Chronic Lymphocytic Leukemia B Cells Express Functional CXCR4 Chemokine Receptors That Mediate Spontaneous Migration Beneath Bone Marrow Stromal Cells

Blood ◽  
1999 ◽  
Vol 94 (11) ◽  
pp. 3658-3667 ◽  
Author(s):  
Jan A. Burger ◽  
Meike Burger ◽  
Thomas J. Kipps

Abstract Chemokines play a central role for lymphocyte trafficking and homing. The mechanisms that direct the tissue localization of B cells from patients with chronic lymphocytic leukemia (B-CLL) are unknown. We found that CLL B cells express functional CXCR4 receptors for the chemokine stromal cell-derived factor-1 (SDF-1), as demonstrated by receptor endocytosis, calcium mobilization, and actin polymerization assays. Moreover, CLL B cells displayed chemotaxis to this chemokine that could be inhibited by monoclonal antibodies (MoAbs) against CXCR4, pertussis toxin, or Wortmannin, a phosphatidylinositol 3-kinase inhibitor. That this chemotaxis may be involved in the homing of CLL cells is argued by studies in which CLL B cells were cocultured with a murine marrow stromal cell line that secretes SDF-1. Within 2 hours, CLL B cells spontaneously migrated beneath such stromal cells in vitro (pseudoemperipolesis). This migration could be inhibited by pretreatment of CLL B cells with anti-CXCR4 MoAbs, SDF-1, or pertussis-toxin. Furthermore, we noted strong downmodulation of CXCR4 on CLL B cells that migrated into the stromal cell layer. These findings demonstrate that the chemokine receptor CXCR4 on CLL B cells plays a critical role for heterotypic adherence to marrow stromal cells and provide a new mechanism to account for the marrow infiltration by neoplastic B cells.

Blood ◽  
1999 ◽  
Vol 94 (11) ◽  
pp. 3658-3667 ◽  
Author(s):  
Jan A. Burger ◽  
Meike Burger ◽  
Thomas J. Kipps

Chemokines play a central role for lymphocyte trafficking and homing. The mechanisms that direct the tissue localization of B cells from patients with chronic lymphocytic leukemia (B-CLL) are unknown. We found that CLL B cells express functional CXCR4 receptors for the chemokine stromal cell-derived factor-1 (SDF-1), as demonstrated by receptor endocytosis, calcium mobilization, and actin polymerization assays. Moreover, CLL B cells displayed chemotaxis to this chemokine that could be inhibited by monoclonal antibodies (MoAbs) against CXCR4, pertussis toxin, or Wortmannin, a phosphatidylinositol 3-kinase inhibitor. That this chemotaxis may be involved in the homing of CLL cells is argued by studies in which CLL B cells were cocultured with a murine marrow stromal cell line that secretes SDF-1. Within 2 hours, CLL B cells spontaneously migrated beneath such stromal cells in vitro (pseudoemperipolesis). This migration could be inhibited by pretreatment of CLL B cells with anti-CXCR4 MoAbs, SDF-1, or pertussis-toxin. Furthermore, we noted strong downmodulation of CXCR4 on CLL B cells that migrated into the stromal cell layer. These findings demonstrate that the chemokine receptor CXCR4 on CLL B cells plays a critical role for heterotypic adherence to marrow stromal cells and provide a new mechanism to account for the marrow infiltration by neoplastic B cells.


Blood ◽  
2010 ◽  
Vol 115 (9) ◽  
pp. 1755-1764 ◽  
Author(s):  
Asish K. Ghosh ◽  
Charla R. Secreto ◽  
Traci R. Knox ◽  
Wei Ding ◽  
Debabrata Mukhopadhyay ◽  
...  

Abstract Microvesicles (MVs) released by malignant cancer cells constitute an important part of the tumor microenvironment. They can transfer various messages to target cells and may be critical to disease progression. Here, we demonstrate that MVs circulating in plasma of B-cell chronic lymphocytic leukemia (CLL) patients exhibit a phenotypic shift from predominantly platelet derived in early stage to leukemic B-cell derived at advanced stage. Furthermore, the total MV level in CLL was significantly greater compared with healthy subjects. To understand the functional implication, we examined whether MVs can interact and modulate CLL bone marrow stromal cells (BMSCs) known to provide a “homing and nurturing” environment for CLL B cells. We found that CLL-MV can activate the AKT/mammalian target of rapamycin/p70S6K/hypoxia-inducible factor-1α axis in CLL-BMSCs with production of vascular endothelial growth factor, a survival factor for CLL B cells. Moreover, MV-mediated AKT activation led to modulation of the β-catenin pathway and increased expression of cyclin D1 and c-myc in BMSCs. We found MV delivered phospho-receptor tyrosine kinase Axl directly to the BMSCs in association with AKT activation. This study demonstrates the existence of separate MV phenotypes during leukemic disease progression and underscores the important role of MVs in activation of the tumor microenvironment.


Blood ◽  
2005 ◽  
Vol 106 (5) ◽  
pp. 1824-1830 ◽  
Author(s):  
Meike Burger ◽  
Tanja Hartmann ◽  
Myriam Krome ◽  
Justyna Rawluk ◽  
Hirokazu Tamamura ◽  
...  

Abstract Growth and survival of chronic lymphocytic leukemia (CLL) B cells are favored by interactions between CLL and nontumoral accessory cells. CLL cells express CXCR4 chemokine receptors that direct leukemia cell chemotaxis. Marrow stromal cells or nurselike cells constitutively secrete CXCL12, the ligand for CXCR4, thereby attracting and rescuing CLL B cells from apoptosis in a contact-dependent fashion. Therefore, the CXCR4-CXCL12 axis represents a potential therapeutic target in CLL. We evaluated the most active CXCR4-specific antagonists (T140, TC14012, TN14003) for their capacity to inhibit CXCL12 responses in CLL cells. T140, or its analogs, inhibited actin polymerization, chemotaxis, and migration of CLL cells beneath stromal cells. CXCL12-induced phosphorylation of p44/42 mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3) was abolished by CXCR4 antagonists. TC14012 and TN14003 antagonized the antiapoptotic effect of synthetic CXCL12 and stromal cell-mediated protection of CLL cells from spontaneous apoptosis. Furthermore, we found that stromal cells protected CLL cells from chemotherapy-induced apoptosis. Treatment with CXCR4 antagonists resensitized CLL cells cultured with stromal cells to fludarabine-induced apoptosis. These findings demonstrate that CXCR4 blocking agents effectively antagonize CXCL12-induced migratory and signaling responses and stromal protection of CLL cells from spontaneous or fludarabine-induced apoptosis. As such, small molecular CXCR4 antagonists may have activity in the treatment of patients with this disease. (Blood. 2005;106:1824-1830)


Blood ◽  
2007 ◽  
Vol 110 (9) ◽  
pp. 3316-3325 ◽  
Author(s):  
Andrea Bürkle ◽  
Matthias Niedermeier ◽  
Annette Schmitt-Gräff ◽  
William G. Wierda ◽  
Michael J. Keating ◽  
...  

Abstract CXCL13 is a homeostatic chemokine for lymphocyte homing and positioning within follicles of secondary lymphoid tissues, acting through its cognate receptor, CXCR5. Moreover, the CXCR5-CXCL13 axis plays a unique role in trafficking and homing of B1 cells. Here, we report that chronic lymphocytic leukemia (CLL) B cells express high levels of functional CXCR5. CXCR5 expression levels were similar on CLL B cells and normal CD5+ B cells, and higher compared with normal CD5− B cells, follicular B-helper T cells (TFH cells), or neoplastic B cells from other B-cell neoplasias. Stimulation of CLL cells with CXCL13 induces actin polymerization, CXCR5 endocytosis, chemotaxis, and prolonged activation of p44/42 mitogen-activated protein kinases. Anti-CXCR5 antibodies, pertussis toxin, and wortmannin inhibited chemotaxis to CXCL13, demonstrating the importance of Gi proteins and PI3 kinases for CXCR5 signaling. Moreover, CLL patients had significantly higher CXCL13 serum levels than volunteers, and CXCL13 levels correlated with β2 microglobulin. We detected CXCL13 mRNA expression by nurselike cells, and high levels of CXCL13 protein in supernatants of CLL nurselike cell cultures. By immunohistochemistry, we detected CXCL13+ expression by CD68+ macrophages in situ within CLL lymph nodes. These data suggest that CXCR5 plays a role in CLL cell positioning and cognate interactions between CLL and CXCL13-secreting CD68+ accessory cells in lymphoid tissues.


Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3149-3149
Author(s):  
Antonina Kurtova ◽  
Maite P. Quiroga ◽  
William G. Wierda ◽  
Michael Keating ◽  
Jan A. Burger

Abstract Contact between chronic lymphocytic leukemia (CLL) cells and accessory stromal cells in tissue microenvironments is considered to play a major role in regulating CLL cell survival and disease progression. Stromal cells of various origins and species, and variable stromal-CLL cell ratios have been used in the past to study CLL-stromal cell interactions and to assess cell-adhesion mediated drug resistance (CAM-DR). Because of the heterogeneity of the currently used in vitro systems to study CLL-MSC interactions, and the importance of these co-culture systems for development and testing of novel agents, we tested a panel of murine and human MSC lines for their capacities to support CLL cell survival and CAM-DR, using various CLL-MSC ratios and fludarabine (F-ara-A) to induce CLL cell apoptosis. We tested four murine, non-transformed MSC lines derived from bone marrow: M210B4, KUM4, ST-2 and KUSA-H1. Also, we tested three human transformed cell lines: Stroma-NKtert, derived from bone marrow and immortalized by human telomerase reverse transcriptase (hTERT), UE6E7-T2 derived from bone marrow and transformed with human papilloma viruses (HPV) E6, E7 and hTERT, and UCB408E6E7Tert33 derived from umbilical cord blood and transformed with hTERT and HPV E6, E7. CLL cells were isolated from peripheral blood of untreated patients and each cell line was tested with at least three different patients according to the following protocol: viability of CLL was tested after 24, 48 and 72 hours by flow cytometry after staining with DiOC6 and propidium iodide. The following conditions were assayed on each of the MSC lines: CLL cells in suspension culture, CLL cells in suspension culture with 10 mM F-ara-A, CLL cells in co-culture with MSC, and CLL cells in co-culture with MSC and with 10 mM F-ara-A. Firstly, we performed titration experiments in order to identify the most appropriate ratio between stromal and CLL cells, using CLL-MSC ratios of 5:1, 10:1, 20:1, 50:1 and 100:1. We found a decline in MSC-derived CLL cell protection at the highest ratio of 100:1, suggesting that ratios of 50:1 or lower provide optimal conditions for in vitro assays. Results shown in Table 1 were assayed using a 20:1 ratio and represented relative viabilities when compared to untreated controls (mean±SEM). Regarding the protective effect of different MSC, we found that all MSC lines demonstrated remarkable protection of CLL cells from spontaneous and F-ara-A-induced apoptosis. We also found that stromal cells that had round shape morphology and easily formed confluent monolayer (M210B4, KUSA-H1, Stroma-NKTert) showed more prolonged protective effect in comparison to cell lines with more spindle shaped morphology (ST-2, KUM4, UE6E7-T2). The failure of UE6E7-T2 and UCB408E6E7Tert33 to demonstrate long-term protection of CLL cells could be related to their own sensitivity to F-ara-A. In this comparative study we demonstrated that both murine and human MSC provide substantial and comparable levels of protection from spontaneous and drug-induced apoptosis. CLL:MSC ratios of 50:1 or lower can be considered ideal for co-culture experiments. Further experiments have to be done to determine the levels of MSC-derived protection in a larger series of CLL samples and in different laboratories for validation. Collectively, in these co-culture assays we can study CLL-MSC interactions and CLL drugs under more standardized conditions that may allow us to evaluate the efficacy of new treatments that target the CLL microenvironment. Time points 24 hours 48 hours 72 hours +Flu + MSC + MSC +Flu +Flu + MSC + MSC +Flu +Flu +MSC + MSC +Flu M210B4 85.2±2.4 117.2±5.0 110.5±4.9 30.8±12.6 138.1±9.5 113.0±2.2 5.2±3.1 138.1±5.1 120.4±3.4 ST-2 93.6±3.0 99.9±2.6 103.1±0.5 51.6±9.4 111.9±2.6 89.8±8.7 13.9±6.3 112.6±5.7 87.0±16.4 KUM-4 93.6±3.0 106.4±1.8 104.2±1.9 51.6±9.4 112.4±2.6 100.8±2.8 13.9±6.3 111.8±6.7 88.5±11.4 KUSA-H1 79.4±7.4 125.1±3.7 118.2±2.0 33.9±10.9 136.0±3.6 107.2±7.0 11.3±6.1 133.6±5.4 84.9±7.6 Stroma-NKTert 79.3±7.0 118.6±7.0 111.0±7.0 30.5±9.5 130.7±9.5 115.6±8.0 7.1±4.3 133.0±11.5 122.7±9.0 UE6E7-T2 79.3±7.0 113.4±3.9 109.3±3.0 30.5±9.5 118.4±4.8 85.0±7.1 7.1±4.3 119.2±6.9 51.0±10.1 UCB408 E6E7Tert33 81.5±7.2 120.2±5.4 111.8±2.7 36.7±9.4 123.7±6.3 86.7±7.7 8.5±6.7 119.7±6.1 50.8±13.0 Table 1. Flu: fludarabine (10mM/ml), MSC: marrow stromal cells


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2857-2857
Author(s):  
Fumito Ishizuka ◽  
Jolene Windle ◽  
David Roodman ◽  
Noriyoshi Kurihara

Abstract Abstract 2857 Poster Board II-833 We reported that sequestosome 1 (p62) plays a critical role in the formation of signaling complexes that result in NF-kB, p38 MAPK, and PI3K activation in the marrow microenvironment of patients with multiple myeloma (MM), and that p62 is a potential therapeutic target for MM. In contrast to treating patients with inhibitors of each of the multiple signaling pathways activated in marrow stromal cells by MM cells (e.g. NF-kB or p38 MAPK), blocking the function of p62 should inhibit the activation of the multiple pathways mediated by p62 and have a broader effect on the bone marrow microenvironment. The goal of this study was to identify the domains of p62 responsible for increased MM cell growth and osteoclast (OCL) formation mediated by NF-kB and p38 MAPK signaling in marrow stromal cells when they interact with myeloma cells, and develop inhibitory peptides as potential therapeutic agents that interfere with p62's role in these signaling complexes. To pursue this objective, we transfected p62−/− stromal cells with p62 deletion constructs and assessed their effects on NF-kB and p38 MAPK signaling induced by MM cells or TNF-a. p62−/− stromal cells support of MM growth or OCL formation was significantly decreased compared to WT stromal cells. We made a series of 5' deletion constructs of p62 that lacked specific p62 domains: ΔPB1 (Δ1) lacks homodimerization domain and binding to PKCz, ΔPB1, ZZ (Δ2) lacks PB1 and RIP1 binding domains, and ΔPB1, ZZ, TBS, (Δ3) the PB1, RIP1, p38 and TRAF6 binding domains have been deleted. These constructs were tested for their capacity to restore p62 function in p62−/−stromal cells and support MM cell growth and OCL formation. GFP-labeled MM1.S myeloma cells were cocultured with p62−/− and WT marrow stromal cells transduced with the different p62 deletion constructs. Transduction of p62−/− stromal cells with the full-length p62 construct restored the capacity of p62−/− stromal cells to enhance the growth of MM cells to levels induced by WT stromal cells. Transduction of p62−/− stromal cells with the Δ1 construct also restored stromal cell support of MM growth. Therefore, the PB1 domain is not important for this function. Transduction of p62−/− stromal cells with the Δ2 construct, resulted in an inability of the stromal cells to support MM cell growth. Additional loss of the p38 and TRAF6 binding domains did not further impair p62−/− stromal cells support of MM cell growth. These results suggest that the RIP1 binding domain plays a critical role in supporting the growth of MM cells by marrow stromal cells. We then examined the capacity of p62−/− stromal cells transduced with various p62 deletion constructs to support OCL formation. Normal CFU-GM, a source of OCL precursors, were cocultured with p62−/− stromal cells transfected with the different p62 cDNA deletion constructs. The Δ1 construct completely rescued p62−/− support of OCL formation. However, Δ2 construct transduced p62−/− stromal cells only partly restored stromal cell support of OCL formation. Transduction of the Δ3 construct did not restore the capacity of the p62−/− stromal cells to support OCL formation. Similarly, transduction of the Δ2 and Δ3 construction decreased WT stromal cell support of MM cell growth. We then tested the feasibility of using transduction domain (PTD) fusion peptides as a potential means of delivering dominant negative p62 constructs into stromal cells in vitro and in vivo to block MM cell growth and VCAM-1 expression induced by marrow stromal cells. PTD binding domain fusion peptides containing NEMO binding protein that blocks NF-kB activity was used as a model system to determine the feasibility of transducing marrow stromal cells with p62 constructs. Addition of PTD-NEMO fusion peptides to stromal cells significantly inhibited WT stromal cell to enhance MM cell growth and VCAM-1 expression on stromal cells, which is the capacity of dependent, in part, on NF-kB signaling. These results demonstrate that the ZZ, p38 MAPK and TRAF-6 domains of p62 together are required for stromal cell support of MM cell growth and OCL formation and suggest that PTD constructs containing dominant negatives for p62 may be a feasible method for blocking p62 function in the MM marrow microenvironment. Disclosures: Roodman: Novartis: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy; Celgene: Consultancy; Acceleron: Consultancy.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1372-1372
Author(s):  
Hendrik W. Van Deventer ◽  
Robert Mango ◽  
Jonathan Serody

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.


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