benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Multiple-Myeloma

To investigate the effects of FTY720 on apoptosis in multiple myeloma cell line U266 and to clarify the molecular mechanism of apoptosis induced by FTY720.. U266 cells were treated with 2.5, 5, 10 and 20 µmol/L of FTY720 for 24 hours, the apoptotic rates were tested by flow cytometry with Annexin-V-FITC/PI staining. Then U266 cells were treated with 20 µmol/L FTY720 for 0, 6, 16 and 24 hours, the apoptotic rates were tested. U266 cells were treated with DMSO and FTY720 separately and then were stained with DAPI for 5 min. Drop the cells to the slides and cover the slide with the glass. The cells were observed by fluorescence microscopy. U266 cells were treated with 5 µmol/L FTY720 or together with different doses of Z-VAD-fmk (12.5, 25, 50 µmol/L), a pancaspase inhibitor, for 24 hours, then the cell viability was tested by CCK-8. U266 cells were treated with 2.5, 5, 10 and 20 µmol/L of FTY720 for 24 hours, the expression of cleaved caspase-3 was tested by Western blot. U266 cells were treated with 0, 5, 10 and 20 µmol/L of FTY720 for 24 hours, the expressions of MCL-1, survivin, BCL-2, BID, BAX, BAK, P-ERK were tested by Western blot.. The apoptotic rate increased in U266 cells treated with FTY720 and showed the characteristic of time-dependent and dose-dependent manner. Karyopyknosis and nuclearfragmentation could be observed in U266 cells treated with FTY720 after being stained with DAPI under fluorescent microscope. The same effect was not observed in the cells treated with DMSO. Z-VAD-fmk could rescue the apoptosis in U266 cells treated with FTY720 in dose-dependent manner. The expression of MCL-1, survivin and BCL-2 decreased in U266 cells treated with FTY720. The cleavage of BID could be observed in U266 cells treated with FTY720. FTY720 had no effect on the expression of BAX, BAK and P-ERK.. FTY720 can induce the apoptosis in U266 cells, the apoptosis was Caspase-3-depended. The apoptosis induced by FTY720 is due to the decrease of MCL-1, survivin and BCL-2, which are the inhibitors of apoptosis. Meanwhile, the apoptosis was also due to the activation of BID, which is pro-apoptotic protein.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Caspase 3; Cell Line, Tumor; Cell Survival; Fingolimod Hydrochloride; Humans; Inhibitor of Apoptosis Proteins; Multiple Myeloma

NF-κB transcription factor plays a key role in the pathogenesis of multiple myeloma in the context of the bone marrow microenvironment. Both canonical and noncanonical pathways contribute to total NF-κB activity. Recent studies have shown a critical role for the noncanonical pathway: selective inhibitors of the canonical pathway present a limited activity, mutations of the noncanonical pathway are frequent, and bortezomib-induced cytotoxicity cannot be fully attributed to inhibition of canonical NF-κB activity.. Multiple myeloma cell lines, primary patient cells, and the human multiple myeloma xenograft murine model were used to examine the biologic impact of dual inhibition of both canonical and noncanonical NF-κB pathways.. We show that PBS-1086 induces potent cytotoxicity in multiple myeloma cells but not in peripheral blood mononuclear cells. PBS-1086 overcomes the proliferative and antiapoptotic effects of the bone marrow milieu, associated with inhibition of NF-κB activity. Moreover, PBS-1086 strongly enhances the cytotoxicity of bortezomib in bortezomib-resistant multiple myeloma cell lines and patient multiple myeloma cells. PBS-1086 also inhibits osteoclastogenesis through an inhibition of RANK ligand (RANKL)-induced NF-κB activation. Finally, in a xenograft model of human multiple myeloma in the bone marrow milieu, PBS-1086 shows significant in vivo anti-multiple myeloma activity and prolongs host survival, associated with apoptosis and inhibition of both NF-κB pathways in tumor cells.. Our data show that PBS-1086 is a promising dual inhibitor of the canonical and noncanonical NF-κB pathways. Our preclinical study therefore provides the framework for clinical evaluation of PBS-1086 in combination with bortezomib for the treatment of multiple myeloma and related bone lesions.

Topics: Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Boronic Acids; Bortezomib; Cell Differentiation; Cell Line, Tumor; Cyclohexanones; Doxorubicin; Epoxy Compounds; Humans; Leukocytes, Mononuclear; Mice; Multiple Myeloma; NF-kappa B; Osteoclasts; Pyrazines; RANK Ligand; Signal Transduction; Transplantation, Heterologous

The oligomerization status of soluble tumor necrosis factor-related apoptosis inducing ligand (TRAIL) trimers has an overwhelming impact on cell death induction in a cell-type dependent fashion. Thus, we evaluated the ability of single and oligomerized TRAIL trimers to induce cell death in human myeloma cells. In all myeloma cell lines analyzed, oligomerized TRAIL trimers induced caspase activation and complete cell death, whereas non-oligomerized TRAIL trimers showed no or only a modest effect. Caspase activation induced by oligomerized TRAIL was blocked in all cell lines by the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (z-VAD-fmk). Cell death induction was largely blocked in two cell lines by z-VAD-fmk, but was only marginally attenuated in three other cell lines, indicating that TRAIL induces caspase-dependent and caspase-independent cell death in myeloma cells. Preceding cell death, TRAIL activated nuclear factor kappaB, c-Jun N-terminal kinase, p38 and p42/44. Although TRAIL-induced stimulation of c-Jun N-terminal kinase and p38 was caspase-dependent in a cell type-specific fashion, activation of nuclear factor kappaB and p42/44 was caspase-independent in all cases. In accordance with activation of the nuclear factor kappaB pathway, we observed transcriptional up-regulation of several well established nuclear factor kappaB target genes. Furthermore, we found that TRAIL activates proinflammatory pathways in approximately 50% of primary myeloma samples. Taken together, our data suggest (a) that oligomerized TRAIL variants are necessary to ensure maximal cell death induction in myeloma cells and (b) TRAIL should be used in combination with anti-inflammatory drugs for treatment of myeloma to avoid and/or minimize any potential side-effects arising from the proinflammatory properties of the molecule.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Caspase Inhibitors; Caspases; Cell Death; Cell Line, Tumor; Humans; Inflammation Mediators; JNK Mitogen-Activated Protein Kinases; Multiple Myeloma; NF-kappa B; Signal Transduction; TNF-Related Apoptosis-Inducing Ligand

The growth and survival of myeloma cells is critically regulated by cells of the bone marrow microenvironment, including osteoblasts. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent inducer of myeloma cell apoptosis, however, this antimyeloma activity is inhibited by osteoprotegerin (OPG) released from osteoblasts. Therefore, we hypothesized that specific agonists of TRAIL death receptors would not be inhibited by OPG released from osteoblasts and thus may represent a novel therapeutic approach in multiple myeloma. In the present study, TRAIL-induced apoptosis was demonstrated to be mediated through both DR4 and DR5. Specific agonist antibodies to DR4 or DR5 dose-dependently induced myeloma cell apoptosis, which was not prevented by OPG or by medium conditioned by osteoblasts. Co-culture of myeloma cells with osteoblasts protected against TRAIL-induced apoptosis of myeloma cells, and this protective effect was due to OPG. In contrast, the co-culture of myeloma cells with osteoblasts had no protective effect on apoptosis induced by specific agonists of DR4 or DR5. TRAIL has been proposed as a potential antitumour therapy, but within the bone marrow microenvironment OPG may interfere with the action of TRAIL. Specific agonists of TRAIL death receptors would not be subject to this inhibition and thus may provide an alternative specific antimyeloma therapy.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Bone Marrow Cells; Cell Line, Tumor; Flow Cytometry; Gene Expression Regulation, Neoplastic; Humans; Multiple Myeloma; Osteoblasts; Osteoprotegerin; Receptors, TNF-Related Apoptosis-Inducing Ligand; Reverse Transcriptase Polymerase Chain Reaction

We have previously reported that an anti-human transferrin receptor IgG3-avidin fusion protein (anti-hTfR IgG3-Av) inhibits the proliferation of an erythroleukemia-cell line. We have now found that anti-hTfR IgG3-Av also inhibits the proliferation of additional human malignant B and plasma cells. Anti-hTfR IgG3-Av induces internalization and rapid degradation of the TfR. These events can be reproduced in cells treated with anti-hTfR IgG3 cross-linked with a secondary Ab, suggesting that they result from increased TfR cross-linking. Confocal microscopy of cells treated with anti-hTfR IgG3-Av shows that the TfR is directed to an intracellular compartment expressing the lysosomal marker LAMP-1. The degradation of TfR is partially blocked by cysteine protease inhibitors. Furthermore, cells treated with anti-hTfR IgG3-Av exhibit mitochondrial depolarization and activation of caspases 9, 8, and 3. The mitochondrial damage and cell death can be prevented by iron supplementation, but cannot be fully blocked by a pan-caspase inhibitor. These results suggest that anti-hTfR IgG3-Av induces lethal iron deprivation, but the resulting cell death does not solely depend on caspase activation. This report provides insights into the mechanism of cell death induced by anti-TfR Abs such as anti-hTfR IgG3-Av, a molecule that may be useful in the treatment of B-cell malignancies such as multiple myeloma.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Avidin; Caspase Inhibitors; Cell Line, Tumor; Cell Proliferation; Cross-Linking Reagents; Deferoxamine; Hematologic Neoplasms; Humans; Immunoglobulin G; Iron; Leukemia, Plasma Cell; Multiple Myeloma; Receptors, Transferrin; Recombinant Fusion Proteins; Siderophores

Enzastaurin (LY317615), an acyclic bisindolylmaleimide, is an oral inhibitor of the protein kinase Cbeta isozyme. The objective of this study was to assess the efficacy of enzastaurin in inducing apoptosis in multiple myeloma (MM) cell lines and to investigate possible mechanisms of apoptosis. Cell proliferation assays were done on a variety of MM cell lines with unique characteristics (dexamethasone sensitive, dexamethasone resistant, chemotherapy sensitive, and melphalan resistant). The dexamethasone-sensitive MM.1S cell line was used to further assess the effect of enzastaurin in the presence of dexamethasone, insulin-like growth factor-I (IGF-I), interleukin-6, and the pan-specific caspase inhibitor ZVAD-fmk. Enzastaurin increased cell death in all cell lines at clinically significant low micromolar concentrations (1-3 micromol/L) after 72 hours of treatment. Dexamethasone and enzastaurin were shown to have an additive effect on MM.1S cell death. Although IGF-I blocked the effect of 1 micromol/L enzastaurin, IGF-I did not abrogate cell death induced with 3 mumol/L enzastaurin. Moreover, enzastaurin-induced cell death was not affected by interleukin-6 or ZVAD-fmk. GSK3beta phosphorylation, a reliable pharmacodynamic marker for enzastaurin activity, and AKT phosphorylation were both decreased with enzastaurin treatment. These data indicate that enzastaurin induces apoptosis in MM cell lines in a caspase-independent manner and that enzastaurin exerts its antimyeloma effect by inhibiting signaling through the AKT pathway.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cell Proliferation; Dexamethasone; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Indoles; Insulin-Like Growth Factor I; Interleukin-6; Multiple Myeloma; Phosphorylation; Protein Kinase C; Protein Kinase C beta; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Signal Transduction

Multiple myeloma is a clonal malignancy of plasma cells that invariably progresses to a chemoresistant state. The PI3K/Akt pathway mediates signals downstream of several growth factors involved in myeloma pathogenesis, and constitutive activation of Akt was observed in myeloma cells. We now report that a staurosporine derivative, N-benzoylated staurosporine or PKC412, induces cell death in myeloma cell lines (RPMI8226S, U266, MM1S and MM1R) with loss of mitochondrial membrane potential Delta psi m, caspase 3 and PARP cleavage. ZVAD.fmk, but not interleukin-6, rescued these cells from PKC412 effects. Upstream of the mitochondria, PKC412 inhibited Bad phosphorylation and attenuated Akt kinase activity by suppressing its phosphorylation on serine residue in its activation loop. Reduced phosphorylation of downstream Akt substrates GSK3 alpha/beta and FKHR was also noted. Stable transfection of 8226S cells with constitutively active Akt (8226S-myAkt) partially protected against PKC412 cytotoxicity. Primary myeloma cells isolated from refractory myeloma patients (n=4), were equally sensitive to PKC412 treatment. More importantly, PKC412 did not affect CFU-GM or BFU-E colony formation. In summary, our results demonstrate that PKC412 suppresses Akt kinase activation and induces apoptosis in myeloma cell lines, as well as primary resistant cells. PKC412 is an appropriate candidate for novel treatment protocols for multiple myeloma.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Caspase 3; Cell Line, Tumor; Enzyme Inhibitors; Flow Cytometry; Humans; Interleukin-6; Membrane Potentials; Mitochondria; Multiple Myeloma; Phosphorylation; Proto-Oncogene Proteins c-akt; Staurosporine

In this study, we have evaluated the cytotoxic effect of combining two HDAC inhibitors, SAHA and TSA, with TRAIL in human multiple myeloma cell lines. Low doses of SAHA or TSA enhanced the cytotoxic and apoptotic effects of TRAIL and upregulated the surface expression of TRAIL death receptors (DR4 and/or DR5). SAHA and TSA induced G1 phase cell cycle growth arrest by upregulating p21(WAF1) and p27(Kip1) expression and by inhibiting E2F transcriptional activity. The enhanced TRAIL effect after pretreatment with HDAC inhibitors was consistent with the upregulation of the proapoptotic Bcl-2 family members (Bim, Bak, Bax, Noxa, and PUMA), the downregulation of the anti-apoptotic members of the Bcl-2 family (Bcl-2 and Bcl-X(L)), and IAPs. SAHA and TSA dissipated the mitochondrial membrane potential and enhanced the release of Omi/HtrA2 and AIF from the mitochondria to the cytosol. The cytotoxic effect of both SAHA and TSA was caspase- and calpain-independent. Inhibition of NF(kappa)B activation by the proteasome inhibitor, MG132, enhanced the apoptotic effect of TSA. Our study demonstrated the enhancing effects of HDAC inhibitors on apoptosis when combined with TRAIL and, for the first time, emphasized the role of AIF in mediating the cytotoxic effects of HDAC inhibitors.

Topics: Amino Acid Chloromethyl Ketones; Annexin A5; Apoptosis; Apoptosis Regulatory Proteins; Calpain; Caspases; Cell Cycle; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p27; DNA-Binding Proteins; Dose-Response Relationship, Drug; Down-Regulation; E2F Transcription Factors; Enzyme Inhibitors; Flow Cytometry; G1 Phase; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Histones; Humans; Immunoblotting; Inhibitory Concentration 50; Leupeptins; Luciferases; Membrane Glycoproteins; Membrane Potentials; Microscopy, Fluorescence; Mitochondria; Multiple Myeloma; NF-kappa B; Phosphorylation; Propidium; Protein Binding; Ribonucleases; Subcellular Fractions; Time Factors; TNF-Related Apoptosis-Inducing Ligand; Transcription Factors; Tumor Necrosis Factor-alpha; Tumor Suppressor Proteins; Up-Regulation

Mitochondria play central roles in cellular metabolism and apoptosis and are a major source of reactive oxygen species (ROS). We investigated the role of ROS and mitochondria in radiation-induced apoptosis in multiple myeloma cells. Two distinct levels of ROS were generated following irradiation: a small increase observed early, and a pronounced late increase, associated with depletion of reduced glutathione (GSH) and collapse of mitochondrial membrane potential (deltapsi(m)). Exogenous ROS and caspase-3 induced deltapsi(m) drop and cytochrome c release from mitochondria, which could be prevented by molecular (dominant-negative caspase-9) and pharmacologic (zVAD-fmk) caspase inhibitors and overexpression of Bcl-2. Exogenous ROS also induced mitochondrial permeability transition (PT) pore opening and cytochrome c release in isolated mitochondria, which could be blocked by inhibition of PT with cyclosporin A. These results indicate that the late ROS production is associated with increased PT pore opening and decreased deltapsi(m), and GSH, events associated with caspase activation and cytochrome c release.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Caspase 3; Caspase 9; Caspases; Cell Death; Cell Line, Tumor; Cell-Free System; Chromatography, High Pressure Liquid; Cytochromes c; Enzyme Activation; Enzyme Inhibitors; Flow Cytometry; Genes, Dominant; Glutathione; Humans; Immunoblotting; Membrane Potentials; Mitochondria; Multiple Myeloma; Oxidative Stress; Reactive Oxygen Species; Subcellular Fractions; Time Factors

Interleukin 6 (IL-6) is an important survival and growth factor for myeloma cells and exerts its effects by activating several transduction pathways, including the Ras cascade. As farnesylation of the activated Ras oncogene product by protein farnesyltransferase (FTase) is a critical step for Ras functional activity, FTase has emerged as a potential target for the development of new anti-cancer agents. Based on our previous demonstration that IL-6-producing myeloma cells are refractory to drug-induced apoptosis, we have analysed the effect of manumycin, a natural FTase inhibitor, on IL-6-producing myeloma cells resistant to Fas-, dexamethasone- and doxorubicin-induced apoptosis. Treatment of myeloma cells with manumycin prevented cell proliferation and induced apoptosis. Western blotting experiments demonstrated that this effect was related to inhibition of the post-translational Ras processing.Further analysis showed that manumycin-induced apoptosis involved caspase-3. Activation of caspase-3, in fact, was observed in 6 h-treated myeloma cells expressing Apo 2.7 antigen, the marker of early apoptosis, whereas their treatment with cell-permeable DEVD-fmk, that irreversibly inhibits caspase-3 activity, prevented their apoptosis. Over-expression of caspase-3 was also demonstrated by reverse transcription-polymerase chain reaction. Finally, over-expression of Bcl-2 and its homologue Bcl-xL was observed in manumycin-treated cells as well as in control myeloma cells, implying that the Bcl-2 family is not involved. FTase inhibitors may thus be proposed as a potential pharmacological weapon, as they block the Ras pathway and induce the apoptosis of drug-resistant IL-6-producing myeloma cells.

Topics: Alkyl and Aryl Transferases; Amino Acid Chloromethyl Ketones; Apoptosis; Caspase 3; Caspase Inhibitors; Caspases; Cell Division; Cell Line; Dexamethasone; Enzyme Activation; Enzyme Inhibitors; Farnesyltranstransferase; Gene Expression; Genes, ras; Humans; Interleukin-6; Multiple Myeloma; Oligopeptides; Polyenes; Polyunsaturated Alkamides; Reverse Transcriptase Polymerase Chain Reaction

The productivity of NS/0 myeloma batch cultures is often compromised by the premature induction of apoptosis, now established to be the predominant method of cell death during culture decline. Caspase proteases have recently been shown to play a major role in the transmission of signals for apoptotic cell death. Using a specific inhibitor that targets a range of caspases (Z-VAD-fmk) we assessed whether inhibition of caspase activity could prolong the viability of NS&vbar;h=0 cells under conditions that cause apoptotic cell death in batch cultures. Z-VAD-fmk was found to significantly reduce apoptotic cell death (by approximately 50%) induced by cytotoxins and to preserve membrane integrity to a similar extent. In conditions of low serum, Z-VAD-fmk reduced certain features of apoptosis (e.g., DNA fragmentation), but only marginally improved viability. In medium-depleted batch cultures, Z-VAD-fmk afforded a delay of between 24 and 48 h in both the induction of apoptosis and loss of viability. Despite an apparent increase in viability in Z-VAD-fmk-treated NS&vbar;h=0 cultures, no improvement in productivity could be demonstrated, suggesting that at least some normal pathways for protein production are shut down upstream of caspase activation. An examination of mitochondrial membrane potential (Deltapsim) in Z-VAD-fmk-treated and untreated NS&vbar;h=0 cells revealed only a small initial difference (5%) in the levels of Deltapsim depolarization. Similar levels of mitochondrial dysfunction, despite caspase inactivity, may therefore be responsible for the comparable productivity in untreated and Z-VAD-fmk-treated cultures. Thus, this study suggests that, while a delay in cell death due to caspase inhibition may reduce problems associated with cellular disintegration, it does not permit productivity improvements in this type of culture.

Topics: Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Caspase 3; Caspase Inhibitors; Caspases; Cell Culture Techniques; Cell Membrane; Culture Media, Serum-Free; Cysteine Proteinase Inhibitors; Intracellular Membranes; Mice; Mitochondria; Multiple Myeloma; Substrate Specificity; Transfection; Tumor Cells, Cultured

p27[KIP1] (p27) is a cyclin dependent kinase inhibitor, involved in the negative regulation of G1 progression in response to a number of anti-proliferative signals. In this study we show, in growing mouse hybridoma (7TD1) and human myeloma (U266) cell lines, that p27 is highly expressed but slightly upregulated when cells are arrested, regardless to the phases of the cell cycle. In contrast, the specific blockade of these cells in early G1 phase reveals the induction of a protein of 23 kDa (p23) specifically recognized by polyclonal anti-p27 antibodies raised against the NH2 terminal part of p27 but not by anti-p21[CIP1] antibodies. Experiments using caspase inhibitors strongly suggest that p23 results from the proteolysis of p27 by a 'caspase-3-like' protease. This cleavage leads to the cytosolic sequestration of p23 but does not alter its binding properties to CDK2 and CDK4 kinases. Indeed, p23 associated in vivo with high molecular weight complexes and coprecipitated with CDK2 and CDK4. We demonstrate by transfection experiments in SaOS-2 cells that p23 induces a G1 phase growth arrest by inhibition of cyclin/CDK2 activity. In summary we describe here a caspase-cleaved form of p27, induced in absence of detectable apoptosis and likely involved in cell cycle regulation.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Caspase 3; Caspase Inhibitors; Caspases; CDC2-CDC28 Kinases; Cell Cycle Proteins; Cell Division; Cell Line; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinase Inhibitor p27; Cyclin-Dependent Kinases; Cyclins; Cysteine Proteinase Inhibitors; Cytosol; Dimethyl Sulfoxide; G1 Phase; Humans; Hybridomas; Interleukin-6; Mice; Microtubule-Associated Proteins; Molecular Weight; Multiple Myeloma; Oligopeptides; Peptide Fragments; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Time Factors; Tumor Cells, Cultured; Tumor Suppressor Proteins