Apoptosis In Myeloma Cells Research Articles

Pembrolizumab Added to First-Line Cyclophosphamide, Bortezomib and Dexamethasone in Newly Diagnosed Transplant Non-Eligible Myeloma Patients: A Phase 2A Open Label, Multi Centre Study

Background: Despite recent improvements, myeloma is still incurable. There is need to add new therapeutic tools. The combination of the proteasome inhibitor (PI) Bortezomib, an alkylator (Cyclophosphamide or Melphalan) and Dexamethasone (Dex) /Prednisone is a widely used first-line therapy. Most patients achieve a rapid response within the first two cycles. The lack of a deep response to the bortezomib-based therapy predicts an inferior outcome, a poor response to newer PIs and limited therapeutic options. Different studies highlighted the role of the PD1/PDL1 pathway in myeloma immune escape and progression. The expression of PDL1 by myeloma cells is higher in relapsed or refractory disease and on minimal residual disease cells. At least one preclinical study showed that the binding of PD1 to PDL1 expressed by the myeloma cells leads to a reverse signal that induces resistance to bortezomib and melphalan. Also, Bortezomib is known to enhance anti-myeloma immune response by different mechanisms, including stimulating myeloma cell apoptosis, sensitizing myeloma cells to natural killer cell mediated killing and enhancing antigen presentation by dendritic cells. This suggests a mutual potentiation between Pembrolizumab and Cyclophosphamide, Bortezomib and Dex (CyBorD). An early immune-based intervention is likely more beneficial. With time and disease progression, the host is more immune-compromised and the disease is more refractory with redundant escape mechanisms. The benefits of early intervention are carefully weighed against the potential risks and other available therapeutic options. The adaptive design of this CMRG-006 trial is meant to select the population with the highest need for treatment improvement while still in the early phase of therapy. We expect the combination of Pembrolizumab and CyBorD to be more effective and well tolerated.Design and Methods: Phase 2A, pilot study. Non-transplant eligible newly diagnosed myeloma patients (NTE-NDMM) will start their standard nine cycles of CyBorD (Cyclophosphamide 300 mg/m 2 PO, Bortezomib 1.5 mg/m 2 SC, and Dex 40 mg PO, all given on days 1, 8, 15 and 22 of 28-day cycle). Patients not having primary disease progression and achieving less than Very Good Partial Response (VGPR) after 2 cycles will be screened for this study during cycle 3. Eligible patients will receive Pembrolizumab 200 mg IV every 3 weeks starting with day 1 of cycle 4 (P-CyBorD). After completion of cycle nine of CyBorD, Pembrolizumab will be administered as a single agent for up to total of 35 doses. The objectives are to evaluate the efficacy and tolerability of P-CyBorD. The key inclusion criteria are having a NTE-NDMM with a measurable disease; no primary progressive disease and not achieving VGPR after two cycles of CyBorD; adequate performance status; and adequate organ functions. The key exclusion criteria include previous exposure to anti-PD1 therapy, intolerance to CyBorD, adverse cardiac history, pulmonary disease, central nervous system disease, congenital or acquired immune suppression, and AL amyloidosis. S ample Size: A maximum of 20 patients will be enrolled to ensure 16 or more patients evaluable for response. Patients with less than VGPR after two cycles of CyBorD have ≤20% probability to achieve ≥VGPR after cycle 9. With the addition of Pembrolizumab, a minimal clinically important difference (MCID) of 10% would be meaningful, and a 50% response rate (≥VGPR) in 16 evaluable patients will be statistically significant.This study is currently recruiting. Clinicaltrials.gov #: NCT04258683. DisclosuresKotb: Amgen: Honoraria; BMS: Honoraria; Merck: Honoraria, Research Funding; Karyopharm: Current holder of individual stocks in a privately-held company; Takeda: Honoraria; Janssen: Honoraria; Celgene: Honoraria; Sanofi: Honoraria, Research Funding; Akcea: Honoraria; Pfizer: Honoraria. Othman: Takeda: Honoraria; Roche: Honoraria; Novartis: Honoraria; Janssen: Honoraria; Sanofi: Honoraria; Celgene: Honoraria. Reece: Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Sanofi: Honoraria; Millennium: Research Funding; BMS: Honoraria, Research Funding; Karyopharm: Consultancy, Research Funding; Amgen: Consultancy, Honoraria; GSK: Honoraria.

Targeting IgE polyadenylation signal with antisense oligonucleotides decreases IgE secretion and plasma cell viability

Allergy regroups numerous complex and various diseases classified as IgE-dependent or non-IgE-dependent hypersensitivities. IgEs are expressed as membrane and secreted forms by B cells and plasma cells, respectively. In IgE-mediated hypersensitivity, IgE secretion and binding to the high-affinity IgE receptor FcεRI on effector cells are responsible for the onset of allergic symptoms; in contrast, surface IgE expression as a B-cell receptor is barely detectable. Our aim was to test an innovative antisense approach to reducing IgE secretion. We designed an antisense oligonucleotide (ASO) targeting the polyadenylation signal of human secreted IgE to redirect IgE transcript polyadenylation from the secreted form to the membrane form. ASO treatments were performed on B cells from transgenic mice expressing humanized IgE (InEps mice), as well as on human primary B cells and myeloma cells. Invivo ASO delivery was tested by using an InEps mouse model. We demonstrated that treatment with a morpholino ASO targeting the secreted IgE polyadenylation signal drastically decreased IgE secretion and inversely increased membrane IgE mRNA expression. In addition, ASO treatment induced apoptosis of IgE-expressing U266 myeloma cells, and RNA sequencing revealed attenuation of their plasma cell phenotype. Remarkably, systemic administration of an ASO coupled with Pip6a as an arginine-rich cell-penetrating peptide decreased IgE secretion invivo. Altogether, this ASO strategy could be an effective way to decrease IgE secretion and allergic symptoms in patients with IgE-dependent allergies, and it could also promote allergen tolerance through apoptosis of IgE+ antibody-secreting cells.

AntagomiR-19a Induced Better Responsiveness to Bortezomib in Myeloma Cell Lines.

Objective Multiple myeloma (MM) is the clonal proliferation of neoplastic plasma cells in the bone marrow. Although bortezomib (BTZ) is a crucial drug for the treatment of MM, drug resistance is a major problem. OncomiR-19a plays an oncogenic role in many cancers, including MM; however, the function of miR-19a in the pathogenesis of MM and drug resistance has not been completely identified. The present research aims to investigate the inhibition of miR-19a by an antagomir to determine BTZ responsiveness, and determine if miR-19a can be a prognostic biomarker for MM. Materials and Methods In this experimental study, viability and apoptosis of myeloma cells were analysed by the colorimetric 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-Diphenyltetrazolium Bromide (MTT) and Annexin V/propidium iodide (PI) flow cytometry assays. Quantitative real-time polymerase chain reaction (qRT-PCR) was implemented to evaluate the expression levels of miR-19a, its targets SOCS3, STAT3, B-cell lymphoma 2 (BCL-2), PTEN and CDKN1A (anti- apoptotic and cell cycle related genes) at the mRNA level. Results miR-19a was downregulated and exacerbated in transfected cells treated with BTZ. The rate of apoptosis in the myeloma cells after BTZ treatment considerably increased, which indicated an increase in the mRNA of SOCS3, PTEN, BCL-2, and CDKN1. A decrease in STAT3 was also observed. ConclusionOncomiR-19a, as a biomarker, may induce better responsiveness to BTZ in myeloma cell lines through its targets SOCS3, STAT3 and PTEN. In the future, this biomarker may provide new therapeutic targets for MM.

Apoptotic Extracellular Vesicles Ameliorate Multiple Myeloma by Restoring Fas-Mediated Apoptosis.

Apoptosis is critical for maintaining bodily homeostasis and produces a large number of apoptotic extracellular vesicles (apoEVs). Several types of cancer cells display reduced expression of Fas on the cell surface and are thus capable of escaping Fas ligand-induced apoptosis. However, it is unknown whether normal cell-derived apoEVs can regulate tumor growth. In this study, we show that apoEVs can induce multiple myeloma (MM) cell apoptosis and inhibit MM cell growth. Systemic infusion of mesenchymal stem cell (MSC)-derived apoEVs significantly prolongs the lifespan of MM mice. Mechanistically, apoEVs directly contact MM cells to facilitate Fas trafficking from the cytoplasm to the cell membrane by evoking Ca2+ influx and elevation of cytosolic Ca2+. Subsequently, apoEVs use their Fas ligand to activate the Fas pathway in MM cells, leading to the initiation of apoptosis. This study identifies the role of apoEVs in inducing MM apoptosis and suggests a potential for apoEVs to treat MM.

Andrographolide, isolated from Andrographis paniculata , induces apoptosis in monocytic leukemia and multiple myeloma cells via augmentation of reactive oxygen species production

Background: Andrographolide (Andro) is a diterpenoid component of the plant Andrographis paniculata that is known for its anti-tumor activity against a variety of cancer cells. Methods: We studied the effects of Andro on the viability of the human leukemia monocytic cell line THP-1 and the human multiple myeloma cell line H929. Andro was compared with cytosine arabinoside (Ara-C) and vincristine (VCR), which are well-established therapeutics against hematopoietic tumors. The importance of reactive oxygen species (ROS) production for the toxicity of each agent was investigated by using an inhibitor of ROS production, N-acetyl-L-cysteine (NAC). Results: Andro reduced the viability of THP-1 and H929 in a concentration-dependent manner. H929 viability was highly susceptible to Andro, although only slightly susceptible to Ara-C. The agents Andro, Ara-C, and VCR each induced apoptosis, as shown by cellular shrinkage, DNA fragmentation, and increases in annexin V-binding, caspase-3/7 activity, ROS production, and mitochondrial membrane depolarization. Whereas Ara-C and VCR increased the percentages of cells in the G0/G1 and G2/M phases, respectively, Andro showed little or no detectable effect on cell cycle progression. The apoptotic activities of Andro were largely suppressed by NAC, an inhibitor of ROS production, whereas NAC hardly affected the apoptotic activities of Ara-C and VCR. Conclusions: Andro induces ROS-dependent apoptosis in monocytic leukemia THP-1 and multiple myeloma H929 cells, underlining its potential as a therapeutic agent for treating hematopoietic tumors. The high toxicity for H929 cells, by a mechanism that is different from that of Ara-C and VCR, is encouraging for further studies on the use of Andro against multiple myeloma.

The Effects of Chidamide Combined with Anti-myeloma Drugs on the Proliferation and Apoptosis of Myeloma Cells

To investigate the effects of chidamide combined with anti-myeloma drugs on the proliferation and apoptosis of myeloma cells. The proliferation inhibition of the cells was detected by CCK-8 method, and flow cytometry was used to detected the apoptosis of the cells. Chidamide could inhibit the proliferation of myeloma cells and promote the apoptosis of primary myeloma plasma cells in a time- and dose-dependent manner (P<0.05). In NCI-H929 cell line, chidamide combined with low-dose bortezomib and lenalidomide showed synergistic effect, while combined with dexamethasone and pomalidomide showed additive effect. In MM.1s cell line, chidamide combined with bortezomib, dexamethasone, lenalidomide and pomalidomide all showed synergistic effects. Chidamide inhibits proliferation of myeloma cells in a time- and dose-dependent manner and promotes apoptosis of primary myeloma plasma cells. Furthermore, it can enhance the inhibitory effect of anti-myeloma drugs.

Andrographolide, isolated from Andrographis paniculata, induces apoptosis in monocytic leukemia and multiple myeloma cells via augmentation of reactive oxygen species production

Background: Andrographolide (Andro) is a diterpenoid component of the plant Andrographis paniculata that is known for its anti-tumor activity against a variety of cancer cells. Methods: We studied the effects of Andro on the viability of the human leukemia monocytic cell line THP-1 and the human multiple myeloma cell line H929. Andro was compared with cytosine arabinoside (Ara-C) and vincristine (VCR), which are well-established therapeutics against hematopoietic tumors. Results: Andro reduced the viability of THP-1 and H929 in a dose-dependent manner. H929 viability was highly susceptible to Andro, although only slightly susceptible to Ara-C. The agents Andro, Ara-C, and VCR each induced apoptosis, as shown by cellular shrinkage, DNA fragmentation, and increases in annexin V-binding, caspase-3/7 activity, reactive oxygen species (ROS) production, and mitochondrial membrane depolarization. The apoptotic activities of Andro were largely suppressed by N-acetyl-L-cysteine (NAC), an inhibitor of ROS production, whereas NAC hardly affected the apoptotic activities of Ara-C and VCR. Furthermore, whereas Ara-C and VCR increased the percentages of cells in the G0/G1 and G2/M phases, respectively, Andro showed little or no detectable effect on cell cycle progression. Conclusions: Andro induces ROS-dependent apoptosis in monocytic leukemia THP-1 and multiple myeloma H929 cells, underlining its potential as a therapeutic agent for treating hematopoietic tumors. Notably, the high sensitivity of H929 cells is encouraging for further studies on the use of Andro against multiple myeloma.

A Randomized Placebo-Controlled Phase II Study of Clarithromycin or Placebo Combined with VCD Induction Therapy Prior to High-Dose Melphalan with Stem Cell Support in Patients with Newly Diagnosed Multiple Myeloma

▪Background: Uncontrolled studies and a case-matched study indicate that clarithromycin might exert synergistic effects in combination with thalidomide or lenalidomide in the treatment of multiple myeloma. Recent cellular studies have shown that the combination of clarithromycin and bortezomib results in increased cytotoxicity compared to bortezomib alone in myeloma cell lines. A possible mechanism underlying this synergistic effect might be simultaneous inhibition of the ubiquitin-proteasome system by bortezomib and the autophagy-lysosome system by clarithromycin resulting in enhanced endoplasmic reticulum stress-mediated apoptosis in myeloma cells (Moriya et al. Int J Oncol 2013).The Danish Myeloma Study Group (DMSG) initiated the CLAIM trial (NCT02573935), a randomized placebo-controlled phase II study, to investigate the efficacy and safety of clarithromycin in combination with the bortezomib containing VCD regimen.Methods: Patients with newly diagnosed multiple myeloma were randomized (1:1) to receive p.o. clarithromycin 500 mg or a matching placebo tablet twice daily for 63 days in combination with VCD induction therapy. The randomization was stratified according to International Staging System stage. The VCD consisted of 21-day cycles of subcut bortezomib 1.3 mg/sqm days 1, 4, 8, 11, i.v. cyclophosphamide 500 mg/sqm on days 1 and 8, and p.o. dexamethasone 40 mg days 1, 2, 4, 5, 8, 9, 11, 12. After induction treatment the patients proceeded to cyclophosphamide priming (2000 mg/sqm), leukapheresis and high-dose melphalan (200 mg/sqm) with hematopoietic stem cell support (HDT). Patients from six Danish hematology departments participated in the trial. Primary endpoint was to compare rate of very good partial response or better response after three cycles of VCD combined with clarithromycin or placebo. Important secondary end-points were to compare very good partial response or better response two months after HDT, number of stem cells harvested, frequency of infections and safety. The responses were assessed according to the IMWG criteria and analyses were by intention to treat.Results: The study was prematurely stopped for safety reasons after the inclusion of 58 patients (36% of the planned study population). The enrolled patients were randomly assigned to clarithromycin (27) or placebo (31), and the clinical characteristics at baseline were balanced (Table I). VGPR or better response after the VCD induction therapy was obtained in 12 patients (44.4%, (95% CI, [25.5 - 64.7]) and in 16 patients (51.6%, [33.1 - 69.8], P = 0.59) in the clarithromycin group and the control group, respectively. There was no difference in the secondary endpoints between the treatment groups (Table I). A total of 26 serious adverse events were reported in 16 (59.3%) patients in the clarithromycin group and 16 serious adverse events in 10 (32.3%) patients in the control group. Seven patients (25.9%) in the clarithromycin group developed severe gastrointestinal complications (SAE ≥ grade 3) comprising pain, neutropenic enterocolitis, paralytic ileus or peptic ulcer. These complications occurred in only one patient in the control group (Table I). Septicaemia with Gram negative bacteria was observed in 5 patients in the clarithromycin group. By contrast, the only case of septicaemia detected in the control group was pneumococcal sepsis associated with pneumonia. In consequence of this imbalance in occurrence of severe gastrointestinal symptoms and septicaemia the study safety board decided to stop inclusion of new patients and to stop administration of the study drug on 16 September 2016.Conclusion: The study was prematurely stopped due to a number of serious adverse events. Although we only could analyse response data in 58 included patients the data do not suggest any effect of clarithromycin when added to the VCD regimen and our trial does not encourage further clinical studies on the combination of clarithromycin and bortezomib. Surprisingly, our study found an increased frequency of serious adverse events, in particular serious gastrointestinal complications and septicaemia, in the clarithromycin group. It emphasizes the need for controlled studies on the effect of clarithromycin, both in assessment of potential anti-myeloma effects as well as assessment of safety measures. [Display omitted] DisclosuresAbildgaard:Takeda: Research Funding.

Deptor As a Target with Chemical Inhibitors; Alternative Therapy in Multiple Myeloma

Multiple myeloma (MM) is a hematological disorder characterized by a proliferation of malignant monoclonal plasma cells in the bone marrow (BM) and/or extramedullary sites. The increase in PFS and overall survival (OS) has been achieved through the introduction of high dose therapy (HDT) with autologous stem cell transplantation (SCT), and the introduction of thalidolamide, bortezomib and lenalidomide. Despite recent progress in OS rates, MM remains an incurable disease and most patients will relapse and require treatment. It is known that inhibition of deptor results in the inhibition of proliferation and induction of apoptosis in myeloma cells. In addition, high levels of deptor are predictive of a poor response to thalidomide in myeloma, indicating that levels of deptor expression is important as a prognostic marker for myeloma patients and would be a possible target for a novel therapeutic strategy, as using a small specific chemical inhibitor of deptor. In this study, we developed a novel small molecule chemical inhibitor (43 M) capable of inducing inhibition of the mTOR/Deptor interaction and results in negative regulation of the deptor that leads in the inhibition of proliferation and induces apoptosis in several cell lines of MM deptor-positive. This effect correlated with the Deptor expression level. The cytotoxic effect of 43 M depends on caspase activity. We analyzed potential mechanisms of 43 M, our findings showed that inhibition of Deptor/mTOR Pathway induces the activation of p70 and AKT. This leads to the induction of apoptosis. We analyzed whether the degradation of 43M-induced deptor-dependent proteosome complex using MG132, and this one prevent deptor degradation. Recent studies describe that the constitutive or inducible activation of the p38 MAPK pathway is considered an important molecular event contributing to the malignant phenotype of the tumor cell in MM. Therefore, these studies identify the interaction of p38 MAPK with Deptor as a new therapeutic target to improve the outcome of patients in MM. We analyzed the possible interaction of p38 MAPK with Debtor mediate a library in yeast. For confirmation of the possible interaction we analyzed the expression of p38 MAPK after treatment with 43 M, the data show that they induce an activation of p38 MAPK and that correlates inversely with the degradation of the deptor. However, simultaneous treatment of MM with 43M and SB203580 does not prevent the induction of 43M-mediated apoptosis. Additionally, the 43M effect was analyzed in a xenografic model of MM cell lines. 8226 MM cell lines were inoculated in 6-week Balb/C nu/ nu mice via s.c. When the tumor reached 500 mm3, they were inoculated on twice with 43 M at different concentrations per group (0, 20 or 40 mg / kg) and the tumor growth and the general state of the mice were subsequently analyzed. Tumor tissue was obtained and the expression of Deptor and 4E-BP1 by IHC was evaluated. The data showed that 43 M significantly inhibited tumor growth at the two doses tested 10 or 20 mg / kg and in tumors decreased the expression of Deptor and induction of 4E-BP1 activation. This study describes for the first time the possible role of Daptor as a therapeutic target using a chemical inhibitor capable of inducing a cytotoxic effect in cell lines positive for Deptor by inducing the degradation of this and activation p38 MAKP in the MM cell lines. In addition, Deptor is reported as an important therapeutic target in an in vivo MM model. DisclosuresNo relevant conflicts of interest to declare.

Structure-Function Relationships of Novel Benzimidazole-Based Inhibitors of the Isoprenoid Biosynthetic Pathway in Myeloma Cells

Malignant plasma cells are characterized by the production of monoclonal protein (MP). Our work has demonstrated that disrupting intracellular MP trafficking by targeting the geranylgeranylation of Rab GTPases results in endoplasmic reticulum stress, induction of the unfolded protein response pathway and apoptosis of myeloma cells. Rab proteins are geranylgeranylated by the enzyme geranylgeranyl transferase II (GGTase II) which uses geranylgeranyl diphosphate as the isoprenoid substrate. We have pursued the development of specific GGTase II and geranylgeranyl diphosphate synthase (GGDPS) inhibitors as potential anti-myeloma agents. A family of compounds incorporating a benzimidazole heterocycle and either a carboxyphosphonate or bisphosphonate was prepared by modification of the appropriate heterocycles. The core benzimidazole phosphonate structure was modified with substituents at either the alpha-carbon position or at the 5 and 6 positions on the benzimidazole (Figure). These compounds were subjected to in vitro enzyme assays for GGTase II and the related prenyltransferases farnesyl transferase (FTase) and GGTase I as well as the synthases farnesyl diphosphate synthase (FDPS) and GGDPS. Cellular disruption of protein prenylation was assessed via immunoblot analysis for Ras (a representative farnesylated protein) and for unmodified Rap1a (a representative geranylgeranylated protein) in human myeloma cells (RPMI-8226, MM.1S). The ability of the novel compounds to disrupt MP trafficking was determined by measuring changes in intracellular lambda light chain levels via ELISA. Confirmation of disruption of Rab geranylgeranylation was achieved by Triton X-114 lysis to obtain detergent (membrane) fractions which were subjected to Rab6 (a representative Rab protein) immunoblot analysis. These studies demonstrated that the nature of the phosphonate head group has a profound impact on enzyme specificity: the carboxyphosphonates have specific activity as GGTase II inhibitors while the bisphosphonate analogues have specific activity as FDPS inhibitors with no cross-reactivity against any of the other tested enzymes. The most potent GGTase II and FDPS inhibitors were the unsubstituted analogues. The carboxyphosphonate 1 was found to have an IC50 of 230 μM against GGTase II and cellular activity starting at 2.5 mM. This represents a two-fold improvement in potency compared with the known GGTase II inhibitor 3-PEHPC. The bisphosphonate 5 has an IC50 of 24 nM against FDPS and cellular activity at ≥ 50 μM. The addition of a methyl group at the alpha-carbon position abrogated the activity of the carboxyphosphonate (2) as a GGTase II inhibitor and the activity of the bisphosphonate (6) as a FDPS inhibitor. The addition of substituents at the 5 and 6 positions (compounds 3, 4, 7 and 8)did not improve potency compared with the parent compounds. Co-incubation with low concentrations of the HMG-CoA reductase inhibitor lovastatin (0.1-1 μM), concentrations which on their own are not sufficient to disrupt protein prenylation, potentiated the cellular activity of the lead GGTase II and FDPS inhibitors. In conclusion, these benzimidazole phosphonates represent novel classes of GGTase II and FDPS inhibitors. These studies highlight the importance of the identity of the phosphonate head-group in dictating enzyme specificity. Further studies are underway to prepare additional benzimidazole analogues in order to improve their potency, advance the understanding of the structure-function relationship, and assess the potential of these compounds as anti-myeloma agents. [Display omitted] DisclosuresWiemer:Terpenoid Therapeutics, Inc: Other: Founder. Holstein:Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy.

A Novel Phthalimide-Derivative, TC11, Induced G2/M Arrest and Apoptosis of High-Risk Myeloma Cells By Interacting with Nucleophosmin1 and α-Tubulin, but Not By Binding to Celeblon

Background and Purpose:Emergence of novel drugs including immunomodulatory drugs (IMiDs) such as thalidomide, lenalidomide and pomalidomide have markedly improved the survival of multiple myeloma (MM) patients. However, IMiDs have substantial limitation in the treatment of MM; little effect on MM patients with high-risk cytogenetic changes and their teratogenicity. Recently it was reported that IMiDs showed anti-tumor activity as well as teratogenicity by directly binding to cereblon (CRBN).We have previously reported that a novel phthalimide-derivative, 2-(2,6-diisopropylphenyl)-5-amino-1H-isoindole-1,3-dione (TC11), induced apoptosis of high-risk MM cells in vivo and also showed anti-osteoclastogenic activity. At the same time, we observed abnormal α-tubulin fragmentation in TC11-treated MM cell (Matsushita et. al. PLoS One 2015). We have also demonstrated that TC11 bound to nucleophosmin 1(NPM1) and α-tubulin using in vitro virus (IVV) method (Shiheido et. al. PLoS One 2012). Interestingly, lenalidomide also bound to NPM1. The purpose of this study is to clarify molecular mechanisms of anti-myeloma effects of TC11.Results and Discussion:(1) Effect of TC11 is CRBN-independent:Recently it was reported that lenalidomide bound to CRBN, resulting in degradation of its substrates, IKZF1/3 and CK1α. In this study, we found that lenalidomide caused degradation of IKZF1/3 and CK1α in the high-risk MM cell line, KMS34. However, TC11 didn't down-regulate CRBN or its substrates, IKZF1/3 and CK1α. Taken together with the result of Biacore assay, TC11 induced MM cell death via CRBN-independent pathway.(2) Cell cycle arrest by TC11 vs. lenalidomide:Then we tried to elucidate molecular mechanisms of TC11 by the microarray analysis of KMS21, which is highly sensitive to TC11 and lenalidomide. Microarray Gene Set Enrichment Analysis (GSEA) indicated that TC11 upregulated the gene set of G2/M checkpoint, however lenalidomide did not. These results were also confirmed by analyzing the DNA contents of MM cells using flow cytometry and by western blot analysis of cell cycle regulators, phosphorylated cdc2 and p21. These data suggest that TC11 induced apoptosis of MM cells by distinct molecular mechanism from lenalidomide probably by regulating G2/M cell cycle. TP53 gene regulates G1/S cell cycle and occasionally deleted in high-risk MM cells. However, TC11 is able to induce apoptosis of TP53 -deleted high-risk MM cells by causing G2/M arrest.(3) Inhibition of tubulin assembly by TC11:Since we have previously showed that TC11 bound to α-tubulin by IVV method, we speculated that TC11 affected tubulin polymerization or depolymerization. Treatment of MM cells with TC11 significantly reduced polymerized fraction of α-tubulin, indicating TC11 inhibited tubulin polymerization. In contrast, lenalidomide did not inhibit either tubulin polymerization or depolymerization. In this regard, the mechanism of TC11 is different from that of lenalidomide.(4) Inhibition of oligomerization of NPM1 by TC11:We have also showed that TC11 bound to NPM1 by IVV method (Shiheido et. al. PLoS One 2012). It has been reported that oligomerized NPM1 had pleiotropic biological functions. Thus we examined whether TC11 affected NPM1 oligomerization using blue native polyacrylamide gel electrophoresis. As a result, TC11 treatment significantly reduced the amount of oligomerized NPM1 fraction. At the same time, we found that TC11 significantly increased in phosphorylation of NPM1 at Ser4, Thr95 and Thr199. It has been reported that phosphorylation of NPM1 inhibited its oligomerization (Mitrea et. al. Proc Natl Acad Sci U S A 2014). Thus, we speculated that TC11-induced phosphorylation resulted in inhibition of oligomerization of NPM1.Conclusion:It was shown that TC11 bound to α-tubulin and NPM1, but not to CRBN. TC11 inhibited tubulin assembly as well as NPM1 oligomerization, leading to G2/M arrest and mitotic catastrophe. These novel molecular events by TC11 induced apoptosis of TP53 -deleted high-risk MM cells. [Display omitted] DisclosuresYonemura:IDAC Theranostics Inc.: Employment. Tabata:IDAC Theranostics Inc.: Employment. Yanagawa:IDAC Theranostics Inc.: Employment. Hattori:Cosmic Corporation Co., Ltd.: Research Funding; Merck Sharp & Dohme: Research Funding; Takeda Pharmaceutical Company Limited.: Research Funding.

Everolimus Shows Synergistic Anti-Myeloma Effects with Bortezomib Via the AKT/mTOR Pathway

Introduction: Multiple myeloma (MM) is characterized by the proliferation of malignant plasma cells and a subsequent overabundance of monoclonal paraprotein (M protein). Everolimus ,as an oral mammalian target of rapamycin (mTOR) inhibitor, plays an important role in multiple myeloma. In the phase I trial explored the use of everolimus in relapsed and/or refractory multiple myeloma patients ,the median time to progression was 90 days (range, 13 to 278 days),and no dose-limiting toxicity was observed at daily dose of 10 mg. At the same time, the observed responses are promising in some testing combination strategies. The pre-clinical activity of pan-histone deacetylase inhibitor LBH589 in combination with everolimus caused potent G0/G1 arrest and induced pronounced apoptosis, the combination led to down regulation of pStat3, cyclins, CDKs and XIAP and up regulation of pro-apoptotic Bcl-2 family proteins. Everolimus enhances the cytotoxicity of bendamustine in multiple myeloma cells through a network of pro-apoptotic and cell-cycle-progression regulatory proteins.Down regulation of vascular endothelial cell growth factor and everolimus synergistic antitumor activity in multiple myeloma cells. Furthermore, In a phase I study of everolimus in combination with lenalidomide in relapsed or refractory multiple myeloma patients, the overall response rate was 65% and median progression-free survival was 5.5 months. Bortezomib was the first therapeutic proteasome inhibitor to be tested in humans with MM. However, the combination of bortezomib and everolimus for the treatment of MM is still less reported.Methods: To evaluate the in vitro and in vivo anti-tumor activity of the combination of everolimus with bortezomib.CCK-8 was used to explore the proliferation of MM cells. Flow cytometry was used to determine the effect on apoptosis of cells.Western blot and Immunohistochemical staining was used to determine the epression of proteins.Results: In our study, the experimental results demonstrated that everolimus combined with bortezomib suppressed cell proliferation. Treatment with 20 nM everolimus in combination with 10 nM bortezomib for 72h achieved the lowest cell survival rate in both U266 and LP-1 MM cell lines. The combination of everolimus and bortezomib was synergistic in both cell lines indicated by combination index (CI) values of <0.8.Flow cytometry was used to determine the effect on apoptosis of bortezomib in combination with everolimus. everolimus alone and bortezomib alone induced approximately 22.5% and 17.2% apoptosis, combination treatment induced28.8% apoptosis in U266 cells, and the results were 15.6%,10.0% and 16.7% in LP-1 cells. Western blot was used to explore the mechanisms. The expression of AKT1, mTOR, p70S6K1, 4EBP1 and NF-kB was significantly down regulated while the expression of Caspase-3was significantly up regulated in combination group than other alone group. Furthermore, Synergistic antitumor effect of everolimus and bortezomib was observed in the animal model carrying the myeloma xenograft on the 25th day after tumor implantation . The results of immunohistochemical staining further demonstrated that the expression of AKT1, mTOR, p70S6K1, 4EBP1 and NF-kB was significantly down regulated and the expression of Caspase-3 was significantly up regulated in combination group.Conclusion:Our results shows synergistic antitumor effects of the combination therapy of bortezomib and everolimus induced myeloma cell apoptosis in vitro and in vivo xenograft mouse model ,which mainly through the inhibition of the AKT/mTOR pathway. Our results provided provide a rationale application for the combinatorial treatment of MM with proteasome inhibitor agents and mTOR inhibitors in future clinical practice. DisclosuresNo relevant conflicts of interest to declare.

The c-Abl inhibitor, radotinib induces apoptosis in multiple myeloma cells via mitochondrial-dependent pathway

Multiple myeloma (MM) is a hematological cancer resulting from accumulated abnormal plasma cells. Unfortunately, MM remains an incurable disease, as relapse is very common. Therefore, there is urgent need to develop new treatment options for MM. Radotinib is a novel anti-cancer drug, currently approved in South Korea for the treatment of chronic myeloid leukemia patients. Its mechanism of action involves inhibition of the tyrosine kinase Bcr-Abl and the platelet-derived growth factor receptor. Generally, the mechanism of inhibition of non-receptor tyrosine kinase c-Abl has played an essential role in the inhibition of cancer progression. However, little is known regarding the effects of the c-Abl inhibitor, radotinib on MM cells. In this study, we analyzed the effect of radotinib on multiple myeloma cells. Interestingly, radotinib caused apoptosis in MM cells including RPMI-8226, MM.1S, and IM-9 cells, even in the absence of c-kit expression in 2 of these lines. Radotinib treatment significantly increased the number Annexin V-positive cells and decreased the mitochondrial membrane potential in MM cells. Additionally, we observed that cytochrome C was localized in the cytosol of radotinib-treated MM cells. Moreover, radotinib decreased the expression of Bcl-2 and Bcl-xL, and increased the expression of Bax and Bak in MM cells. Furthermore, radotinib promoted caspase pathway activation by inducing the expression and activity of caspase-3, -7, and -9. Expression of cleaved PARP-1 was also increased by radotinib treatment in various MM cells. In addition, radotinib significantly suppressed MM cell growth in a xenograft animal model using RPMI-8226 cells, and killed ex vivo myeloma cells from patients. In conclusion, radotinib may play an important role as a candidate agent or chemosensitizer for the treatment of MM.

Effect of TRIM31 Gene Silencing on the Proliferation and Apoptosis of U266 Cells and Its Mechanism

To investigate the effect of the tripartite motif containing 31 (TRIM31) gene silencing on the proliferation and apoptosis of multiple myeloma cells and its possible mechanism. The normal bone marrow plasma cells (nPCs) were selected as control, and the mRNA and protein expression levels of TRIM31 in human multiple myeloma cell lines (U266, RPMI-8226, NCI-H929 and KMS-11) were detected by RT-qPCR and Western blot. Recombinant lentivirol vector containing shRNA-TRIM31 and its negative control were used to infect U266 cells respectively, and the mRNA expression level of TRIM31 in infected cells was detected by RT-qPCR. Then cell proliferation, colony forming and apoptosis were analyzed by CCK-8, soft agar assay, and flow cytometry, respectively. The protein expression levels of TRIM31, cleaved-caspase-3, BCL-2, Bax, p-Akt (Ser473), Akt and PI3K (p110α) were evaluated by Western blot. In addition, the PI3K/Akt signaling pathway-specific inhibitor LY294002 and TRIM31-shRNA lentivirus were used to interfere with U266 cells, and the cell proliferation, apoptosis, and protein expression of p-Akt (Ser473) and Akt were detected by CCK-8, flow cytometry and Western blot, respectively. Compared with nPCs, the expression levels of TRIM31 mRNA and protein in U266, RPMI-8226, NCI-H929 and KMS-11 cells were significantly increased (P<0.001), especially in U266 cells. After lentivirus infection, the levels of TRIM31 mRNA and protein in U266 cells were significantly decreased (P<0.001). TRIM31 silencing significantly inhibited the proliferation of U266 cells (P<0.05), attenuated the ability of cell cloning, improved cell apoptosis, up-regulated the protein expressions of cleaved-caspase-3 and Bas as well as down-regulated expressions of BCL-2, p-Akt (Ser473) and PI3K (p110α). There was no significant effect on Akt protein. Intervention of LY294002 significantly enhanced the inhibition on cell proliferation and the promotion on apoptosis mediated by TRIM31 gene silencing in U266 cells. TRIM31 gene silencing can inhibit U266 cell proliferation and promote its apoptosis, which may be closely related to inhibition of PI3K/Akt signaling pathway.

The Inhibiting Effect of Autophagy Inhibitor ROC-325 on Multiple Myeloma

To investigate the effects of autophagy inhibitor ROC-325 and its combination with bortezomib on the proliferation, apoptosis and autophagy of multiple myeloma cell lines. Multiple myeloma cells were treated with ROC-325 at different concentration. The cell proliferation was detected by CCK-8. Apoptosis was determined by Caspase-3/7 and Caspase-9 activity assays. Autophagy was detected by monodansylcadaverine staining. The apoptosis-related proteins (PARP and Caspase-3) and autophagy-related proteins (P62, Beclin-1, and LC3A/B) were analyzed by Western blot. The combined effect with bortezomib on bortezomib-resistant cell line was detected by CCK-8. ROC-325 inhibited the proliferation of RPMI 8226, RPMI 8226-BTZ100, U266 and IM9 cells in a dose-dependent manner (r=-0.8275, r=-0.9079, r=-0.9422, r=-0.9305), the 72 h IC50 values were 2.795, 4.020, 5.432 and 4.755 μmol/L, respectively. The activity assays of Caspase-3/7 and Caspase-9 showed that their relative activity was increased gradually in proportion to the drug concentration with the statistically significant difference (r=0.9648, r=0.9377, r=0.9318; r=0.9087, r=0.9431, r=0.8914). MDC staining results showed that the number of autophagic vacuoles increased with the rise of ROC-325 concentration (r=0.9565, r=0.9373, r=0.9233). ROC-325 could increase the expression of apoptosis-related proteins (PARP and Caspase-3) and autophagy-related proteins (P62 and LC3-Ⅱ/LC3-Ⅰ), but decrease the expression of Beclin-1 detected by Western blot. The CCK-8 assay showed that ROC-325 combined with bortezomib had synergistic effect on the inhibition of drug resistant cell line RPMI 8226-BTZ100. ROC-325 can inhibit the proliferation, induce the apoptosis of myeloma cells through the mitochondrial pathway, inhibit the autophagy of myeloma cells by affecting the fusion of autophagosomes and lysosomes, and overcome bortezomib resistance by the combination of ROC-325 with bortezomib.

Therapeutic Targeting of Protein Disulfide Isomerase PDIA1 in Multiple Myeloma.

Simple SummaryMultiple myeloma (MM) is a cancer of antibody-producing plasma cells that remains incurable. These cells heavily depend on protein disulfide isomerase, PDIA1, for folding and structural integrity of antibodies and other secretory proteins to avoid unresolvable stress caused if they remain unfolded. High PDIA1 expression confers resistance to proteasome inhibitors and other stressors due to the gain in endoplasmic reticulum (ER) function, while maintaining or increasing vulnerability to PDIA1 inhibition. Here we report the identification and characterization of an orally bioavailable novel PDIA1 inhibitor CCF642-34 that is effective against multiple myeloma in pre-clinical models. PDIA1, the ER resident enzyme essential for the folding of disulfide bond-containing proteins, is upregulated in relapse and refractory myeloma. This increase in PDIA1 confers its sensitivity to CCF642-34, a structurally optimized PDIA1 inhibitor that induces apoptosis in myeloma cells but not in normal bone-marrow-derived CD34+ hematopoietic stem and progenitor cells.Multiple myeloma is a genetically complex hematologic neoplasia in which malignant plasma cells constantly operate at the maximum limit of their unfolded protein response (UPR) due to a high secretory burden of immunoglobulins and cytokines. The endoplasmic reticulum (ER) resident protein disulfide isomerase, PDIA1 is indispensable for maintaining structural integrity of cysteine-rich antibodies and cytokines that require accurate intramolecular disulfide bond arrangement. PDIA1 expression analysis from RNA-seq of multiple myeloma patients demonstrated an inverse relationship with survival in relapsed or refractory disease, supporting its critical role in myeloma persistence. Using a structure-guided medicinal chemistry approach, we developed a potent, orally bioavailable small molecule PDIA1 inhibitor CCF642-34. The inhibition of PDIA1 overwhelms the UPR in myeloma cells, resulting in their apoptotic cell death at doses that do not affect the normal CD34+ hematopoietic stem and progenitor cells. Bortezomib resistance leads to increased PDIA1 expression and thus CCF642-34 sensitivity, suggesting that proteasome inhibitor resistance leads to PDIA1 dependence for proteostasis and survival. CCF642-34 induces acute unresolvable UPR in myeloma cells, and oral treatment increased survival of mice in the syngeneic 5TGM1 model of myeloma. Results support development of CCF642-34 to selectively target the plasma cell program and overcome the treatment-refractory state in myeloma.

M3258 Is a Selective Inhibitor of the Immunoproteasome Subunit LMP7 (β5i) Delivering Efficacy in Multiple Myeloma Models.

Large multifunctional peptidase 7 (LMP7/β5i/PSMB8) is a proteolytic subunit of the immunoproteasome, which is predominantly expressed in normal and malignant hematolymphoid cells, including multiple myeloma, and contributes to the degradation of ubiquitinated proteins. Described herein for the first time is the preclinical profile of M3258; an orally bioavailable, potent, reversible and highly selective LMP7 inhibitor. M3258 demonstrated strong antitumor efficacy in multiple myeloma xenograft models, including a novel model of the human bone niche of multiple myeloma. M3258 treatment led to a significant and prolonged suppression of tumor LMP7 activity and ubiquitinated protein turnover and the induction of apoptosis in multiple myeloma cells both in vitro and in vivo Furthermore, M3258 showed superior antitumor efficacy in selected multiple myeloma and mantle cell lymphoma xenograft models compared with the approved nonselective proteasome inhibitors bortezomib and ixazomib. The differentiated preclinical profile of M3258 supported the initiation of a phase I study in patients with multiple myeloma (NCT04075721).

A novel form of anti-angiogenic molecular antibody drug induces apoptosis in myeloma cells after cultivation upon endothelial feeder cells

The present study aimed to investigate the ability of a novel form of the anti-angiogenic molecular antibody drug to induce Myeloma cell death after cultivation upon endothelial feeder cells. Bevacizumab-loaded chitosan (BCS) nanoparticles (NPs) were prepared by the ionic gelation method. Human U266 cell line and human umbilical vein endothelial cells were co-cultured for 72 h and treated with BCS nanoparticles (10μM) to study their impact on inhibition of cell growth and induction of apoptosis. Death assessments, P53 pro-apoptotic marker expression and the VEGF level were investigated by flow-cytometric analyses of the Annexin V, immunocytochemistry and ELISA, respectively. The endothelial monolayer co-culture showed protection of myeloma cells from apoptosis when exposed to NPs or without any treatment. In present of bevacizumab, the VEGF factor was effectively suppressed, and the p53 expression was significantly increased in bevacizumab-treated myeloma cells co-cultured with HUVECs, compared to other groups. BCS was capable of disturbing the effective interconnections of myeloma cells and HUVECs as supportive cells. Disruptions of tumor cells' connections with their microenvironment and blocking their possible supportive pathways might be a potential strategy to eradicate tumor cells and finally cure such types of cancer.

Bortezomib induces anti-multiple myeloma immune response mediated by cGAS/STING pathway activation.

Proteasome inhibitor bortezomib induces apoptosis in multiple myeloma (MM) cells, and has transformed patient outcome. Using in vitro as well as in vivo immunodeficient and immunocompetent murine MM models, we here show that bortezomib also triggers immunogenic cell death (ICD) characterized by exposure of calreticulin on dying MM cells, phagocytosis of tumor cells by dendritic cells, and induction of MM specific immunity. We identify a bortezomib-triggered specific ICD-gene signature associated with better outcome in two independent MM patient cohorts. Importantly, bortezomib stimulates MM cells immunogenicity via activation of cGAS/STING pathway and production of type-I interferons; and STING agonists significantly potentiate bortezomib-induced ICD. Our studies therefore delineate mechanisms whereby bortezomib exerts immunotherapeutic activity, and provide the framework for clinical trials of STING agonists with bortezomib to induce potent tumor-specific immunity and improve patient outcome in MM.

Blockage of the JAK/STAT3 signaling pathway in multiple myeloma by leelamine

BackgroundLeelamine (LEE) is a lipophilic diterpene amine phytochemical, which can be naturally extracted from pine's bark trees. It has been extensively studied recently for its promising chemopreventive and anti-cancer effects against various cancers such as that of prostate and breast. HypothesisWe examined the potential impact of LEE in affecting the activation of signal transducer and activator of transcription 3 (STAT3) and promoting apoptosis in human multiple myeloma (MM) cells. MethodsWe evaluated the effect of LEE on STAT3 signaling pathway in MM cells by using Western blot analysis and reverse transcription polymerase chain reaction (RT-PCR). Thereafter, apoptosis was evaluated using cell cycle analysis and Annexin V assay. ResultsWe noted that LEE could attenuate the phosphorylation of STAT3 and other up-stream signaling molecules such as JAK1, JAK2, and Src activation in U266 and MM.1S cells. It also diminished STAT3 translocation into the nucleus and enhanced the expression of protein-tyrosine phosphatase epsilon (PTPε). Additionally, LEE caused cell cycle arrest and synergistically augmented the apoptotic actions of bortezomib against MM cells. ConclusionsOur data indicates that LEE could block STAT3 signaling cascade linked to tumorigenesis and can be used in combination with approved anti-cancer agents in attenuating MM growth and survival.