PD-1 Is Expressed on B-Cells in Waldenstrom Macroglobulinemia and Promotes Malignant Cell Viability and Proliferation

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3015-3015
Author(s):  
Stephen M. Ansell
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
B Cells ◽  
Cell Growth ◽  
Cell Lines ◽  
Stromal Cells ◽  
Malignant Cell ◽  
Growth And Survival ◽  
Waldenström Macroglobulinemia ◽  
Waldenstrom Macroglobulinemia

The tumor microenvironment plays an important role in regulating malignant cell growth and mechanisms to enhance anti-tumor immune function have been shown to improve patient outcome. Interactions between programmed death 1 (PD-1) and its ligands (PD-L1 and PD-L2) have been shown to be an important checkpoint in immune regulation. While it is well known that PD-1 is expressed on normal T cells and signaling through PD-1 inhibits T cell function, PD-1 is also expressed on a subset of B-cells but little is known about PD-1 signaling in B-cells. The goal of this study was to determine if the PD-1 is expressed on malignant B cells in Waldenstrom macroglobulinemia (WM) and whether this pathway plays a role in the survival and growth of malignant B cells in this B cell lymphoma. Using flow cytometry, we found that the cell lines MWCL-1, BCWM.1 and RPCI, all derived from patients with Waldenstrom macroglobulinemia, expressed PD-1 to varying degrees on their cell surface. PD-1 expression in the cell lines was further confirmed by RT PCR analysis. Using flow cytometry and immunohistochemistry to examine bone marrow specimens from WM patients, we further confirmed PD-1 expression on CD19+ CD138+ malignant B-cells. Furthermore, intense staining for the ligands PD-L1 and PD-L2 was found by in bone marrows of WM patients when compared to normal bone marrow specimens. When WM cell lines are co-cultured with stromal cells engineered to express PD-L1 or PD-L2, there was a consistent increase in cell viability compared to controls. When malignant B cells from WM patients were co-cultured with stromal cells expressing the ligands, viability was unchanged but there was an increase in cell proliferation, most noticeably when cocultured with cells expressing PD-L2. To determine potential mechanisms that account for upregulation of PD-1 on malignant B-cells, we tested whether cytokines that promote WM cell growth and survival, including IL-6, IL-21 and BAFF, increased PD-1 expression. We found that WM cell lines and patient derived CD19+CD138+WM B-cells (n=4) treated with IL-21 demonstrated an increase in PD-1 expression compared to untreated controls. We conclude that PD-1 is expressed on malignant B-cells in WM and that signaling through PD-1 may promote WM cell growth and survival. Blocking PD-1/PD ligand interactions may therefore be a potential therapeutic strategy in patients with Waldenstrom macroglobulinemia. Disclosures No relevant conflicts of interest to declare.

Interactions Between PD-1 and PD-L1 and PD-L2 Promote Malignant B-Cell Growth in Waldenstrom Macroglobulinemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4334-4334 ◽  
Author(s):  
Deanna M. Grote ◽  
Steven C. Ziesmer ◽  
Lucy S. Hodge ◽  
Tammy L. Price-Troska ◽  
Anne J. Novak ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
B Cells ◽  
Cell Growth ◽  
B Cell ◽  
Lymphoid Tissues ◽  
Intense Staining ◽  
Hek 293 ◽  
Waldenström Macroglobulinemia ◽  
Waldenstrom Macroglobulinemia

Abstract Programmed death 1 (PD-1) is a T cell co-inhibitory receptor with two ligands, PD-L1 and PD-L2. In B-cell malignancies, this pathway plays a major role in immune resistance in the tumor environment by promoting the differentiation of regulatory T-cells and inducing T-cell exhaustion. Recent data have shown that blockade of this pathway can enhance antitumor immune responses. While interactions between PD-1 and its ligands have been studied in various lymphoid tissues, little data exist regarding these interactions in the bone marrow, particularly in patients with Waldenstrom macroglobulinemia (WM). The goal of this study was therefore to determine the expression of PD-1 and its ligands in the bone marrow of patients with WM and to assess the functional role of PD-1 signaling in this disease. Using immunohistochemistry, the expression of PD-1, PD-L1 and PD-L2 in bone marrow (BM) specimens from patients with WM (n=6) was compared to normal control BM. PD-1 expression was modest and the pattern of staining in WM was similar to normal BM. In contrast however, intense staining for PD-L1 and PD-L2 was seen in WM compared to controls. When analyzed by flow cytometry, PD-L1 and PD-L2 expression was seen on malignant B-cells and also on dendritic cells, monocytes and macrophages isolated from the bone marrow. To determine the functional effect of PD-1 signaling in WM, we stably transfected PD-L1 and PD-L2 into the HEK-293 cell line. The WM cell lines, MWCL-1, BCWM.1 and RPCI-WM1 as well as patient specimens, were then cocultured with either the PD-L1 or PD-L2 expressing HEK-293 cells. When compared to cells expressing an empty vector control, proliferation and viability of WM cells was increased when they were cocultured with cells expressing PD-L1 or PD-L2. Addition of blocking antibodies abrogated the increase in proliferation. These results show that PD-L1 and PD-L2 are highly expressed on both malignant B-cells and non-malignant cells within the BM microenvironment in WM and promote malignant B-cell growth. Inhibition of PD-1 signaling may therefore be a promising therapeutic strategy in patients with WM. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Mesenchymal Stromal Cells Orchestrate Follicular Lymphoma Cell Niche Through the CCL2-Dependent Recruitment and Polarization of Monocytes

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1566-1566
Author(s):  
Fabien Guilloton ◽  
Gersende Caron ◽  
Cédric Ménard ◽  
Céline Pangault ◽  
Patricia Amé-Thomas ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
Cell Growth ◽  
Follicular Lymphoma ◽  
B Cell ◽  
Mesenchymal Stromal Cells ◽  
Stromal Cells ◽  
Gene Set Enrichment Analysis ◽  
Cell Niche

Abstract Abstract 1566 Accumulating evidence indicates that infiltrating stromal cells contribute directly and indirectly to tumor growth in a wide range of solid cancers and hematological malignancies. In follicular lymphoma (FL), malignant B cells are found admixed with heterogeneous lymphoid-like stromal cells within invaded lymph nodes and bone marrow (BM). In addition, in vitro functional studies have underlined that mesenchymal cells recruit malignant FL B cells and protect them from spontaneous and drug-induced apoptosis. In particular, we have previously demonstrated that mesenchymal stromal cells (MSC) efficiently support in vitro FL B-cell survival, especially after their engagement towards lymphoid differentiation through treatment with TNF-α and Lymphotoxin-α1β2 (TNF/LT) or after coculture with malignant B cells. However, the mechanisms of this supportive activity remain largely unknown. In this study, we used Affymetrix U133 Plus 2.0 microarrays, to compare the gene expression profile (GEP) of bone marrow-derived MSC (BM-MSC) obtained from 10 FL patients at diagnosis versus 6 age-matched healthy donors (HD). In these conditions, neither the CFU-F concentration in the BM nor the cumulative population doubling of BM-MSC significantly differed between HD and FL patients. Unsupervised analysis was able to perfectly segregate FL-MSC from HD-MSC and we identified, using supervised analyzes, a list of 408 probesets defining FL-MSC signature, including 320 nonredundant genes upregulated in FL-MSC compared to HD-MSC. We then defined the GEP of human lymphoid-like stroma using HD-MSC treated in vitro by TNF/LT and demonstrated, by a Gene Set Enrichment Analysis (GSEA) approach, that the FL-MSC signature is significantly enriched for genes associated with a lymphoid-like commitment. Interestingly, CCL2 was strongly overexpressed by FL-MSC, was upregulated in HD-MSC by coculture with malignant B cells, and was detected at a higher level in FL BM plasma compared to normal BM plasma (504.4 pg/mL [23.8-4413] versus 33.9 pg/mL [5-126.1]; P <.01). In agreement, FL-MSC triggered a more potent CCL2-dependent monocyte migration than HD-MSC. Moreover, FL-MSC and macrophages cooperated to sustain malignant B-cell growth through both protection from apoptosis and enhancement of cell proliferation. Finally, FL-MSC promoted monocyte differentiation towards a proangiogenic LPS-unresponsive phenotype close to that of tumor-associated macrophages. We unraveled a key role for the Notch pathway in this process and identified an overexpression of JAGGED1 in FL-MSC compared to HD-MSC. Altogether, these results highlight the complex role of FL stromal cells that promote direct tumor B-cell growth and orchestrate FL cell niche. The identification and characterization of this intricate network of cell interactions may provide novel therapeutic targets in this disease. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Plasma cells induce apoptosis of pre-B cells by interacting with bone marrow stromal cells

Blood ◽  
1996 ◽  
Vol 87 (8) ◽  
pp. 3375-3383 ◽  
Author(s):  
T Tsujimoto ◽  
IA Lisukov ◽  
N Huang ◽  
MS Mahmoud ◽  
MM Kawano
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Cell Survival ◽  
Cell Lines ◽  
Stromal Cells ◽  
Plasma Cells ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
B Cell Survival

By using two-color phenotypic analysis with fluorescein isothiocyanate- anti-CD38 and phycoerythrin-anti-CD19 antibodies, we found that pre-B cells (CD38+CD19+) signifcantly decreased depending on the number of plasma cells (CD38++CD19+) in the bone marrow (BM) in the cases with BM plasmacytosis, such as myelomas and even polyclonal gammopathy. To clarify how plasma cells suppress survival of pre-B cells, we examined the effect of plasma cells on the survival of pre-B cells with or without BM-derived stromal cells in vitro. Pre-B cells alone rapidly entered apoptosis, but interleukin-7 (IL-7), a BM stromal cell line (KM- 102), or culture supernatants of KM-102 cells could support pre-B cell survival. On the other hand, inhibitory factors such as transforming growth factor-beta1 (TGF-beta1) and macrophage inflammatory protein- 1beta (MIP-1beta) could suppress survival of pre-B cells even in the presence of IL-7. Plasma cells alone could not suppress survival of pre- B cells in the presence of IL-7, but coculture of plasma cells with KM- 102 cells or primary BM stromal cells induced apoptosis of pre-B cells. Supernatants of coculture with KM-102 and myeloma cell lines (KMS-5) also could suppress survival of pre-B cells. Furthermore, we examined the expression of IL-7, TGF-beta1, and MIP-1beta mRNA in KM-102 cells and primary stromal cells cocultured with myeloma cell lines (KMS-5). In these cells, IL-7 mRNA was downregulated, but the expression of TGF- beta1 and MIP-1beta mRNA was augmented. Therefore, these results suggest that BM-derived stromal cells attached to plasma (myeloma) cells were modulated to secrete lesser levels of supporting factor (IL- 7) and higher levels of inhibitory factors (TGF-beta1 and MIP-1beta) for pre-B cell survival, which could explain why the increased number of plasma (myeloma) cells induced suppression of pre-B cells in the BM. This phenomenon may represent a feedback loop between pre-B cells and plasma cells via BM stromal cells in the BM.

The Role of B Cell-Activating Factor (BAFF) in the Biology of Multiple Myeloma (MM).

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3380-3380 ◽  
Author(s):  
Noopur Raje ◽  
Shaji Kumar ◽  
Teru Hideshima ◽  
Kenji Ishitsuka ◽  
Hiroshi Yasui ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
B Cell ◽  
Cell Lines ◽  
Plasma Cells ◽  
Cell Development ◽  
Newly Diagnosed ◽  
Growth And Survival ◽  
Affymetrix U133a ◽  
Apoptotic Proteins

Abstract BAFF is a member of the tumor necrosis factor (TNF) family and is critical for the maintenance and homeostasis of normal B-cell development. Importantly, BAFF promotes the generation of rapidly dividing immunoglobulin secreting plasmablasts from activated memory B cells by enhancing their survival. Given that MM is a cancer of plasma cells and that the signaling cascades implicated in receptor ligand interactions of BAFF are crucial in MM cell biology, we hypothesized that this cytokine may play a critical role in MM cell development, survival, and proliferation. We performed gene expression profiling (GEP) on CD 138+ plasma cells isolated from 90 MM patients (45 newly diagnosed and 45 relapsed) and 11 healthy controls using the Affymetrix U133A arrays. Our data demonstrates increased expression of transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) and B-cell maturation antigen (BCMA), 2 receptors used by BAFF to exert its effects. Our data also shows an increased expression of a proliferation-inducing ligand (APRIL), another member of the TNF family with homology to BAFF. Expression levels of BAFF and BAFF-R could not be determined because of lack of these probe sets on the Affymetrix U133A arrays. GEP analysis shows increased BCMA expression (p&lt;0.0001, student T test) on newly diagnosed and relapsed MM versus normal plasma cells. Flow cytometry on MM cell lines demonstrated a differential expression of the three receptors of BAFF, with BCMA present on most cell lines but BAFF-R expressed at low levels only on LR5 cells and DOX40 MM cells. In contrast, flow cytometry performed on MM patient cells demonstrated the presence of all 3 receptors on CD 138+ cells. ELISA assays performed on 30 MM sera demonstrated a mean BAFF level of 618 pg/ml (range: 128–2126pg/ml) versus 235pg/ml (range: 158–326pg/ml) in 7 normal donor sera. Fifty six% (17/30) of MM patients had BAFF levels in excess of the highest value noted in normals. To understand the role BAFF might play in the biology of MM, we studied the effects of recombinant BAFF (rh-BAFF) on MM cells directly and in the context of its bone marrow microenvironment. (abstract # 554746) rh-BAFF conferred a survival advantage to MM cells and protected them against dexamethasone-induced cytotoxicity. Importantly, anti-apoptotic proteins Bcl2 and Mcl-1 were upregulated, as were growth and survival signals belonging to the JAK/STAT and MAPKinase pathways. Conversely, neutralizing antibody to BAFF blocked, at least in part, blocked the upregulation of anti-apoptotic proteins with associated growth and survival, confirming that these effects were due to BAFF. Importantly, all of these signals were downregulated even in the presence of bone marrow stromal cells (BMSCs). These data therefore show a role for BAFF mediating MM cell survival and provide the framework for inhibiting BAFF, either alone or in combination with dexamethasone, to improve patient outcome in MM.

Inhibition of ERK1/2 Activity by the MEK1/2 Inhibitor AZD6244 (ARRY-142886) Induces Human Multiple Myeloma Cell Apoptosis in the Bone Marrow Microenvironment: A New Therapeutic Strategy for MM.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3460-3460 ◽  
Author(s):  
Yu-Tzu Tai ◽  
Xian-Feng Li ◽  
Iris Breitkreutz ◽  
Weihua Song ◽  
Peter Burger ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Cell Growth ◽  
Cell Lines ◽  
Caspase 3 ◽  
Parp Cleavage ◽  
Dependent Manner ◽  
Growth And Survival ◽  
Cyclin E1 ◽  
Human Multiple Myeloma

Abstract Activation of the extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase (ERK1/2 MAPK) signaling pathway mediates tumor cell growth in many cancers, including human multiple myeloma (MM). Specifically, this pathway mediates MM cell growth and survival induced by cytokines/growth factors (i.e. IL-6, IGF-1, CD40, BAFF) and adhesion to bone marrow stromal cells (BMSCs), thereby conferring resistance to apoptosis in the bone marrow (BM) milieu. In this study, we therefore examined the effect of the MEK1/2 inhibitor AZD6244 (ARRY-142886), on human MM cell lines, freshly isolated patient MM cells and MM cells adhered to BMSCs. AZD6244, inhibits constitutive and cytokine (IL-6, IGF-1, CD40)-stimulated ERK1/2, but not AKT phosphorylation. Importantly, AZD6244 inhibits the proliferation and survival of human MM cell lines, regardless of sensitivity to conventional chemotherapy, as well as freshly isolated patient MM cells. AZD6244 induces apoptosis in patient MM cells even in the presence of BMSCs, as evidenced by caspase 3 activity and PARP cleavage at concentrations as low as 20 nM. AZD6244 overcomes resistance to apoptosis in MM cells conferred by IL-6 and BMSCs, and inhibits IL-6 secretion induced by MM adhesion to BMSCs. AZD6244 suppresses MM cell survival/growth signaling pathways (i.e., STAT3, Bcl-2, cyclin E1, CDK1, CDK3, CDK7, p21/Cdc42/Rac1-activated kinase 1, casein kinase 1e, IRS1, c-maf) and up-regulates proapoptotic cascades (i.e., BAX, BINP3, BIM, BAG1, caspase 3, 8, 6). AZD6244 also upregulates proteins triggering cell cycle arrest (i.e. p16INK4A, p18INK4C, p21/WAF1 [Cdkn1a], p27 [kip1], p57). In addition, AZD6244 inhibits adhesion molecule expression in MM cells (i.e. integrin a4 [VLA-4], integrin b7, ICAM-1, ICAM-2, ICAM-3, catenin a1, c-maf) associated with decreased MM adhesion to BMSCs. These pleiotropic proapoptotic, anti-survival, anti-adhesion and -cytokine secretion effects of AZD6244 abrogate BMSC-derived protection of MM cells, thereby sensitizing them to both conventional (dexamethasone) and novel (perifosine, lenalidomide, and bortezomib) therapies. In contrast, AZD6244 has minimal cytotoxicity in BMSCs and does not inhibit DNA synthesis in CD40 ligand-stimulated CD19 expressing B-cells derived from normal donors at concentrations toxic to MM cells (between 0.02–2 mM). Furthermore, AZD6244 inhibits the expression/secretion of osteoclast (OC)-activating factors (i.e., macrophage inflammatory protein (MIP)-1a, MIP-1b, IL-1b, VEGF) from MM cells. It also downregulates MM growth and survival factors (IL-6, BAFF, APRIL) in OC cultures derived from MM patient peripheral blood mononuclear cells (PBMCs). Significantly, AZD6244 inhibits OC differentiation from MM PBMCs (n=10) in a dose-dependent manner. Together these results provide the preclinical basis for clinical trials with AZD6244 (ARRY-142886) in MM.

Biological Sequelae of TRAF2 Downregulation in Waldenstrom Macroglobulinemia Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3526-3526
Author(s):  
Xavier Leleu ◽  
Lian Xu ◽  
Zachary R. Hunter ◽  
Sophia Adamia ◽  
Evdoxia Hatjiharissi ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
Cell Growth ◽  
Cell Lines ◽  
Genomic Alteration ◽  
Rt Pcr ◽  
Growth And Survival ◽  
Healthy Donors ◽  
Cell Growth And Survival

Abstract Background. Several TNF family members (CD40L and BAFF/BLYS) have been implicated in Waldenstrom’s Macroglobulinemia (WM) cell growth and survival. More recently, abnormalities in the APRIL-TACI pathway have been demonstrated by us in WM cells (Hunter, ASH2006, #228). TRAFs (TNFR-associated factor) are a family of adaptor proteins that mediate signal transduction from multiple members of the TNF receptor superfamily. In particular, TRAFs facilitate pro-apoptotic signaling from the TACI receptor, and TRAF2 is of importance among the TRAF adapter proteins since this protein is required for TNF-alpha-mediated activation of SAPK/JNK MAPK known to be involved in drug-induced death of tumor B cells. We therefore examined the role of TRAF2 in WM growth and survival. Method. We investigated TRAF2, 3 and 5 gene expression in WM patient bone marrow (BM) CD19+ cells and cell lines (BCWM.1, WSU-WM) and compared their expression to BM CD19+ cells from healthy donors. Expression of human TRAF transcripts were determined using real time quantitative RT-PCR (qPCR) based on TaqMan fluorescence methodology. To evaluate the role of TRAF2, a knockdown model was prepared in BL2126 B-cells and BCWM.1 WM cells using electroporation, with resulted ≥50% knockdown efficiency using RT-PCR and immunoblotting. Results. We found that TRAF3 and 5 gene expression was higher in WM versus healthy donors, while TRAF2 expression was lower in 8/13 (60%) patients, using qPCR. TRAFs gene expression did not correlate with tumor burden or WM prognostic markers. We next sought to understand the biological sequelae of TRAF2 deficiency in BL2126 and BCWM.1 cells and found that TRAF2 knockdown induced increased survival at 72 hours in both cell lines. We next studied sequence analysis of 20 WM patients CD19+ BM cells to determine whether there was a TRAF2 genomic alteration, and found heterozygous early termination mutation in exon 5 in 1 (5%) patient. Conclusion. Our data demonstrate that TRAF2 is a commonly dysregulated TNF family adapter protein in patients with WM, with important consequences in WM cell growth and survival.

The Serine/Threonine Kinase Pim-2 Is a Novel Anti-Apoptotic Mediator in Myeloma Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 243-243
Author(s):  
Jin Asano ◽  
Masahiro Abe ◽  
Shiro Fujii ◽  
Osamu Tanaka ◽  
Ai Mihara ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Growth ◽  
Stromal Cells ◽  
Osteoblast Differentiation ◽  
Family Members ◽  
Bone Marrow Microenvironment ◽  
Serine Threonine Kinase ◽  
Growth And Survival ◽  
Threonine Kinase ◽  
Cell Growth And Survival

Abstract Myeloma (MM) cells stimulate bone resorption by enhancing osteoclast (OC) formation and suppress bone formation by inhibiting osteoblast differentiation, leading to destructive bone lesions. In these lesions, OCs and stromal cells with defective osteoblast differentiation create a microenvironment suitable for myeloma cell growth and survival (a MM niche) to protect MM cells from various apoptotic insults. IL-6 and the TNF family members BAFF and APRIL have been demonstrated to be among predominant anti-apoptotic cytokines for MM cells elaborated by the bone marrow microenvironment in MM. The serine/threonine kinase Pim-2 is a novel apoptotic inhibitor which is transcriptionally up-regulated to promote survival of hematopoietic cells in response to environmental growth factors and cytokines. Up-regulation of Pim-2 expression has also been observed in various malignancies including MM. However, the roles for Pim-2 in growth and survival of MM cells are largely unknown. In the present study we therefore investigated the regulatory mechanism for Pim-2 expression in MM cells and the impact of Pim-2 on MM cell growth and survival with special reference to the interaction between MM cells and bone marrow components. Pim-2 protein is constitutively overexpressed in the absence of IL-6 in IL-6-dependent INA-6 as well as IL-6-independent RPMI8226 and U266 MM cell lines. Addition of IL-6, BAFF and TNFalpha up-regulated Pim-2 protein expression in INA-6 and RPMI8226 cells. A JAK/STAT3 inhibitor, cucurbitacin I, suppresses Pim-2 expression induced by IL-6, indicating Pim-2 as a downstream target of a JAK/STAT3 pathway. Stromal cells and OCs are regarded as a predominant cell type in MM bone marrow microenvironment to produce IL-6 and the TNF family members BAFF and APRIL, respectively. Co-cultures with stromal cells as well as OCs enhanced Pim-2 expression in INA-6 cells, suggesting up-regulation of Pim-2 in MM cells by surrounding cells in the bone marrow. In order to clarify the roles for Pim-2 in growth and survival of MM cells we next looked at the effects of Pim-2 siRNA. Suppression of Pim-2 expression by Pim-2 siRNA partly reduced the proliferation of INA-6 cells stimulated by IL-6 as well as the co-cultures with stromal cells or OCs. Pim-2 silencing also enhanced the cytotoxic effects of dexamethason on MM cells. Interestingly, further addition of rapamycin, an inhibitor of mammalian target of rapamycin (mTOR), induces cell death in concert with Pim-2 silencing in INA-6 cells, suggesting a cooperative roles for PI3K/Akt and Pim-2-mediated pathways in growth and survival of MM cells. Furthermore, Pim-2 silencing induced the cleavage of caspase9 but not caspase8; enforced expression of Pim-2 phosphorylated the BH3 only protein Bad; Pim-2 silencing suppressed phosphorylation of Bad by IL-6. Thus, Pim-2 appears to activate the intrinsic pathway of apoptotic machinery involving Bad phosphorylation. Taken together, our results suggest that Pim-2 is an important prosurvival mediator in MM cells, and that up-regulation of its expression in MM cells by bone marrow components may at least in part contribute to resistance to spontaneous and drug-induced apoptosis in MM cells. Therefore, Pim-2 may become a target for novel therapeutic strategies against MM.

CXCR7 Regulates SDF-1 Induced Adhesion and Homing in Multiple Myeloma.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1674-1674 ◽  
Author(s):  
Nicholas Burwick ◽  
Anne-Sophie Moreau ◽  
Xiaoying Jia ◽  
Xavier Leleu ◽  
Judith Runnels ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Flow Cytometry ◽  
Cell Adhesion ◽  
Cell Lines ◽  
Cxcr4 Expression ◽  
Rt Pcr ◽  
Growth And Survival ◽  
Tumor Types

Abstract BACKGROUND: Multiple myeloma (MM) is a plasma cell malignancy that depends on interactions with the bone marrow (BM) microenvironment for growth and survival. In turn, adhesion of MM cells to the BM stroma provides a mechanism of resistance from standard chemotherapeutic agents. Recently, our lab has shown that by disrupting this adhesion using a selective CXCR4 inhibitor named AMD3100, MM cells are more sensitive to the proteasome inhibitor Bortezomib (Ghobrial lab, unpublished data). CXCR4 has been a particularly attractive target because its ligand SDF-1 is known to induce p42/44 MAPK, AKT, and the down-stream anti-apoptotic protein bad in MM cells, leading to increased MM growth and survival. Until recently, CXCR4 was thought to be a canonical receptor for the SDF-1 ligand. However, a second chemokine receptor for SDF-1 was subsequently discovered and named CXCR7. CXCR7 is a novel chemokine receptor that is important in cell adhesion, growth and survival in several tumor types. However, the role of CXCR7 in multiple myeloma (MM) has yet to be explored. Furthermore, the ability of SDF-1 ligand to regulate MM function via CXCR7 has not been studied. METHODS: The MM cell lines (U266, MM1.S, RPMI, OPM2, OPM1) were used. After informed consent was obtained, primary bone marrow samples from MM patients were collected. CD138 positive mononuclear cells were isolated by microbead selection. The expression of CXCR7 on MM cell lines and patient samples was confirmed using flow cytometry and RT-PCR analysis. For functional in vitro and ex-vivo assays, the CXCR7 selective antagonist 733 was used (ChemoCentryx Inc., Mountain View, CA). RESULTS: Here we show that CXCR7 was expressed on all tested MM cell lines and primary patient samples as demonstrated by flow cytometry and RT-PCR. Furthermore, CXCR7 was found to regulate SDF-1 induced MM cell adhesion, as demonstrated by in vitro assays using a small molecule compound specific for CXCR7 (733). The CXCR7 antagonist showed significant inhibition of adhesion of MM cell lines and patient samples to fibronectin, endothelial cells and stromal cells, with 50% reduction of adhesion at 5nM of the CXCR7 inhibitor, and with similar activity compared to 20uM of AMD3100 (CXCR4 inhibitor). However, unlike CXCR4, CXCR7 did not effect trans-well migration to SDF-1 chemokine. Interestingly, both receptors were found to be important for trans-endothelial migration of MM cells. Moreover, pre-treatment with 733 reduced homing of MM cells to the BM niche in vivo. Previous studies have failed to show signaling in response to CXCR7 in many tumor types. Here, we demonstrate that treatment with 733 inhibited SDF-1 induced pERK and pAKT, ribosomal pS6Kinase, pGSK3, pSTAT3, pFAK and pPAK signaling pathways, confirming a role for CXCR7 in facilitating SDF-1 signaling. This effect was further confirmed using immunofluorescence. To investigate whether CXCR7 and CXCR4 interact directly, we examined the effect of 733 and AMD3100 on CXCR4 expression and found that AMD3100 significantly inhibited CXCR4 expression, while 733 had no effect on CXCR4 expression, even in the presence of SDF-1. The CXCR7 inhibitor had no effect on the survival of MM cells using MTT and flow cytometry analysis, while high doses of 733 (1uM) had modest inhibition of proliferation. Interestingly, 733 prevented the growth advantage induced by 30nM SDF-1 at 24 hrs. CONCLUSION: Together, these results demonstrate the importance of CXCR7 in regulating MM adhesion and homing, and highlight the differential effects of CXCR4 and CXCR7 in regulating SDF-1 signaling in MM, thus providing a rationale for targeting the SDF-1/CXCR7 axis in MM.

Biological and Molecular Characterization by Integrative Genomics Approach of CMA-03/06, a Newly Established Interleukin-6 Independent Variant of the CMA-03 Human Myeloma Cell Line.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1814-1814
Author(s):  
Donata Verdelli ◽  
Lucia Nobili ◽  
Katia Todoerti ◽  
Laura Mosca ◽  
Sonia Fabris ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cell Line ◽  
Molecular Characterization ◽  
Cell Lines ◽  
Stromal Cells ◽  
Interleukin 6 ◽  
Myeloma Cell ◽  
Growth And Survival ◽  
Genome Wide

Abstract Abstract 1814 Poster Board I-840 Background The growth and survival of multiple myeloma (MM) cells in the bone marrow microenvironment is regulated by functional complex interactions between the tumor cells and the surrounding bone marrow stromal cells mediated by adhesion molecules and the production of several cytokines of which interleukin-6 (IL-6) has been identified as the most important. Major advances in the investigation of MM biology were made possible by the availability of human myeloma cell lines (HMCLs). The IL-6-dependent CMA-03 cell line was established in our laboratory from a peritoneal effusion of a refractory relapsed MM patient. By gradually decreasing the IL-6 added to the culture, an IL-6-independent variant, CMA-03/06, could be obtained. Aims. To perform a biological and molecular characterization of this novel cell line, and to provide insights into the signaling pathways and target genes involved in the growth and survival of CMA-03/06. Methods. The growth, immunophenotypic, cytogenetic and fluorescence in situ hybridization (FISH) characterization of CMA-03/06 cell line was performed by means of standard procedures. IL-6 production into the culture media was determined using a high sensitivity IL-6 specific ELISA. Genome-wide profiling data were generated by means of Affymetrix GeneChip® Human Mapping 250K Nsp arrays; copy number (CN) alterations were calculated using the DNAcopy Bioconductor package, based on circular binary segmentation method. Global gene expression profiling (GEP) was performed by means of the GeneChip® Human Gene 1.0 ST Arrays (Affymetrix); the supervised analyses were done using the SAM software version 3.0. Results Unlike CMA-03, the addition of IL-6 to the culture medium of CMA-03/06 cells or co-culture with multipotent mesenchymal stromal cells did not induce an increase in CMA-03/06 proliferation. IL-6 was not detected in the supernatants from either CMA-03 or CMA-03/06 cell lines within 48 h, suggesting that the IL-6 independence of CMA03/06 cells is not a result of the development of an autocrine IL-6 loop. Nevertheless, IL-6 induced the activation of STAT3 and STAT1 in both cell lines, even if a slight constitutive STAT3 phosphorylation was found in CMA-03/06. The immunophenotypic analysis showed a significant difference in the expression of three antigens in the 2 cell lines: CD45 was considerably reduced in CMA-03/06 cells, whereas they were found positive for both chains of IL-6 receptor, CD126 and CD130, almost undetectable in CMA-03. Conventional cytogenetic and FISH analyses did not reveal differences between the 2 HMCLs. The genome-wide analysis allowed the identification of about 100 altered chromosomal regions common to both HMCLs, mostly DNA gains. Comparison of CMA-03/06 and CMA-03 cells evidenced a different CN in only 15 small chromosomal regions, 8 of which did not contain any transcript, whereas few genes were located on the other ones. GEP analysis of CMA-03/06 compared with CMA-03 identified 21 upregulated and 47 downregulated genes, many of which particularly relevant for MM biology, mainly involved in cellular signaling, cell cycle, cell adhesion, cell development, regulation of transcription, immunologic, inflammatory or defense activity, apoptosis. None of the genes differentially expressed in CMA-03/06 compared with CMA-03 except 1 were positioned on the chromosomal regions showing a different CN. Finally, CMA-03/06 cell line showed a lower susceptibility to camptothecin-induced apoptosis compared to CMA-03 cells. Conclusions Our data show the IL-6 independence of CMA-03/06 cell line in the absence of an autocrine IL-6 loop; the cells, however, maintain the IL-6 signaling pathway responsiveness. A consistent number of genes particularly relevant for MM biology were found deregulated in CMA-03/06 cell line compared with CMA-03. Furthermore, CMA-03/06 cell line shows an increased resistance to apoptosis. The novel CMA03/06 cell line may thus represent a suitable model for studies investigating molecular mechanisms involved in clonal evolution towards IL-6 and/or stroma-independent growth and survival of myeloma cells. Disclosures No relevant conflicts of interest to declare.

ZAP-70 Enhances Migration of Malignant B Cells towards Lymphoid Organs in a Burkitt Lymphoma Xenograft Model

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2844-2844
Author(s):  
Noelia Purroy ◽  
Eva Calpe ◽  
Pau Abrisqueta ◽  
Cecilia Carpio ◽  
Carles Palacio ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
B Cells ◽  
Tumor Growth ◽  
B Cell ◽  
Cell Lines ◽  
Ectopic Expression ◽  
Xenograft Model ◽  
Lymphoid Organs ◽  
Transfected Cells

Abstract Abstract 2844 Introduction. ZAP-70 (ξ-associated protein) is a protein tyrosine kinase of the Syk/ZAP family that plays a crucial role in cellular activation in T and NK cells. High expression of ZAP-70 protein in malignant cells from Chronic Lymphocytic Leukemia (CLL) correlates with adverse clinical prognostic features, such as unmutated IgHV genes, short time to progression, and short survival. Moreover, ZAP-70 protein has been related to aggressive features of the CLL cells, such as enhanced B-cell receptor (BCR) signaling and higher migration capacity. To further investigate into the mechanisms by which ZAP-70 protein influences the clinical outcome of patients with CLL, we analyzed the functional consequences of ZAP-70 ectopic expression in malignant B-cells. For this, Ramos and Raji (Burkitt) B-cell lines were stably transfected with a ZAP-70 expressing vector (pEGFP-N2ZAP-70). Raji transfectant showed constitutively phosphorylated ZAP-70 protein, whilst Ramos cells required stimulation with 5 μg/ml F(ab') 2 anti-IgM to get ZAP-70 activated. ZAP-70 expression induced the upregulation of the chemokine receptor CCR7, thus giving the cells the ability to better respond and migrate towards CCL21 (own data, Blood 2011 pre-published). CCR7 ligands (chemokines CCL21 and CCL19) are mainly expressed in high endothelial venules and the T zones from secondary lymphoid organs. The aims of this study were firstly to evaluate in vivo the migratory/invasive capability of pEGFP-N2ZAP-70 transfected Raji and Ramos cell lines compared to pEGFP Raji and Ramos cell lines; and later, to compare the overall survival (OS) of mice injected with pEGFP-N2ZAP-70 transfected cells to those injected with only pEGFP transfected cells. Methods. For this, a total of 27 7- to 8-week old SCID (CB17Crl) mice were used. Mice were inoculated intravenously with 5×106 cells of each cell line (6 mice with Raji-GFP, 5 mice with Raji-GFP-ZAP-70, 5 mice with Ramos-GFP and 10 mice with Ramos-GFP-ZAP-70). Mice were observed for the onset of hind legs paralysis, dyspnea, or evidence of tumor growth, once symptoms appeared, mice were euthanized and lymphoid and non-lymphoid organs were obtained for further analysis of the presence of GFP-positive cells by flow cytometry and immunohistochemistry. Results. Twenty-six out of twenty-seven injected mice were included in the analysis. The excluded mouse was found dead before it could be euthanized to obtain the organs. In the Raji xenograft model, 11/11 (100%) of mice had hind legs paralysis as the first symptom to appear. The median survival was 19 days for GFP-ZAP-70 and 16 days for GFP injected mice. There were no statistically significant differences between survival of GFP-ZAP-70 and GFP injected mice (OS was 66.7% [95% CI 38.4–100] vs 33.3% [95% CI 0–71.1], p=0.784, at 19 and 16 days, respectively). In the Ramos xenograft model, 6/15 (40%) of mice showed hind legs paralysis as the first symptom to appear, as well as evidence of abdominal tumor growth in 6/15 (40%), whereas in 3/15 (20%) the established event was dyspnea. The median survival in Ramos xenograft model was 40 days for GFP-ZAP-70 and 38 days for GFP injected mice. Again there were no statistically significant differences between survival of GFP-ZAP-70 and GFP Ramos injected mice (OS was 50% [95% CI 18.4–81.6] vs 40% [95% CI 0–83.8], p=0.180, at 40 and 38 days, respectively). By flow cytometry analysis of GFP cells we found that in the Raji xenograft model there were statistically significant differences between the migration of GFP-ZAP-70 and GFP injected cells towards bone marrow (21.5% vs 5.17, p=0.011), spleen (0.08% vs 0.01%, p=0.006) and thymus (0.00% vs 0.02%, p=0.037). The highest percentages of GFP positive cells were found in bone marrow samples (mean, 9.85%), whereas in spleen and thymus the percentages of GFP positive cells were all below 0, 1%. There was no statistically significant difference between the cellular migration in the Ramos xenograft model in any of the organs analyzed. Conclusion. In conclusion, malignant B-lymphocytes with ectopic expression of activated ZAP-70 protein show enhanced ability to migrate towards and infiltrate lymphoid organs in a xenograft model, specially the bone marrow, although it does not translate into a worse survival of the animals. Further specific immunohistochemical assays to determine infiltrated areas by ZAP-70 expressing lymphocytes are in process. Disclosures: No relevant conflicts of interest to declare.

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