Fludarabine uptake mechanisms in B-cell chronic lymphocytic leukemia

Blood ◽  
2003 ◽  
Vol 101 (6) ◽  
pp. 2328-2334 ◽  
Author(s):  
Mı́riam Molina-Arcas ◽  
Beatriz Bellosillo ◽  
F. Javier Casado ◽  
Emili Montserrat ◽  
Joan Gil ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Chronic Lymphocytic Leukemia ◽  
Expression Patterns ◽  
Individual Variability ◽  
Lymphocytic Leukemia ◽  
Mrna Levels ◽  
Nucleoside Transporter ◽  
Drug Bioavailability

Nucleoside derivatives are currently used in the treatment of hematologic malignancies. Although intracellular events involved in the pharmacologic action of these compounds have been extensively studied, the role of plasma membrane transporters in nucleoside-derived drug bioavailability and action in leukemia cells has not been comprehensively addressed. We have monitored the amounts of mRNA for the 5 nucleoside transporter isoforms cloned so far (CNT1, CNT2, CNT3, ENT1, and ENT2) in several human cell types and in normal human leukocytes. We then examined the expression patterns of these plasma membrane proteins in patients with chronic lymphocytic leukemia (CLL) and correlated them with in vitro fludarabine cytotoxicity. Despite a huge individual variability in the mRNA amounts for every transporter gene expressed in CLL cells (CNT2, CNT3, ENT1, and ENT2), no relationship between mRNA levels and in vitro fludarabine cytotoxicity was observed. Fludarabine accumulation in CLL cells was mostly, if not exclusively, mediated by ENT-type transporters whose biologic activity was clearly correlated with fludarabine cytotoxicity, which reveals a role of ENT-mediated uptake in drug responsiveness in patients with CLL.

Distinct gene expression patterns in chronic lymphocytic leukemia defined by usage of specific VH genes

Blood ◽  
2006 ◽  
Vol 107 (5) ◽  
pp. 2090-2093 ◽  
Author(s):  
Dirk Kienle ◽  
Axel Benner ◽  
Alexander Kröber ◽  
Dirk Winkler ◽  
Daniel Mertens ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chronic Lymphocytic Leukemia ◽  
Expression Patterns ◽  
Gene Expression Pattern ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Expression Of Genes ◽  
Vh Genes ◽  
Signaling Activation

The mutation status and usage of specific VH genes such as V3-21 and V1-69 are potentially independent pathogenic and prognostic factors in chronic lymphocytic leukemia (CLL). To investigate the role of antigenic stimulation, we analyzed the expression of genes involved in B-cell receptor (BCR) signaling/activation, cell cycle, and apoptosis control in CLL using these specific VH genes compared to VH mutated (VH-MUT) and VH unmutated (VH-UM) CLL not using these VH genes. V3-21 cases showed characteristic expression differences compared to VH-MUT (up: ZAP70 [or ZAP-70]; down: CCND2, P27) and VH-UM (down: PI3K, CCND2, P27, CDK4, BAX) involving several BCR-related genes. Similarly, there was a marked difference between VH unmutated cases using the V1-69 gene and VH-UM (up: FOS; down: BLNK, SYK, CDK4, TP53). Therefore, usage of specific VH genes appears to have a strong influence on the gene expression pattern pointing to antigen recognition and ongoing BCR stimulation as a pathogenic factor in these CLL subgroups.

scholarly journals Dissecting the Prognostic Significance and Functional Role of Progranulin in Chronic Lymphocytic Leukemia

Cancers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 822 ◽  
Author(s):  
Lena Schulze-Edinghausen ◽  
Claudia Dürr ◽  
Selcen Öztürk ◽  
Manuela Zucknick ◽  
Axel Benner ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Stromal Cells ◽  
Prognostic Significance ◽  
Lymphocytic Leukemia ◽  
Cancer Associated Fibroblast ◽  
Survival Gene ◽  
Potential Use

Chronic lymphocytic leukemia (CLL) is known for its strong dependency on the tumor microenvironment. We found progranulin (GRN), a protein that has been linked to inflammation and cancer, to be upregulated in the serum of CLL patients compared to healthy controls, and increased GRN levels to be associated with an increased hazard for disease progression and death. This raised the question of whether GRN is a functional driver of CLL. We observed that recombinant GRN did not directly affect viability, activation, or proliferation of primary CLL cells in vitro. However, GRN secretion was induced in co-cultures of CLL cells with stromal cells that enhanced CLL cell survival. Gene expression profiling and protein analyses revealed that primary mesenchymal stromal cells (MSCs) in co-culture with CLL cells acquire a cancer-associated fibroblast-like phenotype. Despite its upregulation in the co-cultures, GRN treatment of MSCs did not mimic this effect. To test the relevance of GRN for CLL in vivo, we made use of the Eμ-TCL1 CLL mouse model. As we detected strong GRN expression in myeloid cells, we performed adoptive transfer of Eμ-TCL1 leukemia cells to bone marrow chimeric Grn−/− mice that lack GRN in hematopoietic cells. Thereby, we observed that CLL-like disease developed comparable in Grn−/− chimeras and respective control mice. In conclusion, serum GRN is found to be strongly upregulated in CLL, which indicates potential use as a prognostic marker, but there is no evidence that elevated GRN functionally drives the disease.

ZAP-70 Expression Is Associated with Increased Migration to SDF-1 in Chronic Lymphocytic Leukemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 587-587
Author(s):  
Yuji Miura ◽  
Elinor Lee ◽  
Federica Gibellini ◽  
Therese White ◽  
Gerald Marti ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Cxcr4 Expression ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Short Exposure ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Western Blots ◽  
Stroma Cell

Abstract Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of mature B lymphocytes in the peripheral blood (PB), lymph nodes (LN) and bone marrow (BM). Increasing evidence suggests that CLL cells depend on survival and proliferation signals provided by stroma cells in LN and BM. The chemokine receptor CXCR4 (CD184) and its ligand stromal cell-derived factor-1 (SDF-1) play an important role in trafficking of lymphocytes and may guide CLL cells to stroma cell niches. ZAP70 expression has prognostic value in CLL but the functional consequences of ZAP70 expression remain incompletely defined. Given that ZAP70 has been implicated in CXCR4 signaling its expression could enhance migration to SDF-1 and thereby promote interactions with stroma cells. As measured by flow cytometry, CXCR4 expression on leukemic cells obtained from different anatomic sites differed; cells from the PB (n=24, median 71% above isotype control) expressed CXCR4 more strongly than cells from BM (n=21, median 39%) and from LN (n=9, median 24%). Expression of CD69, an activation marker, followed a reverse pattern with cells from LN and BM typically showing higher expression than cells from PB, albeit with not detectable difference in expression in several patients. In vitro CLL cells from PB migrated in a dose dependent manner to SDF-1, and cells that had migrated down-modulated CXCR4 expression (89% before migration - 54% after migration). After exposure to SDF-1 CXCR4 expression decreased rapidly and remained virtually absent for at least 24 hours. Several mechanisms apparently decrease CXCR4 expression after contact with SDF-1, including internalization (given rapid re-expression of CXCR4 when SDF-1 is washed off after short exposure), protein degradation or inhibition of translation (evidenced by a decrease in total CXCR4 protein on Western blots), and mRNA degradation or transcriptional inhibition (decrease in mRNA levels more than 6 hours from SDF-1 exposure). In vitro migration of ZAP70(+) CLL cells toward SDF-1 through a 5μm membrane (Migration Index [MI] of 12.0, n=5) was significantly increased compared to ZAP70(−) CLL cells (MI of 2.9, n=4, p<0.05). To exclude effects of contaminating cells we repeated these assays with purified CLL cells (negative selection) with similar results. To model the complex interactions of CLL cells with stroma, we cultured PB derived leukemic cells with or without murine marrow stroma cells (S17). CXCR4 expression on CD19+ cells decreased from 90% without S17 to 50% when cultured on S17 cells, consistent with the known SDF-1 secretion by the murine stroma cell line. Conversely, CD69 expression increased from 58% without S17 to 71% with S17 cells. In addition, culturing of CLL cells on an S17 stroma cell layer extended their survival by several weeks when compared to cultures without S17 cells. Our data is consistent with a model in which CLL cells migrate along an SDF-1 gradient to stroma cell niches in BM and LN where they are activated. ZAP70 expression is associated with more effective migration in an SDF-1 gradient and thereby may facilitate access to growth and survival signals which then could contribute to the more progressive nature of ZAP70(+) CLL. The interaction between leukemic cells and stroma may represent a novel target for therapy of patients with CLL.

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

Blood ◽  
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.

CD72 Expression Patterns in ZAP70 Positive and Negative Chronic Lymphocytic Leukemia: Potential Regulatory Role in BCR Signalling

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4159-4159
Author(s):  
Francisco P. Careta ◽  
Rodrigo A. Panepucci ◽  
Daniel M Matos ◽  
Rodrigo Proto-Siqueira ◽  
Wilson A. Silva-Junior ◽  
...  
Keyword(s):  
B Cells ◽  
Chronic Lymphocytic Leukemia ◽  
Expression Patterns ◽  
Surrogate Marker ◽  
Lymphocytic Leukemia ◽  
Negative Regulator ◽  
Beta Catenin ◽  
Cell Surface Glycoprotein ◽  
Expression Levels

Abstract Introduction: Absence of mutations in IgVH genes or higher number of ZAP70+ cells (as a surrogate marker) in chronic lymphocytic leukemia (CLL) B-cells defines a patient group with a poorer clinical course. These features relate to the role of BCR signalling in the proliferation and survival of CLL B-cells, and establish a link between these markers and the biology of CLL prognostic subgroups. The identification of additional players in this context may help to better understand the molecular basis of this disease and contribute to develop new therapeutic approaches. A search for genes potentially related to BCR signalling, when comparing mutated and unmutated CLL cases using serial analysis of gene expression, revealed a 4-fold increase of CD72 tags in unmutated samples, a specific B cell surface glycoprotein known to transmit both positive and negative signals in BCR signalling. Objective: This finding lead us to explore the potential role of CD72 on BCR signalling in distinct CLL prognostic subgroups, as defined by ZAP70 expression. Methods: Percentage of ZAP70+ and CD72+ cells were evaluated by flow cytometry on gated CD19+CD5+ cells in 25 CLL samples. Positive cases for ZAP70 and CD72 were defined using a cut-off of 35% and 40% positive cells, respectively. Real time PCR was used to quantify the expression levels of 3 genes related to proliferation and survival, RELB, Beta-Catenin (CTNNB1) and AKT1, on 16 CD19+ enriched (purity &gt; 90%) CLL samples. Results: Samples were classified as 11 ZAP70+ and 14 ZAP70−. Median percentage of CD72+ cells in ZAP70+ was significantly higher than for ZAP70− cases (82% compared to 39%, respectively, P=0.0029). Furthermore, percentages of CD72 and ZAP70 were positively correlated (r=0.5930 and P=0.0009). Interestingly, ZAP70+ cases were restricted to CD72+ cases (n=11, CD72+ZAP70+ [+/+]), whereas six CD72+ cases were ZAP70− (ZAP70−CD72+ [−/+]). Finally, there were 8 cases CD72−ZAP70− [−/−]. No differences among these 3 groups were observed in regard to laboratory parameters (white blood cells, total lymphocytes, lymphocyte percentage, haemoglobin, haematocrit and platelet number). Despite the reduced number of samples analysed (6 +/+, 6 −/− and 4 −/+), transcripts for RELB (P&lt;0.05), CTNNB1 (P&lt;0.05), and AKT1(P=0.057) were expressed at higher levels in ZAP70+CD72+ than in ZAP70−CD72+ samples. Additionally, the transcripts were expressed at higher levels in ZAP70−CD72− than in ZAP70−CD72+ samples, and this difference was statistically significant (P&lt;0.05) for CTNB1 and AKT1, but not for RELB (P=0.054). Conclusion: Our data indicate that higher percentages of ZAP70+ cells are associated with higher expression levels of transcripts related to proliferation and survival of CLL B-cells. In the absence of ZAP70 expression, CD72 may act as a negative regulator of the BCR pathway, as indicated by the lowest levels of transcripts on ZAP70−CD72+ cases.

Chronic Lymphocytic Leukemia-Associated Macrophages: Not Just Nurse Cells

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 46-46
Author(s):  
Loic Ysebaert ◽  
Mary Poupot ◽  
Yovan Sanchez-Ruiz ◽  
Camille Laurent ◽  
Guy Laurent ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Conditioned Medium ◽  
Apoptotic Cell ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Lymphocytic Leukemia ◽  
Functional Interpretation

Abstract Abstract 46 Introduction: CLL cells interact with many accessory cells in an environment mimicking that of normal mature B cells. Role of antigen, cytokines, adhesion pathways are critical for many aspects in the disease course (proliferation/survival, migration or homing, drug resistance, and presumably relapse). Nurse-like cells (NLC) belong to a monocytic-derived, bystander population among CLL lymph node and spleen stromal cells. Aim: To investigate the nature, functions, and location of NLC within CLL microenvironment. Methods: Gene expression profiles (GEP) from in vitro expanded NLC from patients (n=10) were produced and compared to those from normal CD14+ monocytes, M1-polarized macrophages, M2-polarized macrophages and tumor-associated macrophages (produced in the lab or downloaded from GEO datasets). Principal Component Analysis was used to categorize these five populations of cells and in-house-built GSEA software was used for functional interpretation of their relevant gene lists. Protein expression patterns were validated with multi-analyte ELISArray kits, proteome profiler arrays, flow cytometry (FC) or immunohistochemistry (IHC). Results: New insights into the physiopathological role of NLC in CLL are suggested from five lines of evidence: 1/a Òmonocytic gene signatureÓ (i.e. a set of 549 genes) is shared by the NLC and the monocyte subtypes. The genes over-represented in NLC vs normal monocytes pinpointed positive modulation of apoptotic cell clearance (scavenger, mannose and complement receptors, LXRalpha), lipid metabolism (Apolipoprotein E, PPAR signaling), extracellular matrix-receptor interactions (integrins, SPARC, Matrix MetalloProteinases) and actin cytoskeleton remodeling. 2/unsupervised clustering show that NLC represent an M2-skewed, TAM-like cell population. They down-regulate mRNA and proteins for classic M1 inflammatory markers (e.g. IL-1, IL-6, IL-12, COX2) while increase secretion of TGFbeta, IL-10, CCL17 and CCL22 soluble factors. 3/these and previously published observations suggest that B-CLL-to-NLC interactions may orchestrate immunosuppression in this disease. PBMCs from Òwatch and waitÓ CLL patients (all stage A/Rai 0, mutated IgVH, low risk cytogenetics profile) or healthy donors were stimulated with anti-CD3/CD28 beads + IL-2, either in standard RPMI+10% FCS or in conditioned medium (CM, after 14d CLL-NLC co-culture in vitro) and their proliferation/phenotype were compared after 2 weeks. Significant expansion of T cells with Treg (CD4+CD25+FoxP3+) phenotype was observed only from CLL PBMCs grown in conditioned medium (mean % Treg: 2.85 vs 3.05 in CM for normal PBMCs, and 1.54 vs 15.9 in CM for CLL PBMCs, P< 0.05). 4/although NLC make immune synapses with live B-CLL, they do not phagocytose them. Over-expression of CD47 (ÒdonÕt eat meÓ signal) by B-CLL cells (mfi= 3490 vs 2581 on normal cells, P< 0.05, n=18) may provide them with a protective signal against NLC. 5/from our GEP, flow cytometric and IHC analyses, we propose CD163 (classic M2 marker) as a reliable tool to identify NLC in vivo. Although in vitro, CLL cells can pervert healthy donor monocytes into NLC, only CLL-derived NLC are truly CD14+ CD163+. In vivo, CD163 staining reveals putative NLC in CLL lymph nodes(LN)/spleen sections but not in bone marrow. In LN from all patients, NLC reside in the subcapsular areas and line vessel structures, suggesting a role in CLL cells trafficking. Most interestingly, NLC infiltrate pseudofollicles structures only in a subset of cases. We will present updated IHC and clinical presentation correlation studies. Conclusions: Our results suggest that the role of NLC in CLL might be broader than initially thought. Beside of nursing and conferring drug resistance, NLC may also be crucial in the setting of immunosuppression, of CLL cells recruitment, and should thus be considered as therapeutic targets. Disclosures: Off Label Use: GA101 is not currently approved for CLL treatment.

scholarly journals Intraclonal Diversification Occurs in Chronic Lymphocytic Leukemia Expressing B Cell Receptors Belonging to the IGHV4 Gene Family

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 944-944
Author(s):  
Filippo Vit ◽  
Francesca Maria Rossi ◽  
Tiziana D'Agaro ◽  
Tamara Bittolo ◽  
Antonella Zucchetto ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Research Funding ◽  
Excision Repair ◽  
Lymphocytic Leukemia ◽  
Mrna Levels ◽  
Direct Role ◽  
Region Gene ◽  
Mutational Status ◽  
Ighv Gene

Abstract Background. The pivotal role of the Immunoglobulin (Ig) receptor and antigenic stimulation have been proven to be landmarks for the understanding of the ontogeny and evolution of chronic lymphocytic leukemia (CLL). In addition, the mutational status of the Immunoglobulin Heavy-Chain Variable region gene (IGHV) was confirmed to be a reliable prognostic factor, supporting an antigen-driven model of CLL development. To clarify aspects regarding an antigenic involvement in CLL evolution, studies focusing on intraclonal diversification (ID) of Ig genes have provided relevant information, although mainly conducted in a pre-Next Generation Sequencing (NGS) era. Aim. To apply a NGS approach to investigate ID in CLL. Methods. IGHV genes from 530 CLL patients with Royal Masden Hospital score 4-5 (Fig. 1A) was sequenced using NGS (Lymphotrack). The bio-informatic pipeline was based on the pRESTO/ChangeO packages. Specific pathological clones were selected based on the presence of same IGHV, junction genes and with similar HCDR3 sequence according to Hamming's distance. Through the R-Alakazam package, we generated rarefaction curves to evaluate the clonal diversity inside the pathological clone (Fig. 1B). Focusing on the Simpson index (represented by the Hill number of order q=2), which gives more weight to larger clones minimizing the smaller ones (Fig. 1B), we selected a Diversity Score (DS) of 4 for the definition of cases without ID (clonal; DS <4) and cases with ID (intraclonal; DS ≥4) (Fig. 1B). Results. Using the reported threshold we identified 469 (88.5%) clonal cases, expressing a single clone (Fig. 1C), and 61 (11.5%) cases with ID (median DS 9.2, range 4.4-66.0) characterized by the presence of two or multiple pathological clones expressing the same IGHV gene and HCDR3 (Fig. 1C). Notably, cases with ID expressed both a mutated (M) (39/61, 63.9%) and an unmutated (UM) (22/61, 36.1%; p=0.066) IGHV gene configuration (Fig. 1C). Of note, we observed a significant skewing toward the usage of VH4-family genes when comparing cases with ID (38/61, 62.3%) vs. cases without ID (78/469, 16.6%; p<0.0001, Fig 1D). Moreover, the IGHV4-39 and IGHV4-34 genes were the most used genes in the context of cases with ID (Fig. 1E), although none of them belonging to known stereotyped subsets. By focusing on VH4-family only cases, we observed that cases with ID and UM IGHV genes displayed higher mutation frequencies in WA/TW motifs, a mutational signature which suggests an involvement of both Activation-Induced (Cytidine) Deaminase (AID) and error-prone polymerase eta (Fig. 1F), a pattern not observed in its counterpart with UM IGHV genes but without ID (Fig. 1F). Conversely, in cases with ID and M IGHV genes, mutations preferentially clustered in AID hotspots (WRC/GYW motifs), suggesting a direct role of AID and the Base Excision Repair machinery in the mutational overload (Fig. 1F). Consistently, M IGHV cases with ID expressed significantly higher AID mRNA levels than M IGHV cases without ID (p=0.0024; Fig. 1G). These expression levels were overall comparable with those found in UM IGHV cases, irrespective to the evidence of ID (Fig. 1G), which however were not associated with an increased number of mutations in AID-specific hotspots (Fig. 1F). Conclusions. By taking advantage of a new method for ID assessment in CLL, we demonstrated that ID prevalently affects VH4-family cases which display different mutational patterns dependent to the IGHV gene status. This data are in keeping with previous reports indicating the IGHV4 genes as particularly prone to generate immunoglobulin subjected to continuous/persistent stimulation by external/auto-antigens, hence particularly prone to generate features of ID. Further experiments in selected cases with ID through a non-random barcode strategy are needed. Disclosures Zaja: Sandoz: Honoraria; Celgene: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Amgen: Honoraria; Janssen: Honoraria; Takeda: Honoraria; Abbvie: Honoraria.

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

Blood ◽  
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.

AICAR Induces Apoptosis in Chronic Lymphocytic Leukemia Cells through the Mitochondrial Pathway and Independently of p53 Pathway and AMPK Activation.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4819-4819
Author(s):  
Joan Gil ◽  
Antonio F Santidrián ◽  
Diana M González-Gironès ◽  
Daniel Iglesias-Serret ◽  
Llorenç Coll-Mulet ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
B Lymphocytes ◽  
Mitochondrial Pathway ◽  
Lymphocytic Leukemia ◽  
Mrna Levels ◽  
Ampk Activation ◽  
Cytochrome C Release ◽  
Cell Technologies ◽  
Induced Apoptosis

Abstract Abstract 4819 AICAR (5-aminoimidazole-4-carboxamide riboside or acadesine) induces apoptosis in different cell types including chronic lymphocytic leukemia (CLL) cells. Here, we have analyzed the mechanisms involved in AICAR-induced apoptosis in CLL cells. AICAR induced apoptosis through the mitochondrial pathway, since inhibition of caspase-8 did not protect CLL cells from AICAR-induced apoptosis and caspase inhibition did not alter cytochrome c release induced by AICAR. AICAR induced a significant increase in the mRNA levels of the proapoptotic BH3-only genes BIM, BNIP3, BNIP3L, HRK, MOAP1, and NOXA. These changes were AICA ribotide (ZMP) accumulation-dependent and adenosine monophosphate-activated protein kinase (AMPK) activation-independent in CLL cells. Furthermore, AICAR induced the accumulation of NOXA protein in all CLL samples and BIM protein in about half of these samples, without modifying the levels of other BCL-2 family proteins analyzed. Importantly, AICAR induced apoptosis irrespective of the tumor suppressor TP53 and ataxia telangiectasia mutated status in CLL cells. AMPK activation with phenformin or A-769662 did not induce apoptosis in CLL cells. Finally, AICAR induced apoptosis in B lymphocytes from AMPKa1−/− mice. Taken together, our results demonstrate that AICAR induces apoptosis in B lymphocytes through the mitochondrial pathway by an AMPK- and p53-independent mechanism. Disclosures: Gil: Advancell-In Vitro Cell Technologies S.L.: Patents & Royalties, Research Funding. Campàs:Advancell-In Vitro Cell Technologies : Employment, Patents & Royalties.

Functional Effects Of NOTCH1 Mutations In Chronic Lymphocytic Leukemia Patients

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4117-4117
Author(s):  
Francesca Arruga ◽  
Branimir Gizdic ◽  
Sara Serra ◽  
Tiziana Vaisitti ◽  
Davide Rossi ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Chronic Lymphocytic Leukemia ◽  
Signaling Pathway ◽  
Lymphocytic Leukemia ◽  
Mrna Levels ◽  
Nuclear Staining ◽  
Notch1 Signaling ◽  
Notch1 Mutations

Abstract Chronic lymphocytic leukemia (CLL), is characterized by the expansion of mature B lymphocytes present in blood, bone marrow and lymphoid organs. Clinical behavior is highly heterogeneous, thus requiring timely identification of high-risk patients. NOTCH1 encodes a trans-membrane receptor acting as a ligand-activated transcription factor. NOTCH signaling initiates when the ligand, from either the Jagged or Delta families, binds to the receptor and induces successive proteolytic cleavages, resulting in the release and nuclear translocation of the NOTCH intra-cellular domain (NICD). Signaling is terminated by phosphorylation of the PEST domain of NOTCH1, triggering its ubiquitination and proteasomal degradation. Whole exome sequencing approaches have revealed NOTCH1 mutations in 5-10% newly diagnosed CLL cases, with their prevalence increasing to 15-20% in progressive or relapsed patients. The most frequent mutation is 7544-7545delCT frameshift deletion in exon 34, resulting in disruption of the C-terminal PEST domain. Truncation of the PEST domain is predicted to result in NOTCH1 impaired degradation, stabilization of the active NOTCH1, and deregulated signaling. The present study was undertaken with the aim to compare NOTCH1 expression and functional role in CLL patients harboring wild type (WT) or mutated (M) NOTCH1 gene. NOCTH1 mRNA and surface protein were expressed at comparable high levels in peripheral blood (PB) CLL cells obtained from NOTCH1 M and WT patients, consistent with a more general requirement of NOTCH1 signaling in this leukemia. However, at a variance of NOTCH1 WT cases, NOCTH1 M patients displayed remarkable accumulation of both the intermediate molecular species of the activated NOCTH1 receptor, as well as of the active NICD. Consistently, by gene expression profiling NOCTH1 M patients displayed significantly higher levels of HES1 and DTX1, the main NOTCH1 target genes. Overall, these data suggest a more active signaling pathway in NOTCH1 M CLL than in NOTCH1 WT cases. Expression of NOTCH1 and of its target gene (DTX1) varied across disease compartments, being higher in CLL cells obtained from the lymph nodes (LN), as compared to paired samples derived from the PB or the bone marrow (BM). By immunohistochemical analyses of primary LN tissue samples, NOTCH1 M CLL showed an intense nuclear staining as opposed to the more cytoplasmic distribution observed in NOTCH1 WT samples. These data suggest a more active NOTCH1 signaling in CLL residing in the LN microenvironment and confirm the functional effect of NOTCH1 mutations in vivo. When PB CLL cells were cultured in vitro in the absence of any supporting layer or stimulation, they showed a rapid down regulation of the NOTCH pathway, with complete loss of NICD after 24 hours paralleled by a sharp decrease in HES1 and DTX1 transcription. Consistently, levels of presenilin-1 (PSEN1), the catalytic subunit of the g-secretase complex, were also down-regulated offering a partial mechanistic explanation for the NICD loss. NOTCH1 mRNA levels remained unchanged, with accumulation of the receptor at the plasma membrane. These effects were independent of NOTCH1 mutation status and suggested the dependence of NOTCH1 signaling activation upon in vivo microenvironmental interaction, even in NOTCH1 M CLL. Within primary LN biopsies from CLL patients, the NOTCH1 ligand, was highly expressed on CD68+ elements of myeloid origin. This observation prompted the in vitro recreation of a lymphoid niche by co-culturing Jagged1+ nurse-like cells (NLC) with autologous CLL cells. Under these conditions, NOTCH1 activity in CLL cells was sustained over time, as shown by Q-PCR analyses of DTX1 and PSEN1. Moreover, NLCs protect NOTCH1 M CLL cells from fludarabine-induced apoptosis. This microenvironment-induced chemoresistance was prevented by pre-treatment of NOTCH1 M CLL cells with specific g-secretase inhibitors, to block NOTCH1 activation. Taken together, these results show that the 7544-7545delCT mutation in the PEST domain of NOTCH1 has a stabilizing effect on NOTCH1 signaling pathway. They also show that micro-environmental interactions are critical in activating NOTCH1 pathway both in the M and WT patients. Lastly, these results show that NOTCH1 signals micht create local conditions that favour drug resistance, thus making NOTCH1 a potential molecular target in CLL. Disclosures: No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document