Pre-Clinical Validation of Polo-Like Kinase 1 as a Therapeutic Target in Multiple Myeloma with the Selective Inhibitor BI2536.

Abstract BACKGROUND: The centrosome is the cellular organelle that nucleates the mitotic spindle. Polo-like kinase 1 (Plk1), a centrosome-associated serine/threonine kinase, serves as a key regulator of multiple steps in mitosis. Plk1 is overexpressed in a broad spectrum of tumor types, and its expression often correlates with poor patient prognosis. We have previously observed centrosome amplification in myeloma, and have validated other components of the myeloma centrosome and mitotic apparatus as therapeutic targets. The present study explored the expression of Plk1 in myeloma and the effect of BI2536, a potent and selective inhibitor of Plk1, on myeloma cells in the pre-clinical setting. METHODS: Plk1 expression was assayed in a panel of myeloma cell lines (MMCL) and AutoMACS-purified CD138+ patient bone marrow plasma cells (BMPC). The anti-myeloma effects of BI2536, alone or in combination with conventional agents, were assayed on myeloma cells with proliferation (MTS) and apoptosis (Annexin V/propidium iodide) assays. The phenotype of treated cells was examined with DNA content analysis and immunofluorescence microscopy. The efficacy of BI2536 monotherapy was evaluated in NOD/SCID mice bearing RPMI8226 xenografts. RESULTS: Plk1 is ubiquitously expressed in myeloma to varying degrees in both MMCL and BMPC. BI2536 inhibited the proliferation of MMCL (RPMI 8226, U266, LP-1 and KMS-11) and patient BMPC at nanomolar concentrations. The addition of BI2536 was able to overcome resistance to dexamethasone. Bortezomib in combination with BI2536 had significantly increased anti-myeloma effects compared to the use of either agent alone. BI2536-treated MMCL accumulated 4N DNA content prior to undergoing apoptosis. The phenotype of BI2536-treated cells is consistent with inhibition of Plk1, showing prometaphase arrest and monopolar mitotic spindles in a dose-dependent fashion. BI2536 induces regression of human myeloma xenografts in NOD/SCID mice. Taken together, BI2536 is a promising new agent for the treatment of multiple myeloma. This work provides further evidence that Plk1 and the amplified myeloma centrosome are targets for therapy.

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Ruxolitinib Regulates the Autophagy Machinery in Multiple Myeloma Cells

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520620666200218105159 ◽

2020 ◽

Vol 20 (18) ◽

pp. 2316-2323 ◽

Cited By ~ 3

Author(s):

Alican Kusoglu ◽

Bakiye G. Bagca ◽

Neslihan P.O. Ay ◽

Guray Saydam ◽

Cigir B. Avci

Keyword(s):

Multiple Myeloma ◽

Cell Line ◽

B Lymphocyte ◽

Plasma Cells ◽

Annexin V ◽

Myeloma Cell ◽

Control Group ◽

Multiple Myeloma Cell ◽

Ic50 Values ◽

Stat Pathway

Background: Ruxolitinib is a selective JAK1/2 inhibitor approved by the FDA for myelofibrosis in 2014 and nowadays, comprehensive investigations on the potential of the agent as a targeted therapy for haematological malignancies are on the rise. In multiple myeloma which is a cancer of plasma cells, the Interleukin- 6/JAK/STAT pathway is emerging as a therapeutic target since the overactivation of the pathway is associated with poor prognosis. Objective: In this study, our purpose was to discover the potential anticancer effects of ruxolitinib in ARH-77 multiple myeloma cell line compared to NCI-BL 2171 human healthy B lymphocyte cell line. Methods: Cytotoxic effects of ruxolitinib in ARH-77 and NCI-BL 2171 cells were determined via WST-1 assay. The autophagy mechanism induced by ruxolitinib measured by detecting autophagosome formation was investigated. Apoptotic effects of ruxolitinib were analyzed with Annexin V-FITC Detection Kit and flow cytometry. We performed RT-qPCR to demonstrate the expression changes of the genes in the IL-6/JAK/STAT pathway in ARH-77 and NCI-BL 2171 cells treated with ruxolitinib. Results: We identified the IC50 values of ruxolitinib for ARH-77 and NCI-BL 2171 as 20.03 and 33.9μM at the 72nd hour, respectively. We showed that ruxolitinib induced autophagosome accumulation by 3.45 and 1.70 folds in ARH-77 and NCI-BL 2171 cells compared to the control group, respectively. Treatment with ruxolitinib decreased the expressions of IL-6, IL-18, JAK2, TYK2, and AKT genes, which play significant roles in MM pathogenesis. Conclusion: All in all, ruxolitinib is a promising agent for the regulation of the IL-6/JAK/STAT pathway and interferes with the autophagy mechanism in MM.

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Targeting the methyltransferase SETD8 impairs tumor cell survival and overcomes drug resistance independently of p53 status in multiple myeloma

Clinical Epigenetics ◽

10.1186/s13148-021-01160-z ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Laurie Herviou ◽

Sara Ovejero ◽

Fanny Izard ◽

Ouissem Karmous-Gadacha ◽

Claire Gourzones ◽

...

Keyword(s):

Multiple Myeloma ◽

Plasma Cells ◽

Myeloma Cell ◽

Histone H4 ◽

Myeloma Cells ◽

Functional Studies ◽

Replicative Stress ◽

Poor Outcome ◽

Subsequent Decrease ◽

Lysine Methyltransferase

Abstract Background Multiple myeloma (MM) is a malignancy of plasma cells that largely remains incurable. The search for new therapeutic targets is therefore essential. In addition to a wide panel of genetic mutations, epigenetic alterations also appear as important players in the development of this cancer, thereby offering the possibility to reveal novel approaches and targets for effective therapeutic intervention. Results Here, we show that a higher expression of the lysine methyltransferase SETD8, which is responsible for the mono-methylation of histone H4 at lysine 20, is an adverse prognosis factor associated with a poor outcome in two cohorts of newly diagnosed patients. Primary malignant plasma cells are particularly addicted to the activity of this epigenetic enzyme. Indeed, the inhibition of SETD8 by the chemical compound UNC-0379 and the subsequent decrease in histone H4 methylation at lysine 20 are highly toxic in MM cells compared to normal cells from the bone marrow microenvironment. At the molecular level, RNA sequencing and functional studies revealed that SETD8 inhibition induces a mature non-proliferating plasma cell signature and, as observed in other cancers, triggers an activation of the tumor suppressor p53, which together cause an impairment of myeloma cell proliferation and survival. However, a deadly level of replicative stress was also observed in p53-deficient myeloma cells treated with UNC-0379, indicating that the cytotoxicity associated with SETD8 inhibition is not necessarily dependent on p53 activation. Consistent with this, UNC-0379 triggers a p53-independent nucleolar stress characterized by nucleolin delocalization and reduction of nucleolar RNA synthesis. Finally, we showed that SETD8 inhibition is strongly synergistic with melphalan and may overcome resistance to this alkylating agent widely used in MM treatment. Conclusions Altogether, our data indicate that the up-regulation of the epigenetic enzyme SETD8 is associated with a poor outcome and the deregulation of major signaling pathways in MM. Moreover, we provide evidences that myeloma cells are dependent on SETD8 activity and its pharmacological inhibition synergizes with melphalan, which could be beneficial to improve MM treatment in high-risk patients whatever their status for p53.

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

Blood ◽

10.1182/blood.v95.2.610 ◽

2000 ◽

Vol 95 (2) ◽

pp. 610-618 ◽

Cited By ~ 87

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.

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Amphiregulin Is Produced by Myeloma Cells and Is Involved in Tumor-Environment Interactions in Multiple Myeloma.

Blood ◽

10.1182/blood.v104.11.4306.4306 ◽

2004 ◽

Vol 104 (11) ◽

pp. 4306-4306

Author(s):

Karène Mahtouk ◽

Dirk Hose ◽

Thierry Reme ◽

John De Vos ◽

Michel Jourdan ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Growth Factors ◽

Plasma Cells ◽

Myeloma Cell ◽

Erbb Receptors ◽

Heparin Binding ◽

Myeloma Cells ◽

Heparin Binding Growth Factors ◽

Egf Family

Abstract Multiple myeloma (MM) is characterized by the accumulation of clonal malignant plasma cells in the bone marrow. One of the hallmarks of plasma cells is the expression of the heparan-sulfate proteoglycan syndecan-1. In epithelial cells, syndecan-1 plays a major role as a coreceptor for heparin-binding growth factors and chemokines. This stresses that heparin-binding growth factors may play a major role in the biology of MM cells. Recently we have demonstrated that heparin-binding EGF-like growth factor (HB-EGF), one of the ten members of the Epidermal Growth Factor (EGF) family, is produced by the tumor microenvironment and is able to trigger myeloma cell growth. As amphiregulin (AREG) is another member of the EGF family that also binds heparan-sulphate chains, we investigated its role in MM. We looked for AREG expression on a panel of 7 normal plasmablastic cells (PPCs), 7 normal bone marrow plasma cells (BMPCs), purified MM cells from 65 patients and 20 myeloma cell lines (HMCLs), with Affymetrix U133A+B microarrays. We showed that primary MM cells overexpress AREG compared to normal BMPCs and PPCs. We then investigated the expression of the ErbB receptors with real-time RT-PCR. Myeloma cells variably expressed the 4 ErbB receptors. Normal BMPCs also expressed ErbB1 and ErbB2 unlike PPCs that did not express any ErbB receptors. We demonstrated that the high AREG expression by primary myeloma cells may have a dual effect. On the one hand, AREG stimulated IL-6 production and growth of bone-marrow stromal cells that highly express the AREG ErbB1 receptor. On the other hand, AREG could promote HMCL proliferation, suggesting that a functional autocrine loop involving AREG and ErbB receptors is involved in MM cell growth. Finally, we looked for the effect of ErbB inhibitors on MM cells of 14 patients cultured for 6 days together with their bone marrow environment. A pan-ErbB inhibitor (PD-169540, Pfizer) and an ErbB1-inhibitor (IRESSA, Astrazeneca) induced strong MM cell apoptosis in respectively 71% of patients (10 of 14) and 29% of patients (4 of 14). Of major interest, when PD169540 or IRESSA were combined with dexamethasone, they induced a dramatic myeloma cell death (respectively 92% and 69% inhibition of MM cell survival), while non-myeloma cells were unaffected. Thus ErbB activation is critical to trigger MM-cell survival in short-term culture. In conclusion, our findings provide evidence for a major role of AREG and HB-EGF in the biology of multiple myeloma and identify ErbB receptors as putative therapeutic targets. These data emphasize the interest of clinical evaluation of specific-ErbB-inhibitors in patients with MM, either used alone or in combination with dexamethasone.

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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 ◽

10.1182/blood.v116.21.1915.1915 ◽

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.

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Targeting EZH2 in Multiple Myeloma Could be Promising for a Subgroup of MM Patients in Combination with IMiDs

Blood ◽

10.1182/blood.v128.22.311.311 ◽

2016 ◽

Vol 128 (22) ◽

pp. 311-311 ◽

Cited By ~ 4

Author(s):

Laurie Herviou ◽

Alboukadel Kassambara ◽

Stephanie Boireau ◽

Nicolas Robert ◽

Guilhem Requirand ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Board Of Directors ◽

Research Funding ◽

Plasma Cells ◽

Newly Diagnosed ◽

Advisory Committees ◽

Myeloma Cells ◽

Ezh2 Expression ◽

Bone Marrow Plasma

Abstract Multiple Myeloma is a B cell neoplasia characterized by the accumulation of clonal plasma cells within the bone marrow.Epigenetics is characterized by a wide range of changes that are reversible and orchestrate gene expression. Recent studies have shown that epigenetic modifications play a role in multiple myeloma (MM) by silencing various cancer-related genes. We investigated the epigenetic genes differentially expressed between normal bone marrow plasma cells (BMPC ; N=5) and MM plasma cells from patients (N=206). Using SAM (Significance Analysis of Microarrays) analysis, only 12 genes significantly differentially expressed between BMPC and MM cells (ratio > 2 and FDR (false discovery rate) < 5%) were identified, including the EZH2 histone methyltransferase. EZH2, the enzymatic subunit of Polycomb Repressive Complex 2, is a histone methyltransferases able to repress gene expression by catalyzing H3K27me3 histone mark. EZH2 overexpression has been associated with numerous hematological malignancies, including MM. We thus studied EZH2 role in MM physiopathology and drug resistance. EZH2 expression was analyzed in normal bone marrow plasma cells (BMPCs; N=5), primary myeloma cells from newly diagnosed patients (MMCs; N=206) and human myeloma cell lines (HMCLs; N=40) using Affymetrix microarrays. EZH2 gene is significantly overexpressed in MMCs of patients (median 574, range 105 - 4562) compared to normal BMPCs (median = 432; range: 314 - 563) (P < 0.01). The expression is even higher in HMCLs (median 4481, range 581 - 8455) compared to primary MMCs or BMPCs (P < 0.001). High EZH2 expression is associated with a poor prognosis in 3 independent cohorts of newly diagnosed patients (Heidelberg-Montpellier cohort - N=206, UAMS-TT2 cohort - N=345 and UAMS-TT3 cohort - N =158). Furthermore, GSEA analysis of patients with high EZH2 expression highlighted a significant enrichment of genes involved in cell cycle, downregulated in mature plasma cells vs plasmablasts, and EZH2 targets. Specific EZH2 inhibition by EPZ-6438 EZH2 inhibitor induced a significant decrease of global H3K27me3 in all the HMCLs tested (P < 0.01) and inhibited MM cell growth in 5 out of the 6 HMCLs tested. The inhibitory effect of EZH2 inhibitor on MM cell growth appeared at day 6 suggesting that it is mediated by epigenetic reprogramming. To confirm that EZH2 is also required for the survival of primary MMCs from patients, primary MM cells (n = 17 patients) co-cultured with their bone marrow microenvironment and recombinant IL-6 were treated with EPZ-6438. As identified in HMCLs, EZH2 inhibition significantly reduced the median number of viable myeloma cells by 35% (P = 0.004) from a subset of patients (n=9) while the other group (n=8) was resistant. Of interest, EPZ-6438 induced a significant global H3K27me3 decrease in both groups of patient. RNA sequencing of 6 HMCLs treated with EPZ-6438 combined with H3K27me3 ChIP analyses allowed us to create an EZ GEP-based score able to predict HMCLs and primary MM cells sensitivity to EZH2 inhibitors. We also observed a synergy between EPZ-6438 and Lenalidomide, a conventional drug used for MM treatment. More interestingly, pretreatment of myeloma cells with EPZ-6438 significantly re-sensitize drug-resistant MM cells to Lenalidomide. Investigating the effect of EPZ-6438/Lenalidomide combination in MMC, we identified that IKZF1, IRF4 and MYC protein levels were significantly more inhibited by the combination treatment (65.5%, 63.9% and 14.8% respectively) compared with Lenalidomide (51.5%, 43% and 2.2%) or EPZ-6438 (45.2%, 38.7% and 6.2%) alone. Clinical trials are ongoing with EZH2 inhibitors in lymphoma and could be promising for a subgroup of MM patients in combination with IMiDs. Furthermore, the EZ score enables identification of MM patients with an adverse prognosis and who could benefit from treatment with EZH2 inhibitors. Disclosures Goldschmidt: Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Chugai: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Hose:EngMab: Research Funding; Takeda: Other: Travel grant; Sanofi: Research Funding.

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A gp130 Interleukin-6 Transducer-Dependent SCID Model of Human Multiple Myeloma

Blood ◽

10.1182/blood.v91.12.4727.412k35_4727_4737 ◽

1998 ◽

Vol 91 (12) ◽

pp. 4727-4737 ◽

Cited By ~ 1

Author(s):

Cosette Rebouissou ◽

John Wijdenes ◽

Patrick Autissier ◽

Karin Tarte ◽

Valerie Costes ◽

...

Keyword(s):

Multiple Myeloma ◽

Interleukin 6 ◽

Myeloma Cell ◽

Scid Mice ◽

Term Survival ◽

Myeloma Cells ◽

Tumoral Cells ◽

Human Myeloma Cells

Agonist antihuman gp130 transducer monoclonal antibodies (MoAbs) were used in SCID mice to grow myeloma cells whose survival and proliferation is dependent on gp130 transducer activation. The agonist anti-gp130 MoAbs neither bound to murine gp130 nor activated murine cells and, as a consequence, did not induce interleukin-6 (IL-6)–related toxicities in mice. They have a 2-week half-life in vivo when injected in the peritoneum. The agonist antibodies made possible the in vivo growth of exogenous IL-6–dependent human myeloma cells as well as that of freshly explanted myeloma cells from 1 patient with secondary plasma cell leukemia. Tumors occurred 4 to 10 weeks after myeloma cell graft and weighed 3 to 5 g. They grew as solid tumors in the peritoneal cavity and metastasized to the different peritoneal organs: liver, pancreas, spleen, and intestine. Tumoral cells were detected in blood and bone marrow of mice grafted with the XG-2 myeloma cells. Tumoral cells grown in SCID mice had kept the phenotypic characteristics of the original tumoral cells and their in vitro growth required the presence of IL-6 or agonist anti-gp130 MoAbs. Myeloma cells from 4 patients with medullary involvement persisted for more than 1 year as judged by detectable circulating human Ig. However, no tumors were detected, suggesting a long-term survival of human myeloma cells without major proliferation. These observations paralleled those made in in vitro cultures as well as the tumor growth pattern in these patients. This gp130 transducer-dependent SCID model of multiple myeloma should be useful to study various therapeutical approaches in multiple myeloma in vivo.

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A Role for Syntenin-1 in Multiple Myeloma Cell Survival

Blood ◽

10.1182/blood-2018-99-113594 ◽

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.

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Mcl-1 Is Overexpressed in Multiple Myeloma and Correlates with Disease Severity.

Blood ◽

10.1182/blood.v104.11.1419.1419 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1419-1419

Author(s):

Soraya Wuilleme-Toumi ◽

Nelly Robillard ◽

Patricia Gomez-Bougie ◽

Philippe Moreau ◽

Steven Le Gouill ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Disease Severity ◽

Cell Lines ◽

Plasma Cells ◽

Myeloma Cell ◽

Lymphocytic Leukemia ◽

Myeloma Cells

Abstract Multiple Myeloma (MM) is a fatal malignancy of B-cell origin characterized by the accumulation of plasma cells within the bone marrow. The expression of the pro-survival members of the Bcl-2 family has been shown to be a key process in the survival of myeloma cells. More particularly, Mcl-1 expression turned out to be critical for their survival. Indeed, knockdown of Mcl-1 by antisenses induces apoptosis in myeloma cells. Finally, Mcl-1 was found to be the only anti-apoptotic Bcl-2 family member which level of expression was modified by cytokine treatment of myeloma cells. For these reasons, we have evaluated the expression of Mcl-1 in vivo in normal, reactive and malignant plasma cells (PC) i.e., myeloma cells from 55 patients with MM and 20 human myeloma cell lines using flow cytometry. We show that Mcl-1 is overexpressed in MM in comparison with normal bone marrow PC. Forty-seven percent of patients with MM at diagnosis (p=.017) and 80% at relapse (p=.014 for comparison with diagnosis) overexpress Mcl-1. Of note, only myeloma cell lines but not reactive plasmocytoses have abnormal Mcl-1 expression, although both plasmocyte expansion entities share similar high proliferation rates (>20%). Of interest, Bcl-2 as opposed to Mcl-1, does not discriminate malignant from normal PC. This shows that the overexpression of Mcl-1 is clearly related to malignancy rather than to proliferation. It will be important to know whether the overexpression of Mcl-1 is related to an abnormal response to cytokines like Interleukin-6 or to mutations of the promoter of the Mcl-1 gene as already described in B chronic lymphocytic leukemia. Finally, level of Mcl-1 expression is related to disease severity, the highest values being correlated with the shortest event-free survival (p=.01). In conclusion, Mcl-1 which has been shown to be essential for the survival of human myeloma cells in vitro is overexpressed in vivo in MM and correlates with disease severity. Mcl-1 represents a major therapeutical target in MM.

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Lovastatin and Thalidomide Have an Synergic Effect on the Rate of Multiple Myeloma Cell Apoptosis in Short Term Cell Cultures.

Blood ◽

10.1182/blood.v106.11.5121.5121 ◽

2005 ◽

Vol 106 (11) ◽

pp. 5121-5121

Author(s):

Monika Podhorecka ◽

Piotr Klimek ◽

Norbert Grzasko ◽

Anna Dmoszynska

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Cell Cultures ◽

Plasma Cells ◽

Annexin V ◽

Myeloma Cell ◽

Synergic Effect ◽

Treatment Resistant ◽

Short Term ◽

Multiple Myeloma Cell

Abstract Multiple myeloma is characterized by an accumulation of plasma cells in the bone marrow. Despite many therapeutic regimens introduced recently, the prognosis for patients suffering from treatment-resistant or relapsing multiple myeloma is still very poor. Thus, there is an urgent medical need for novel innovative drugs. Thalidomide is successfully used in myeloma patients being reported to induce apoptosis or G1 growth arrest of plasma cells, regulate microvessel density and cytokine secretion. Statins, largely used for the treatment of hypercholesterolemia, seem to be promising drug in multiple myeloma also. High dose of lovastatin has been shown to have antiproliferative effect by inhibition of malignant cell proliferation and inducing programmed cell death. The aim of this study was the assessment of multiple myeloma cells apoptosis induced by mixture of lovastatin and thalidomide in short-term cell cultures. We analyzed plasmocytes of bone marrow samples obtained from 10 patients with treatment-resistant or relapsing multiple myeloma. To assess apoptosis we used Annexin V and propidium iodide binding. We also examined the regulation of BCL-2 and BAX protein expression in the population of CD138+ plasmocytes. The cells were analyzed with use of flow cytometry technique. The experiments were done before and after 72 hours of cell culture. We observed an increase of apoptotic cell number in all cultures supplemented with analyzed drugs in comparison to 0 h culture and to 72 h control. The percentage of Annexin V positive cells in culture with lovastatin and thalidomide mixture was significantly higher in comparison to culture with lovastatin or thalidomide alone (the mean percentages were 33.40 versus 27.04 and 26.49, respectively, p<0.05). The BCL-2/BAX ratio was lower in cell cultures supplemented with mixture of lovastatin and thalidomide (mean ratio 0.95) in comparison to cultures supplemented with lovastatin or thalidomide alone (mean ratio 1.25 and 1.17, p=0.06 and 0.05, respectively) indicating the tendency to apoptosis induction in analyzed cells. Basing on these results we can conclude that lovastatin and thalidomide may have an synergic effect on the rate of multiple myeloma cell apoptosis and may act together on BCL-2 and BAX regulation. Thus, further research should establish both the precise mechanism of this synergic action of statins and thalidomide and the new therapeutic option for myeloma patients.

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