Vincristine Potentiates the Anti-Leukemia Effect of the Aurora Kinase Inhibitor VE-465 by Enhancing Apoptosis in Myeloid Leukemia Cells.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2762-2762
Author(s):  
Ken Ohmine ◽  
Tadashi Nagai ◽  
Kozue Yoshida ◽  
Shin-ichiro Fujiwara ◽  
Mitsuyo Uesawa ◽  
...  
Keyword(s):  
Cell Lines ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Aurora Kinase ◽  
Leukemia Cells ◽  
Aurora Kinases ◽  
Aurora Kinase Inhibitors ◽  
M Phase ◽  
G1 Cells

Abstract Abstract 2762 Poster Board II-738 Introduction: Aurora kinases (Aurora-A, Aurora-B, Aurora-C) play an essential role in the regulation of mitosis. It has been shown that deregulation of aurora kinases is involved in tumorgenesis and that these kinases are overexpressed in a variety of tumor cells. Aurora kinase inhibitors are potential small-molecule agents for treatment of various kinds of tumors including leukemia, and clinical trials of several aurora kinase inhibitors against certain types of tumors are currently being carried out. However, mono-therapy with other small-molecule agents sometimes shows only limited clinical efficacy for treatment of leukemia, and the establishment of efficacious combination therapies therefore appears to be an attractive approach for making good use of aurora kinase inhibitors. Methods: We examined the cytotoxic effects of VE-465, a specific aurora kinase inhibitor, in combination with various conventional anti-leukemia agents, including doxorubicin, daunorubicin, idarubicin, mitoxantron, cytocine arabinoside, vincristine and etoposide, on AML cell lines (HL60, U937, THP-1, KY821), CML cell lines (KCL22, K562, KU812) and primary leukemia cells from a patient with AML in order to try to determine an effective therapeutic combination. Results: Steel and Peckham isobologram analyses demonstrated that a combination of VE-465 and vincristine had a synergistic/additive inhibitory effect on the growth of all leukemia cell lines as well as primary leukemia cells examined in this study. Flow cytometric analysis showed that the percentage of G2/M-phase cells was significantly increased at 12 h when VE-465 was added to THP-1 cells as a single agent. At 48 h, however, the percentage of sub-G1 cells was increased, with a decrease in the percentage of G2/M-phase cells, suggesting that VE-465 initially induced the cells into blockage of the cell cycle at M-phase, which may be caused by VE-465-mediated inhibition of aurora kinase activity, and that cells at G2/M arrest were subsequently induced to apoptosis. Importantly, vincristine enhanced VE-465-mediated induction of sub-G1 cells. Consistent with these results, vincristine enhanced VE-465-induced increase in the levels of cleaved caspase 3, cleaved caspase 7, cleaved caspase 9 and cleaved PARP. The level of Phospho-Chk2 was markedly increased by the combination, suggesting that Chk2-mediated activation of the G2/M checkpoint is involved in the induction of apoptosis. Interestingly, VE-465 alone and VE-465 in combination with vincristine markedly increased the level of phospho-ERK1/2, suggesting that the combination alters a network of cellular signaling pathways. Taken together, the results suggest that vincristine potentiated the effect of VE-465 by enhancement of apoptosis, resulting in effective inhibition of the growth of leukemia cells. In contrast to the combination of VE-465 and vincristine, however, combinations of VE-465 and other anti-leukemia agents showed no synergistic inhibition but rather had antagonistic effects on growth. Conclusion: Co-administration of VE-465 and most of the conventional anti-leukemia agents might have little clinical value. However, the results of this study indicate the utility of the combination of VE-465 and vincristine as a potential therapy for myeloid leukemia. Disclosures: No relevant conflicts of interest to declare.

Targeting Aurora Kinases in Acute Lymphoblastic Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4907-4907
Author(s):  
Ya-Ping Chen ◽  
Hui-Ju Lin ◽  
Kung-Chao Chang ◽  
Jiann-Shiuh Chen ◽  
Ming-Ying Tsai ◽  
...  
Keyword(s):  
Cell Lines ◽  
Drug Sensitivity ◽  
Kinase Inhibitors ◽  
Lymphoblastic Leukemia ◽  
Aurora Kinase ◽  
Drug Resistant ◽  
Rt Pcr ◽  
Aurora Kinases ◽  
Aurora Kinase Inhibitors ◽  
Mdr 1

Abstract Abstract 4907 Introduction: Despite improved treatment outcome in acute lymphoblastic leukemia (ALL), drug resistance and disease recurrence remain major obstacles in specific subgroups. Thus, there is an urgent need to identify new targets for therapy. Several studies showed that Aurora kinases were therapeutic targets in cancer therapy, including solid tumors and hematological malignancies. Here we describe preclinical testing of Aurora kinase inhibitors in ALL and the molecular mechanism of different drug activity. Materials and methods: Quantitative RT-PCR and Western blot were used to assess the expressions of Aurora kinases and their activators in ALL. RT-PCR was used to detect the expression of MDR-1. To test activity against Aurora kinases, different ALL cell lines were treated with various concentrations of Aurora kinase inhibitors “VE-465 and VX-680”. The effects of Aurora kinase inhibitors on the cell cycle were evaluated by flow cytometry. Gene expression profiling was performed to identify the candidate targets which regulate the different drug sensitivity. Transient knockdown and overexpression of candidate genes in ALL cell lines were also employed in this study. Results: Nine ALL cell lines treated with Aurora kinase inhibitors (VE-465 and VX-680) exhibited different drug sensitivity. Five ALL cell lines were sensitive to drug treatment with IC50 around 10–40 nM, including MLL-AF4-positive and BCR-ABL-positive cell lines. However, RPMI-8402 was one of the three cell lines which were resistant to VE-465 and VX-680 with IC50 more than 10 μM. Among these sensitive ALL cell lines, treatment of Aurora kinase inhibitors resulted in an increased G2/M and sub-G1 populations. In contrast, drug-resistant ALL cell lines showed increased polyploidy status after exposure to Aurora kinase inhibitors. The different treatment efficacy was not related to the expression of Aurora kinases, their activators or MDR-1. In order to elucidate the molecular mechanism to regulate the different drug sensitivity, microarray study was performed. It showed that treatment of Aurora kinase inhibitors resulted in differential expressions of genes (75 up-regulated and 90 down-regulated genes) and CDKN1Awas one of the potential molecules which regulated the treatment diversity. RT-PCR and Western blot confirmed the cDNA microarray data: CDKN1A was up-regulated after treatment with Aurora kinase inhibitors in the drug-sensitive cell lines, but no change in the level of CDKN1A in the drug-resistance cell lines. Knockdown of CDKN1A in drug-sensitive cell lines impaired the treatment activity. Over-expression of CDKN1A in drug-resistant cell lines increased the anti-leukemia effect of Aurora kinase inhibitors. Conclusion: These data suggest that treatment with Aurora kinase inhibitors may be a novel and effective therapy in specific subgroups of ALL, including MLL-AF4-positive ALL. These data show that status of Aurora kinases, their activators or MDR-1 does not correlate with the drug susceptibility in ALL cell lines. The susceptibility to Aurora kinase inhibitors in ALL depends on the activation status of CDKN1A. Disclosures: No relevant conflicts of interest to declare.

Aurora Kinase Inhibitors in Head and Neck Cancer

2018 ◽  
Vol 18 (3) ◽  
pp. 199-213
Author(s):  
Guangying Qi ◽  
Jing Liu ◽  
Sisi Mi ◽  
Takaaki Tsunematsu ◽  
Shengjian Jin ◽  
...  
Keyword(s):  
Head And Neck Cancer ◽  
Cancer Therapy ◽  
Kinase Inhibitors ◽  
Biological Function ◽  
Aurora Kinase ◽  
Aurora Kinases ◽  
Related Research ◽  
Chemotherapy Drugs ◽  
Aurora Kinase Inhibitors

Aurora kinases are a group of serine/threonine kinases responsible for the regulation of mitosis. In recent years, with the increase in Aurora kinase-related research, the important role of Aurora kinases in tumorigenesis has been gradually recognized. Aurora kinases have been regarded as a new target for cancer therapy, resulting in the development of Aurora kinase inhibitors. The study and application of these small-molecule inhibitors, especially in combination with chemotherapy drugs, represent a new direction in cancer treatment. This paper reviews studies on Aurora kinases from recent years, including studies of their biological function, their relationship with tumor progression, and their inhibitors.

scholarly journals Aurora Kinases and Potential Medical Applications of Aurora Kinase Inhibitors: A Review

2015 ◽  
Vol 7 (10) ◽  
pp. 742-751 ◽  
Author(s):  
Paschalis Gavriilidis ◽  
Alexandros Giakoustidis ◽  
Dimitrios Giakoustidis
Keyword(s):  
Kinase Inhibitors ◽  
Aurora Kinase ◽  
Medical Applications ◽  
Aurora Kinases ◽  
Aurora Kinase Inhibitors

Targeting Aurora Kinases as Therapy in Multiple Myeloma.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3484-3484
Author(s):  
Yijiang Shi ◽  
Tony Reiman ◽  
Weiqun Li ◽  
Christopher Maxwell ◽  
Linda Pilarski ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Genetic Instability ◽  
Kinase Inhibitors ◽  
Aurora Kinase ◽  
Cell Cycle Checkpoints ◽  
Normal Peripheral Blood ◽  
Aurora Kinases ◽  
Over Expression ◽  
Aurora Kinase Inhibitors

Abstract The aurora kinases A and B are critical for facilitating cell cycle transit from G2 through to cytokinesis. As important regulators of the mitotic event, they are being tested as potential targets in cancer therapy. Multiple myeloma (MM) is a B cell malignancy characterized by progressive genetic instability, suggesting a disruption of cell cycle checkpoints has occurred that normally arrest cells at G2M or within mitosis when injury to the mitotic machinery occurs. Since these deficient checkpoints would prevent cell cycle arrest and potential repair and may render MM cells susceptible to apoptotic death in mitosis, we tested the anti-myeloma effecy of two separate agents that inhibit aurora kinases. Both agents induced cytoreduction of MM cell lines and primary myeloma samples at nM concentrations while normal peripheral blood lymphocytes and CLL cells were not affected. MM cells were not protected by IL-6 or activating mutations of RAS. Anti-myeloma effects were characterized by induction of tetraploidy followed by apoptosis. The myeloma apoptotic effect correlated well with the inhibition of aurora kinase activity as shown by reduction of histone 3B phosphorylation (substrate of auroras). Furthermore, stable ectopic over-expression of aurora kinase A significantly protected MM cells against aurora inhibitors but had no effect on apoptosis induced by velcade. As expression of the centrosomal protein RHAMM in MM cells may contribute to genetic instability, we tested effects of RHAMM over-expression on the sensitivity to aurora inhibitors. Although RHAMM over-expression in transfected MM cells was very modest, it significantly enhanced sensitivity to apoptosis induced by aurora kinase inhibitors. These results suggest the potential for aurora kinase inhibitors in multiple myeloma especially in patients where RHAMM is over-expressed.

scholarly journals Changes in ABC Transporter Expression during Hematopoiesis Cause Lineage-Biased Cytopenias in Patients Treated with Aurora Kinase Inhibitors

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4292-4292
Author(s):  
Brooke A. Furlong ◽  
Ryan R. Posey ◽  
David B. Chou ◽  
Christos Kyprianou ◽  
Lucy R. O'Sullivan ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Small Molecule ◽  
Abc Transporters ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Early Stage ◽  
Aurora Kinase ◽  
Advisory Committees ◽  
Healthy Human ◽  
Aurora Kinase Inhibitors

Abstract Chemotherapy-induced cytopenias are a prevalent and significant issue that worsens clinical outcomes and hinders the effective treatment of cancer. While they are classically associated with traditional cytotoxic chemotherapies, they also occur with newer targeted small molecule drugs and the factors that determine the hematotoxicity profiles of chemotherapies are not fully understood. Here, we explore why Aurora kinase inhibitor drugs cause preferential neutropenia when compared to the cytopenic profiles of targeted small molecule cancer drugs that are FDA approved. By studying drug responses of healthy human hematopoietic cells in vitro and analyzing existing published clinical datasets, we provide evidence that the enhanced vulnerability of neutrophil-lineage cells to Aurora kinase inhibitors is acquired at an early stage of differentiation and is caused by developmental changes in the expression pattern of ATP-binding cassette (ABC) transporters. These data show that hematopoietic cell-intrinsic expression of ABC transporters may be an important factor that determines how some chemotherapies affect the bone marrow. Disclosures David: AstraZeneca: Current Employment. Randle: AstraZeneca: Current Employment. Polanska: AstraZeneca: Current Employment. Urosevic: AstraZeneca: Current Employment. Travers: AstraZeneca: Ended employment in the past 24 months. Ingber: Emulate: Membership on an entity's Board of Directors or advisory committees; BOA Biomedical: Membership on an entity's Board of Directors or advisory committees; Freeflow Medical Devices Inc: Membership on an entity's Board of Directors or advisory committees.

scholarly journals Epigenetic Drug Screen on Resistant CLL Cells Reveals Aurora Kinase Inhibitors As Enhancers of CD20 Expression and Sensitizers to Treatment with CD20 Monoclonal Antibodies

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4407-4407
Author(s):  
Veronika Kozlova ◽  
Aneta Ledererova ◽  
Michael Doubek ◽  
Jiri Mayer ◽  
Sarka Pospisilova ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Cell Lines ◽  
Research Funding ◽  
Kinase Inhibitors ◽  
Aurora Kinase ◽  
Epigenetic Drugs ◽  
Aurora Kinase Inhibitors ◽  
Epigenetic Drug ◽  
Cd20 Expression ◽  
Resistant Cells

Abstract Background: Chronic lymphocytic leukemia (CLL) still remains an incurable disease. In spite of tremendous success of some targeted agents, the main mode of therapy in routine practice relies on the application of CD20 monoclonal antibodies (mAbs). Yet, majority of patients relapses and fails the immunotherapy, the major reason presumably being low expression of CD20 target protein on the surface of malignant cells. Whereas the molecular mechanisms regulating CD20 are largely unknown, the possibility to modulate CD20 levels seems an appealing strategy to enhance the success rate of CD20 immunotherapy. Aim: We aimed to screen epigenetic drug library on our generated immunotherapy-resistant CLL cell lines in order to reveal drugs able to upregulate CD20 expression and thereby sensitize cells to further CD20-mAb treatment. Methods: Through chronic cell exposure to gradually increasing doses of CD20 mAbs we have generated cells permanently resistant to anti-CD20 immunotherapy. These cells have strongly reduced CD20 expression. Epigenetic drug library (182 drugs) was applied on such cells in triplicates at 10uM concentration for 72 hours and changes in CD20 expression were determined by flow cytometry. Viability of the cells treated with epigenetic drugs in combination with CD20 mAb was measured by a CellTiter-Glo assay. Results: Screening the library of 182 epigenetic drugs on immunotherapy-resistant CD20-low cells revealed multiple drugs that were able to upregulate CD20 expression more than 2-fold. Among these were significantly enriched multiple inhibitors of Aurora kinases (AURK). In fact, there were 12 diverse Aurora kinase inhibitors among the top 16 hits. In parallel, we performed another epigenetic screen on our resistant cells, combining the epigenetic drugs with the addition of CD20-mAb Rituximab (RTX) to search for drugs able to sensitize cells to RTX treatment. Aurora kinase inhibitors were again found among the top three groups of strongest immunotherapy sensitizers. We could then validate several selected AURK inhibitors in individual experiments and showed that the upregulation of CD20 was concentration dependent. Importantly, we did not observe any induction of CD20 in non-B cell lines upon AURK inhibitor treatment. On contrary, we found that AURK inhibitors triggered marked increase in CD20 in cell lines resistant to both RTX and also to another CD20 mAb Ofatumumab, whereas they had only minor effect upon wildtype cells. The increase in CD20 was sustained for extended time periods. Pretreating resistant cells with AURK inhibitors followed by RTX treatment induced a profound shift in the viability curve, leading to a 50-fold improvement in EC50 for RTX as compared to cells without pretreatment. Conclusion: Aurora kinase inhibitors are able to specifically and strongly enhance expression of CD20 antigen on the surface of immunotherapy-resistant cells and thereby they strongly sensitize cells to further treatment with CD20 mAbs. These inhibitors thus seem as suitable candidates for combination therapy together with CD20 antibodies. This research has been financially supported by the Ministry of Education, Youth and Sports of the Czech Republic under the project CEITEC 2020 (LQ1601) and by the research grant AZV-MZ-CR 15-33561AA-4/2015 and grant MUNI/A/0968/2017. Disclosures Doubek: Janssen: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Affimed: Research Funding; AbbVie: Consultancy, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Novartis: Consultancy. Mayer:Eisai: Research Funding; Novartis: Research Funding; Johnson & Johnson: Research Funding; Roche: Research Funding; Affimed: Research Funding.

Analysis of Protein Biology to Increase Efficacy of Aurora Kinase Inhibitors for Multiple Myeloma Therapy.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1699-1699
Author(s):  
Robert P. Evans ◽  
Kim Laginha ◽  
Linda M. Pilarski ◽  
Andrew Belch ◽  
Tony Reiman
Keyword(s):  
Multiple Myeloma ◽  
Cancer Cells ◽  
Protein Interactions ◽  
Kinase Inhibitors ◽  
Aurora Kinase ◽  
Protein Protein Interactions ◽  
Aurora Kinases ◽  
Aurora Kinase Inhibitors ◽  
Anti Cancer ◽  
Novel Protein

Abstract Despite improvement in therapeutic regimes which have extended survival of patients with multiple myeloma, the search for novel targets to further advance treatment options continues. It is critical to the success of targeted cancer therapy that the rational selection of drugs be derived from the molecular and cellular biology of protein targets. Furthermore, studies have indicated that focused combination drug therapy could produce remarkable improvement in patient outcomes. Aurora kinases A/B/C (AURK), components of the centrosome and important for cell cycle function, are promising new targets in the treatment of numerous types of cancer. We have previously validated AURKs as a therapeutic target in pre-clinical models of multiple myeloma. In this study our aim is to better define the biology of AURKs in both normal and malignant cells, with the goal of identifying rational strategies for improving the therapeutic potential of Aurora kinase inhibitors (AKIs) as anti-cancer agents. We use a systematic two-pronged approach to map post-translational modifications and novel protein-protein interactions that define the interactome of AURKs. We also examine whether Aurora kinase interactions and posttranslational modifications are significantly different in cancer cells compared to normal cells. Increased understanding of Aurora kinase biology will help develop mechanisms to intensify the anti-cancer effects of AKIs. SUMOylation is a recently discovered posttranslational modification of numerous proteins that has been linked to many cancer types. A small ubiquitin-like modifier (SUMO) group is conjugated at the canonical ubiquitin site of a protein to alter its function, stability or sub-cellular localization. We believe that Aurora kinases may be differentially SUMOylated in cancer cells compared to normal cells, and that SUMOylation of Aurora kinases in cancer cells may alter their function and their susceptibility to AKI therapy. Here we have determined putative SUMOylation sites of all three AURKs in silico and also have evidence of AURK SUMOylation using an in vitro assay and also in human HEK293 cells. Furthermore, the gene encoding the central SUMO conjugating enzyme - UBC9 - is expressed at higher levels in CD138+ malignant plasma cells compared to other CD138−bone marrow cells in myeloma patients. As part of our strategy, we have also used Tandem Affinity Purification (TAP) technology to identify novel protein-protein interactions of Aurora kinases. In the initial stage, we have established stable expressing clones in a human cancer cell line and a normal line that express TAP-tagged AURKA/B or C. In pilot experiments we have successfully isolated pure recombinant AURKA along with interacting proteins using the TAP method. Using mass spectrometry (MS/MS) protein ID, we have identified putative protein interaction partners with AURKA which have implications in general cancer biology and centrosomal structure. In the future, these interactions will be validated using conventional biochemical methods before being tested in myeloma cell lines.

Pan-Aurora Kinase Inhibitor Mk-0457 Synergistically Potentiates Apo2L/Trail Cytotoxicity in Multiple Mieloma Cells Sensitive and Resistant to Bortezomib.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1837-1837
Author(s):  
Paolo Lunghi ◽  
Laura Mazzera ◽  
Antonio Costanzo ◽  
Nicola Giuliani ◽  
Vittorio Rizzoli ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Combined Treatment ◽  
Aurora Kinase ◽  
Differential Sensitivity ◽  
Caspase 8 ◽  
Aurora Kinase Inhibitors ◽  
Dunnett Test ◽  
Induced Apoptosis ◽  
Rpmi 8226

Abstract Abstract 1837 Poster Board I-863 Multiple Myeloma (MM) cells are extremely resistant to apoptosis and currently new potential drug combinations are under investigation. Aurora kinase inhibitors have been shown to abrogate proliferation and induce apoptosis in human myeloma cells lines (HMCLs) and primary myeloma cells. In addition previous studies have shown the antimyeloma activity of Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (Apo2L/TRAIL) as a single agent or in combination with certain chemotherapeutic agents. The aim of this study was to investigate whether the combined treatment with pan-Aurora kinase inhibitor MK-0457 also known as VX-680(Vertex/Merck) and Apo2L/TRAIL has cytotoxic effects on MM cells. Because we found that MK-0457 (0.2–0.5 μM) partially activated the extrinsic caspase-8 mediated pathway both in HMCLs RPMI 8226 (highly sensitive to Apo2L/TRAIL: median lethal dose (LD50) at 48 hours was 4.9 ng/mL), and bortezomib-resistant 8226/R5 (barely sensitive to Apo2L/TRAIL: LD50 at 48 hours was 90.9 ng/mL) we attempted to examine whether MK-0457 potentiates the Apo2L/TRAIL-mediated apoptosis in HMCLs that have differential sensitivity to Apo2L/TRAIL. We first analyzed the pharmacologic interactions between MK-0457 and Apo2L/TRAIL using a fixed-ratio experimental design and found that the combined treatment resulted in the synergistic induction of apoptosis in both HMCLs (Chou-Talalay method): after 48 hours of treatment the averaged Combination Index values calculated from the ED50 (50% effective dose), ED75 and ED90, in MK-0457 plus Apo2L/TRAIL were 0.04 ± 0.05 and 0.03 ± 0.02 in RPMI 8226 and 8226/R5 respectively. Consistent with these results, we found that Aurora-A and -B were expressed at similar levels in RPMI 8226 and 8226/R5 cells and we demonstrated that the functional knock-out of Aurora-A or -B gene expression by small interfering (si)RNAs significantly increased (P< .001 Dunnett test) the TRAIL- induced apoptosis in both HMCLs. To investigate the molecular mechanisms by which MK-0457/Apo2L/TRAIL induced MM cell apoptosis first we compared the effect on caspase activation in RPMI 8226 and 8226/R5. The cells were treated with MK-0457 (0.2–0.5 μM) and/or Apo2L/TRAIL (2.4 ng/mL and 9.6 ng/mL in RPMI 8226 and 8226/R5 respectively) for 24 hours and caspase activation and PARP fragmentation were analyzed by Western blotting: the treatment with MK-0457 strongly potentiated the Apo2L/TRAIL -induced activation of caspase-8, caspase-3 and PARP cleavage in both HMCLs. In addition, a strong activation of caspase-9 was observed in the MK-0457/Apo2L/TRAIL-treated 8226/R5. Using caspase blocking peptides, specific siRNA against caspase-8 or caspase-9 and Western immunoblotting we demonstrated the involvement of primarily caspase-8 and -3 in MK-0457/Apo2L/TRAIL -induced apoptosis in RPMI 8226 and 8226/R5: the inhibition of caspase-8 significantly (P< .001 Dunnett test) reduced the MK-0457/Apo2L/TRAIL -induced apoptosis in both cell lines. Moreover, the pancaspase inhibitor Z-VAD-FMK protected MM cells from MK-0457/Apo2L/TRAIL -induced apoptosis, confirming that caspase activity was indispensable in MK-0457/Apo2L/TRAIL -induced apoptosis. Since antiapoptotic Mcl-1 and proapoptotic Bim play a pivotal role in controlling MM cell survival and apoptosis, and Bim, as previously demonstrated, can interfere with the activation of both intrinsic and extrinsic apoptotic pathways in MM cells, we analyzed their expression in MK-0457/Apo2L/TRAIL treated cells. We found that monotreatment with neither MK-0457 nor Apo2L/TRAIL (or their combination) was able to substantially modulate the expression of Mcl-1 or Bim in RPMI 8226; in contrast in HMCL 8226/R5, that showed low sensitivity to Apo2L/TRAIL, the treatment with Apo2L/TRAIL increased the intracellular amount of the anti-apoptotic protein Mcl-1 and MK-0457 reverted Apo2L/TRAIL-induced up-regulation of Mcl-1, thus correlating with the enhanced cytotoxicity of combined treatment. In conclusion, our data indicate that targeting aurora kinase potentiates the apoptotic effect of Apo2L/TRAIL in MM cells with differential sensitivity to Apo2L/TRAIL through the activation of the extrinsic pathway. More important, MK-0457/Apo2L/TRAIL can induce apoptosis in MM cells displaying resistance to bortezomib. Together, these findings suggest that a strategy combining Aurora kinase inhibitors with Apo2L/TRAIL warrants attention in MM. Disclosures: Lunghi: MERCK sharp and Dohme: Research Funding. Bonati:MERCK sharp and Dohme: Research Funding.

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