CD28 and CD86 Are Necessary for Myeloma Cell Survival.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2946-2946
Author(s):  
Catherine M Gavile ◽  
Jayakumar R Nair ◽  
Kelvin P Lee ◽  
Sagar Lonial ◽  
Lawrence H. Boise
Keyword(s):  
T Cells ◽  
Growth Factor ◽  
Cell Survival ◽  
Cell Line ◽  
Cell Lines ◽  
Plasma Cells ◽  
Surface Expression ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
Growth And Survival

Abstract Abstract 2946 Multiple myeloma (MM) is a hematologic malignancy characterized by the aberrant proliferation of plasma cells. Myeloma cells retain most of the physiological characteristics of their normal counterpart – the long-lived plasma cell. Myeloma cells secrete immunoglobulin and reside in the bone marrow, where they rely heavily on interactions with the stroma for survival signals. While recent advances in therapeutics have led to an increase in median survival post-diagnosis, the disease remains incurable. Understanding the pathways which mediate growth and survival of these cells will help in identifying new targets that can potentially further improve patient outcomes. CD28 is a receptor better known for its role in T-cell signaling through interaction with its ligands, CD80 or CD86. Interaction between CD28 on T-cells and CD80/86 on antigen-presenting cells leads to survival and proliferation of T-cells. Recent work has shown that the CD80/86-CD28 pathway also plays an important role in normal plasma cell generation and survival. Interestingly, high expression of CD28 and CD86 are poor prognostic markers for myeloma patients. Previous work has shown that CD28 activation provides survival signals for myeloma cells in growth-factor deficient conditions. It has also been shown that CD28 on the myeloma cell interacts with CD80/86 on the dendritic cell, which induces secretion of IL-6 (by the DC), an important myeloma growth factor. However, it is not known if CD28 or CD86 play a role in steady state growth and survival of myeloma cells. In order to determine the role of each of these 2 molecules in myeloma physiology, we knocked-down either CD28 or CD86 on the myeloma cell via lentivirus-mediated shRNAs. We found that knockdown of CD86 leads to apoptosis in 3 myeloma cell lines (RPMI8226, MM1.s, and KMS18). Four days after infection with the lentivirus containing shCD86, 45.7±4.9 and 60.3±4.6 percent control apoptosis was observed in RPMI8226 and MM1.s respectively, while less death was observed in KMS18 (17.6±1.6). CD28-knockdown resulted in apoptosis as well (24.9±4.3 for RPMI8226, 26.8±4.1 for MM1s, 21.8±3.8 for KMS18, percent control apoptosis). Consistent with these findings, we were unable to establish a myeloma cell line with stable knockdown of either CD28 or CD86. Additionally, RPMI8226 cells stably transfected to over-express either Bcl-2, Bcl-xL, or Mcl-1 are protected from cell death induced by CD86 or CD28 silencing. These data suggest that CD28 and CD86 are essential to prevent apoptosis of myeloma cells in vitro. To confirm these findings we determined the effects of CTLA4-Ig on myeloma survival. CTLA4-Ig inhibits CD86-CD28 signaling by binding to CD86, blocking its interaction with CD28. We found that treatment of RPMI8226 and MM1.s cells with CTLA4-Ig caused apoptosis in the myeloma cells after 2 days (23.9±3.9 for RPMI8226 and 20.4±6.2 for MM1.s, percent control apoptosis). Thus like normal plasma cells, CD28 and CD86 are required for the survival of myeloma cells. To determine why silencing of CD86 has a more potent effect than CD28 silencing on myeloma cell survival in 2 out of 3 cell lines, we investigated the effects of silencing on cell surface expression of each of these proteins. CD28 and CD86 mRNA and protein levels were silenced to similar levels by their cognate hairpins. However, in MM.1s and RPMI8226 we found that silencing of CD28 resulted in an increase in CD86 surface expression. This increase was also observed at the mRNA level and in the cells over-expressing Bcl-2 family members, indicating that this is not simply due to the selection of the highest expressing cells. These data suggest a feedback loop exists to regulate CD28-CD86 signaling in myeloma cells. Surprisingly, in the KMS18 cell line, we observe the converse effect, where silencing of CD86 resulted in upregulation of CD28. This provides a likely explanation for why these cells are less susceptible to CD86 silencing than the other two lines. Interestingly, blocking CD86 with CTLA4-Ig treatment also resulted in a modest upregulation in CD28 surface expression of MM.1s and RPMI8226, which suggests that silencing CD86 and binding of CD86 with a soluble receptor are not equivalent, and that multiple signaling feedback pathways exist to regulate the expression of this receptor-ligand pair that is necessary for myeloma cell survival. Disclosures: No relevant conflicts of interest to declare.

scholarly journals A Role for Syntenin-1 in Multiple Myeloma Cell Survival

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1008-1008
Author(s):  
Tyler Moser-Katz ◽  
Catherine M. Gavile ◽  
Benjamin G Barwick ◽  
Sagar Lonial ◽  
Lawrence H. Boise
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Cell Death ◽  
Cell Survival ◽  
Cell Lines ◽  
Plasma Cells ◽  
Surface Expression ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
Rpmi 8226

Abstract Multiple myeloma is the second most common hematological malignancy in the U.S. with an estimated 30,700 new diagnoses in 2018. It is a clonal disease of plasma cells that, despite recent therapeutic advances, remains incurable. Myeloma cells retain numerous characteristics of normal plasma cells including reliance on survival signals in the bone marrow for long term viability. However, malignant transformation of plasma cells imparts the ability to proliferate, causing harmful bone lesions in patients, and in advanced stages independence of the bone-marrow microenvironment. Therefore, we are investigating the molecular mechanisms of myeloma cell survival that allow them to become extramedullary. We identified syntenin-1 (SDCBP) as a protein involved in myeloma cell survival and a potential therapeutic target. Syntenin-1 is an adapter protein that has been shown to regulate surface expression of several transmembrane proteins by binding with membrane phospholipids and mediating vesicular trafficking of proteins throughout the cell. Syntenin-1 regulates the surface expression of CD138, a plasma/myeloma cell marker. Syntenin-1 has been shown to regulate apoptosis in numerous cancer cell lines including breast cancer, glioma, and pancreatic cancer but its role in multiple myeloma survival has not been studied. To determine if syntenin-1 expression has an effect on myeloma cell survival, we utilized the CoMMpass dataset (IA12), a longitudinal study of myeloma patients that includes transcriptomic analysis throughout treatment. We found that patients with the highest expression of syntenin-1 mRNA (top quartile) had significantly worse overall survival, progression-free survival, and a shorter response duration than those in the bottom quartile of expression. To determine if syntenin-1 has a role in myeloma cell survival, we used short hairpin RNA to knock down syntenin-1 (shsyn) in RPMI 8226 and MM1.s myeloma cell lines. We then determined the amount of cell death using Annexin-V staining flow cytometry four days following lentiviral infection. We found increased cell death in syntenin-1-silenced cells compared to our empty vector control in both RPMI 8226 (control=42.17%, shsyn=71.53%, p=0.04) and MM1.s cell lines (control=8.57%, shsyn=29.9%, p=0.04) suggesting that syntenin-1 is important for myeloma cell survival. Syntenin-1 contains two PDZ domains that allow it to bind to receptor proteins via their corresponding PDZ-binding motifs. We therefore wanted to look at correlation of syntenin-1 expression with CD138 and CD86, two PDZ-binding domain containing proteins expressed on the surface of myeloma cells. Using the CoMMpass dataset, we found patients with high expression of syntenin-1 had a median expression of CD86 that was twice as high as the total population (P<0.0001) while syntenin-1-low patients expressed CD86 at levels that were half as much as the population (P<0.0001). In contrast, there was no clear relationship between syntenin-1 and CD138 mRNA expression. Indeed if one takes into account all patients, there is a positive correlation between CD86 and syntenin-1 expression (r=0.228, P<0.0001) while there is a negative correlation between CD138 and syntenin-1 (r=-0.1923, P<0.0001). The correlation with CD86 but not CD138 suggests a previously undescribed role for syntenin-1 in myeloma cells. Our lab has previously shown that expression of CD86 is necessary for myeloma cell survival, and signals via its cytoplasmic domain to confer drug resistance. Silencing syntenin-1 results in a decrease in CD86 surface expression. However, there is no change in CD86 transcript or total cellular CD86 protein levels in our shsyn treated cells. Moreover, knockdown of CD86 resulted in increased protein expression and transcript levels of syntenin-1. Taken together, these data suggest that syntenin-1 may regulate CD86 expression on the cell surface. Our data supports a novel role for syntenin-1 in myeloma cell viability and as a potential regulator of CD86 surface expression. The role of syntenin-1 has not previously been explored in multiple myeloma and determining its molecular function is warranted as it may be an attractive target for therapeutic treatment of the disease. Disclosures Lonial: Amgen: Research Funding. Boise:AstraZeneca: Honoraria; Abbvie: Consultancy.

PRL-3 Regulates Myeloma Cell Survival, Proliferation, Adhesion and Migration

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1321-1321
Author(s):  
Tobias Schmidt Slordahl ◽  
Kristine Misund ◽  
Torstein Baade Ro ◽  
Magne Borset
Keyword(s):  
Growth Factor ◽  
Cell Survival ◽  
Cell Line ◽  
Cell Lines ◽  
Western Blotting ◽  
Plasma Cells ◽  
Myeloma Cell ◽  
Retroviral Transduction ◽  
And Migration ◽  
Rpmi 8226

Abstract Abstract 1321 Introduction: Multiple myeloma (MM) is a neoplastic monoclonal proliferation of bone marrow plasma cells. Despite advances in treatment in recent years, MM is still a fatal disease. Phosphatase of regenerating liver-3 (PRL-3) is a protein expressed in primary MM cells and MM cell lines, but not in normal plasma cells. A recent study showed that siRNA against PRL-3 suppresses MM-cell migration (Fagerli et al, 2008) and another study has identified PRL-3 as a marker gene for a subgroup of patients with MM (Broyl et al, 2010). Methods: The human myeloma cell lines INA-6, ANBL-6, IH-1, OH-2 and RPMI-8226 were used in this study. Apoptosis was measured by Annexin V-FITC binding by flow cytometry, proliferation was measured by methyl-3H-thymidine incorporation, migration against a stromal cell derived factor-1α (SDF-1α) gradient was studied in a Transwell two-chamber assay and adhesion was measured as percentage adhered cells to fibronectin after stimulation with the pro-adhesive cytokines hepatocyte growth factor (HGF), insulin like growth factor-1 (IGF-1) and SDF-1α. RT-PCR and Western blotting were used to measure expression of pro- and anti-apoptotic proteins. Western blotting was used to map intracellular signaling pathways. INA-6 cells stably expressing exogenous PRL-3 were generated using retroviral transduction. The small molecular inhibitor PRL-3 Inhibitor I was used for PRL-3 inhibition. Results: PRL-3 inhibitor I reduced survival of the myeloma cell lines INA-6, ANBL-6, IH-1, OH-2 and RPMI-8226. IC50 was between 15 and 50 μM depending on cell line. Treatment with the inhibitor down-regulated the anti-apoptotic protein Mcl-1 and led to activation of the intrinsic apoptotic pathway. Inhibition of PRL-3 reduced interleukin (IL)-6-induced phosphorylation of STAT-3. Treatment with 10 μM of PRL-3 inhibitor I also significantly reduced migration against a SDF-1α gradient and HGF-, IGF-1- and SDF-1α -mediated adhesion of the cell line INA-6. By retroviral transduction we made PRL-3-overexpressing INA-6 cells. INA-6 cells are dependent on IL-6 to grow, but overexpression of PRL-3 led to a major increase in cell proliferation even in the absence of IL-6 as well as increased survival at suboptimal concentrations of IL-6. Conclusion: PRL-3 is expressed in MM cells but not in normal plasma cells and can represent a cancer-specific target. Overexpression of PRL-3 in the IL-6-dependent human myeloma cell line INA-6 renders the cells less dependent of IL-6 and increases survival and proliferation. On the other hand, the use of an inhibitor against PRL-3 significantly decreases survival of five MM-cell lines and reduces adhesion and migration of the cell line INA-6. IL-6-STAT3 signaling is important in MM cell survival and proliferation and we here show that PRL-3 possibly influences cell survival as a positive regulator of this signaling pathway. This study indicates that PRL-3 could be important in the pathogenesis of MM and a potential target in the treatment of MM. Disclosures: No relevant conflicts of interest to declare.

Expression of functional interleukin-15 receptor and autocrine production of interleukin-15 as mechanisms of tumor propagation in multiple myeloma

Blood ◽  
2000 ◽  
Vol 95 (2) ◽  
pp. 610-618 ◽  
Author(s):  
Inge Tinhofer ◽  
Ingrid Marschitz ◽  
Traudl Henn ◽  
Alexander Egle ◽  
Richard Greil
Keyword(s):  
Multiple Myeloma ◽  
Cell Survival ◽  
Cell Lines ◽  
Plasma Cells ◽  
Constitutive Expression ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
Cytotoxic Treatment ◽  
Interleukin 15 ◽  
Induced Apoptosis

Interleukin-15 (IL-15) induces proliferation and promotes cell survival of human T and B lymphocytes, natural killer cells, and neutrophils. Here we report the constitutive expression of a functional IL-15 receptor (IL-15R) in 6 of 6 myeloma cell lines and in CD38high/CD45low plasma cells belonging to 14 of 14 patients with multiple myeloma. Furthermore, we detected IL-15 transcripts in all 6 myeloma cell lines, and IL-15 protein in 4/6 cell lines and also in the primary plasma cells of 8/14 multiple myeloma patients. Our observations confirm the existence of an autocrine IL-15 loop and point to the potential paracrine stimulation of myeloma cells by IL-15 released from the cellular microenvironment. Blocking autocrine IL-15 in cell lines increased the rate of spontaneous apoptosis, and the degree of this effect was comparable to the pro-apoptotic effect of depleting autocrine IL-6 by antibody targeting. IL-15 was also capable of substituting for autocrine IL-6 in order to promote cell survival and vice versa. In short-term cultures of primary myeloma cells, the addition of IL-15 reduced the percentage of tumor cells spontaneously undergoing apoptosis. Furthermore, IL-15 lowered the responsiveness to Fas-induced apoptosis and to cytotoxic treatment with vincristine and doxorubicin but not with dexamethasone. These data add IL-15 to the list of important factors promoting survival of multiple myeloma cells and demonstrate that it can be produced and be functionally active in an autocrine manner.

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.

Serum/Glucocorticoid-Regulated Kinase 1 (SGK1) Is a Prominent Target Gene of the Transcriptional Response to Cytokines In Multiple Myeloma and Supports the Growth of Myeloma Cells

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1915-1915
Author(s):  
Unn-Merete Fagerli ◽  
Thorsten Stühmer ◽  
Toril Holien ◽  
Randi Utne Holt ◽  
Ove Bruland ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Growth Factors ◽  
Cell Lines ◽  
Plasma Cells ◽  
Conflicts Of Interest ◽  
Transcriptional Response ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
Growth And Survival ◽  
Stat3 Phosphorylation

Abstract Abstract 1915 Multiple myeloma is a paradigm for a malignant disease that exploits external stimuli of the microenvironment for growth and survival. A thorough understanding of the complex interactions between malignant plasma cells and their surrounding requires a detailed analysis of the transcriptional response of myeloma cells to environmental signals. We hypothesized that the intracellular signals evoked by cytokines converge and regulate transcription of a set of genes that are common targets for several growth factors and therefore constitute pivotal mediators of the tumor-promoting effects of autocrine or paracrine stimuli. To identify such targets, we determined the changes in gene expression induced by IL-6, TNFalpha, IL-21 or co-culture with bone marrow stromal cells in myeloma cell lines. Among a limited set of genes that were consistently activated in response to growth factors, a prominent transcriptional target of cytokine-induced signaling in myeloma cells was the gene encoding the serine/threonine kinase SGK1, which is a down-stream effector of PI3-kinase and highly homologous to AKT. We could demonstrate a rapid, strong and sustained induction of SGK1 in the cell lines INA-6, ANBL-6, IH-1, OH-2 and MM.1S as well as in primary myeloma cells. Pharmacologic inhibition of the JAK/STAT pathway abolished STAT3 phosphorylation and SGK1 induction. In addition, shRNA-mediated knock-down of STAT3 reduced basal and induced SGK1 levels, demonstrating the involvement of the JAK/STAT3 signaling pathway in SGK1 induction. Furthermore, down-regulation of SGK1 by shRNAs resulted in decreased proliferation and viability of myeloma cell lines. Our results indicate that SGK1 is a highly cytokine-responsive gene in myeloma cells promoting their growth and survival and represents an attractive candidate for further evaluation as a therapeutic target. Disclosures: No relevant conflicts of interest to declare.

Identification and Hierarchy of Clonogenic Factors for Human Myeloma Cells: IL-6 for CD45+ Versus IL-6 and Growth Factors for CD45-.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3407-3407
Author(s):  
Martine Amiot ◽  
Regis Bataille ◽  
Madeleine Collette ◽  
Geraldine Descamps ◽  
Catherine Pellat-deceunynck
Keyword(s):  
Growth Factors ◽  
Cell Lines ◽  
Plasma Cells ◽  
Treatment Strategies ◽  
Myeloma Cell ◽  
Myeloma Cells ◽  
Growth And Survival ◽  
Essential Growth ◽  
Cell Malignancy ◽  
Clonogenic Cells

Abstract Multiple Myeloma (MM) is a fatal plasma-cell malignancy characterized by the accumulation of malignant plasma cells within the bone marrow. IL-6 and IGF-1 are known to be essential growth and survival factors in this malignancy. Beside these well characterized growth factors, other growth factors such as HGF, HB-EGF and FGF have been involved in this malignancy. Even though all of them seem to be involved in myeloma cell proliferation, the hierarchy of each growth factor remains to be established. In the present study, a serum-free cytokine-free and collagen-based assay which does not allow the generation of endogeneous myeloma colonies was used to identify the clonogenic factors of fourteen myeloma cell lines. We selected seven myeloma cell lines expressing CD45 on 100% of cells and seven other cell lines lacking CD45 expression. IL-6 is the only clonogenic factor able to stimulate both CD45+ and CD45- myeloma cell lines, generating myeloma colonies from 10 of 14 myeloma cell lines. For some cell lines (LP-1, L363 and XG-2) the percentage of clonogenic cells reached 40% to 50% indicating that clonogenic cells are CD138+ and do not represent a particular CD138-subpopulation. In contrast, the other growth factors (IGF-1, FGF, HGF and HB-EGF) stimulate only some CD45-myeloma cell lines and at a less extend than IL-6. Among them, IGF-1 is the most potent, generating myeloma colonies from 5 of 8 CD45- myeloma cell lines. We searched for a correlation between myeloma-colony formation and the signaling pathway induced by IGF-1 and FGF in MM cells. It appears that activation of both the PI3Kinase and ERK pathway by IGF-1 and FGF fully correlates with their capacity to stimulate the clonogenicity of CD45-myeloma cell lines. In conclusion, the CD45 phenotype of myeloma cells discriminates their signaling and proliferative response to IL-6 and growth factors. These results give a strong rational to the stratification of prognostic value discriminating CD45+ from CD45- MM. Furthermore, treatment strategies for CD45- patients should combined the disruption of signaling induced by both IL-6 and IGF-1 (or other growth factors) whereas CD45+ patients could be targeted through IL-6 only.

scholarly journals Altered expression of Pax-5 gene in human myeloma cells

Blood ◽  
1996 ◽  
Vol 87 (10) ◽  
pp. 4311-4315 ◽  
Author(s):  
MS Mahmoud ◽  
N Huang ◽  
M Nobuyoshi ◽  
IA Lisukov ◽  
H Tanaka ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cell ◽  
Cell Line ◽  
Cell Lines ◽  
Plasma Cells ◽  
Myeloma Cell ◽  
Altered Expression ◽  
Myeloma Cells ◽  
Normal Plasma ◽  
Human Myeloma Cells

Recent phenotypic analysis of plasma cells showed that normal plasma cells do express the B-cell lineage-specific molecule CD19, but their malignant counterpart (myeloma cells) are CD19-. To clarify the meaning of loss of CD19 antigen on myeloma cells, we first compared the expression of CD19 and Pax-5 genes among B cells, normal plasma cells, myeloma cell lines, and primary myeloma cells, because the Pax-5 gene was reported to encode the transcriptional factor, B-cell-specific activating protein (BSAP), necessary for CD19 gene expression. Neither CD19 nor Pax-5 mRNA could be detected in those primary myeloma cells and cell lines, whereas normal plasma cells did express both CD19 and Pax-5 mRNA. Furthermore, we could confirm that BSAP-binding activity was not detected in the nuclear extract from CD19- myeloma cell line (KMS-5) but was detected in CD19+ B-cell line (Raji) by gel-shift assay. We further examined the expression of E2A and Id genes, because E2A and Id are considered to be positive and negative regulators in the expression of Pax-5 gene, respectively. However, no significant differences in the expression of these E2A and Id-2 genes could be observed between myeloma cells and normal plasma cells. Therefore, these data suggest that the altered expression of Pax-5, but not E2A or Id, is responsible for the loss of CD19 expression in human myeloma cells, although the underlying mechanism of the altered Pax-5 gene expression remains to be clarified.

Regulation of Multiple Myeloma Survival and Progression by CD1d

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2720-2720
Author(s):  
Emmanouil Spanoudakis ◽  
Ming Hu ◽  
Kikkeri Naresh ◽  
Evangelos Terpos ◽  
Valeria Melo ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Survival ◽  
Cell Lines ◽  
Plasma Cells ◽  
Hla Class I ◽  
Myeloma Cell ◽  
Dependent Manner ◽  
Myeloma Cells ◽  
Therapeutic Implications

Abstract Downregulation of conventional HLA molecules from the surface of tumour cells is an important mechanism for tumour immune evasion, survival and progression. Whether CD1d, a non-conventional, glycolipid-presenting HLA class I-like molecule can affect tumour cell survival is not known. To test this we studied expression of surface CD1d on plasma cells from different stages of multiple myeloma (MM) using flow-cytometry. Expressing results as the ratio of the Geo MFI CD1d/isotype IgG1 we found that while CD1d expression was comparable between MGUS (n=8) and newly diagnosed MM patients (n=14; Geo MFI MGUS: 8.61±4.3 vs new MM: 7.1±4.72, p&gt;0.05), in relapsed/advanced disease CD1d was significantly lower (Geo MFI:1.92±0.9, p&lt;0.003 vs MGUS and new MM) and completely lost in 4 out of 5 myeloma cell lines at protein and RNA level. Further, 4 out of 8 paired, same-patient trephine biopsies stained with anti- CD1d showed drastic loss of CD1d expression in advanced compared to early disease. These results confirmed loss of CD1d expression during disease progression and suggested that CD1d impacts negatively on myeloma cell survival. Consistent with this, we found that engagement of CD1d by 2 different anti-CD1d mAbs and as compared to isotypic IgG or media control, induces cell death (i.e., Annexin+) of the CD1d-expressing B lymphoblastoid cell line C1R-CD1d, of myeloma cell lines with retrovirally restored expression of CD1d and purified, CD1d-expressing primary myeloma cells in a dose- and time-dependent manner, coincident with loss of mitochondrial membrane potential (MMP) as assessed by DioC3 staining. Biochemical analysis of relevant cell death pathways showed that MMP loss is associated with overexpression of the pro-apoptotic protein Bax but as demonstrated by immunoblotting and pharmacological inhibition it is caspase- independent. By introducing appropriate CD1d retroviral constructs into CD1d- myeloma cell lines we showed that anti-CD1d-induced cell death requires the cytoplasmic tail but not a Tyr residue critical for lysosomal sorting of CD1d. Finally, we found that anti-CD1d co-operates with anti-myeloma agents in the killing of myeloma cells. Thus, these findings provide evidence linking a novel function of CD1d in the regulation of cell death with tumour survival and progression and might have pathogenetic and therapeutic implications for other CD1d-expressing hematopoietic malignancies as well as myeloma.

Toll-Like Receptor Activation Promotes Multiple Myeloma Cell Growth and Survival By Suppression Of Endoplasmic Reticulum Stress Factor CHOP

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3112-3112 ◽  
Author(s):  
Tina Bagratuni ◽  
Efstathios Kastritis ◽  
Christine Liacos ◽  
Evangelos Eleutherakis-Papaiakovou ◽  
Nikolaos Kanellias ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Mrna Expression ◽  
Cell Lines ◽  
Plasma Cells ◽  
Myeloma Cell ◽  
Mrna Levels ◽  
Myeloma Cells ◽  
Growth And Survival ◽  
Pre Treatment

Abstract Multiple Myeloma (MM) patients are vulnerable to infections, which remain a major cause of death, including early death. During infection, human immune cells sense the presence of invading pathogens through the toll-like receptor family (TLR) of receptors. TLRs detect microbes to activate transcriptional programs that orchestrate adaptive responses to specific insults. This means that they induce the endoplasmic reticulum (ER) unfolded protein response (UPR) to accommodate essential protein translation. If the UPR fails to resolve the protein-folding defect, due to severe and prolonged ER stress, apoptosis is activated. However, the timing sequence of the prolonged ER stress has probably implications for ER stress-induced apoptosis that might help cells to adapt under these conditions rather than driving them to apoptosis. Studies have shown that prolonged ER stress occurs in response to microbes and specifically when cells are exposed to lipopolysaccharide (LPS), a TLR4 activator. The prolonged stress, possibly arising from a massive increase in protein synthesis, has shown to suppress CHOP, an apoptosis biomarker, in ER-stressed macrophages, while low levels of CHOP expression promotes B cell survival. Expression and function of TLRs in MM has recently become the focus of several studies and although the regulatory role of TLRs in MM plasma cells has been reported, the underlying molecular mechanisms remain unclear. It has been shown that human myeloma cell lines (HMCL) and primary myeloma cells express high levels of TLRs and specifically of TLR-4 and TLR-9. The aim of our study was to investigate TLR4 signaling in myeloma cells and to explore possible implications with endoplasmic reticulum unfolded protein response as a potential mechanism of drug resistance. We initially investigated whether TLR-4 is expressed in human myeloma cell lines and primary myeloma cells and we found that TLR-4 mRNA is expressed at increased levels (2-10 fold) both in HMCLs and primary cells. To test the hypothesis that TLR-4 signaling may suppress CHOP expression during sustained UPR response, two myeloma cell lines, H929 and U266, were pre-treated with low dose LPS (1 ng/mL) and then subjected to ER stress conditions by treatment with tunicamycin (TM). LPS pre-treatment significantly decreased CHOP mRNA expression after 24 hours. Despite the marked suppression of CHOP, LPS pre-treatment of these myeloma cell lines did not suppress ATF4 mRNA levels which also were not altered by TM treatment. LPS pre-treatment did not also suppress XBP-1 splicing compared to the control ER-stressed cells. To test the specificity of these effects, the same set of experiments where performed on other cancer tissues such as ovarian cancer cell lines. Interestingly, although LPS pre-treatment increased TLR-4 mRNA expression in SKOV3 ovarian cancer cell line, CHOP mRNA levels remained intact prior and after treatment while TM treatment did not make any difference in CHOP mRNA expression. These results suggest the relevance of exploring this pathway in tissues such as plasma cells which are highly dependent on the UPR as a repair mechanism. Pre-treated LPS and TM samples of HMCLs were also subjected to Annexin-PI staining to determine the amount of apoptosis. As expected, pre-treated LPS myeloma cells which were exposed to TM had 30% lower Annexin-FITC stained cells compared to the TM-stressed cells only. These data suggest that blockage of CHOP by TLR4 ligands may promote the growth and survival of MM cells. We then examined the impact of therapy with bortezomib on TLR4 and CHOP mRNA expression in primary tumors cells which were collected before and at day 7 after bortezomib-based therapy from 6 myeloma patients. In 5 out of 6 cases TLR-4 expression was significantly up-regulated and was accompanied with a coupled down-regulation of CHOP mRNA expression. In conclusion, our data suggest that the TLR-4 signaling pathway might provide a translational control pathway which enables cells to carry out essential protein synthesis and avoid CHOP-induced apoptosis. Further exploration of this pathway is needed to establish its role as a potential mechanism of drug resistance. Disclosures: No relevant conflicts of interest to declare.

scholarly journals An inhibitor of the EGF receptor family blocks myeloma cell growth factor activity of HB-EGF and potentiates dexamethasone or anti–IL-6 antibody-induced apoptosis

Blood ◽  
2004 ◽  
Vol 103 (5) ◽  
pp. 1829-1837 ◽  
Author(s):  
Karène Mahtouk ◽  
Michel Jourdan ◽  
John De Vos ◽  
Catherine Hertogh ◽  
Geneviève Fiol ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Growth Factor ◽  
Cell Growth ◽  
Cell Lines ◽  
Stromal Cells ◽  
Egf Receptor ◽  
Myeloma Cell ◽  
Factor Activity ◽  
Myeloma Cells ◽  
Induced Apoptosis

Abstract We previously found that some myeloma cell lines express the heparin-binding epidermal growth factor–like growth factor (HB-EGF) gene. As the proteoglycan syndecan-1 is an HB-EGF coreceptor as well as a hallmark of plasma cell differentiation and a marker of myeloma cells, we studied the role of HB-EGF on myeloma cell growth. The HB-EGF gene was expressed by bone marrow mononuclear cells in 8 of 8 patients with myeloma, particularly by monocytes and stromal cells, but not by purified primary myeloma cells. Six of 9 myeloma cell lines and 9 of 9 purified primary myeloma cells expressed ErbB1 or ErbB4 genes coding for HB-EGF receptor. In the presence of a low interleukin-6 (IL-6) concentration, HB-EGF stimulated the proliferation of the 6 ErbB1+ or ErbB4+ cell lines, through the phosphatidylinositol 3-kinase/AKT (PI-3K/AKT) pathway. A pan-ErbB inhibitor blocked the myeloma cell growth factor activity and the signaling induced by HB-EGF. This inhibitor induced apoptosis of patients'myeloma cells cultured with their tumor environment. It also increased patients' myeloma cell apoptosis induced by an anti–IL-6 antibody or dexamethasone. The ErbB inhibitor had no effect on the interaction between multiple myeloma cells and stromal cells. It was not toxic for nonmyeloma cells present in patients' bone marrow cultures or for the growth of hematopoietic progenitors. Altogether, these data identify ErbB receptors as putative therapeutic targets in multiple myeloma.

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