Apoptosis In Myeloma Cells Research Articles

Effect of bortezomib on proliferation and apoptosis of myeloma cells by activating Wnt/β-catenin signaling pathway.

Effect of bortezomib on proliferation and apoptosis of myeloma cells by activating Wnt/β-catenin signaling pathway was investigated. Myeloma cells RPMI-8226 treated with different concentrations of bortezomib were used as experimental groups, and the untreated cells were used as the control group. The proliferation and apoptosis in all groups of cells were detected, as well as the expression levels of Wnt/β-catenin signaling pathway-related proteins, β-catenin and c-Myc. The results revealed that bortezomib could inhibit the proliferation of myeloma cells. The apoptotic rates of RPMI-8226 cells in the groups treated with 20, 50 and 80 nmol/l of bortezomib were 12.08±0.61, 35.97±3.11 and 57.22±5.47%, respectively, which were significantly higher than that in the control group (8.28±0.39%) (P<0.05). The expression levels of β-catenin and c-Myc in the experimental groups were significantly lower than those in the control group (P<0.05). Bortezomib can reduce the expression level of Wnt/β-catenin signaling pathway-related proteins, β-catenin and c-Myc, and may inhibit cell proliferation and accelerate apoptosis by activating the Wnt/β-catenin signaling pathway.

Updated analysis of a phase I/II study of venetoclax in combination with daratumumab and dexamethasone, +/- bortezomib, in patients with relapsed/refractory multiple myeloma.

8511 Background: Venetoclax (Ven) is a selective, potent, oral BCL-2 inhibitor that induces apoptosis in multiple myeloma (MM) cells in vitro. It has shown synergistic activity with bortezomib (V) and dexamethasone (d). Combination of the CD38 monoclonal antibody daratumumab (D) with Ven is hypothesized to further increase anti-myeloma activity based on dual mechanisms of pro-apoptotic effects on tumor cells and enhanced immune stimulation. Methods: This ongoing Phase 1/2, nonrandomized, multicenter study (NCT03314181) is evaluating safety, efficacy and pharmacokinetics (PK) of VenDd +/- V in patients (pts) with relapsed/refractory MM. In Part 1, pts with t(11;14) who received ≥1 prior line of therapy (PI and an immunomodulatory drug) were treated with VenDd [Ven QD + D 16 mg/kg IV + d 40 mg weekly]. In Part 2, pts irrespective of t(11;14) status, non-refractory to PIs and who received 1–3 prior lines of therapy were treated with VenDVd [Ven QD + D 16 mg/kg IV + V (1.3 mg/m2) + d (20 mg)]. A randomized, open-label expansion (Part 3) will further evaluate and compare safety and efficacy of VenDd (400 or 800 mg Ven dose levels) with control DVd in pts with t(11;14). Results: As of Dec 05, 2019, 48 pts were enrolled. Part 1 included 24 pts with t(11;14), median age 63 (range 51–76). Part 2 included 24 pts, median age 65 (range 41–80) of which 6 (25%) had t(11;14). Frequent adverse events (AEs; VenDd/VenDVd) were fatigue (71%/25%), diarrhea (58%/46%), nausea (46%/50%), insomnia (33%/50%), upper respiratory tract infection (33%/21%), cough (42%/9%), and dyspnea (25%/25%). Frequent Grade ≥ 3 AEs in pts on VenDd were neutropenia (17%), hypertension (12%), fatigue and hyperglycemia (8% each), and in pts on VenDVd were insomnia (21%), diarrhea and thrombocytopenia (8% each). Nine pts had infection-related Grade ≥ 3 AEs (5 VenDd, 4 VenDVd). Eighteen pts had a serious AE (11 VenDd, 7 VenDVd) with pyrexia (n = 3) being most common. One pt on VenDVd died of progressive disease. PK analyses showed that addition of D and V did not impact Ven exposure. Median follow-up time (VenDd/VenDVd) was 10 and 9 months. Overall response rate in VenDd/VenDVd was 96%/92% and 96%/79% had ≥ very good partial response rate. Median progression free survival and duration of response were not reached. Conclusions: Pts treated with VenDd +/- V continue to demonstrate a tolerable safety profile with encouraging efficacy, notably among pts with t(11;14) treated with VenDd. Safety, efficacy, PK, and cytogenetics analyses will be updated for presentation. Clinical trial information: NCT03314181 .

Long non-coding RNA OIP5-AS1 suppresses multiple myeloma progression by sponging miR-27a-3p to activate TSC1 expression

BackgroundMultiple myeloma (MM) is a prevalent hematological malignancy. Long noncoding RNAs are correlated with the development of MM. In this project, the function of lncRNA opa interacting protein 5-antisense 1 (OIP5-AS1) in MM and the potential mechanistic pathway were explored.MethodsThe expression of OIP5-AS1, microRNA (miR)-27a-3p and tuberous sclerosis 1 (TSC1) was analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) assay. Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8) assay, colony formation assay and Bromodeoxyuridine (BrdU) staining. And cell apoptosis was evaluated by flow cytometry assay. Cell metastasis was assessed utilizing transwell assay. Western blot analysis was employed to detect protein level. The target relation between miR-27a-3p and OIP5-AS1 or TSC1 was confirmed via dual-luciferase reporter assay and RNA immunoprecipitation assay. Tumor xenograft assay was conducted to measure the function of OIP5-AS1 in vivo.ResultsThe expression levels of OIP5-AS1 and TSC1 were decreased in MM, whereas miR-27a-3p was upregulated. High level of OIP5-AS1 could predict favourable prognosis of MM patients. Overexpression of OIP5-AS1 inhibited cell viability, colony formation ability, migration and invasion, induced cell cycle arrest in G1 phase and apoptosis of MM cells in vitro as well as repressed tumorigenesis in vivo. MiR-27a-3p was a target of OIP5-AS1, and reversed the impact of OIP5-AS1 on MM cells. MiR-27a-3p directly targeted TSC1. Silencing of miR-27a-3p repressed MM progression by elevating TSC1 expression. OIP5-AS1 upregulated TSC1 by sponging miR-27a-3p.ConclusionOIP5-AS1 repressed multiple myeloma progression by regulating miR-27a-3p/TSC1 axis.

Growth inhibition and apoptosis of human multiple myeloma cells induced by 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid derivatives.

Multiple myeloma is a blood cell cancer and can cause symptoms such as bone loss and fatigue. Recent studies have shown that the bone marrow microenvironment may mediate tumor proliferation, drug resistance, and migration of the multiple myeloma cells. Synthetic triterpenoids have been used for the treatment of cancer due to their antiproliferative and anti-inflammatory effects. The objective of this study is to examine the effect of 2-cyano-3, 12 dioxoolean-1,9-dien-28-oic acid (CDDO) derivatives on human multiple myeloma cells. Three CDDO derivatives, such as CDDO-methyl ester, CDDO-trifluroethyl amide, and CDDO-imidazolide (Im), were tested on the growth of human multiple myeloma cells. Our results show that all CDDO derivatives decrease the viability of multiple myeloma cells in a dose- and time-dependent manner, with CDDO-Im being the most potent. CDDO-Im was selected to investigate whether its inhibitory effect on multiple myeloma cell growth is due to cell cycle arrest and induction of apoptosis. The results suggest that CDDO-Im may inhibit cell cycle progression in the G0/G1 phase and induce the intrinsic apoptotic pathway. The effect of CDDO-Im on multiple myeloma cells was evaluated in a Transwell model using myeloma cells co-culturing with human HS-5 stromal cells to simulate the bone marrow microenvironment in vitro. The results showed that CDDO-Im induced multiple myeloma cell apoptosis in the presence of HS-5 cells, albeit to a lower extent than in multiple myeloma cells cultured alone. In conclusion, our data suggest that CDDO-Im inhibits the growth of multiple myeloma cells, either cultured alone or co-cultured with bone marrow stromal cells, through the induction of apoptosis.

Effects of miR-32 targeting PTEN on proliferation and apoptosis of myeloma cells.

To explore the effects of micro ribonucleic acid (miR)-32 on the proliferation and apoptosis of myeloma cells, and to verify whether it exerts its function by targeting phosphatase and tensin homolog deleted on chromosome ten (PTEN). The differentially expressed miRNAs were screened in healthy people and myeloma patients. The myeloma U266 cells transfected with negative control (NC) were used as control group, those transfected with miR-32 inhibitor as transfection group, and those transfected with miR-32 inhibitor and treated with PTEN inhibitor SF1670 as the transfection + inhibitor group. Then, the cell proliferation and apoptosis in each group were detected using the 5-Ethynyl-2'-deoxyuridine (EdU) kit and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay, respectively. Finally, the expressions of apoptosis-related proteins B-cell lymphoma-2 (Bcl-2), Bcl-2 homologous antagonist/killer (Bak), caspase-9, and survivin were detected. The expressions of some miRNAs and genes in myeloma patients were significantly different from those in healthy people. In myeloma patients, miR-32, miR-126, miR-123, and miR-183 were significantly highly expressed, while miR-5, miR-76, and miR-50 were remarkably lowly expressed. After myeloma U266 cells were transfected with the miR-32 inhibitor, the expression of miR-32 markedly declined. In addition, the mRNA expression of PTEN in myeloma cells rose after transfection with the miR-32 inhibitor, and declined after addition of the PTEN inhibitor SF1670, which were consistent with the results of Western blotting. Besides, the proliferation ability of myeloma cells was evidently weakened after transfection with the miR-32 inhibitor, while it was restored to a certain extent after addition of the PTEN inhibitor SF1670. Moreover, the number of apoptotic myeloma cells was remarkably larger after transfection with the miR-32 inhibitor, while it was remarkably smaller after addition of the PTEN inhibitor SF1670. The expressions of pro-apoptotic proteins Bak and caspase-9 in myeloma cells were significantly increased after transfection with the miR-32 inhibitor (p<0.05), and significantly decreased after addition of the PTEN inhibitor SF1670, while the expressions of anti-apoptotic proteins Bcl-2 and survivin were opposite to those of Bak and caspase-9. MiR-32 targeting PTEN will have certain effects on the proliferation and apoptosis of myeloma cells.

Combination Lenalidomide/Bortezomib Treatment Synergistically Induces Calpain-Dependent Ikaros Cleavage and Apoptosis in Myeloma Cells.

Multiple myeloma had been successfully treated by combining lenalidomide and bortezomib with reports suggesting benefits of such a combination even in relapsed/refractory cases. Recently, it was demonstrated that Ikaros degradation by lenalidomide happens via proteasome-dependent pathway and this process is critical for the eradication of myeloma cells. On the basis of this, an antagonistic effect should be observed if a combination of both these agents were used, which however is not the observation seen in the clinical setting. Our study demonstrates that when these agents are combined they exhibit a synergistic activity against myeloma cells and degradation of Ikaros happens by a proteasome-independent calcium-induced calpain pathway. Our study identifies the crucial role of calcium-induced calpain pathway in inducing apoptosis of myeloma cells when this combination or lenalidomide and bortezomib is used. We also report that this combination enhanced the expression of CD38 compared with lenalidomide alone. Thus, data from our study would establish the rationale for the addition of daratumumab along with this combination to further enhance therapeutic activity against multiple myeloma. IMPLICATIONS: Lenalidomide and bortezomib combination degrades IKZF1 in multiple myeloma through a calcium-dependent calpain and caspase pathway. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/18/4/529/F1.large.jpg.

Novel conjugates of endoperoxide and 4-anilinoquinazoline induce myeloma cell apoptosis by inhibiting the IGF1-R/AKT/mTOR signaling pathway.

4-anilinoquinazoline-containing inhibitors of the epidermal growth factor receptor (EGFR) are widely used in non-small cell lung cancer patients with mutated EGFR, but they are less effective in multiple myeloma (MM), a fatal malignancy derived from plasma cells. The present study designed a series of novel compounds by conjugating a peroxide bridge to the 4-anilinoquinazoline pharmacophore. Further studies showed that these agents such as 4061 and 4065B displayed potent activity to induce MM cell apoptosis by upregulating pro-apoptotic p53 and Bax while downregulating pro-survival Bcl-2. The mechanistic analysis revealed that both 4061 and 4065B inhibited IGF1-R, AKT and mTOR activation in a concentration dependent manner but had no effects on the expression of their total proteins, suggesting the conjugates of endoperoxide and 4-anilinoquinazoline may exert its anti-myeloma activity by targeting the IGF1-R/AKT/mTOR pathway.

Disulfiram/copper markedly induced myeloma cell apoptosis through activation of JNK and intrinsic and extrinsic apoptosis pathways

Disulfiram (DSF) is an FDA approved anti-alcoholism drug in use for more than 60 years. Recently, antitumor activity of the DSF/copper (DSF/Cu) complex has been identified. Its anti-multiple myeloma activity, however, has barely been investigated. In the present study, our results demonstrated that the DSF/Cu complex induced apoptosis of MM cells and MM primary cells. The results indicated that DSF/Cu significantly induced cell cycle arrest at the G2/M phase in MM.1S and RPMI8226 cells. Moreover, JC-1 and Western blot results showed that DSF/Cu disrupted mitochondrial membrane integrity and cleaved caspase-8 in MM cells, respectively, suggesting that it induced activation of extrinsic and intrinsic apoptosis pathways. Interestingly, DSF/Cu induced caspase-3 activation was partly blocked by Z-VAD-FMK (zVAD), a pan-caspase inhibitor, indicating at caspase-dependent and -independent paths involved in DSF/Cu induced myeloma cell apoptosis machinery. Additionally, activation of the c-Jun N-terminal kinase (JNK) signaling pathway was observed in DSF/Cu treated MM cells. More importantly, our results demonstrated that DSF/Cu significantly reduced tumor volumes and prolonged overall survival of MM bearing mice when compared with the controls. Taken together, our novel findings showed that DSF/Cu has potent anti-myeloma activity in vitro and in vivo highlighting valuable clinical potential of DSF/Cu in MM treatment.

Deep profiling of apoptotic pathways with mass cytometry identifies a synergistic drug combination for killing myeloma cells.

Multiple myeloma is an incurable and fatal cancer of immunoglobulin-secreting plasma cells. Most conventional therapies aim to induce apoptosis in myeloma cells but resistance to these drugs often arises and drives relapse. In this study, we sought to identify the best adjunct targets to kill myeloma cells resistant to conventional therapies using deep profiling by mass cytometry (CyTOF). We validated probes to simultaneously detect 26 regulators of cell death, mitosis, cell signaling, and cancer-related pathways at the single-cell level following treatment of myeloma cells with dexamethasone or bortezomib. Time-resolved visualization algorithms and machine learning random forest models (RFMs) delineated putative cell death trajectories and a hierarchy of parameters that specified myeloma cell survival versus apoptosis following treatment. Among these parameters, increased amounts of phosphorylated cAMP response element-binding protein (CREB) and the pro-survival protein, MCL-1, were defining features of cells surviving drug treatment. Importantly, the RFM prediction that the combination of an MCL-1 inhibitor with dexamethasone would elicit potent, synergistic killing of myeloma cells was validated in other cell lines, in vivo preclinical models and primary myeloma samples from patients. Furthermore, CyTOF analysis of patient bone marrow cells clearly identified myeloma cells and their key cell survival features. This study demonstrates the utility of CyTOF profiling at the single-cell level to identify clinically relevant drug combinations and tracking of patient responses for future clinical trials.

Correlation of Nucleostemin with Programmed Death-ligand-1 in Multiple Myeloma U266 Cells

To investigate the correlation of nucleostemin (NS) gene with programmed death ligand-1 (PD-L1) in myeloma cells and the effect of NS expression down-regulation on the apoptosis of multiple myeloma cells, and to evaluate the associations among NS, PD-L1 and biological behavior of MM cells, and the feasibility of both NS and PD-1 as markers reflecting the status of MM cells. The NS gene expression in U266 cells was down-regulated by NS-RNAi-GV248 recombinant lentivirus, the real-time PCR was used to detect the mRNA expression of NS, PD-L1 and PI3K/AKT/mTOR. The Western blot and flow cytometry were used to detect the expression of NS and PD-L1. The Annexin V-APC/7-AAD staining method was used to detect the apoptosis of U266 cells before and after knocking out the NS gene. Under the condition of MOI=10, the transfection efficiency was more than 75% by means of the fluorescent microscopy; real-time PCR showed that compared with the negative control group (1.002±0.026), the mRNA expression of NS, PD-L1 and PI3K/AKT/mTOR gene in the transfection group (0.415±0.089) was significantly reduced (P＜0.05). The results of flow cytometry and Western blot showed that the protein expression of PD-L1 was significantly down-regulated after transfection. After down-regulation of NS gene expression, the apoptosis of U266 cells increased (P＜0.05). The abnormal high expression of NS and PD-L1 genes exists in U266 cells, moreover, the down-regulation of PD-L1 and the related PISK/AKT/mTOR pathway gene expression appears after down-regulation of NS gene expression, which suggest that the cell biological changes resulted from above-mentioned results, show a synergestic effect on U266 cells.

Bone Morphogenetic Protein 4 Gene Therapy in Mice Inhibits Myeloma Tumor Growth, But Has a Negative Impact on Bone.

ABSTRACTMultiple myeloma is characterized by accumulation of malignant plasma cells in the bone marrow. Most patients suffer from an osteolytic bone disease, caused by increased bone degradation and reduced bone formation. Bone morphogenetic protein 4 (BMP4) is important for both pre‐ and postnatal bone formation and induces growth arrest and apoptosis of myeloma cells. BMP4‐treatment of myeloma patients could have the potential to reduce tumor growth and restore bone formation. We therefore explored BMP4 gene therapy in a human‐mouse model of multiple myeloma where humanized bone scaffolds were implanted subcutaneously in RAG2−/− γC−/−mice. Mice were treated with adeno‐associated virus serotype 8 BMP4 vectors (AAV8‐BMP4) to express BMP4 in the liver. When mature BMP4 was detectable in the circulation, myeloma cells were injected into the scaffolds and tumor growth was examined by weekly imaging. Strikingly, the tumor burden was reduced in AAV8‐BMP4 mice compared with the AAV8‐CTRL mice, suggesting that increased circulating BMP4 reduced tumor growth. BMP4‐treatment also prevented bone loss in the scaffolds, most likely due to reduced tumor load. To delineate the effects of BMP4 overexpression on bone per se, without direct influence from cancer cells, we examined the unaffected, non‐myeloma femurs by μCT. Surprisingly, the AAV8‐BMP4 mice had significantly reduced trabecular bone volume, trabecular numbers, as well as significantly increased trabecular separation compared with the AAV8‐CTRL mice. There was no difference in cortical bone parameters between the two groups. Taken together, BMP4 gene therapy inhibited myeloma tumor growth, but also reduced the amount of trabecular bone in mice. Our data suggest that care should be taken when considering using BMP4 as a therapeutic agent. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Updated Analysis of Bellini, a Phase 3 Study of Venetoclax or Placebo in Combination with Bortezomib and Dexamethasone in Patients with Relapsed/Refractory Multiple Myeloma

Updated Analysis of Bellini, a Phase 3 Study of Venetoclax or Placebo in Combination with Bortezomib and Dexamethasone in Patients with Relapsed/Refractory Multiple Myeloma

Panobinostat Potentiates Melphalan-Induced Apoptosis of Myeloma Cells and Minimizes Untoward Side Effects in Multiple Myeloma

Introduction: Studies demonstrating the dynamic interplay between protein acetylation status, cell cycle progression and apoptosis in multiple myeloma (MM) cells have provided a strong rationale for the use of the nonselective histone deacetylase inhibitor (HDACi) panobinostat, as a therapeutic option for MM. However, despite the promising preclinical data, the clinical responses achieved after treatment of MM patients with single-agent panobinostat have been disappointing. On the other hand, this HDACi has been shown to function synergistically with a range of structurally and functionally diverse chemical compounds, including genotoxic drugs, biologically active polypeptides, and novel immune therapies. Since a better understanding of the molecular pathways targeted by panobinostat in MM cells may provide a better rationale for the selection of new drug combinations with synergistic potential, herein we investigate the mechanistic basis for the action of the combination treatment of panobinostat and melphalan in MM. Methods: Malignant bone marrow plasma cells (BMPCs) and peripheral blood mononuclear cells (PBMCs) of 26 unselected newly diagnosed MM patients (12F/14M; median age 60 years, range 42-66) were analyzed. PBMCs from 25 apparently healthy controls were examined in parallel. Cells were pre-treated or not with 5nM panobinostat for 24h, then treated with 100μg/ml melphalan for 5min and critical DNA damage response and repair (DDR/R) signals, including fundamental DNA repair mechanisms [nucleotide excision repair (NER) using Southern blot analysis; interstrand cross-links repair (ICL/R) using quantitative-PCR; double-strand breaks repair (DSB/R) using immunofluorescence quantification of γH2AX foci by confocal microscopy], cells' viability, cytotoxicity and apoptosis rates were evaluated. Moreover, in untreated cells, chromatin organization (using micrococcal nuclease digestion-based analysis) and the levels of certain DNA repair proteins associated with NER and DSB/R mechanisms (using western blot) were also analyzed. The study was approved by the Institutional review board of Alexandra Hospital and all subjects provided informed consent. The study was conducted according to the Declaration of Helsinki. Results: Following ex vivo panobinostat-only treatment, both BMPCs and PBMCs showed acetylation of histone H4 and significant relaxation of chromatin structure. On the other hand, only BMPCs showed a dramatic panobinostat-induced decrease in the levels of critical DNA repair proteins associated with NER (XPC, ERCC3, DDB2) and DSB/R (RAD50, MRE11, KU70, KU80, DNA-PK) mechanisms. No significant effect of panobinostat treatment on the DNA repair proteins was observed in PBMCs from the same ΜΜ patients and in PBMCs from healthy controls. In BMPCs from MM patients, panobinostat potentiates melphalan cytotoxicity, through the inhibition of critical DNA repair mechanisms and the resulting intensification of melphalan-induced DNA damage. Indeed, combined treatment of BMPCs with panobinostat and melphalan significantly reduced the NER, ICL/R and DSB/R capacity of the cells, resulting in significantly increased DNA damage burden compared with melphalan-only treatment (all P&lt;0.01). Moreover, co-treatment of BMPCs with panobinostat and melphalan resulted in significant enhancement of the cytotoxicity and apoptosis rates of the cells, while it significantly reduced BMPCs' viability compared with melphalan-only treatment (P&lt;0.001). In contrast to the BMPCs results, panobinostat pre-treatment of PBMCs from the same patients reduced melphalan-induced toxicity through amelioration of the DNA repair capacity of these cells and the resulting lower melphalan-induced DNA damage burden. Indeed, co-treatment of PBMCs with panobinostat and melphalan significantly increased the NER, ICL/R and DSBs/R capacity of the cells, decreased DNA damage burden, reduced cytotoxicity and apoptosis rates, while it significantly increased PBMCs' viability compared with melphalan-only treatment (all P&lt;0.05). Conclusion: Our data demonstrate that panobinostat potentiates melphalan-induced apoptosis of myeloma cells, and in parallel it helps minimize untoward side effects, thus paving the way to combination therapies with lower side effects and improved anti-myeloma efficacy. Disclosures Dimopoulos: Sanofi Oncology: Research Funding. Terpos:Medison: Honoraria; Takeda: Honoraria, Other: Travel expenses, Research Funding; Janssen: Honoraria, Other: Travel expenses, Research Funding; Genesis: Honoraria, Research Funding; Celgene: Honoraria; Amgen: Honoraria, Other: Travel expenses, Research Funding.

Receptor Tyrosine Kinase AXL: A Potential Strategy to Counter Immune Suppression and Dormancy in Multiple Myeloma

Introduction The AXL receptor tyrosine kinase (AXL) has emerged as a promising therapeutic target for cancer therapy. Recent studies revealed a crucial role of AXL signaling in proliferation, survival, dormancy and therapy resistance in different cancers including lung cancer, hepatocellular cancer and AML. In this study, we aimed to investigate the role of AXL in Multiple Myeloma (MM), focusing on myeloma cell dormancy and AXL expression in different cellular components of the bone marrow microenvironment. Material &amp; Methods To investigate dormancy, we used the syngeneic murine 5TGM1 MM model. 5TGM1-GFP+cells were DiD-labeled and injected intravenously in naïve C57BL/KaLwRij mice. At end-stage, GFP+DiD+('dormant', non-proliferating) and GFP+DiD-('proliferating') MM cells were analyzed by flow cytometry for AXL expression. In addition, AXL expression was also analyzed in CD11b+ myeloid cells and in in vitrogenerated macrophages from the 5TMM model. The effects of AXL inhibition by R428 (BGB324|Bemcentinib, Sigma-Aldrich), a highly potent and AXL-specific small molecular inhibitor, on viability and induced apoptosis of MM cells was determined by Cell Titer Glo and AnnexinV/7AAD staining respectively. AXL expression in human myeloma cell lines (HMCL) (JJN3, U266 and LP-1) and murine 5TGM1 cells was analyzed by qRT-PCR and cytospin stainings. Patient cohorts (TT2/TT3) were used to correlate AXL expression and overall survival. Plasma of healthy donors and MM patients was analyzed by ELISA (R&amp;D). Results Using the in vivo5TGM1 dormancy model, we demonstrated an increased expression of AXL (4x higher) in dormant MM cells compared to proliferating MM cells (n=3, p&lt;0,05). Myeloma cell lines (JJN3, U266, 5TGM1) had a very low AXL expression, however, treatment with melphalan induced a more than twofold increase in AXL expression (n=3, p&lt;0.05). The combination of melphalan and R428 significantly increased apoptosis of JJN3 (&gt;10%), U266 (&gt;20%) and LP-1 (&gt;10%) cells compared to single agent therapy (n=6) (p&lt;0.01). Using patient cohorts, we observed that AXL expression correlated with a good overall survival (p=0.006). In addition, plasma samples of patients (n=31) showed a decreased expression of AXL compared to samples of healthy controls (n=9) (p&lt;0.001). This confirms our hypothesis that AXL is associated with dormancy and therefore correlates with a better overall survival. In a second part, we investigated AXL expression in 5TMM-derived myeloid cells and macrophages (n=3). We observed a high expression of AXL in myeloid derived suppressor cells and tumor associated macrophages compared to myeloma cells. In addition, we observed that myeloid cells were much more sensitive to R428 compared to MM cells (n=5, p&gt;0.01). Conclusion We observed that AXL is highly expressed in dormant MM cells and environmental myeloid cells. Despite its association with a good prognosis in MM, AXL serves as an interesting target to eradicate dormant myeloma cells as AXL inhibitors affect viability and induce apoptosis of myeloma cells, especially in combination with melphalan. Therefore, AXL can be considered as a new therapeutic strategy, to target both the immunosuppressive myeloid cells and the residual cancer cells in MM patients. Disclosures No relevant conflicts of interest to declare.

Characterization of Complete Lncrnas Transcriptome Reveals Expression of Lncrnas As a Prognostic Factor and Linc-Smilo As a Potential Therapeutic Target in Multiple Myeloma

Deregulation of long non-coding RNAs (lncRNAs) is emerging as a common feature of different human tumors and their investigation may uncover novel biomarkers and oncogenic mechanisms. Previous studies have suggested that the alteration of some lncRNAs may play an important role in the pathogenesis of multiple myeloma (MM); however, the complete expression landscape of lncRNAs has not been elucidated. In the present work we characterized the lncRNAs transcriptome of MM and determined the potential involvement of lncRNAs in the pathogenesis and clinical behavior of MM. To characterize the MM transcriptome, we performed paired-end strand-specific RNA sequencing (ssRNA-seq) in 38 purified plasma cell (PC) samples from MM patients and in 3 bone marrow PCs (BMPCs) of healthy donors, as well as in distinct normal B-cell populations (Naïve, Centroblasts, Centrocytes, Memory and Tonsilar PCs). We identified 40,511 novel lncRNAs that were expressed, accounting for more than half of MM transcriptome (56%). This group of novel lncRNAs together with previously annotated lncRNAs comprised most (82%) of the MM transcriptome. We studied the transcriptional heterogeneity in MM samples and observed that lncRNAs showed a much more heterogeneous expression than coding genes, suggesting that these elements could contribute to the biological heterogeneity of the disease. Moreover, to determine differentially expressed genes, each MM patient was compared to normal BMPCs, detecting 19,886 lncRNAs deregulated (10,351 overexpressed and 9,535 downregulated) in more than 50% of patients. We then analyzed the transcriptional dynamics of MM considering the different stages of B-cell differentiation and focused on a group of 989 lncRNAs that were upregulated specifically in plasma cells from MM in comparison with the rest of B-cell stages (MM-specific lncRNAs). Next, we aimed to determine whether upregulation of MM-specific lncRNAs in MM was under epigenetic control so we analyzed the distribution of six histone modifications with non-overlapping functions (H3K4me3, H3K4me1, H3K27ac, H3K36me3, H3K27me3, and H3K9me3) of within the lncRNAs of interest by ChIP-seq in MM cases as compared to normal B cell subtypes. We detected 89 lncRNAs with de novo epigenomic activation. These data suggest an epigenetic rewiring in MM where the loci of most MM-specific lncRNAs are in an inactive state in normal cells and become active in MM. We focused on a specific lncRNA, LINC-SMILO, de novo epigenetically active and expressed in MM cells to determine whether upregulation of this lncRNA could play a role in the pathogenesis of the disease. Knockdown of LINC-SMILO in 3 different MM cell lines (MM.1S, MM.1R and KMS-11) using two different shRNAs, resulted in reduced proliferation and induction of apoptosis of myeloma cells. Using low input RNA-seq (MARS-seq), we found that inhibition of LINC-SMILO was associated with activation of ERVs (Endogenous retroviruses) and increase in interferon (IFN) induced genes and activation of IFN pathways, essential for MM cells survival. Finally, we aimed to determine whether the use of specific lncRNAs could improve the current prognostic stratification of MM patients using the IA11 release of CoMMpass data. We analyzed the prognostic value of lncRNAs using COX regression analysis and Backward elimination of Stepwise regression analysis, obtaining that the overexpression of the lncRNA PDLIM1P4 together with 1q amplification and 17p deletion stratified MM patients in three different risk groups (Figure 1). In summary, our study shows that the lncRNA transcriptome is widely altered in MM and suggests that some of the identified lncRNAs have marked prognostic influence and can be used as potential therapeutic targets for MM. Disclosures Paiva: Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche, and Sanofi; unrestricted grants from Celgene, EngMab, Sanofi, and Takeda; and consultancy for Celgene, Janssen, and Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria. Melnick:KDAc Therapeutics: Membership on an entity's Board of Directors or advisory committees; Constellation Pharmaceuticals: Consultancy; Epizyme: Consultancy; Janssenn: Research Funding.

Loss of IRF4 Results in Multiple Myeloma Cell Apoptosis through the Transcriptional up-Regulation of the BH3-Only Proteins Bmf and BIM

The transcription factor IRF4 is essential for the survival of both normal plasma cells and the plasma cell malignancy multiple myeloma (MM). However the basis for this dependency remains uncertain, with the prevailing view that IRF4 loss in MM induces "death by a thousand cuts." Here we have explored the genetic basis for IRF4 addiction through CRISPR-Cas9 mediated deletion of IRF4 in three lenalidomide sensitive MM cells lines (MM1S, OPM2 and H929) and one resistant cell line (RPMI-8226). Loss of IRF4 resulted in marked loss of viability, irrespective of lenalidomide sensitivity, which was driven by two distinct mechanisms: 1) induction of apoptosis, which was rescued through prior deletion of apoptotic mediators BAX and BAK, and 2) proliferative arrest, which persisted despite rescue from apoptosis. RNA-sequencing following IRF4 inactivation identified a core group of 86 genes whose dysregulation was shared across all 4 MM cell lines. We identified 31 common down-regulated genes (IRF4 activated), including several with previously described roles in survival (such as KLF2, TNFRSF17/BCMA and MYB). Furthermore, MYC, a previously identified target of IRF4 known to play an important role in MM pathogenesis and survival, was down-regulated in 3 of the 4 cell lines. Most surprisingly, IRF4 inactivation resulted in 55 common up-regulated genes that included two BH3-only pro-apoptotic proteins, BMF and BCL2L11 (BIM). Up-regulation of BMF appeared more marked than BIM with an average fold change of 6.5x (range 2.7 - 10.3) vs 1.9x (range: 1.8 - 2.2) respectively. Remarkably, genetic ablation of BMF in the OPM2 cell line and BMF/BIM in the MM1S largely protected from the cell death observed following IRF4 inactivation, suggesting that IRF4 maintains MM survival through the transcriptional repression of BMF and BIM. Our results confirm the vital role of IRF4 for MM proliferation and survival, and shed further light into its critical downstream transcriptional targets. Most interestingly, we have demonstrated that the 'killer blow' appears to be the concerted effect of the BH3-only pro-apoptotic proteins BMF and BIM. Disclosures Huang: Genentech: Patents &amp; Royalties: DCSH is an employee of the Walter and Eliza Hall Institute which receives milestone and royalty payments related to venetoclax.

JX06, a Novel PDK1 Inhibitor, Induces Myeloma Cell Apoptosis By Metabolic Reprogramming and Works Synergistically with Bortezomib

Background: Despite the efficacy of novel agents, multiple myeloma (MM) is still an incurable disease. In order to achieve a cure, it is necessary to develop new therapeutic drugs, which target different pathways from the present anti-MM agents. PDK1 (pyruvate dehydrogenase kinase 1) is a glucose metabolism-related protein often induced by HIF-1. PDK1 inactivates PDH (pyruvate dehydrogenase) through phosphorylation, leading to enhanced glycolysis in the cytoplasm and suppression of oxidative phosphorylation in the mitochondria. PDK1 that is highly expressed in plasma cells is a downstream target of IRF4. We previously reported that PDK1 inhibition is a potent therapeutic strategy in MM (Fujiwara S et al. Br. J. Cancer; 108 (1): 170-178. 2013). However, PDK1 inhibitors, which are effective at low concentrations, are limited at present, making PDK1 inhibition difficult to apply in the clinic. In the present study, we examined the efficacy and mechanism of action of JX06, a novel PDK1 inhibitor, against MM cells. Materials and methods: MM cell lines (NCI-H929,KMS-12PE,KMS-12BM,U266, KMM1, RPMI-8226) were treated with PDK1 inhibitor, JX06, in vitro. Caspase inhibitor, Z-VAD-FMK, was used in combination with JX06 to study the mechanism of JX06 induced MM cell death. Mitochondrial pyruvate carrier (MPC) inhibitor, UK5099, was utilized to block pyruvate transportation into the mitochondria. Bortezomib was used in combination with or without JX06. Growth inhibition of MM cell lines by JX06 were examined by WST-8 assay. Cytotoxicity of primary MM cells by JX06 was examined using flow cytometry after staining with 7AAD. Caspase 3 activity and PDH phosphorylation of MM cell lines were determined by Western blot. Cell cycle analysis of MM cell lines treated with or without JX06 was performed by flow cytometry using BrdU. Detection of apoptosis in MM cell lines were examined by Annexin V and PI staining followed by flow cytometry analysis. Results: JX06 suppressed cell growth of various MM cell lines and primary myeloma cells at low concentrations (0.5-1.0 µM). MM cell death by JX06 accompanied caspase 3 activation and this cell death was suppressed under addition of Z-VAD-FMK, indicating that JX06 induced apoptosis in MM cells. Moreover, phosphorylation of PDH, known as a target of PDK1, was significantly suppressed under JX06 treatment, demonstrating that indeed JX06 exerts anti-MM effect by inhibiting PDK1-PDH pathway. Addition of UK5099 to JX06 suppressed JX06-induced MM cell death, demonstrating that the efficacy of JX06 depends on pyruvate transported into the mitochondria through MPC. There was no significant difference in cell cycle distribution between JX06 treated MM cells compared to control, suggesting that JX06 exerts cytotoxicity independent of cell cycle phase. Moreover, significant increase of cell death was observed in NCI-H929 cell line treated in combination with 0.25 µM JX06 and 2.5 nM bortezomib, although bortezomib alone at concentration of 2.5 nM didn't induce cell death. Conclusion: We demonstrated that JX06 could induce apoptosis of MM cell lines and primary MM cells by inhibiting PDK1. JX06-induced MM cell death is mediated by metabolic shift from glycolysis in the cytoplasm to oxidative phosphorylation in the mitochondria (Fig. 1). Considering its efficacy and the distinct mechanism of action from the current anti-MM agents, JX06 can be a promising anti-MM agent. Furthermore, JX06 not only works as single agent, but can also enhance the efficacy of current anti-MM drugs, suggesting this combination lead to better treatment response and less toxicity. Disclosures Matsuoka: Kyowa Kirin Co., Ltd.: Research Funding; Bristol-Myers Squibb Corp.: Research Funding; Chugai Pharmaceutical Co., Ltd.: Honoraria.

Effects of lncRNA HOTAIR on proliferation and apoptosis of myeloma cells through NF-κB pathway.

The aim of this study was to explore the influences of long non-coding ribonucleic acid (lncRNA) homeobox transcript antisense intergenic RNA (HOTAIR) on the proliferation and apoptosis of myeloma cells and its molecular mechanism. The myeloma cells were randomly divided into three groups, including: group A (myeloma cell group), group B [HOTAIR-small-interfering RNA (siRNA) group], and group C (HOTAIR negative control group). The Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was performed to detect the expression of lncRNA HOTAIR in myeloma cells. The flow cytometry was adopted to determine the apoptosis of myeloma cells. Meanwhile, the protein expression of nuclear factor-kappa-light-chain-enhancer of activated B cells (NF-κB) was detected via Western blotting. In addition, the activity of the myeloma cells was measured using methyl thiazolyl tetrazolium (MTT) assay. The expression of HOTAIR in group A, group B, and group C was (2.19 ± 0.33), (1.37 ± 0.25), and (2.51 ± 0.27), respectively. Compared with group A and group C, the expression of HOTAIR was significantly downregulated in group B, in which the cells interfered with siRNAs. The expression of HOTAIR was significantly higher in group C than group A and group B (p<0.05). HOTAIR expression reached the highest level in group C, followed by group A and group B, respectively. The results of MTT indicated that the activity of the myeloma cells significantly increased at 24 h, 48 h, and 72 h in group C when compared with group A and group B. However, the activity of the myeloma cells was relatively low in group B, showing a slow rising trend. The activity of myeloma cells in group A remarkably increased when compared with group B, but it was lower than group C. Furthermore, the activity of the myeloma cells was higher in group C than group B (p<0.05). Western blotting indicated that the protein expression of NF-κB in group A, group B, and group C was (0.79 ± 0.22), (0.51 ± 0.17), and (0.95 ± 0.31), respectively. Compared with group A and group C, the protein expression of NF-κB was significantly downregulated in group B (the cells interfered with siRNAs) (p<0.05). Meanwhile, the protein expression of NF-κB was markedly higher in group C than in group A and group B (p<0.05). The protein expression of NF-κB was the highest in the cells of group C. Flow cytometry demonstrated that the apoptosis rate in group A, group B, and group C was (9.57 ± 1.71), (20.33 ± 1.63), and (8.74 ± 1.23), respectively. Compared with group A and group C, the apoptosis was significantly elevated in group B, in which the cells interfered with siRNAs (p<0.05). Compared with group A, the number of apoptotic myeloma cells significantly decreased in group C (p<0.05). LncRNA HOTAIR activates the expression of NF-κB in myeloma cells and promotes the proliferation of myeloma cells.

282P - Inhibition of miR-144 and miR-199 promote myeloma pathogenesis via upregulation of versican and FAK/STAT3 signaling

BackgroundMultiple Myeloma (MM) is second most common hematological malignancy characterized by uncontrolled proliferation of abnormal plasma cells in bone marrow. microRNAs are newly emerged nowadays for their involvement in post-transcriptional regulation of certain genes. Earlier, we reported overexpression of an extracellular matrix protein, Versican (VCAN) in MM especially in the stroma but its involvement in disease pathogenesis has not been reported yet. Hence, we studied the role of VCAN via its regulation by microRNAs on myeloma pathogenesis. MethodsThe molecular expression of VCAN was investigated in myeloma cell lines (RPMI8226 & U266). The antagomirs of microRNAs (miR-144 and miR-199) were then transfected into myeloma cells to investigate the effect on VCAN expression along with the effect on proliferation, apoptosis, migration and invasion of myeloma cells. In addition, signaling pathways affected by the inhibition of miR-144 and miR-199 were also identified. The functional regulation of VCAN by miR-144 and miR-199 was also confirmed by reporter luciferase assay in which VCAN 3’UTR was transfected to the myeloma cells. ResultsThe expression of VCAN was found at minimal level in both the myeloma cells. The transfection of antagomirs of miR-144 and miR-199 significantly enhanced the transcript and protein levels of VCAN in myeloma cells. Further, myeloma cells parameters found to be altered in favor of disease progression such as cell proliferation, migration and invasion increased with simultaneous inhibition of apoptosis. In addition, antagomirs mediated upregulation of VCAN promote myeloma progression via activation of FAK/STAT3 signaling. Moreover, transfection of wild type VCAN 3’UTR resulted in significant decrease in luciferase activity which got restored by mutating the binding site of microRNAs. ConclusionsmiR-144 and mir-199 antagomirs mediated over-expression of VCAN promoted the myeloma pathogenesis in vitro with downstream activation of FAK and STAT3 signaling. These findings, therefore, affirm the translational importance of microRNAs which could be adopted as a mean for targeting VCAN and might emerge as an effective therapy for better management of MM in clinical settings in future. Legal entity responsible for the studyAIIMS, New Delhi, India. FundingAll India Institute of Medical Sciences, Council of Scientific and Industrial Research. DisclosureAll authors have declared no conflicts of interest.

Akt inhibition synergizes with polycomb repressive complex 2 inhibition in the treatment of multiple myeloma

Polycomb repressive complex 2 (PRC2) components, EZH2 and its homolog EZH1, and PI3K/Akt signaling pathway are focal points as therapeutic targets for multiple myeloma. However, the exact crosstalk between their downstream targets remains unclear. We herein elucidated some epigenetic interactions following Akt inhibition and demonstrated the efficacy of the combined inhibition of Akt and PRC2. We found that TAS‐117, a potent and selective Akt inhibitor, downregulated EZH2 expression at the mRNA and protein levels via interference with the Rb‐E2F pathway, while EZH1 was compensatively upregulated to maintain H3K27me3 modifications. Consistent with these results, the dual EZH2/EZH1 inhibitor, UNC1999, but not the selective EZH2 inhibitor, GSK126, synergistically enhanced TAS‐117‐induced cytotoxicity and provoked myeloma cell apoptosis. RNA‐seq analysis revealed the activation of the FOXO signaling pathway after TAS‐117 treatment. FOXO3/4 mRNA and their downstream targets were upregulated with the enhanced nuclear localization of FOXO3 protein after TAS‐117 treatment. ChIP assays confirmed the direct binding of FOXO3 to EZH1 promoter, which was enhanced by TAS‐117 treatment. Moreover, FOXO3 knockdown repressed EZH1 expression. Collectively, the present results reveal some molecular interactions between Akt signaling and epigenetic modulators, which emphasize the benefits of targeting PRC2 full activity and the Akt pathway as a therapeutic option for multiple myeloma.