An Investigational Proteasome Inhibitor MLN9708 (MLN2238) Induces Apoptosis In Human Multiple Myeloma Cells In Vitro

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3066-3066
Author(s):  
Aisha Masood ◽  
Kasyapa Chitta ◽  
Kiersten M Miles ◽  
Nazmul H Khan ◽  
Remi Adelaiye ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
Proteasome Inhibitor ◽  
Conflicts Of Interest ◽  
Active Form ◽  
Biologically Active ◽  
Mitochondrial Outer Membrane ◽  
Dependent Manner ◽  
In Vivo Models

Abstract Abstract 3066 Targeting the proteasome has proven to be one of the most effective therapeutic strategies in the treatment of multiple myeloma (MM), and the proteasome inhibitor bortezomib is approved for treatment of MM. However its clinical efficacy is compromised by the acquired resistance in patients, necessitating the development of new therapeutics. Several new proteasome inhibitors are under investigation for their therapeutic efficacy in MM. MLN9708 (Millennium Pharmaceuticals, Inc., Cambridge, MA) is a proteasome inhibitor which shows refined pharmacokinetic and pharmacodynamic properties in preclinical studies and is currently in Phase I clinical development. Upon exposure to aqueous solutions or plasma, MLN9708 rapidly hydrolyzes to MLN2238, the biologically active form. MLN2238 was used for all of the studies reported here, in which we report the efficacy of MLN2238 on three established MM cell lines-KMS11, OPM2 and U266. MLN2238 was found to inhibit the chymotrypsin-like proteasomal activity of all MM cell lines in a dose dependent manner. Investigation of the IC50 of MLN2238 on these cell lines demonstrated that KMS11 is the most sensitive (IC50 of 15.9 nM) while U266 was found to be the least sensitive cell line (IC50 of 511 nM). OPM2 cells also showed intermediate sensitivity with an IC50 of 58.6 nM. MLN2238 induced apoptosis in KMS11 cells as evidenced by annexin V staining and PARP-1 cleavage. Cleavage of caspases 9 and 3 suggested activation of the intrinsic apoptotic pathway by MLN2238. Furthermore, MLN2238 treatment was shown to increase the mitochondrial outer membrane permeability (MOMP) and decrease BCL-2 levels. Evaluation of the expression of PSMB5, the preferred proteasomal subunit target for both bortezomib and MLN2238, revealed that it is expressed at approximately 3 fold more in KMS11 cells as compared to U266, suggesting a possible mechanism for higher sensitivity of KMS11 to the proteasomal inhibitor, MLN2238. This preclinical evaluation confirms the anti-myeloma effects of MLN2238, warranting further in-depth evaluation in both in vitro and in vivo models of MM. Disclosures: No relevant conflicts of interest to declare.

Investigational Agent MLN2238/MLN9708, a Specific, Orally Available, Small Molecule Proteasome Inhibitor, Shows Promising In Vitro Activity Against Multiple Myeloma Cell Lines

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3014-3014
Author(s):  
Giada Bianchi ◽  
Vijay G. Ramakrishnan ◽  
Teresa Kimlinger ◽  
Jessica Haug ◽  
S. Vincent Rajkumar ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Er Stress ◽  
Cell Lines ◽  
Small Molecule ◽  
Proteasome Inhibitor ◽  
Research Funding ◽  
Proteasome Inhibitors ◽  
Biologically Active ◽  
Investigational Agent

Abstract Abstract 3014 Background: Proteasome inhibitors have proven particularly effective in treatment of multiple myeloma, the second most frequent hematologic malignancy in the western world. Bortezomib, the first in class proteasome inhibitor in clinical use, was first approved in 2003 via fast FDA track, given the remarkable activity shown during phase II clinical trials. Nevertheless, more than 50% of multiple myeloma patients did not respond to single agent bortezomib when administered as second line agent. Moreover, bortezomib is only available for intravenous administration, representing a cumbersome therapy for patients, and its use is limited by significant toxicities (especially peripheral neuropathy). MLN9708 (Millennium Pharmaceuticals, Inc.), an investigational orally available, small molecule, is a potent, specific and reversible inhibitor of the 20S proteasome. It is currently under clinical investigation for the treatment of hematologic and non-hematologic malignancies. Upon exposure to aqueous solutions or plasma, MLN9708 rapidly hydrolyzes to MLN2238, the biologically active form, and MLN2238 was used for all of the preclinical studies reported here. In vitro biochemistry studies have shown that MLN2238 has a faster dissociation rate from the proteasome compared to bortezomib, and in vivo studies of MLN2238 have shown antitumor activity in a broader range of tumor xenografts when compared to bortezomib. Given these encouraging preclinical results, we set to investigate the anti-myeloma activity of MLN2238 in vitro. Results: MLN2238 proved to have anti-proliferative and pro-apoptotic activity against a broad range of MM cell lines with EC50 at 24 hours ranging between 10 and 50 nM, even in relatively resistant MM cell lines (OPM2, DOX6, RPMI, etc.). In MM.1S cells, induction of apoptosis was time and dose dependent and related to activation of both caspase 8 and 9. When compared to MM.1S treated for 24 hours with EC50 dose of bortezomib, treatment with EC50 dose of MLN2238 resulted in the same extent of caspases cleavage occurring at an earlier time point (8-12 hours), possibly suggesting more rapid onset and/or irreversibility of apoptosis in cells treated with MLN2238. Treatment with MLN2238 was associated with early, but persistent induction of endoplasmic reticulum (ER) stress with BiP being induced 2–4 hours after treatment with EC50 dose and gradually increasing over time. While bortezomib has been associated with early induction and late decrease in proteins involved in ER stress, MLN2238 appears to induce a persistent rise in these factors, suggesting either more sustained proteasome blockade with stabilization of proteasome substrates or de-novo induction of unfolded protein response (UPR) genes. MLN2238 also proved effective in reducing phosphorylation of ERK1-2 with no overall alteration in the total ERK level, thus accounting for the observed reduction in proliferation upon treatment. Preliminary data indicate potential for additive and synergistic combination with widely used drugs, including doxorubicin and dexamethasone. Conclusion: While further clinical data are needed to establish the effectiveness of MLN2238 in the treatment of multiple myeloma, these preliminary nonclinical data, together with the favorable biochemical and pharmacokinetic properties, including oral bioavailability, make the investigational agent MLN9708 an appealing candidate for treatment of multiple myeloma. Further in vitro data could help establish whether a difference in the apoptotic mechanisms exist between MLN2238 and other proteasome inhibitors, primarily bortezomib, and could also help inform combination treatment approaches aimed at increasing effectiveness, overcoming bortezomib resistance and decreasing toxicity. Disclosures: Kumar: Celgene: Consultancy, Research Funding; Millennium: Research Funding; Merck: Consultancy, Research Funding; Novartis: Research Funding; Genzyme: Consultancy, Research Funding; Cephalon: Research Funding.

scholarly journals The Efficacy of a Novel Oral Proteasome Inhibitor NNU546 in Multiple Myeloma

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5586-5586
Author(s):  
Ye Yang ◽  
Yongqiang Zhu ◽  
Chunyan Gu
Keyword(s):  
Multiple Myeloma ◽  
Proteasome Inhibitor ◽  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Active Form ◽  
Selective Inhibition ◽  
Endoplasmic Reticulum Stress Response ◽  
Pharmacologically Active ◽  
Intravenous And Oral Administration

Proteasome inhibition demonstrates highly effective impact on multiple myeloma (MM) treatment. In this study we aimed to examine a novel well tolerated orally applicable proteasome inhibitor NNU546 and its hydrolyzed pharmacologically active form NNU219. NNU219 showed more selective inhibition to proteasome catalytic subunits and less off-target effect than bortezomib ex vivo. Furthermore, intravenous and oral administration of NNU219 and NNU546, respectively, led to a more sustained pharmacodynamic inhibition of proteasome activities compared with bortezomib. Intriguingly, NNU219 exhibited potential anti-MM activity on both MM cell lines and primary samples in vitro. The anti-MM activity of NNU219 was determined to be associated with induction of G2/M-phase arrest, as well as induction of apoptosis via activation of the caspase cascade and endoplasmic reticulum stress response. At well-tolerated doses, significant growth-inhibitory effects of NNU219 and NNU546 were observed in 3 different human MM xenograft mouse models and significant anti-MM activity was observed even in the presence of a bone marrow microenvironment. Taken together, these findings provided the basis for clinical trials of NNU546 to determine its potential as a candidate for MM treatment. Disclosures No relevant conflicts of interest to declare.

scholarly journals Anti-tumor activity of a novel proteasome inhibitor D395 against multiple myeloma and its lower cardiotoxicity compared with carfilzomib

2021 ◽  
Vol 12 (5) ◽  
Author(s):  
Xuxing Shen ◽  
Chao Wu ◽  
Meng Lei ◽  
Qing Yan ◽  
Haoyang Zhang ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Proteasome Inhibitor ◽  
Osteoclast Differentiation ◽  
Dependent Manner ◽  
Serum Enzyme ◽  
Herg Channels ◽  
Anti Tumor Activity ◽  
Dose Dependent

AbstractCarfilzomib, a second-generation proteasome inhibitor, has significantly improved the survival rate of multiple myeloma (MM) patients, but its clinical application is still restricted by drug resistance and cardiotoxicity. Here, we identified a novel proteasome inhibitor, D395, and assessed its efficacy in treating MM as well as its cardiotoxicity at the preclinical level. The activities of purified and intracellular proteasomes were measured to determine the effect of D395 on the proteasome. CCK-8 and flow cytometry experiments were designed to evaluate the effects of D395 on cell growth and apoptosis. The effects of D395 and carfilzomib on serum enzyme activity, echocardiography features, cardiomyocyte morphology, and hERG channels were also compared. In our study, D395 was highly cytotoxic to MM cell lines and primary MM cells but not normal cells, and it was well tolerated in vivo. Similar to carfilzomib, D395 inhibited osteoclast differentiation in a dose-dependent manner. In particular, D395 exhibited lower cardiotoxicity than carfilzomib in all experiments. In conclusion, D395 is a novel irreversible proteasome inhibitor that has remarkable anti-MM activity and mild cardiotoxicity in vitro and in vivo.

Preclinical Evaluation of the Proteasome Inhibitor MLN9708 (MLN2238) In Chronic Lymphocytic Leukemia Cells

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4634-4634
Author(s):  
Aisha Masood ◽  
Kiersten M Miles ◽  
Nazmul H Khan ◽  
Drusilla Akhtar ◽  
Remi Adelaiye ◽  
...  
Keyword(s):  
Cell Death ◽  
Chronic Lymphocytic Leukemia ◽  
Proteasome Inhibitor ◽  
Active Form ◽  
Lymphocytic Leukemia ◽  
Biologically Active ◽  
Autologous Serum ◽  
Mitochondrial Outer Membrane ◽  
Apoptosis Pathway ◽  
Intrinsic Apoptosis Pathway

Abstract Abstract 4634 The proteasome is an important therapeutic target in multiple hematological malignancies. The proteasome inhibitor bortezomib has demonstrated significant clinical activity in multiple myeloma and mantle cell lymphoma. However, clinically bortezomib has failed to demonstrate efficacy in chronic lymphocytic leukemia (CLL); the exact reason for this remains unknown. MLN9708 (Millennium Pharmaceuticals, Inc., Cambridge, MA) is a proteasome inhibitor which has a shorter proteasome dissociation half life than bortezomib and is currently in Phase I clinical development. Upon exposure to aqueous solutions or plasma, MLN9708 rapidly hydrolyzes to MLN2238, the biologically active form. MLN2238 was used for all of the studies reported here, in which we evaluated the antileukemic effects of MLN2238 in primary CLL cells from 16 patients. MLN 2238 induced a time and dose dependent decrease in CLL cell viability in 12 (75%) patient cells in vitro. Cell death was shown to be due to the induction of apoptosis confirmed by Annexin V staining of CLL cells and cleavage of PARP-1, an indicator of apoptosis. Biochemical analysis showed that caspase 3 and 9 were activated in these cells, indicating that MLN2238 induces cell death through the intrinsic apoptosis pathway. We noted increased mitochondrial outer membrane permeability (MOMP) in the presence of MLN2238, which suggests the engagement of the mitochondria in MLN2238 induced apoptosis in CLL cells. Evaluation of non-responding CLL patient samples demonstrated that increased expression of PSMB5 is associated with lack of sensitivity to MLN2238. Furthermore, incremental addition of autologous serum in responding CLL samples resulted in upregulation of PSMB5 levels, resulting in protection against MLN2238 induced cell death. Our preclinical observations demonstrate for the first time that MLN2238 can induce death in primary CLL cells, and support further investigation in CLL. Disclosures: No relevant conflicts of interest to declare.

Membrane Lipid Biosynthesis As a Potential Therapeutic Target in Multiple Myeloma

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1836-1836
Author(s):  
Carolyne Bardeleben ◽  
Alan Lichtenstein
Keyword(s):  
Multiple Myeloma ◽  
Er Stress ◽  
Cell Lines ◽  
Cell Apoptosis ◽  
Plasma Cells ◽  
Conflicts Of Interest ◽  
Membrane Lipid ◽  
Dependent Manner ◽  
Kennedy Pathway ◽  
Phosphatidylcholine Synthesis

Abstract Abstract 1836 Phosphatidylcholine (PC) is the most prominent phospholipid in mammalian endoplasmic reticulum (ER) membranes. The rate-limiting step in PC synthesis through the Kennedy pathway is the conversion of phosphocholine + cytidine triphosphate (CTP) to cytidine diphosphocholine, (CDP)-choline, via the enzyme CTP:phosphocholine cytidylyltransferase (CCT) (see figure). Multiple myeloma (MM) cells may be particularly dependent on this biosynthetic reaction because of their high consistent level of ER stress and requirement to continuously replenish ER membranes. Indeed, CCT-null mice have a defect in differentiation of B lymphocytes to plasma cells and deficiencies in Ig synthesis. To test whether this pathway remains critical in survival of malignant MM cells, we exposed MM cell lines to an inhibitor shown to inhibit CCT activity, HexPC. HexPC induced apoptosis in all MM cell lines in a concentration- and time-dependent manner. The addition of lysophosphatidylcholine (LPC), presumably converted to PC independently of the Kennedy pathway, completely rescued MM cell apoptosis. In contrast, similar concentrations of LPC in the same cell lines could not rescue apoptosis induced by bortezomib. An additional intervention to inhibit phosphatidylcholine synthesis, namely inducing pyrimidine starvation, also resulted in MM cell apoptosis and down-regulation of CDP-choline levels. Apoptosis of MM cells induced by HexPC was associated with induction of ER stress as shown by enhanced phosphorylation of IRE1 and eIF-2alpha. This ER stress was also prevented when LPC was added to HexPC although LPC could not prevent similar ER stress induced by bortezomib. These results underscore the importance of this phosphatidylcholine synthesis pathway in MM cells and provide new targets for future therapy. Disclosures: No relevant conflicts of interest to declare.

Identification of Tight Junction Protein (TJP)-1 As a Modulator of Sensitivity to Doxorubicin and Cisplatin in Models of Multiple Myeloma

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3962-3962
Author(s):  
Xing-Ding Zhang ◽  
Robert Z. Orlowski ◽  
Lin Yang
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
Hela Cells ◽  
Conflicts Of Interest ◽  
Myeloma Cell ◽  
Cancer Center ◽  
In Vivo Models ◽  
Junction Protein ◽  
Rpmi 8226

Abstract Abstract 3962 Background: Therapeutic advances in multiple myeloma have improved the outcomes of patients with this malignant plasma cell disorder, but the disease course is still strongly influenced by both innate, or primary, as well as acquired, or secondary mechanisms of drug resistance. Identification and validation of genes that may mediate these phenotypes is therefore of importance, since they could be useful prognostic markers, and also potential targets to overcome the emergence of resistance, or possibly preclude its emergence altogether. Methods: To identify non-redundant determinants of chemoresistance, we designed a robust, high-throughput RNA interference (RNAi) screen targeting 9610 human genes. The screen involved retroviral-mediated transduction first of HeLa cervical carcinoma cells with either the RNAi library, or with non-targeting retrovirus particles. After infection, cells were selected with puromycin, and treated with different concentrations of doxorubicin and cisplatin. Doxorubicin (Dox) treatment led to 33 surviving colonies from the cells transduced with the shRNA library, cisplatin (Cis) treatment led produced 22 surviving colonies, while non-targeting retrovirus-infected cells failed to form colonies after treatment. Screening was performed to identify the shRNA target gene(s) in each colony, and genes that were identified in both Dox- and Cis-treated HeLa cells, and that were expressed in myeloma cells, were selected for further study. These studies were supported by the M. D. Anderson Cancer Center SPORE in Multiple Myeloma. Results: TJP1 (zona occludens (ZO)-1) was identified as one gene whose knockdown promoted survival in Dox- and Cis-treated HeLa cells, and which was expressed in myeloma cell lines and in primary plasma cells. To further examine its potential role in myeloma chemosensitivity, we performed mRNA and protein expression profiling in a panel of 11 cell lines and observed that TJP1 expression was silenced in 3 cell lines (ARP-1, INA-6, and MOLP-8), while it was moderately to highly expressed in 7 cell lines (including RPMI 8226, MM1.S, and U266). Comparing TJP1-positive MM1.S cells to TJP1-null MOLP-8 cells, the latter displayed a significantly higher median inhibitory concentration to Dox and Cis. Knockdown of TJP1 in RPMI 8226 and U266 cells, which produced a >75% target suppression, was sufficient to reduce the proportion of apoptotic cells in the sub-G1 fraction after treatment with Dox or Cis compared to control cells. Conversely, MOLP-8 cells transfected with human TJP1 cDNA exhibited an increase in the sub-G1 population in response to Dox and Cis treatment compared to vector controls. Conclusion: Taken together, these studies support the hypothesis that TJP1 expression mediates myeloma cell resistance to the DNA damaging agents doxorubicin and cisplatin. Further studies are underway to determine the mechanism by which TJP1 influences chemosensitivity, and to validate its impact using in vivo models. Disclosures: No relevant conflicts of interest to declare.

Inhibition Of PI3K Classia Kinases Using GDC0941 Overcomes Protection Of Multiple Myeloma Cells In The Bone Marrow Microenvironment

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3169-3169
Author(s):  
Hugh Kikuchi ◽  
Amofa Eunice ◽  
Maeve McEnery ◽  
Farzin Farzaneh ◽  
Stephen A Schey ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Cell Proliferation ◽  
Bone Resorption ◽  
Cell Lines ◽  
Stromal Cells ◽  
Conflicts Of Interest ◽  
Pi3k Pathway ◽  
Dependent Manner ◽  
Dose Dependent

Abstract Despite of newly developed and more efficacious therapies, multiple myeloma (MM) remains incurable as most patient will eventually relapse and become refractory. The bone marrow (BM) microenvironment provides niches that are advantageous for drug resistance. Effective therapies against MM should ideally target the various protective BM niches that promote MM cell survival and relapse. In addition to stromal mesenchymal/myofibroblastic cells, osteoclasts play a key supportive role in MM cell viability. Additionally, 80% of patients develop osteolytic lesions, which is a major cause of morbidity. Increased osteoclast activity is characteristic in these patients and targeting osteoclast function is desirable to improve therapies against MM. Osteoclasts need to form an F-actin containing ring along the cell margin that defines a resorbing compartment where protons and degradative enzymes are secreted for dissolution of bone mineral. Remodelling of F-actin and vesicle secretion are regulated by the class IA PI3K pathway during osteoclastic bone resorption. Additionally, it has recently been shown that inhibition of the class IA PI3K pathway in MM cells with GDC0941 induces apoptosis-mediated killing. We hypothesised that GDC0941 could be used as a therapeutic agent to overcome MM-induced osteoclast activation. GDC0941 inhibited maturation of osteoclasts derived from BM aspirates from MM patients in a dose dependent manner. This correlated with decreased bone resorption of osteoclasts cultured on dentine discs. Exposure of mature osteoclasts to GC0941 resulted in abnormal organisation of larger F-actin rings, suggesting a negative effect on the dynamics of the actin cytoskeleton required for bone resorption. We also found that GDC-0941 can prevent protection of the MM cell lines MM1.S and MM1.R by osteoclasts against killing. GDC-0941 alone blocked MM cell proliferation independently of the presence of BM stromal cells and synergised with other therapeutic agents including Lenalidomide, Pomalidomide, Bortezomid and Dexamethasone. We also found that in the presence of MM cells, Dexamethasone (a drug commonly used alone or in combination with new drugs against MM) induced the proliferation of BM stromal cells and adhesion of MM cells on this protective stroma in a dose dependent manner. Dexamethasone is highly effective at MM cell killing when cells are cultured alone. However, we found that at low doses (below 1 uM) and in the presence of BM stromal cells, Dexamethasone could induce MM cell proliferation. GDC0941 enhanced Dexamethasone killing even in the presence of BM stromal cells by blocking Dexamethasone-induced stromal cell proliferation and adhesion of MM cells on the stroma. Targeting individual the PI3K Class IA isoforms alpha, beta, delta or gamma proved to be a less efficient strategy to enhance Dexamethasone killing. Previous work has shown that efficacy of targeting individual PI3K Class I A isoforms would be low for activation of caspases in MM cells as it would be dependent on relative amounts of isoforms expressed by the MM patient. GDC-0941 also inhibited the proliferation of MM1.R and RPMI8266 MM cell lines, which are less sensitive to treatment to Dexamethasone. Co-culture of MM cells with BM stromal cells induced the secretion of IL-10, IL-6, IL-8, MCP-1 and MIP1-alpha. The dose-dependant increased proliferation of Dexamethasone-treated MM cells in the presence of the BM stroma correlated with the pattern of secretion of IL-10 (a cytokine that can induce B-cell proliferation) and this was blocked by the combination of Dexamethasone with GDC0941. GDC-0941 alone or in combination with Dexamethasone was more efficacious at inducing MM cell apoptosis in the presence of the BM stroma cells vs treatment of MM cells alone. These are very encouraging results as they suggest that GDC-0941 in combination with Dexamethasone would be potentially highly efficacious for targeting MM cells in the BM microenvironment. We are currently performing in vivo data using C57BL/KaLwRij mice injected with 5T33-eGFP MM cells that will be discussed at the meeting. We propose that MM patients with active bony disease may benefit from treatment with GDC0941 alone or in combination with currently used therapeutic drugs against MM. Disclosures: No relevant conflicts of interest to declare.

Antitumor Activity of a Novel Proteasome Inhibitor BSc2118 Against Multiple Myeloma

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 5725-5725
Author(s):  
Meirong Zang ◽  
Lanting Liu ◽  
Xin Li ◽  
Wei Li ◽  
Ulrike Kuckelkorn ◽  
...  
Keyword(s):  
Cell Lines ◽  
Proteasome Inhibitor ◽  
Molecular Mechanisms ◽  
Plasma Cells ◽  
Conflicts Of Interest ◽  
Proteasome Activity ◽  
Autophagy Flux ◽  
Ubiquitinated Proteins ◽  
Rpmi 8226

Abstract Background: Although the first generation of proteasome inhibitor bortezomib is very effective, the development of resistance limits it long-term utility. In this study, we explored the efficiency and molecular mechanisms of the novel, irreversible proteasome inhibitor BSc2118, particularly, the reversal of bortezomib resistance. Materials and Methods: Human MM cell lines (MM.1S, MM.1R, RPMI-8226, U266, NCI-H929) were treated with BSc2118 at various concentrations for 48h, and assessment for cell viability by CCK-8 assay. MM.1S and MM.1R cells were treated with BSc2118 for 24 hours, and cell cycle and apoptosis analysis were conducted by flow cytometry. Associated molecules were detected by qRT-PCR and western blot. Chymotrypsin-like proteasome activity assay was performed by using the 20S proteasome assay kit. Ubiquitinated proteins were isolated and determined with ubiquitin enrichment kit. Results: Our results revealed that treatment of MM cell lines with BSc2118 inhibits the chymotrypsin-like proteasome activity and induces accumulation of ubiquitinated proteins. BSc2118 inhibits MM cell growth and induces MM apoptosis via induction of G2/M phase arrest, activation of cleaved caspase-3, caspase-8 and caspase-9 and PARP, increasing p53, p21 and E2F1, and inhibition of autophagy in MM.1S, MM.1R and RPMI-8226 cell lines. In addition, BSc2118 dramatically inhibits cytokines mRNA, such as IL-6, VEGF and bFGF in both myeloma cells line and primary bone marrow stromal cells from myeloma patients. More importantly, BSc2118 could overcome bortezomib resistance in vitro by using primary CD138 positive plasma cells from bortezomib-resistant myeloma patients and bortezomib resistance cell line ANBL-6 (ANBL-6.BR), most likely as the consequence of inhibition of autophagy flux which is responsible for bortezomib resistance. Conclusion: Our study revealed BSc2118, a novel irreversible proteasome inhibitor, exerts anti-MM effect, mainly through activation of caspase pathway and inhibition of basal autophagy. It is of great importance that BSc2118 could overcome bortezomib resistance via inhibition of autophagy flux. A head to head of BSc2118 versus Bortezomib is performing in human plasmacytoma xenograft tumor model to evaluate drug safety, anti-tumor efficiency, in particular, reversal of bortezomib resistance. Our preclinical study supports clinical evaluation of BSc2118, particularly, overcomes bortezomib resistance, as a potential MM therapy. Disclosures No relevant conflicts of interest to declare.

scholarly journals An Immune Based, Anti-CD138 Targeting Antibody for the Treatment of Multiple Myeloma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5617-5617 ◽  
Author(s):  
Tengteng Yu ◽  
Lijie Xing ◽  
Liang Lin ◽  
Jiye Liu ◽  
Kenneth Wen ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
Myeloma Cell ◽  
Dependent Manner ◽  
Cellular Cytotoxicity ◽  
Adcc Activity ◽  
Effector Cells ◽  
Equity Ownership ◽  
Dose Dependent

Abstract CD138 (Syndecan-1), a member of integral membrane family of heparan sulfate proteoglycans (HSPGS), is highly expressed on differentiated plasma cells (PC) and is both a primary diagnostic biomarker of multiple myeloma (MM) as well as an indicator of poor clinical prognosis. This surface antigen is an attractive candidate for targeted immunotherapy for MM, given its constitutive expression during disease progression, including smoldering myeloma, a relatively early asymptomatic phase of disease that is potentially amenable to early treatment. We here investigated the targeted use of chimeric anti-CD138 monoclonal antibody (mAb) 1610 and confirm its in vitro anti-tumor potency based on an immune directed cellular cytotoxicity against a diverse panel of CD138 positive MM cell lines, both resistant or sensitive to conventional and current MM therapies and varying levels of CD138 expression as measured by cell immunostaining and quantitative RT-PCR. Antibody-dependent cellular cytotoxicity (ADCC) was evaluated using a calcein-AM based release assay in the presence of human natural killer (NK) effector cells purified from four different healthy donors. MAb 1610 lysed CD138-expressing MM cell lines in a dose dependent manner. This ADCC activity was mAb 1610 specific (in comparison to isotype control), CD138 target dependent, and mediated in the presence of human NK effector cells (co-cultured at an effector:target cell ratio of 20:1). MAb 1610 dependent-cytotoxicity was observed at concentrations as low as 0.01 µg/ml with maximal lysis occurring at approximately 1 µg/ml and extrapolated sub-nanomolar ED50 potencies (Table 1) based on these data. All MM cell lines were subject to mAb 1610-mediated lysis, albeit with slightly different sensitivities that modestly correlated with their relative CD138 cell surface expression levels. This anti CD138 mAb-dependent cellular toxicity included MM1SR and H929R cell lines, both of which are resistant to lenalidomide. MAb 1610 induced specific cell lysis of JJN3 cells, but not of CD138 knock out JJN3 cells or CD138-negative B lymphocytes, further confirming that mAb 1610 specifically induced ADCC against-CD138 expressing MM cells in a target specific manner. Using an orthogonal cytometric based assay, the ability of mAb 1610, in a dose-dependent manner, to activate NK cells was also shown in the presence of CD138 target cells, as evidenced by increased expression of CD107 (a marker for NK cell degranulation) and cytokine production in NK cells. Importantly, the CD138 targeting cytotoxic activities of mAb 1610 translationally extend to MM cells autologously derived directly from MM patients with newly diagnosed and relapsed/refractory diseases. The concomitant use of autologously derived effector cells from these patients to mediate antibody dependent myeloma cell killing further suggests the relevance of anti-CD138 directed immune-based therapeutic strategy in humans. In further replication of human disease, we also co-cultured MM1.S or MM1.R cells with human bone marrow stromal cells (BMSCs) which support myeloma cell growth by promoting an immunosuppressive microenvironment within the BM. Importantly, mAb 1610-dependent cytotoxicity against MM1.S or MM1.R cells was not attenuated by the co-presence of BMSCs. Similarly, IL-6 (10 ng/ml) did not significantly affect mAb 1610-induced ADCC activity, indicating a mechanism of action that can overcome growth promotion, immune suppression, and drug resistance conferred by the tumor promoting BM microenvironment. Taken together, these in vitro studies further demonstrate as a proof-of-concept the use of an antibody CD138 targeting strategy mediated through an immune based mechanism of myeloma plasma cell killing. Based on these results, optimization and further biological characterization of chimeric mAb 1610 in advance of pre-clinical studies is anticipated. Disclosures Myette: Visterra Inc.: Employment. Chaganty:Visterra Inc.: Employment. Adari:Visterra Inc.: Employment. Tissire:Visterra Inc.: Employment. Deotale:Visterra Inc.: Employment. Shriver:Visterra Inc.: Employment. Munshi:OncoPep: Other: Board of director. Anderson:Millennium Takeda: Consultancy; Gilead: Membership on an entity's Board of Directors or advisory committees; OncoPep: Equity Ownership, Other: Scientific founder; C4 Therapeutics: Equity Ownership, Other: Scientific founder; Celgene: Consultancy; Bristol Myers Squibb: Consultancy.

scholarly journals The Contribution of Proteasome Subunits to Myeloma Cell Viability and Proteasome Inhibitor Sensitivity

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4337-4337
Author(s):  
Chang-Xin Shi ◽  
Yuan Xiao Zhu ◽  
Laura Ann Bruins ◽  
Cecilia Bonolo De Campos ◽  
William Stewart ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Drug Resistance ◽  
Cell Viability ◽  
Cell Lines ◽  
Proteasome Inhibitor ◽  
Conflicts Of Interest ◽  
Myeloma Cell ◽  
Resistance Function ◽  
Proteasome Subunits ◽  
Underlying Mechanisms

Background Bortezomib (BTZ) is highly effective in the treatment of multiple myeloma; however, emergent drug resistance is common. The underlying mechanisms of such proteasome inhibitor resistance are still incompletely understood. Methods To further understand its resistant mechanism, we generated eight multiple myeloma (MM) cell lines resistant to bortezomib (BTZ) by exposure to increasing drug concentration: five of them acquired novel PSMB5 mutations. Given the rarity of similar mutations in over 1,500 analyzed MM patients, we explored in depth the role of the proteasome on MM cell viability and BTZ sensitivity by systematically deleting the major proteasome targets of BTZ by CRISPR. Results We demonstrated that MM cell lines without PSMB5 were surprisingly viable (mutation corresponding yeast gene pre2 is lethal). PSMB5 mutated, BTZ resistant, MM cell lines were re-sensitized to BTZ when PSMB5 was experimentally deleted, implying that this mutation is activating in its drug resistance function. In contrast PSMB6 knockout was lethal to MM cell lines, which were efficiently rescued by re-introduction of wild type PSMB6. Interestingly, reduction in PSMB6 levels also prevented the splicing of the major catalytic subunits PSMB5, PSMB7, PSMB8 and PSMB10. PSMB6 engineered with no splicing function or catalytic activity, also restored viability, inferring that the contribution of PSMB6 to proteasome structure is more important than functional activity. Supporting this observation, BTZ sensitivity was restored in resistant MM cells line by introducing low level expression of mutated PSMB6 lacking splicing function. As with PSMB6, PSMB7 knockout was lethal to MM cell lines. In contrast, loss of immunoproteasome subunits PSMB8 and PSMB9 was neither lethal nor restored sensitivity to BTZ. Our results demonstrate that expression of the three constitutive proteasome subunits PSMB5, PSMB6 and PSMB7 is highly co-dependent. This dependence is relying on the structure, but not the function, of PSMB5 and PSMB6. Conclusions In summary, PSMB5 and PSMB6, but not PSMB8 and PSMB9, are highly relevant for BTZ sensitivity in MM. Absence of PSMB6 or PSMB7, but not PSMB5, was lethal in MM cell lines. Expression of PSMB5, PSMB6 and PSMB7 was highly co-dependent. Together these findings suggest that the modulation of expression rather than function of PSMB5, PSMB6 or PSMB7 may be a new therapeutic strategy. Disclosures No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document