signaling

Abstract Serum IgM would be expected to bind chronic lymphocytic leukemia B cells through two different mechanisms. The first mechanism is via interactions between the immunoglobulin heavy chain CDR3 of the leukemic B cell receptors (BCRs) and internal epitopes located in the FR2 and FR3 regions of serum IgM molecules, analogous to the recently identified cell-autonomous BCR-BCR interaction. The latter interaction represents a general feature of human CLL BCRs and was recently shown to be positively selected during leukemia development in the Eμ-TCL1 transgenic murine model. The second mechanism is by binding of serum IgM to the recently identified Fc receptor for IgM (FcμR), which is overexpressed on CLL B cells. In the present study we investigated the consequences of the interaction between serum IgM and CLL cells. Incubation of CLL cells with Alexa488-conjugated human IgM resulted in strong cell surface labeling, confirming that IgM binds to CLL cells. Binding was substantially inhibited by preculture of CLL cells with Fcμ, suggesting that IgM interacts with CLL B cells primarily through the FcμR. To investigate whether IgM also binds to the leukemic BCRs, we analyzed activation of downstream BCR signaling pathways and expression of a well-defined set of BCR-target genes (Herishanu Y et al, Blood. 2011;117:563-74) in CLL cells cultured in the presence or absence of purified IgM. After three hours in culture with polyclonal or monoclonal human IgM, 5 of the 7 investigated BCR target genes (OAS3, RGS1, GFI1, CCND2 and KLF4) showed a 2- to 9-fold increase with respect to unstimulated CLL cells, whereas the remaining two genes (EGR1 and EGR2) were not induced. The induced BCR target genes were also upregulated to an equal or even greater extent by Fcμ, suggesting that these effects are primarily or exclusively caused by binding of IgM to the FcμR. Analysis of downstream signaling events, such as SYK and ERK phosphorylation, also showed similar induction by IgM and Fcμ. However, intracellular Ca2+ flux was induced to a substantially greater extent with IgM, suggesting that certain effects are mediated by a direct interaction between serum IgM and the leukemic cell BCRs. Since co-ligation of the FcμR was recently shown to enhance the survival of anti-IgM-stimulated murine B lymphocytes (Ouchida R et al, J Immunol. 2015;194:3096-101), we investigated the consequences of IgM binding on CLL cell survival. CLL cells from 18 patients were cultured with or without purified human IgM for 72 hours and then analyzed by Annexin V/PI staining. A modest but significant increase in the percentage of viable CLL cells was observed in the presence of IgM (percentage of viable CLL cells without IgM: 40.5±17.8; with IgM: 43.8±18.4; P =0.016), which was replicated in a smaller series of samples cultured with Fcμ (n=12, percentage of viable CLL cells without Fcμ: 41.1±17.8; with Fcμ: 49.5±15.6; P =0.019). Altogether, these data suggest that binding of serum IgM results in activation of prosurvival pathways in CLL cells and that this effect is most likely mediated by co-triggering the FcμR and BCR. Disclosures No relevant conflicts of interest to declare.

Download Full-text

Suppression of Anti-Tumor Immunity in Chronic Lymphocytic Leukemia Via Interleukin-10 Production

Blood ◽

10.1182/blood.v128.22.3215.3215 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3215-3215

Author(s):

Sara S Alhakeem ◽

Mary K McKenna ◽

Sunil K Nooti ◽

Karine Z Oben ◽

Vivek M Rangnekar ◽

...

Keyword(s):

Bone Marrow ◽

T Cells ◽

Chronic Lymphocytic Leukemia ◽

B Cell ◽

Tumor Immunity ◽

Lymphocytic Leukemia ◽

Clonal Variation ◽

Bcr Signaling

Abstract The most common human leukemia is B-cell chronic lymphocytic leukemia (B-CLL), which is characterized by a progressive accumulation of abnormal B-lymphocytes in blood, bone marrow and secondary lymphoid organs. Typically disease progression is slow, but as the number of leukemic cells increases, they interfere with the production of other important blood cells, causing the patients to be in an immunosuppressive state. To study the basis of this immunoregulation, we used cells from the transgenic Eμ-Tcl1 mouse, which spontaneously develop B-CLL due to a B-cell specific expression of the oncogene, Tcl1. Previously we showed that Eμ-Tcl1 CLL cells constitutively produce an anti-inflammatory cytokine, IL-10. Here we studied the role of IL-10 in CLL cell survival in vitro and the development of CLL in vivo. We found that neutralization of IL-I0 using anti-IL-10 antibodies or blocking the IL-10 receptor (IL-10R) using anti-IL-10R antibodies did not affect the survival of CLL cells in vitro. On the other hand, adoptively transferred Eμ-Tcl1 cells grew at a slower rate in IL-10R KO mice vs. wild type (WT) mice. There was a significant reduction in CLL cell engraftment in the spleen, bone marrow, peritoneal cavity and liver of the IL-10R KO compared to WT mice. Further studies revealed that IL-10 could be playing a role in the tumor microenvironment possibly by affecting anti-tumor immunity. This was seen by a reduction in the activation of CD8+ T cells as well as a significantly lower production of IFN-γ by CD4+ T cells purified from CLL-injected WT mice compared to those purified from CLL-injected IL-10R KO mice. These studies demonstrate that CLL cells suppress host anti-tumor immunity via IL-10 production. This led us to investigate possible mechanisms by which IL-10 is produced. We found a novel role of B-cell receptor (BCR) signaling pathway in constitutive IL-10 secretion. Inhibition of Src or Syk family kinases reduces the constitutive IL-10 production by Eμ-Tcl1 cells in a dose dependent manner. In addition, we found that Eμ-Tcl1 CLL cells exhibit clonal variation in their IL-10 production in response to BCR cross-linking. Further studies are being performed to understand the mechanisms by which BCR signaling affects IL-10 production. Disclosures No relevant conflicts of interest to declare.

Download Full-text