scholarly journals The Apoptosis Induction of Oleandrin on Osteosarcoma Cells through Regulating Mitochondrial- and Death Receptor-Dependent Apoptotic Pathways in Vitro

2016 ◽  
Author(s):  
Yunlong Ma ◽  
Bin Zhu ◽  
Lei Yong ◽  
Chunyu Song ◽  
Xiao Liu ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cell Apoptosis ◽  
Caspase 3 ◽  
Treatment Time ◽  
Death Receptor ◽  
Caspase 8 ◽  
Osteosarcoma Cells ◽  
Caspase 9 ◽  
Apoptotic Pathway

Our previous study has found the anti-tumor activity of oleandrin in osteosarcoma cells in vitro, but the signal transduction process of cell apoptosis induced by oleandrin is uncertain, which is explored in this study. Fluorescence staining and flow cytometry (FCM) was performed to detect the cell apoptosis, intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). Caspase-3 activity was detected using a commercial kit. The protein expression of cytoplasmic cytochrome c, mitochondrial cytochrome c, bcl-2, bax, caspase-9, Fas, FasL, caspase-8 and caspase-3 was detected using western blot. A pan-caspase inhibitor, z-VAD-fmk, was applied to block the apoptotic pathway and the apoptosis status were re-tested. We found that oleandrin significantly induced the increased apoptosis of U2OS cells. Meanwhile, the intracellular ROS was elevated, but the MMP decreased. The cytochrome c in mitochondria was notably decreased but increased in cytoplasm. The caspase-3 activity was also enhanced with the increase of drug concentration and treatment time. Oleandrin also down-regulated the level of bcl-2, but remarkably up-regulated the expression of bax, cleaved caspase-9, Fas, FasL, cleaved caspase-8 and cleaved caspase-3. Furthermore, the pre-treatment with z-VAD-fmk almost completely reverted the oleandrin-induced apoptosis. The results suggested that oleandrin induces the apoptosis of osteosarcoma cells via mitochondrial- and death receptor-dependent pathways.

109. TROPHOBLAST DEPORTATION IS DEPENDENT UPON CASPASES 3, 8 AND ROCK

2009 ◽  
Vol 21 (9) ◽  
pp. 28
Author(s):  
K. J. Askelund ◽  
P. Stone ◽  
L. W. Chamley
Keyword(s):  
Caspase 3 ◽  
First Trimester ◽  
Normal Pregnancy ◽  
Maternal Blood ◽  
Caspase 8 ◽  
Caspase 9 ◽  
Apoptotic Pathway ◽  
Apoptosis Pathway ◽  
Villous Trophoblast

Background: Trophoblast deportation is the process whereby multinucleated fragments of the syncytiotrophoblast are shed from the placenta into the maternal blood. It is estimated that 150,000 are shed from the placenta and deported daily in normal pregnancy and that more are shed during preeclampsia1. In normal pregnancy deported trophoblasts are thought to die by apoptosis, which is also increased in villous trophoblast in preeclampsia2. However, experimental confirmation that apoptosis leads to trophoblast shedding is required and it is not clear which components of the apoptotic pathway are involved in trophoblast shedding. Objectives: To determine the effect of inhibiting caspase 3 (executioner), caspases 8 and 9 (initiators), and Rho-associated kinase (ROCK; bleb formation) on the number of trophoblasts shed from first trimester human placentae. Methods : Using an in vitro placental explant model of trophoblast deportation, first trimester placentae were cultured for 72 hours in media containing specific inhibitors of ROCK, caspases 3, 8 or 9. Trophoblasts shed from quintuple explants/inhibitor from five placentae were depleted of contaminating leucocytes and erythrocytes, labelled with trypan blue and the sizes and numbers of shed trophoblasts quantified using a Nexcelom automated counter. Results: The number of trophoblasts that were shed from the explants was significantly increased (p=0.04) when caspase 3 (2.4 fold) and caspase 8 (2.7 fold) were inhibited. There was no significant change following caspase 9 inhibition. The number of shed trophoblasts was significantly decreased when ROCK was inhibited. None of the inhibitors significantly altered the size of the shed trophoblasts. Conclusion: Our data suggest that the apoptosis pathway is involved in trophoblast shedding in vitro from first trimester placentae. That caspase 8 but not caspase 9 affected shedding suggests trophoblasts from normal placentae are induced to die via the extrinsic apoptosis pathway. Aberrant regulation of the apoptosis pathway may contribute to pregnancy pathology.

scholarly journals ClC-5 Downregulation Induces Osteosarcoma Cell Apoptosis by Promoting Bax and tBid Complex Formation

2021 ◽  
Vol 10 ◽  
Author(s):  
Fei Peng ◽  
Weisong Cai ◽  
Jianping Li ◽  
Haohuan Li
Keyword(s):  
Complex Formation ◽  
Cell Apoptosis ◽  
Caspase 3 ◽  
Osteosarcoma Cell ◽  
Osteosarcoma Cells ◽  
Caspase 9 ◽  
Poor Overall Survival ◽  
Apoptotic Pathway ◽  
Normal Bone ◽  
Pathway Activation

Osteosarcoma is the most common malignant bone tumor. Chloride (Cl−) channels-mediated Cl− movement plays an important role in regulating the functions of various cancer cells, but its role in osteosarcoma remains unclear. In this study, we found that ClC-5 was increased in osteosarcoma tissues compared with normal bone tissues. Patients with high ClC-5 expression showed poor overall survival relative to those patients with low ClC-5 expression. Higher ClC-5 expression and lower intracellular Cl− concentration ([Cl−]i) were observed in osteosarcoma cells compared with normal osteoblasts. Lowering [Cl−]i increased the viability of osteosarcoma cells, which was markedly blocked by ClC-5 downregulation. Knockdown of ClC-5 significantly induced osteosarcoma cell apoptosis and increased the release of cytochrome c from mitochondria to cytosol, concomitantly with cleavage of caspase-9, caspase-3, and PARP. The effect of ClC-5 downregulation on osteosarcoma cell apoptosis and viability was abolished by caspase-3 and caspase-9 inhibitors, but not caspase-8 inhibitor. Furthermore, ClC-5 inhibition promoted Bax translocation from cytosol to mitochondria. Immunoprecipitation showed that ClC-5 interacted with Bax and ClC-5 downregulation enhanced Bax and tBid complex formation. Collectively, we demonstrate that ClC-5 downregulation induces osteosarcoma cell apoptosis via mitochondria-dependent apoptotic pathway activation by promoting Bax and tBid association and subsequent Bax translocation.

Mechanism of induction of pancreatic acinar cell apoptosis by hydrogen sulfide

2006 ◽  
Vol 291 (3) ◽  
pp. C503-C510 ◽  
Author(s):  
Yang Cao ◽  
Sharmila Adhikari ◽  
Abel Damien Ang ◽  
Philip K. Moore ◽  
Madhav Bhatia
Keyword(s):  
Acinar Cell ◽  
Cell Apoptosis ◽  
Caspase 3 ◽  
Death Receptor ◽  
Annexin V ◽  
Pancreatic Acinar Cell ◽  
Apoptotic Pathway ◽  
Pancreatic Acini ◽  
Phosphatidylserine Externalization

The present study investigated the mechanism of mouse pancreatic acinar cell apoptosis induced by H2S in an in vitro system, using isolated pancreatic acini. Treatment of pancreatic acini with 10 μM NaHS (a donor of H2S) for 3 h caused phosphatidylserine externalization as shown by annexin V binding, an indicator of early stages of apoptosis. This treatment also resulted in the activation of the caspase cascade and major changes at the mitochondrial level. Caspase-3, -8, and -9 activities were stimulated by H2S treatment. Treatment with inhibitors of caspase-3, -8, and -9 significantly inhibited H2S-induced phosphatidylserine externalization as shown by reduced annexin V staining. The mitochondrial membrane potential was collapsed in H2S-treated acini as evidenced by fluorescence microscopy and quantitative analysis. Furthermore, the treatment of acini with H2S caused the release of cytochrome c by the mitochondria. To investigate the mechanism underlying pancreatic acinar cell apoptosis, we also characterized the protein expression of a range of molecules that are each known to influence the apoptotic pathway. Among proapoptotic proteins, Bax expression was activated in H2S-treated cells but not Bid, and the antiapoptotic proteins Bcl-XL and Bcl-2 did not show any activation in pancreatic acinar cell apoptosis. The death effector domain-containing protein Flip is downregulated in H2S-treated acini. These results demonstrate the induction of pancreatic acinar cell apoptosis in vitro by H2S and the involvement of both mitochondrial and death receptor pathways in the process of apoptosis.

scholarly journals TNF-αInduced the Enhanced Apoptosis of Mesenchymal Stem Cells in Ankylosing Spondylitis by Overexpressing TRAIL-R2

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Zhenhua Liu ◽  
Liangbin Gao ◽  
Peng Wang ◽  
Zhongyu Xie ◽  
Shuizhong Cen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Ankylosing Spondylitis ◽  
Cytochrome C ◽  
Caspase 3 ◽  
Death Receptor ◽  
Unknown Etiology ◽  
Caspase 8 ◽  
Necrosis Factor Alpha ◽  
Cytosolic Cytochrome

Ankylosing spondylitis (AS) is an autoimmune disease with unknown etiology. Dysregulated mesenchymal stem cells (MSCs) apoptosis may contribute to the pathogenesis of autoimmune diseases. However, apoptosis of MSCs from patients with AS (ASMSCs) has not been investigated yet. The present study aims to assess the apoptosis of bone marrow-derived ASMSCs and to investigate the underlying mechanisms of altered ASMSCs apoptosis. We successfully induced the apoptosis of ASMSCs and MSCs from healthy donors (HDMSCs) using the combination of tumor necrosis factor alpha (TNF-α) and cycloheximide (CHX). We found that ASMSCs treated with TNF-αand CHX showed higher apoptosis levels compared to HDMSCs. During apoptosis, ASMSCs expressed significantly more TRAIL-R2, which activated both the death receptor pathway and mitochondria pathway by increasing the expression of FADD, cleaved caspase-8, cytosolic cytochrome C, and cleaved caspase-3. Inhibiting TRAIL-R2 expression using shRNA eliminated the apoptosis differences between HDMSCs and ASMSCs by partially reducing ASMSCs apoptosis but minimally affecting that of HDMSCs. Furthermore, the expression of FADD, cleaved caspase-8, cytosolic cytochrome C, and cleaved caspase-3 were comparable between HDMSCs and ASMSCs after TRAIL-R2 inhibition. These results indicated that increased TRAIL-R2 expression results in enhanced ASMSCs apoptosis and may contribute to AS pathogenesis.

scholarly journals Direct Effect of Septic Plasma in Human Cell Lines Viability

2018 ◽  
Vol 47 (1-3) ◽  
pp. 270-276
Author(s):  
Grazia Maria Virzì ◽  
Chiara Borga ◽  
Chiara Pasqualin ◽  
Silvia Pastori ◽  
Alessandra Brocca ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cell Viability ◽  
Cell Lines ◽  
Caspase 3 ◽  
Test Group ◽  
Organ Injury ◽  
Enzyme Linked Immunosorbent Assay ◽  
Caspase 9 ◽  
Renal Tubular Cells

Background: Sepsis is a life-threatening condition often associated with a high incidence of multiple organs injury. Several papers suggested the immune response by itself, with the production of humoral inflammatory mediators, is crucial in determining organ injury. However, little is known of how sepsis directly induces organ injury at the cellular levels. To assess this point, we set up an in vitro study to investigate the response of renal tubular cells (RTCs), monocytes (U937) and hepatocytes (HepG2) after 24 h-incubation with septic patients’ plasma. Methods: We enrolled 26 septic patients (“test” group). We evaluated cell viability, apoptosis and necrosis by flow cytometer. Caspase-3,-8,-9 and cytochrome-c concentrations have been analyzed using the Human enzyme-linked immunosorbent assay kit. Results: We found that a decrease of cell viability in all cell lines tested was associated to the increase of apoptosis in RTCs and U937 (p < 0.0001) and increase of necrosis in HepG2 (p < 0.5). The increase of apoptosis in RTCs and U937 cells was confirmed by higher levels of caspase-3 (p < 0.0001). We showed that apoptosis in both RTCs and U937 was triggered by the activation of the intrinsic pathway, as caspase-9 and cytochrome-c levels significantly increased (p < 0.0001), while caspase-8 did not change. This assumption was strengthened by the significant correlation of caspase-9 with both cytochrome-c (r = 0.73 for RTCs and r = 0.69 for U937) and caspase-3 (r = 0.69 for RTCs and r = 0.63 for U937). Conclusion: Humoral mediators in septic patients’ plasma induce apoptosis. This fact suggests that apoptosis inhibitors should be investigated as future strategy to reduce sepsis-induced organ damages.

scholarly journals Silica nanoparticles inducing the apoptosis of spermatocyte cell through microRNA-450b-3p targeting MTCH2-mediating mitochondrial signaling pathway

2020 ◽  
Author(s):  
Guiqing Zhou ◽  
Jianhui Liu ◽  
Xiangyang Li ◽  
Yujian Sang ◽  
Yue Zhang ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Silica Nanoparticles ◽  
Caspase 3 ◽  
Reproductive Toxicity ◽  
Control Group ◽  
Caspase 9 ◽  
Protein Expressions ◽  
Underlying Mechanisms

Abstract Background: Silica nanoparticles (SiNPs) are found in environmental particulate matter and are proven to have adverse effects on fertility. The relationship and underlying mechanisms between miRNAs and apoptosis induced by SiNPs during spermatogenesis is currently ambiguous. Experimental design: The present study was designed to investigate the role of miRNA-450b-3p in the reproductive toxicity caused by SiNPs. In vivo, 40 male mice were randomly divided into control and SiNPs groups, 20 per group. The mice in the SiNPs group were administrated 20 mg/kg SiNPs by tracheal perfusion once every 5 days, for 35 days, and the control group were given the equivalent of a normal luminal saline. In vitro, spermatocyte cells were divided into 0 and 5 μg/mL SiNPs groups, after passaged for 30 generations, the GC-2spd cells in 5 μg/mL SiNPs groups were transfected with miRNA-450b-3p and its mimic and inhibitor. Results: In vivo, the results showed that SiNPs damaged tissue structures of testis, decreased the quantity and quality of the sperm, reduced the expression of miR-450b-3p, and increased the protein expressions of the MTCH2, BID, BAX, Cytochrome C, Caspase-9, and Caspase-3 in the testis. In vitro, SiNPs obviously repressed the viability and increased the LDH level and apoptosis rate, decreased the levels of the miR-450b-3p, significantly enhanced the protein expressions of the MTCH2, BID, BAX, Cytochrome C, Caspase-9, Caspase-3; while the mimic of miR-450b-3p reversed the changes induced by SiNPs, but inhibitor further promoted the effects induced by SiNPs.Conclusion: The result suggested that SiNPs could induce the spermatocyte apoptosis by inhibiting the miR-450b-3p expression to target promoting the MTCH2 resulting in activating mitochondrial apoptotic signaling pathways in the spermatocyte cells.

LPA protects intestinal epithelial cells from apoptosis by inhibiting the mitochondrial pathway

2003 ◽  
Vol 284 (5) ◽  
pp. G821-G829 ◽  
Author(s):  
Wenlin Deng ◽  
De-An Wang ◽  
Elvira Gosmanova ◽  
Leonard R. Johnson ◽  
Gabor Tigyi
Keyword(s):  
Epithelial Cells ◽  
Cytochrome C ◽  
Protein Expression ◽  
Caspase 3 ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Caspase 9 ◽  
Cytochrome C Release ◽  
Apoptotic Pathway ◽  
Antiapoptotic Activity

We previously showed ( Gastroenterology 123: 206–216, 2002) that lysophosphatidic acid (LPA) protects and rescues rat intestinal epithelial cells (IEC-6) from apoptosis. Here, we provide evidence for the LPA-elicited inhibition of the mitochondrial apoptotic pathway leading to attenuation of caspase-3 activation. Pretreatment of IEC-6 cells with LPA inhibited campothecin-induced caspase-9 and caspase-3 activation and DNA fragmentation. A caspase-9 inhibitor peptide mimicked the LPA-elicited antiapoptotic activity. LPA elicited ERK1/ERK2 and PKB/Akt phosphorylation. The LPA-elicited antiapoptotic activity and inhibition of caspase-9 activity were abrogated by pertussis toxin, PD 98059, wortmannin, and LY 294002. LPA reduced cytochrome c release from mitochondria and prevented activation of caspase-9. LPA prevented translocation of Bax from cytosol to mitochondria and increased the expression of the antiapoptotic Bcl-2 mRNA and protein. LPA had no effect on Bcl-xl, Bad, and Bak mRNA or protein expression. These data indicate that LPA protects IEC-6 cells from camptothecin-induced apoptosis through Gi-coupled inhibition of caspase-3 activation mediated by the attenuation of caspase-9 activation due to diminished cytochrome c release, involving upregulation of Bcl-2 protein expression and prevention of Bax translocation.

scholarly journals Ginsenoside Rb1 Protects Neonatal Rat Cardiomyocytes from Hypoxia/Ischemia Induced Apoptosis and Inhibits Activation of the Mitochondrial Apoptotic Pathway

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Xu Yan ◽  
Jinwen Tian ◽  
Hongjin Wu ◽  
Yuna Liu ◽  
Jianxun Ren ◽  
...  
Keyword(s):  
Caspase 3 ◽  
Neonatal Rat ◽  
Ginsenoside Rb1 ◽  
Caspase 9 ◽  
Apoptotic Pathway ◽  
Rat Cardiomyocytes ◽  
Mitochondrial Apoptotic Pathway ◽  
Neonatal Rat Cardiomyocytes ◽  
Hypoxia Ischemia

Aim. To investigate the effect of Ginsenoside Rb1 (GS-Rb1) on hypoxia/ischemia (H/I) injury in cardiomyocytesin vitroand the mitochondrial apoptotic pathway mediated mechanism.Methods. Neonatal rat cardiomyocytes (NRCMs) for the H/I groups were kept in DMEM without glucose and serum, and were placed into a hypoxic jar for 24 h. GS-Rb1 at concentrations from 2.5 to 40 µM was given during hypoxic period for 24 h. NRCMs injury was determined by MTT and lactate dehydrogenase (LDH) leakage assay. Cell apoptosis, ROS accumulation, and mitochondrial membrane potential (MMP) were assessed by flow cytometry. Cytosolic translocation of mitochondrial cytochrome c and Bcl-2 family proteins were determined by Western blot. Caspase-3 and caspase-9 activities were determined by the assay kit.Results. GS-Rb1 significantly reduced cell death and LDH leakage induced by H/I. It also reduced H/I induced NRCMs apoptosis induced by H/I, in accordance with a minimal reactive oxygen species (ROS) burst. Moreover, GS-Rb1 markedly decreased the translocation of cytochrome c from the mitochondria to the cytosol, increased the Bcl-2/ Bax ratio, and preserved mitochondrial transmembrane potential (ΔΨm). Its administration also inhibited activities of caspase-9 and caspase-3.Conclusion. Administration of GS-Rb1 during H/Iin vitrois involved in cardioprotection by inhibiting apoptosis, which may be due to inhibition of the mitochondrial apoptotic pathway.

JS-K, a Novel Nitric Oxide (NO) Generator, Induces Cytochrome c Release and Caspase Activation in HL-60 Myeloid Leukemia Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3415-3415
Author(s):  
Paul J. Shami ◽  
Vidya Udupi ◽  
Margaret Yu ◽  
Swati Malaviya ◽  
Joseph E. Saavedra ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Caspase 3 ◽  
Myelogenous Leukemia ◽  
Leukemia Cells ◽  
Caspase 8 ◽  
Caspase 9 ◽  
Cytochrome C Release ◽  
Dose Dependent Fashion ◽  
Acute Myelogenous ◽  
Dose Dependent

Abstract NO induces differentiation and apoptosis in Acute Myelogenous Leukemia (AML) cells. Glutathione S-Transferases (GST) play an important role in multidrug resistance and are upregulated in 90% of AML cells. We have designed a novel prodrug class that releases NO on metabolism by GST. O2-(2,4-Dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate (JS-K, a member of this class) has potent antileukemic activity. We have previously shown that JS-K induces apoptosis in HL-60 cells by a caspase dependent mechanism (Molecular Cancer Therapeutics2:409-417,2003). The purpose of this study was to determine the pathway through which JS-K induces apoptosis. Western blot analysis showed that treatment of HL-60 cells with JS-K (0 – 1 μM) for 6 hours results in release of Cytochrome c from mitochondria in a dose dependent fashion. Treatment with JS-K resulted in a dose dependent activation of Caspase 9. Sixteen and 24 hours after exposure to 1 μM JS-K, Caspase 9 activity was induced by 393 ± 93% and 237 ± 13% of control, respectively (p = 0.03 at the 24 hours time point). Treatment with JS-K resulted in a dose dependent activation of Caspase 3. Twenty four hours after exposure to 1 μM JS-K, Caspase 3 activity was 208 ± 3.4 % of control (p = 0.02). Treatment with JS-K also resulted in a dose dependent activation of Caspase 8, but to a lesser extent than Caspase 9 and 3. Twenty four hours after exposure to 1 μM JS-K, Caspase 8 activity was 144 ± 5.3 % of control (p = 0.04). We conclude that JS-K activates the intrinsic pathway of apoptosis in leukemia cells by inducing the release of Cytochrome c from mitochondria. (NO1-CO-12400).

Intracellular NAD+ Depletion Enhances Bortezomib-Induced Myeloma Cytotoxicity

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 330-330
Author(s):  
Antonia Cagnetta ◽  
Michele Cea ◽  
Chirag Acharya ◽  
Teresa Calimeri ◽  
Yu-Tzu Tai ◽  
...  
Keyword(s):  
Cell Death ◽  
Synergistic Effect ◽  
Cell Lines ◽  
Caspase 3 ◽  
Statistical Significance ◽  
Caspase 8 ◽  
Caspase 9 ◽  
Nicotinamide Phosphoribosyltransferase

Abstract Abstract 330 Background: Our previous study demonstrated that inhibition of nicotinamide phosphoribosyltransferase (Nampt) acts by severely depleting intracellular NAD+ content and thus eliciting mitochondrial dysfunction and autophagic MM cell death. The proteasome inhibitor Bortezomib induces anti-MM activity by affecting a variety of signaling pathways. However, as with other agents, dose-limiting toxicities and the development of resistance limit its long-term utility. Here, we demonstrate that combining Nampt inhibitor and bortezomb induces synergistic anti-MM cell death both in vitro using MM cell lines or patient CD138+ MM cells and in vivo in a human plasmacytoma xenograft mouse model. Material and Methods: We utilized MM.1S, MM.1R, RPMI-8226, and U266 human MM cell lines, as well as purified tumor cells from patients relapsing after prior therapies. Cell viability and apoptosis assays were performed using Annexin V/PI staining. Intracellular NAD+ level and proteasome activity were quantified after 12, 24, and 48h exposure to single/combination drugs by specific assays. In vitro angiogenesis was assessed by Matrigel capillary-like tube structure formation assay. Immunoblot analysis was performed using antibodies to caspase-8, caspase-9, caspase-3, PARP, Bcl-2, and tubulin. CB-17 SCID male mice (n = 28; 7 mice/EA group) were subcutaneously inoculated with 5.0 × 106 MM.1S cells in 100 microliters of serum free RPMI-1640 medium. When tumors were measurable (3 weeks after MM cell injection), mice were treated for three weeks with vehicle alone, FK866 (30mg/kg 4 days weekly), Bortezomib (0.5 mg/kg twice weekly), or FK866 (30 mg/kg) plus Bortezomib (0.5 mg/kg). Statistical significance of differences observed in FK866, Bortezomib or combination-treated mice was determined using a Student t test. Isobologram analysis was performed using “CalcuSyn” software program. A combination index < 1.0 indicates synergism. Results/Discussion: Combining FK866 and Bortezomib induces synergistic anti-MM activity in vitro against MM cell lines (P<0.005, CI < 1) or patient CD138-positive MM cells (P< 0.004). FK866 plus Bortezomib-induced synergistic effect is associated with: 1)activation of caspase-8, caspase-9, caspase-3, and PARP; 2) improved intracellular NAD+ dissipation; 3) suppression of chymotrypsin-like, caspase-like, and trypsin-like proteolytic activities; 4) inhibition of NF-kappa B signaling; and 5) inhibition of angiogenesis. Importantly, the ectopic overexpression of Nampt rescues this observed synergistic effect; conversely, Nampt knockdown by RNAi significantly enhances the anti-MM effect of bortezomib. In the murine xenograft MM model, low dose combination FK866 (30 mg/kg) and Bortezomib (0.5 mg/kg) is well tolerated, significantly inhibits tumor growth (P < 0.001), and prolongs host survival (2–2.5 months in mice receiving combined drugs, P = 0.001). These findings demonstrate that intracellular NAD+ levels represent a major determinant in the ability of bortezomib to induce apoptosis of MM cells, providing the rationale for clinical protocols evaluating FK866 together with Bortezomib to improve patient outcome in MM. Disclosures: Munshi: Celgene: Consultancy; Millenium: Consultancy; Merck: Consultancy; Onyx: Consultancy.

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