Sphingolipids as a novel target for the treatment of multiple myeloma.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e19534-e19534
Author(s):  
Yubin Kang ◽  
Jagadish Kummetha Venketa
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Line ◽  
Cell Lines ◽  
Apoptotic Cell ◽  
Myeloma Cell ◽  
Sphingolipid Metabolism ◽  
Myeloma Cell Line ◽  
Myeloma Cells ◽  
Novel Target

e19534 Background: Multiple myeloma (MM) is the second most common hematological malignancy in the United States and accounts for ~10,600 deaths annually. MM remains an incurable disease and almost all patients will eventually relapse and become refractory to currently available therapeutic agents. There is an unmet need for better understanding the disease’s molecular pathways and for identifying novel therapeutic targets. Sphingolipid metabolism is being increasingly recognized as a key pathway in tumor cell proliferation and in tumor sensitivity to anticancer drugs. We hypothesize that altered sphingolipid metabolism plays an important role in the pathogenesis of MM, thus providing a novel target in the treatment of MM. Methods: We first assayed sphingolipid metabolism including sphingolipid metabolites and sphingolipid metabolizing genes in myeloma cell lines, in freshly isolated human primary CD138+myeloma cells, and in publically available dataset. We then tested the efficacy of the selective SK2 inhibitor (ABC294640) and the SK2 shRNA in killing myeloma cells in vitro. Results: 1) Compared to immortalized B cells, the levels of pro-apoptotic ceramides were decreased whereas the proliferative sphingosine 1-phosphate (S1P) was increased in myeloma cell lines. 2) The expression of several key sphingolipid-metabolizing genes including sphingosine kinase (SK) 1 and 2 was altered in freshly isolated human primary bone marrow myeloma cells and in publically available microarray dataset. 3) The selective SK2 inhibitor (ABC294640) induces apoptotic cell death and inhibits myeloma cell growth with an IC50of ~20 μM in 9 myeloma cell lines. 4) Interestingly, OPM-1 myeloma cell line was extremely sensitive to ABC294640 with an IC50of <5 µM whereas U266 myeloma cell line was resistant to ABC294640. SK2 shRNA induced apoptotic cell death in OPM-1, but not in U266 cells. We are currently investigating the molecular mechanisms underlying the resistance of U266 myeloma cells to ABC294640. Conclusions: Our data demonstrated that sphingolipid metabolism provides an attractive target in the treatment of refractory/relapased multiple myeloma.

Sphingolipids As a Novel Target For The Treatment Of Multiple Myeloma

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3163-3163 ◽  
Author(s):  
Jagadish Kummetha Venkata ◽  
Robert K Stuart ◽  
Luciano J Costa ◽  
Ningfei An ◽  
Houjian Cai ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Growth ◽  
Cell Lines ◽  
Stromal Cells ◽  
Myeloma Cell ◽  
Sphingolipid Metabolism ◽  
Myeloma Cells ◽  
S1p Receptors

Abstract Introduction Multiple Myeloma (MM) is the second most common hematological malignancy in the United States and accounts for ∼10,600 deaths annually. MM remains an incurable disease and almost all patients will eventually relapse and become refractory to currently available therapeutic agents. There is an unmet need for better understanding of the disease’s molecular pathways and identifying novel therapeutic targets. Sphingolipid metabolism is being increasingly recognized as a key pathway in cancer biology. In particular, sphingosine kinases (SK1 and SK2) provide a potential site for manipulation of the ceramide / sphingosine 1-phosphate (S1P) rheostat that regulates the balance between tumor cell proliferation and apoptosis, as well as tumor sensitivity to drugs. Currently, very little is known about sphingolipid metabolism in MM. We herein for the first time provide a detailed analysis of sphingolipid metabolism in MM and demonstrate the potential of targeting SK2 for the treatment of MM. Methods We first quantified sphingolipid metabolites and sphingolipid metabolizing genes in myeloma cell lines, in freshly isolated human primary CD138+ myeloma cells, and in a publically available gene expression dataset from MM patients. We then tested the anti-myeloma activity of SK2-specific shRNA and determined the efficacy of a selective SK2 inhibitor (ABC294640) in killing myeloma cell lines and primary human myeloma cells in vitro. The mechanistic pathway of apoptosis was analyzed by immunoblotting and flowcytometry. MM cell lines stably expressing luciferase and eGFP were generated for xenograft experiments and for in vitro co-cultures with stromal cells. Results From the publically available GSE6477 microarray data set, we found that one third of the genes involved in sphingolipid metabolism were significantly different in CD138+ MM cells from newly diagnosed MM patients compared to normal individuals, including SK2 and S1P receptors. In 5 MM cell lines compared to immortalized B cells (IBC), 19 key sphingolipid metabolites were measured, and we found that ceramides were significantly reduced whereas S1P was significantly increased. mRNA analyses of 11 sphingolipid metabolizing genes including S1P receptors in 7 MMs showed that SK1, SK2, and alkaline ceramidases were significantly increased compared to IBC. Furthermore, we isolated CD138+ myeloma cells from 21 MM patients and found that 13 of the patients had higher SK2 expression in CD138+ MM cells compared to CD138-cells. These data demonstrated abnormal sphingolipid metabolism and dys-regulated SK2 in myeloma cells. We generated SK2-specific shRNA and found that SK2 shRNA down-regulated SK2 mRNA, inhibited proliferation, and induced death in myeloma cells, suggesting that SK2 is important in myeloma cell survival. We then tested the efficacy of ABC294640 (the most-advanced, non-lipid SK2 inhibitor) in 6 MM cell lines. ABC294640 inhibited myeloma cell growth with an IC50s of ∼30 μM, including steroid-resistant and doxorubicin-resistant myeloma cells. ABC294640 inhibited MM cell growth as early as 6 hours after exposure and induced apoptotic cell death as demonstrated by Annexin V staining, PARP cleavage and caspase 9 activation. ABC294640 inhibited primary human CD138+MM cells with the same efficacy as with MM cell lines, demonstrating the potential of ABC294640 for the treatment of MM. Additionally, we found that blocking S1P receptors with FTY720 (a S1PR agonist with receptor degradation) induced apoptosis in MM cells. We performed extensive mechanistic and signaling pathway analyses and found that ABC294640 inhibited Mcl-1 and C-Myc expression, but had no effects on Bcl2. Furthermore, ABC294640 induced cell death by directing Mcl-1 to proteosomal degradation. MM is dependent on the bone marrow niche microenvironment for survival and progression. We found that ABC294640 was effective in inducing apoptosis in MM cells even in the presence of stromal cells. Finally, we are currently testing the in vivo effect of ABC294640 alone and in combination with bortezomib, thalidomide and dexamethasone in MM xenograft model transplanted with MM cells stably expressing luciferase. Our early preliminary results were encouraging. Conclusion Our data demonstrate that sphingolipid metabolism is abnormal and provides an attractive target in the treatment of refractory/relapsed MM. Disclosures: Costa: Otsuka: Research Funding.

Combination of Akt/PKB Inhibition (Perifosine) and Farnesyl Transferase Inhibition (Tipifarnib) Results in Increased Cell Death in Myeloma Cells Lines.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1568-1568 ◽  
Author(s):  
Rajni Sinha ◽  
Ebenezer David ◽  
Emily Zeilter ◽  
Claire Torre ◽  
Jonathan L. Kaufman ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Proliferation ◽  
Cell Death ◽  
Combination Therapy ◽  
Cell Line ◽  
Cell Lines ◽  
Single Agent ◽  
Myeloma Cell ◽  
Myeloma Cell Line

Abstract Introduction Multiple myeloma is a clonal plasma cell malignancy characterized by proliferation and accumulation of plasma cells in the bone marrow. Most patients are incurable with the current treatment modalities. Clearly novel agents are needed to improve the outcome for patients with myeloma. We have previously shown that the combination of bortezomib and tipifarnib results in synergistic myeloma cell death. This increase in apoptosis is associated with down regulation of phosphorylated AKT, a potent anti-apoptotic signaling molecule. Therefore, agents that target AKT represent ideal compounds for further study in myeloma. Perifosine is a novel, oral bioavailable alkylphospholipid. Perifosine has displayed apoptotic and antipropliferative activity in vitro and in vivo in several human cancer models including leukemia. Perifosine exerts its actions by interfering with key intracellular pathways including AKT, MAPK, JNK, p21waf1. Our hypothesis is that targeting AKT via multiple upstream pathways will result in increased myeloma cell apoptosis. Therefore, we assessed the effects of single agent perifosine with and without tipifarnib on multiple myeloma cell lines. Method The myeloma cell line RPMI8226 was used. Cell viability and proliferation were assessed using MTT assays. Cells were incubated with increasing concentrations of both agents alone and in combination. Cell proliferation was assayed at 24, 48 and 72 hours. Western blots were then carried out to evaluate the effects of the intracellular protein PDK1, one of the critical signaling molecules that phosphorylates and activates AKT. Results As we and others have previously shown, tipifarnib at concentrations that can be achieved clinically is associated with minimal cytotoxicity. At 5 μM, tipifarnib decrease proliferation by only 20%. In contrast, there is a potent dose response effect of single agent perifosine (Fig. 1). These results were apparent as early as 24 hours. When tipifarnib at 5 μM is used in combination with a subtherapeutic dose of perifosine (2 μM), there is a marked decrease in cell proliferation (Fig. 2). In addition, combination therapy resulted in a reduction in the phosphorylated form of PDK1, a critical finding that was not seen with either drug alone. Conclusion Combination therapy with tipifarnib and perifosine results in less cell proliferation compared to either agent used alone in the RPMI8226 myeloma cell line. The dosages employed in these in-vitro studies are lower than those used in previously published data and are clinically achievable. Studies targeting other cell lines including MM.1R, MM.1S, and U266 are in progress. Analysis of AKT, Caspase 3, 8 and 9 are being explored to help delineate the mechanism of this novel combination. The goal is to develop further effective treatment options for patients with myeloma. Figure 1 Figure 1. Figure 2 Figure 2.

Perifosine Induces DR4/DR5 Expression Leading to Apoptosis That Can Be Enhanced with Exogenous TRAIL, and Blocked with Strategies Directed at DR4/DR5 Inhibition.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3446-3446 ◽  
Author(s):  
Ebenezer David ◽  
Rajni Sinha ◽  
Jonathan L. Kaufman ◽  
Sagar Lonial
Keyword(s):  
Multiple Myeloma ◽  
Flow Cytometry ◽  
Cell Death ◽  
Cell Line ◽  
Cell Lines ◽  
Myeloma Cell ◽  
Resistant Cell ◽  
Resistant Cell Line ◽  
Rt Pcr ◽  
Myeloma Cells

Abstract Background: Perifosine is an oral AKT inhibitor which exerts a marked cytotoxic effect on human tumor cell lines. It is currently being tested in several phase II trials for the treatment of major cancers including multiple myeloma. While the proposed mechanism of action relates to downregulation of AKT expression, overepxression of constitutively active AKT does not abrogate perifosine induced cell death suggesting alternative mechanisms. Hypothesis: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL, Apo2 ligand) effectively kills multiple myeloma cells in vitro after binding to their membrane specific receptors TRAIL-R1 (DR4) and TRAIL-R2 (DR5). It is our hypothesis that DR4/DR5 upregulation occurs in response to perifosine treatment, and thus may be additive with exogenous TRAIL. Materials and Methods: TRAIL-sensitive myeloma cell lines (MM.1S, RPMI8226, MM.1R) and TRAIL- resistant myeloma cell lines (U266) were used in this study. Apoptosis was assessed by annexin-V binding assay using flow-cytometry and cell death was assessed by MTT assay. Recombinant human TRAIL, chimeras of DR4 and DR5 were obtained from R&D systems. Results: Perifosine alone(5μM and 10μM) induced apoptosis of MM.1S in 40% and 50% of the treated cells as measured by flow cytometry, that increased to 81% and 91% when 50ng/ml of TRAIL was added to 5μM and 10 μM of perifosine. TRAIL alone induced only nominal apoptosis. Use of the TRAIL resistant U266 cell line showed only minimal apoptosis in response to perifosine, TRAIL, or the combination of both agents. Perifosine also induced DR4 and DR5 expression in less than 2hrs upon the Perifosine exposure in MM.1S as shown by RT-PCR. The combination of perifosine and TRAIL was not sequence specific. Furthermore, we observed that the enhanced apoptosis induced by perifosine and TRAIL in combination was almost or partially blocked by the administration of the DR4 and DR5 blocking antibodies only in the case of MM.1S, MM.1R, RPMI8226 TRAIL sensitive cells lines. Apoptosis was completely blocked in the case of U266 TRAIL resistant cell line when the chimera antibodies were used with perifosine alone or in combination with TRAIL. Conclusion and future directions: Perifosine, an agent proposed to function via inhibition of p-AKT and PDK-1, may have other effects on cell cycle regulation and it pro-apoptotic effects may be partially related to the TRAIL pathway. Our data suggests that an additional mechanism of action relates to the effect perifosine has on DR4 and DR5 expression thus directly effecting apoptosis via the TRAIL mediated effects. The limited response the trail resistant cell line U266 cells suggest that the TRAIL resistant myeloma cells have less DR4 or DR5 surface receptors as compared to the TRAIL sensitive cell lines, MM.1S, MM.1R, and RPMI8226 further validating this alternative mechanism. Further experiments such as inhibition of DR4, DR5, and FADD by small interfering RNAs, RT-PCR, the response in primary myeloma cells and also using more TRAIL resistant cell lines to support our preliminary observations are currently in progress.

Ruthenium(II)-arene complexes with dibenzoylmethane induce apoptotic cell death in multiple myeloma cell lines

2017 ◽  
Vol 454 ◽  
pp. 139-148 ◽  
Author(s):  
Riccardo Pettinari ◽  
Fabio Marchetti ◽  
Agnese Petrini ◽  
Claudio Pettinari ◽  
Giulio Lupidi ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Lines ◽  
Apoptotic Cell ◽  
Myeloma Cell ◽  
Apoptotic Cell Death ◽  
Arene Complexes ◽  
Multiple Myeloma Cell

Expression of TRAIL Receptors on the Multiple Myeloma Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4868-4868
Author(s):  
Juan Li ◽  
Junhe Li ◽  
Shaokai Luo ◽  
Yin Zhao
Keyword(s):  
Multiple Myeloma ◽  
Cell Line ◽  
Mononuclear Cells ◽  
Myeloma Cell ◽  
Myeloma Cell Line ◽  
Killing Effect ◽  
Myeloma Cells ◽  
Decoy Receptors ◽  
Trail Receptors ◽  
Chemotherapy Agents

Abstract Objective To study the different expression of death receptors and decoy receptors on mononuclear cells from patients with multiple myeloma and myeloma cell line KM3 and compare the different expression of TRAIL receptors after chemotherapy or exposure to doxorubicin, to explore the mechanisms by which TRAIL selectively kills tumor cells. Methods Semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometry was used to investigate the expression of four receptors on mononuclear cells in 23 multiple myeloma patients and myeloma cell line KM3 and 15 controls, we furthermore compared the changes of expression mode after chemotherapy and incubation of KM3 cell with sub-clinical concentration of Doxorubicin. Results There finds only DR4 and DR5 on KM3 cell line without the expression of DcR1 and DcR2. Expression of DR4 and DR5 on mononuclear cells of MM patients is higher than that of controls (P&lt;0.05), but DcR1 and DcR2 expression was lower than that of controls (P&lt;0.05), after chemotherapy and exposure to Doxorubicin, the expression of DR5 on MM cells was up-regulated (P&lt;0.05) Conclusions The expression of four receptors on myeloma cells and normal controls was significantly different, which might account for the selective killing effect of TRAIL on MM cells. DR5 was up-regulated on KM3 when incubating with Doxorubicin and after chemotherapy which suggests chemotherapy agents might enhance the apopotosis of MM cells through up-regulating of DR5 receptor.

Multiple Myeloma: Interleukin-15 Antagonizes Bone Morphogenetic Protein-Induced Apoptosis and Growth Inhibition.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3444-3444
Author(s):  
Magne Rekvig ◽  
Anne-Tove Brenne ◽  
Torstein Baade Ro ◽  
Anders Waage ◽  
Magne Borset ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Growth Inhibition ◽  
Cell Line ◽  
Caspase 3 ◽  
Myeloma Cell ◽  
Stimulus Figure ◽  
Myeloma Cell Line ◽  
Myeloma Cells ◽  
Induced Apoptosis

Abstract Multiple myeloma has two distinct features: Expansion of malignant plasma cells within the bone marrow accompanied by skeletal destruction. Bone morphogenetic proteins (BMPs) have been shown to induce apoptosis and inhibit growth in myeloma cells. BMPs are members of the TGF-β superfamily of proteins capable of inducing bone formation, and regulate proliferation, differentiation and apoptosis. We have investigated myeloma cell apoptosis and proliferation with BMP-4 and −6 in concert with the myeloma cell growth factors interleukin (IL)-2, IL-6, IL-10, IL-15, IL-21, tumor necrosis factor (TNF)-α and insulin-like growth factor (IGF)-1. Eight samples of highly purified myeloma cells from patients and a human myeloma cell line, IH-1 (Brenne AT et al. Blood. 2002 May 15;99(10):3756–62.), were used in this study. Cytokine concentrations used in the referred experiments were for BMP-4 20ng/ml, BMP-6 250ng/ml, IL-15 20ng/ml and IL-6 0,1ng/ml, respectively. Growth inhibition was measured in a proliferation assay by methyl-[3H]-thymidine incorporation and apoptosis by annexin V- FITC-binding/PI-uptake on flow cytometry. IL-15 antagonized growth inhibition (Figure A) and prevented apoptosis induced by BMP-4 (Figure B) and BMP-6 in the myeloma cell line IH-1. IL-15 also antagonized the growth inhibition induced by BMP-4 and/or BMP-6 in three out of eight patient samples. Neither IL-6, nor any of the other investigated cytokines were able to rescue the myeloma cells from growth inhibition and apoptosis induced by BMP-4 and -6. Among the investigated cytokines, we found that IL-15 has a unique capability to antagonize BMP- induced apoptosis and growth inhibition in myeloma cells. We examined cleavage of the proapoptotic protein caspase-3 and found that BMP-4 activated caspase-3 in the IH-1 cell line. This activation of caspase-3 was blocked by IL-15 but not by IL-6. We have demonstrated a possible mechanism for myeloma cells to escape apoptosis and growth-inhibition within the bone marrow. Intramedullar levels of IL-15 and BMPs may play a role in the pathogenesis of multiple myeloma. Figure A. Proliferation in response to BMP-4 stimulus Figure A. Proliferation in response to BMP-4 stimulus Figure B. Apoptosis in response to BMP-4 stimulus Figure B. Apoptosis in response to BMP-4 stimulus

MYC Responsible for down-Regulation of CD33 Expression in Human Myeloma Cells

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5116-5116
Author(s):  
Karim Shamsasenjan ◽  
Ken-ichiro Otsuyama ◽  
Mohd S. Iqbal ◽  
Maged S. Mahmoud ◽  
Michio M. Kawano
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Myeloma Cell ◽  
Myeloma Cell Line ◽  
Down Regulation ◽  
Myeloma Cells ◽  
Expression Levels ◽  
Stat3 Phosphorylation ◽  
Serum Crp ◽  
Human Myeloma Cells

Abstract Human myeloma cells from about 10% of cases with multiple myeloma expressed CD33 and have monocytoid morphology with convoluted nuclei, and all these patients had no increase in serum CRP values. In CD33(+) myeloma cells as well as myeloma cell lines, CD33 expression levels were correlated with the increased expression levels of CEBPA (C/EBPα) gene. This correlation was confirmed by the finding that transfection with the CEBPA gene induced CD33 expression in a CD33(−) myeloma cell line. As suggested by the lack of an increase in serum CRP values in CD33(+) myelomas, IL-6 down-regulated the expression of CD33 in CD33(+) myeloma cell lines along with the down-regulation of CEBPA gene expression. Cucurbitacin I (STAT3 inhibitor) but not U0126 (MAPK inhibitor) could abolish the effect of IL-6. Furthermore, IL-6 up-regulated the expression of MYC via STAT3 phosphorylation and MYC bound to the promoter region of CEBPA gene followed by the down-regulation of the CEBPA expression. It was confirmed that introduction of shRNA for MYC into a CD33(+) myeloma cell line blocked the IL6-induced down-regulation of CD33 and CEBPA expression. Therefore, these results indicate that IL-6 can reverse the expression level of CD33 by up-regulating MYC followed by the down-regulation of CEBPA expression.

Interfering with Arginine Metabolism As a New Treatment Strategy for Multiple Myeloma

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3005-3005
Author(s):  
Bjoern Jacobi ◽  
Lea Stroeher ◽  
Nadine Leuchtner ◽  
Hakim Echchannaoui ◽  
Alexander Desuki ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Death ◽  
Cell Lines ◽  
Caspase 3 ◽  
Xenograft Model ◽  
Myeloma Cell ◽  
Intracellular Protein ◽  
Myeloma Cells ◽  
Induction Of Apoptosis

Abstract Introduction Starvation of tumor cells from the amino acid arginine has recently gained particular interest because of the downregulation of the rate-limiting enzyme argininosuccinate synthethase 1 (ASS1) in various cancer entities. ASS1-deficient cells cannot resynthesize arginine from citrulline and are therefore considered arginine auxotrophic. The arginine depleting enzyme arginine deiminase (ADI-PEG20, Polaris Pharmaceuticals) is currently tested in phase I-III clinical trials for different arginine auxotrophic cancers. The natural arginine analogue canavanine can compete with arginine for arginyl-tRNA-binding sites and consequently be incorporated into nascent proteins instead of arginine. Canavanine could therefore potentially further disturb intracellular protein homeostasis, especially under arginine deprivation. The sensitivity of myeloma cells towards arginine depletion strategies has not been analyzed so far. Methods Human myeloma cell lines and CD138-sorted primary human myeloma cells from patient bone marrow were screened for ASS1 expression by western blotting (WB). The cells were cultured in arginine free medium and assessed for proliferation and metabolic activity (CFSE/MTT assays), apoptosis (caspase-3 cleavage) and cell death (annexinV/propidium iodide). Canavanine was supplied in both arginine-sufficient and -deficient conditions. The level of intracellular protein stress was determined by WB and/or flow cytometry analysis for ubiquitinated proteins, phosphorylated eukaryotic initiation factor 2α (peIF2α) and the spliced isoform of the X-Box binding protein 1 (Xbp1s). Repetitive ADI-PEG20 ± canavanine application i.p. were tested in vivo in an U266 myeloma xenograft model in NOD/SCID/IL2Rcg-/- (NSG) mice. Arginine and canavanine levels in plasma were determined by HPLC. Tumor growth was measured, mice were assessed for survival, weight and side effects. Tumor tissues were analyzed for caspase-3 cleavage and Ki67 expression by immunohistochemistry. Results 5 of 6 myeloma cell lines were negative for ASS1. Also, ASS1 was either not or only weakly expressed in the majority of primary CD138+ myeloma patient samples. Arginine starvation induced an arrest of cell proliferation and/or metabolic activity of primary myeloma cells and myeloma cell lines after 18-24 h. Addition of citrulline could only rescue ASS1 positive myeloma cells due to the intracellular resynthesis of arginine. Arginine starvation alone led to delayed induction of apoptosis (e.g. 35% cell death of NCI-H929 cells after 72 h of treatment). Addition of 100 mM canavanine strongly increased cell death specifically in the context of arginine deficiency (e.g. cell death in NCI-H929 cells: 87% after 24 h, 100 % after 48h) while it was non-toxic and had no effect on cell viability under physiological arginine conditions. Co-application of canavanine induced ubiquitination of cellular proteins and led to the prolongation of a fatal unfolded protein response (UPR) as measured by markedly elevated Xbp1s levels. Prolonged UPR ultimately led to the induction of apoptosis as reflected by annexin V binding and caspase-3 cleavage. In an U266 myeloma NSG xenograft model, systemic arginine depletion by ADI-PEG20 suppressed tumor growth in vivo and significantly prolonged median survival of mice when compared with the control group (22±3 vs. 15±3 days). Canavanine treatment alone had no influence on viability (13±0 days). However, the combination of ADI-PEG20 and canavanine demonstrated the longest median survival (27±7 days). Histological examination of explanted tumors showed the highest rates of caspase-3 cleavage in the ADI-PEG20/canavanine group. Conclusion Myeloma cells are mostly arginine auxotrophic and can be selectively targeted by arginine starvation. Combination of arginine depletion with the arginine analogue canavanine leads to a highly efficient and specific tumor cell eradication and should be further optimized in multiple myeloma preclinical models. Disclosures Bomalaski: Polaris Pharmaceuticals Inc.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Panobinostat Induces Upregulation of CD38 and Augments the Anti-Myeloma Efficacy of Daratumumab in Pre-Clinical Models

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4481-4481 ◽  
Author(s):  
Estefania Garcia-Guerrero ◽  
Tea Gogishvili ◽  
Sophia Danhof ◽  
Martin Schreder ◽  
Celine Pallaud ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Flow Cytometry ◽  
Cell Line ◽  
Myeloma Cell ◽  
Target Cells ◽  
Myeloma Cell Line ◽  
Myeloma Cells ◽  
Cd38 Expression ◽  
Clinical Models ◽  
Pre Treatment

Abstract Background: Immunotherapy with monoclonal antibodies (mAbs) has recently entered the clinical arena in multiple myeloma, including Daratumumab that targets CD38 on malignant plasma cells. The efficacy of mAbs depends on antigen density and expression of accessory ligands on target cells to initiate cell- and complement-dependent effector mechanisms. Here, we investigate the use of the histone deacetylase inhibitor (HDACi) Panobinostat to modulate target antigen expression and ligand profile on myeloma in favor of potent mAb-mediated recognition and destruction. We show that Panobinostat augments CD38 expression specifically on myeloma cells and demonstrate powerful synergy with anti-CD38 mAb Daratumumab in pre-clinical models. Methods: The myeloma cell line MM1.S and primary myeloma cells were treated with titrated doses of Panobinostat (0, 10, 25 nM) and expression of CD38 and a panel of additional target molecules including B-cell maturation antigen (BCMA) and SLAMF7, as well as accessory ligands analyzed by flow cytometry at 24, 48 and 72 hours. Antibody-dependent cellular cytotoxicity (ADCC) against Panobinostat treated and untreated myeloma cells was analyzed at 4 and 20 hours after addition of PBMC at an effector to target ratio of 25:1 in the presence of Daratumumab (1, 10, 50 ug/mL) or an isotype control antibody. Results: We first treated the myeloma cell line MM1.S with Panobinostat and analyzed its direct cytotoxic anti-myeloma effect. Consistent with previous work, the percentage of live MM1.S myeloma cells had decreased to 85% and 50% after 48 hours of exposure to 10 and 25 nM respectively. We analyzed expression of CD38 on residual live, i.e. 7-AAD negative MM1.S cells by flow cytometry and observed a 1.5 (10 nM) and 2-fold (25 nM) increase of CD38 expression by mean fluorescence intensity (MFI) compared to baseline levels and untreated control cells. The increase in CD38 expression was already detectable after 24 hours and plateaued between 48 and 72 hours. We confirmed our observation in primary myeloma cells from multiple donors (n=4) and detected an even stronger increase to 2 (10 nM) and 4-fold (25 nM) higher CD38 expression compared to untreated cells at 48 hours. Interestingly, expression of BCMA and SLAMF7 was not increased after Panobinostat treatment at all tested concentrations and time points in both MM1.S and primary myeloma. We confirmed that Panobinostat-induced upregulation of CD38 specifically occurred in myeloma, and neither observed this phenomenon in a panel of leukemia and lymphoma cell lines including Raji (Burkitt) and JeKo-1 (mantle cell), nor on resting/activated primary CD8+ and CD4+ T cells that we isolated from peripheral blood of several donors (n=3). Next, we were interested in determining whether the increase in CD38 expression enabled superior anti-myeloma activity of the anti-CD38 mAb Daratumumab. Panobinostat pre-treatment was done for 48 hours at 10 nM as this is a clinically achievable serum level with currently approved regimens. Indeed, significantly higher ADCC was mediated by Daratumumab at all tested concentrations (1, 10 and 50 ug/mL) against MM1.S that we had exposed to Panobinostat. At 4 hours, ADCC was 45% and 25% in Panobinostat-treated and untreated MM1.S respectively, and at 20 hours, near-complete, >90% ADCC of Panobinostat-pre-treated MM1.S had occurred, whereas only 65% of MM1.S were eliminated by Daratumumab without Panobinostat pre-treatment. These data were confirmed in multiple experiments with MM1.S and PBMC from different donors, and with primary myeloma cells. Experiments to evaluate synergy of Panobinostat and Daratumumab therapy in a xenograft model (NSG/MM1.S) are ongoing. Conclusions: Our data demonstrate that the HDACi Panobinostat induces upregulation of CD38 on myeloma and a subsequent dramatic increase of Daratumumab-mediated ADCC in pre-clinical models. These data suggest that Panobinostat could be used synergistically with Daratumumab in a clinical setting to increase response rates and extend duration of responses to Daratumumab. Panobinostat has a known ability to modulate the transcriptional profile of myeloma cells and our data demonstrate for the first time that this ability can be utilized to augment the therapeutic index of antibody-based immunotherapy in multiple myeloma. Disclosures Pallaud: Novartis: Employment. Lehmann:Novartis: Employment. Hudecek:Novartis: Research Funding.

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.

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