GLORIA

GEOMAR Library Ocean Research Information Access

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Material
Language
  • 1
    In: Blood, American Society of Hematology, Vol. 126, No. 23 ( 2015-12-03), p. 3010-3010
    Abstract: Background: The role of dysregulation of the proto-oncogene MYC in both early and late myeloma progression events is well established. Among key MYC -downstream targets is upregulation of ribosomal biogenesis, resulting in increased protein translational capacity and biomass accumulation that is characteristic of neoplastic cells. Thus, given the relationship between myeloma pathobiology, MYC dysregulation, and ribosomal biogenesis, we hypothesized that selective targeting of ribosomal RNA (rRNA) transcription with the small molecule RNA polymerase (pol) I inhibitor CX-5461 (Senhwa Biosciences) may represent a novel therapeutic strategy in myeloma. Methods: Studies with CX-5461 were performed in human myeloma cell lines, isogenic p53 wild-type (wt) and knock-out (KO) p53 cells generated using sequence-specific zinc-finger nucleases, drug-resistant cell lines, primary patient samples, and myeloma murine xenograft models using NOD-SCID IL2Rgnull mice. Results: CX-5461 treatment of p53 wt (MM1.S, MOLP-8) and p53 mutant (U266, RPMI-8226) myeloma cell lines demonstrated a time- and dose-dependent decrease in cell proliferation with a median inhibitory concentration (IC50) at nM levels after 72 hours. A corresponding increase in cleaved-PARP, cleaved caspase-9, and cleaved caspase-3 expression was seen on Western blot as well as increased Annexin V staining on flow cytometry analysis, although this was more pronounced in p53 wt versus mutant cell lines. CX-5461 also retained activity in a panel of cell lines resistant to standard myeloma therapeutic agents (bortezomib, carfilzomib, lenalidomide, and doxorubicin) and in primary patient samples, including a heavily pretreated relapsed/refractory patient and a de novo plasma cell leukemia patient with del 17p. In vivo studies using a systemic isogenic MM1.S p53 wt and KO myeloma murine xenograft model demonstrated significant improvement in median overall survival in the CX-5461-treated p53 wt cohort (41 days vs. not reached, P .05), although outcomes were more modest in the p53 KO cohort with only a trend towards improved survival (P.1) in the drug-treated mice. To probe the p53-independent effects of CX-5461, gene expression profiling and gene set enrichment analysis was performed on isogenic MM1.S and MOLP-8 p53 wt and KO myeloma cell lines treated with CX-5461 or vehicle. These results suggested downregulation of MYC downstream targets as one p53-independent effect of RNA pol I inhibition. qPCR and Western blot studies revealed rapid downregulation of MYC at the transcript level within 1-hour of CX-5461 treatment followed by decreases in MYC protein levels. Previous studies have suggested ribosomal biogenesis is tightly controlled by an auto-regulatory feedback mechanism in which ribosomal proteins such as RPL5 and RPL11 can bind to the 3'UTR of MYC mRNA and facilitate its degradation through the RNA-induced silencing complex (RISC). Because RNA pol I inhibition is known to induce a nucleolar stress response and increase the availability of free ribosomal proteins, RISC-mediated degradation of MYC mRNA was explored as one possible mechanism of CX-5461-mediated MYC downregulation. Indeed, treatment with CX-5461 led to increased pull-down of RPL5 when immunoprecipitated with the RISC subunit TAR (HIV-1) RNA Binding Protein 2 (TARBP2) compared to vehicle-treated controls, and RNA immunoprecipitation assays with the catalytic RISC subunit, Argonaute 2 (AGO2), demonstrated enrichment of MYC mRNA with CX-5461 treatment. These results suggest that CX-5461 may induce degradation of MYC through the cooperative binding of ribosomal proteins, RISC subunits, and MYC mRNA. Finally, to evaluate the role of MYC expression and ribosomal biogenesis in relation to CX-5461 sensitivity, MYC was overexpressed in the H1112 myeloma cell line, which at baseline does not harbor a MYC translocation. MYC overexpression in H1112pCDH-myc cells led to increased basal pre-rRNA transcript levels compared to H1112pCDH cells, and furthermore, led to enhanced sensitivity to CX-5461. Conclusion: RNA pol I inhibition by CX-5461 is a promising target in myeloma therapy, with downregulation of MYC representing one mechanism of action. Moreover, increased MYC expression enhances sensitivity to CX-5461, providing rationale for the clinical translation of CX-5461 for the treatment of myeloma and other MYC-driven cancers. Disclosures O'Brien: Senhwa Biosciences, Inc.: Employment. Keats:Translational Genomic Research Institute: Employment. Orlowski:Bristol-Myers Squibb: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Spectrum Pharmaceuticals: Research Funding; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Acetylon: Membership on an entity's Board of Directors or advisory committees; Onyx Pharmaceuticals: Consultancy, Research Funding; Millennium Pharmaceuticals: Consultancy, Research Funding; Forma Therapeutics: Consultancy; Genentech: Consultancy; BioTheryX, Inc.: Membership on an entity's Board of Directors or advisory committees; Array BioPharma: Consultancy, Research Funding.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2015
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    In: Blood, American Society of Hematology, Vol. 122, No. 21 ( 2013-11-15), p. 4438-4438
    Abstract: Ribosomal RNA (rRNA) forms a major component of ribosomes, which play a critical role in cellular growth and proliferation through regulation of protein synthesis. Increased rRNA transcription and ribosomal biogenesis have been associated with tumorigenesis, and recent reports have suggested that inhibition of rRNA transcription by CX-5461 (Senhwa Biosciences), a novel selective small-molecule inhibitor of RNA polymerase (pol) I, induces cell death in several human tumor types by both p53-dependent and independent mechanisms. These findings led to our hypothesis that selective RNA pol I inhibition with CX-5461 could be a rational new approach to therapy for both wild-type (wt) and mutant p53 multiple myeloma models. Methods Studies with CX-5461 were performed in wt p53 and mutant p53 cell lines, zinc-finger nuclease (ZFN) p53 knock-out (KO) isogenic myeloma cell lines, and bortezomib and carfilzomib-resistant myeloma cell lines. Results Treatment of wt p53 (MM1.S, MOLP8) and mutant p53 (U266, RPMI-8226) myeloma cell lines demonstrated a time and dose dependent decrease in cell proliferation after exposure to CX-5461 with a median inhibitory concentration (IC50) range of 50-100 nM after a 72-hour incubation. A corresponding increase in cleaved PARP, cleaved caspase-9, and cleaved caspase-3 expression was seen on Western blot, as well as increased Annexin V staining on flow cytometry analysis. Notably, the degree of Annexin V staining was less in the p53 mutant cell lines compared to the wt p53 cells at any given drug concentration, but strong apoptotic signaling could be induced in mutant p53 cell lines when using higher concentrations of CX-5461. In addition, co-culturing myeloma cells with GFP+ HS5 stromal cells to mimic the bone marrow microenvironment did decrease the therapeutic effect of CX-5461, but again could be overcome with higher drug concentrations [250-500 nM]. Similar results were seen when isogenic MM1.S ZFN p53 KO cells were used, whose sensitivity to CX-5461 was comparable to that of wt p53 cells. Finally, CX-5461 was also tested on drug-resistant myeloma cell lines that were generated by exposing cells to low concentrations of bortezomib (RMPI-8266, KAS-6/1, ANBL-6) or carfilzomib (KAS-6/1) over time. These drug-resistant cell lines showed sensitivity to CX-5461 with an IC50 in the 100-250 nM concentration range. Gene expression profiling (GEP) of isogenic MM1.S ZFN p53 KO and wt cells revealed that gene expression perturbations by CX-5461 were primarily p53-independent. Additional GEP and pathway analysis in other isogenic ZFN p53 wt and KO cell lines is currently ongoing, with a particular interest in p53-independent mechanisms that may explain the efficacy of CX-5461 in both wt and mutant p53 myeloma models. Conclusion RNA pol I inhibition by CX-5461 is a promising approach to myeloma therapy, with low nanomolar drug activity seen in wt p53, mutant p53, and drug-resistant myeloma cell line models, providing a rationale for translation of CX-5461 into the clinic for the treatment of multiple myeloma. Disclosures: O'Brien: Senhwa Biosciences, Inc: Employment. Orlowski:Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Resverlogix: Research Funding; Array Biopharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Merck: Membership on an entity’s Board of Directors or advisory committees.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2013
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    Online Resource
    Online Resource
    American Society of Hematology ; 2013
    In:  Blood Vol. 122, No. 21 ( 2013-11-15), p. 3845-3845
    In: Blood, American Society of Hematology, Vol. 122, No. 21 ( 2013-11-15), p. 3845-3845
    Abstract: Intravenous Immunoglobulin G (IVIg) has been in wide use for over 20 years and is approved for treatment of immune deficiencies, autoimmune disease and acute infections. The ability of IVIg to suppress inflammation would also suggest it has a role to play in suppressing the growth of malignant cells, particularly given the now accepted bidirectional relationship between inflammation and cancer. In several case reports, patients with malignancies such as Kaposi’s sarcoma, thyroid cancer and peripheral nerve sheath tumors experienced remission of their malignancies after receiving IVIg for immune deficiency(Shoenfeld and Krause 2004). Furthermore, a clinical trial in patients with advanced melanoma also reported a therapeutic effect of the anti-inflammatory dose of IVIg of 2 g/Kg (Schachter, Katz et al. 2007). These reports suggest that the pooled IgG of over 10,000 healthy donors is an unrealized and potentially useful anti-cancer agent that may augment both current and new chemotherapy regimens. However, the mechanism of response may not be limited to effects on inflammation or immunity, and might include a direct effect on tumor cells. To address this, we investigated the effect of IVIg on cell lines of non-Hodgkin’s lymphoma and multiple myeloma (MM). Methods A panel of MM and other cell lines derived from Burkitt’s lymphoma (BL) and mantle cell lymphoma (MCL) were treated with dialyzed IVIg (10 mg/ml), which is in the 1-2 g/Kg anti-inflammatory clinically achievable range. The effects were evaluated both alone or in combination with proteasome inhibitors, bortezomib (BZB) and carfilzomib (CFZ), or the HSP90 inhibitors 17AAG and AUY-922. The efficacy of these drugs have their clinical utility limited due to HSP70-1 induction hence, IVIg makes a good choice for combination therapy. Results Treatment with 10 mg/ml IVIg suppressed the growth of all cell lines at 3 days compared to the bovine serum albumin control. This effect was accompanied by a G1cell cycle arrest and suppression of pro-tumor cytokines including IL-6, IL-8, IL-10 and GM-CSF. The combination of IVIg with BZB or CFZ was synergistic, and IVIg also resensitized BZB-resistant MM cells to BZB. The combination of IVIg and the HSP90 inhibitors 17AAG or AUY-922 was highly synergistic at suppressing the cells growth. IVIg strongly suppressed the expression of HSP70-1 both alone and when induced by HSP90 inhibitors. Varying the sequence of administration revealed that pretreatment with IVIg for 24 hours was superior in growth suppression compared to simultaneous administration of IVIg with 17AAG or AUY922 or pretreatment with 17AAG or AUY-922. IVIg treatment also suppressed expression of mutant p53, for which HSP70-1 serves as a cochaperone. Conclusions IVIg has a potent ability to suppress MM, MCL and BL cell growth, through a mechanism that may involve its suppression of HSP70-1 expression. We hypothesize that IVIg contains IgG against HSP70-1, which results in enhanced HSP70-1 turnover and blocks the heat shock response induced by proteasome and HSP90 inhibitors. This mechanism would raise the possibility that IVIg could enhance the efficacy of targeted inhibitors, and inhibit mechanisms used by malignancies to evade these agents. Given its long clinical experience and exceptional safety profile, IVIg could be rapidly incorporated into the treatment of hematological malignancies. References Schachter, J., U. Katz, et al. (2007). “Efficacy and safety of intravenous immunoglobulin in patients with metastatic melanoma.” Annals of the New York Academy of Sciences 1110: 305-314. Shoenfeld, Y. and I. Krause (2004). “i.v.IG for autoimmune, fibrosis, and malignant conditions: our experience with 200 patients.” Journal of clinical immunology 24(2): 107-114. Disclosures: Orlowski: Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Resverlogix: Research Funding; Array Biopharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Merck: Membership on an entity’s Board of Directors or advisory committees.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2013
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    In: Blood, American Society of Hematology, Vol. 112, No. 11 ( 2008-11-16), p. 3618-3618
    Abstract: Background: The ubiquitin-proteasome pathway has been validated as a target for NHL with the recent approval of bortezomib for mantle cell lymphoma (MCL). In addition to anti-tumor activity, however, proteasome inhibitors have pleiotropic effects, including activation of anti-apoptotic heat shock proteins, and their use clinically is complicated by toxicities such as peripheral neuropathy. By targeting E3 ubiquitin ligases, which are involved in ubiquitination of only a small subset of cellular proteins, it may be possible to achieve more specific anti-tumor effects with a better therapeutic index. One attractive target is HDM-2, which is responsible for ubiquitination of the p53 tumor suppressor. Methods: To evaluate the therapeutic potential of agents targeting HDM-2, we studied the impact of the small molecule JNJ-26854165, an inhibitor of HDM-2-function, in both p53 wt and mut cell line models. Results: Treatment of wt p53 NHL cell lines with JNJ-26854165 induced a dose- and time-dependent inhibition of proliferation, with an IC50 in the 0.02–0.3 μM range. Cell death, which was typically seen within 48 hours of HDM-2 inhibition, occurred through induction of type I PCD, as judged by the appearance of increased staining with Annexin V and activation of caspase 3. While cell lines with mut p53 were generally less sensitive than their wt p53 counterparts, JNJ-26854165 remained potent, with an IC50 in the 0.05–0.6 μM range. The latter cell lines showed a longer kinetics of death, with PCD being seen within 72 hours of drug exposure. Notably, in these mut p53 cell lines, very little Annexin V staining or caspase 3 activation was seen, consistent with a minor role for type I PCD. Instead, mut p53 cell lines demonstrated an increased content of acidic vacuoles by acridine orange staining, increased expression of Beclin 1 and Sequestosome 1/p62, and conversion of microtubule-associated protein 1 light chain 3 form I to form II, consistent with activation of type II PCD, or autophagy. Also, electron microscopy showed an increased presence of autophagosomes and autolysosomes, further supporting the activation of this pathway. Combinations of JNJ-26854165 with other agents, including rapamycin, doxorubicin, and an inhibitor of Bcl 2, showed enhanced anti-proliferative effects in a sequence-dependent fashion, which were greatest when the chemotherapeutic preceded the HDM-2 inhibitor. Combination index analysis revealed that these interactions met criteria for synergy. Conclusions: Inhibition of the function of HDM-2 using JNJ-26854165 is a promising approach that is effective against both wt and mut p53 models by activating type I and type II PCD, respectively. The effectiveness of JNJ-26854165 was enhanced in combination with currently used chemotherapeutics in a sequence specific manner, providing a rationale for translation of this novel approach into the clinic.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2008
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 5
    In: Blood, American Society of Hematology, Vol. 128, No. 22 ( 2016-12-02), p. 3296-3296
    Abstract: Background: The ubiquitin-proteasome system (UPS) has been validated as a target in multiple myeloma (MM) through the success of proteasome inhibitors such as bortezomib, but drug resistance is an emerging challenge. Targeting some of the upstream components of the UPS, such as the E1 ubiquitin activating enzyme (UAE), could therefore be a promising alternative. TAK-243 (MLN7243) specifically blocks the ubiquitin conjugation cascade through the formation of a TAK-243-ubiquitin adduct, thereby inhibiting the UAE. Our aim was to explore the effectiveness of TAK-243 against pre-clinical myeloma models, and to understand some its mechanisms of action. Methods: We performed pre-clinical studies in myeloma cell lines and mouse models using TAK-243. Downstream effects were evaluated using viability, apoptosis assays, western blotting, gene expression profiling (GEP), and Reverse Phase Protein Array (RPPA) techniques. Results: MM1.S and MOLP-8 TP53 wild-type cell lines were sensitive to TAK-243, with median inhibitory concentrations (IC50) of 25 nM at 24 hours based on viability assays. In otherwise isogenic cell lines in which TP53 was suppressed using genome editing techniques, the IC50 was ~40 nM, but higher TAK-243 concentrations of 100 nM overcame resistance due to TP53 inactivation. Similarly, TAK-243 was able to overcome resistance to both conventional (dexamethasone) and novel (bortezomib, lenalidomide) drugs in paired sensitive and resistant cell line models. After treatment with TAK-243, Annexin V and TO-PRO3 staining determined that viable MM1.S cells were induced into early or late apoptosis. This was accompanied by a significant increase in cleaved caspase-3, -8, and -9 as detected by flow cytometry, and in cleaved caspase-7 detected by RPPA and western blot. Exposure to TAK-243 reduced the cellular content of ubiquitin-protein conjugates, and did not enhance expression levels of a fusion protein degraded by the proteasome in a ubiquitin-independent manner, indicating the lack of direct proteasome inhibition. GEP analysis and RPPA detected enhanced expression of p53-pathway related proteins, including MDM2, TP53, and p21 in TAK-243 treated MM1.S cells. Several mRNAs and proteins in the ER stress pathway, including ATF6, ATF4, IRE1a and XBP1 were also elevated, as were many non-coding RNAs and DNA-damage related genes. Combination experiments in MM cell lines demonstrated synergy between TAK-243 and lenalidomide, pomalidomide, panobinostat, melphalan and doxorubicin. Finally, TAK-243 demonstrated in vivo antitumor activity against MM1.S and MOLP-8 xenograft models when dosed at 12.5 mg/kg IV twice-weekly for 2 weeks (tumor growth inhibition of 60% and 73%, respectively). Elevation of BiP, ATF4, XBP1s and cleaved-caspase 3 was detected within the first 24 hrs after dosing in the sensitive MM1.S xenografts. In contrast, RPMI 8226 cells, which showed a 2000 nM IC50 in cell culture, were also resistant to TAK-243 in vivo, with no tumor growth inhibition detected. Conclusions: TAK-243 is a UAE inhibitor that is active against myeloma cells in vitro and in xenograft models in vivo, overcomes conventional and novel drug resistance, and its action is associated with stimulation of the TP53 and ER stress pathways. Thus, it may deserve further evaluation as an anti-myeloma agent. Disclosures Berger: Takeda Pharmaceuticals: Employment. Hyer:Takeda Pharmaceuticals: Employment. Chattopadhyay:Takeda Pharmaceuticals: Employment. Syed:Takeda Pharmaceuticals: Employment. Shi:Takeda Pharmaceuticals: Employment. Yu:Takeda Pharmaceuticals International Co, Cambridge, MA: Employment. Shinde:Takeda Pharmaceuticals: Employment. Kreshock:Takeda Pharmaceuticals: Employment. Tirrell:Takeda Pharmaceuticals: Employment. Menon:Takeda Pharmaceuticals: Employment. Orlowski:Takeda Pharmaceuticals: Research Funding.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2016
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 6
    Online Resource
    Online Resource
    American Society of Hematology ; 2011
    In:  Blood Vol. 118, No. 21 ( 2011-11-18), p. 2726-2726
    In: Blood, American Society of Hematology, Vol. 118, No. 21 ( 2011-11-18), p. 2726-2726
    Abstract: Abstract 2726 Background: The ubiquitin-proteasome pathway has been validated as a target for multiple myeloma (MM) and mantle cell lymphoma (MCL) by the demonstration of the effectiveness of the proteasome inhibitor bortezomib (BZB) in these malignancies. E3 ubiquitin ligases are involved in ubiquitination of a small subset of cellular proteins and play an integral part in regulation of turnover of cellular proteins. HDM-2 is the E3 ubiquitin ligase responsible for degradation and regulation of the p53 tumor suppressor, and HDM-2 inhibitors such as nutlin (NUT) and MI-63 stabilize p53 and enhance its pro-apoptotic effects in the absence of DNA damage. Methods: To evaluate the mechanisms through which wild type p53 MCL and MM cells could evade the therapeutic effects of HDM-2 inhibitors, we generated cell lines resistant to MI-63 and Nutlin. Resistant lines were generated by growing cells over a period of 3 months in increasing concentrations of either MI-63 or NUT until the cells were resistant to 10 mM of either agent. Results: H929 MM and Granta-519 MCL cells resistant to MI-63 (MI63R) were cross resistant to NUT, and NUT resistant (NUTR) cells displayed resistance to MI-63. Indeed, treatment of resistant cells with either MI-63 or NUT resulted in enhanced proliferation of these cells. MI-63R and NUTR cells showed enhanced resistance to both BZB and doxorubicin, whilst unexpectedly maintaining sensitivity to RITA (reactivation of p53 and induction of tumor cell apoptosis). Immunoblot analysis indicated increased levels of p53 in resistant cells at baseline and upon treatment with MI-63, NUT, or doxorubicin, but these treatments failed to induce p21 and HDM-2. Sequencing of genomic DNA from these cells for both HDM-2 and p53 genes indicated no alteration in the sequence of HDM-2. However, substitution mutations were found within p53 encompassing exons 4 through 8 for both NUTR and MI63R cells. When RITA was used in the resistant cells, an SG2 cell cycle arrest was seen at 48 hours post treatment. A time course analysis indicated that resistant cells treated with RITA displayed up-regulation of HDM-2, PUMA and NOXA from around 12 hours, with a corresponding induction of PARP cleavage from 48 to 72 hours. These data suggested RITA was able to restore wtp53 function resulting in induction of p53 transcriptional targets and thereby overcoming resistance to NUT and MI-63. The combination of either MI-63 or NUT with RITA demonstrated that simultaneous addition of the agents or pretreatment with RITA resulted in an enhancement of cell death over RITA alone. This result indicates that RITA restored the function of mutp53 within MI-63 and NUT resistant cells and thereby resensitized the cells to the effects of MI-63 or NUT. Conclusions: Chronic exposure of MM and MCL cells to HDM-2 inhibitors resulted in cross resistance to other inhibitors in the same class through mutation of p53 as the primary mechanism of resistance. HDM-2 inhibitor resistant cells did remain sensitive to the effects of RITA through restoration of p53 function, and restoring the sensitivity of such cells to agents that promote p53's pro apoptotic effects may be a rational strategy for translation to the clinic. Disclosures: No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2011
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 7
    Online Resource
    Online Resource
    American Society of Hematology ; 2011
    In:  Blood Vol. 118, No. 21 ( 2011-11-18), p. 925-925
    In: Blood, American Society of Hematology, Vol. 118, No. 21 ( 2011-11-18), p. 925-925
    Abstract: Abstract 925 Blockade of IGF-1R with OSI-906 Overcomes Bortezomib-resistance in Multiple Myeloma Deborah J. Kuhn, Hua Wang, Richard J. Jones, Chad C. Bjorklund, Robert Z. Orlowski The Department of Lymphoma & Myeloma, The University of Texas M. D. Anderson Cancer Center, Houston, TX Intro: Bortezomib (Velcade®) therapy is now one of the standards of care in the treatment of newly diagnosed and relapsed/refractory multiple myeloma. Unfortunately, like many other novel agents, the emergence of drug resistance often results in a reduced response to any subsequent therapies that contain bortezomib. Identifying the molecular signaling pathways predominant in bortezomib-resistance can lead to the discovery of therapies that can overcome or prevent the emergence of such resistance all together. Design: In order to improve our understanding of the mechanisms responsible for bortezomib-resistance, our group has developed cell line models of interleukin (IL)-6-dependent and –independent bortezomib-resistant multiple myeloma. Results: Gene expression profiling identified insulin-like growth factor (IGF-1) signaling as one pathway that was induced in bortezomib-resistant myeloma cell lines. Its role was validated in molecular studies that showed exogenous IGF-1 protected drug-naïve cells from bortezomib, while shRNA-mediated knockdown of the IGF-1 receptor (IGF-1R) in bortezomib-resistant models restored sensitivity to this proteasome inhibitor. We then evaluated whether targeting IGF-1R with the clinically relevant inhibitor OSI-906 (OSI Pharmaceuticals, Inc.) could be a valid strategy to overcome bortezomib-resistance. OSI-906 alone preferentially induced cell death in bortezomib-resistant cell lines, while drug-naïve cell populations were relatively spared. Simultaneous addition of bortezomib and increasing concentrations of OSI-906 enhanced the amount of cell death. Also, OSI-906 preferentially induced apoptosis as measured by Annexin V staining. Knockout of IGF-1R gene expression using lentiviral shRNAs in bortezomib-resistant cell lines decreased sensitivity to OSI-906 compared to their scrambled control counterparts, underscoring the importance of IGF-1R signaling in these cells. Conversely, lentiviral overexpression of IGF-1R in drug-naïve wild-type cell lines reduced apoptosis when these models were exposed to OSI-906. Next, we determined whether OSI-906 alone would have an effect on MDA-MM-002, a cell line developed from the pleural effusion of a patient with advanced myeloma. MDA-MM-002 cells, which are resistant to a number of chemotherapeutics, including bortezomib, showed no decrease in viable cell populations when treated with OSI-906 alone. However, when combined with bortezomib, there was a dose-dependent decrease in the viable cell population. Importantly, flank xenograft models of bortezomib-resistant myeloma cells in immunodeficient mice remained insensitive to bortezomib treatment, but showed a dose-dependent response to OSI-906 as evidenced by decrease tumor cell growth, and caspase-3 and PARP cleavage. Examination of synergy profiles using isobologram analysis demonstrated a high degree of synergy with OSI-906 and bortezomib over the use of either drug alone. Conclusions: In addition to the important role of IGF-1 in myeloma biology, the findings herein provide an excellent rationale for using OSI-906 to target IGF-1 signaling in combination with bortezomib as an approach to overcome, or possibly even prevent outgrowth of resistance to bortezomib in myeloma patients. Disclosures: No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2011
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 8
    Online Resource
    Online Resource
    AME Publishing Company ; 2017
    In:  Translational Cancer Research Vol. 6, No. S9 ( 2017-12), p. S1398-S1401
    In: Translational Cancer Research, AME Publishing Company, Vol. 6, No. S9 ( 2017-12), p. S1398-S1401
    Type of Medium: Online Resource
    ISSN: 2218-676X , 2219-6803
    Language: Unknown
    Publisher: AME Publishing Company
    Publication Date: 2017
    detail.hit.zdb_id: 2901601-0
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 9
    In: Blood, American Society of Hematology, Vol. 133, No. 14 ( 2019-04-04), p. 1572-1584
    Abstract: Three proteasome inhibitors have garnered regulatory approvals in various multiple myeloma settings; but drug resistance is an emerging challenge, prompting interest in blocking upstream components of the ubiquitin-proteasome pathway. One such attractive target is the E1 ubiquitin-activating enzyme (UAE); we therefore evaluated the activity of TAK-243, a novel and specific UAE inhibitor. TAK-243 potently suppressed myeloma cell line growth, induced apoptosis, and activated caspases while decreasing the abundance of ubiquitin-protein conjugates. This was accompanied by stabilization of many short-lived proteins, including p53, myeloid cell leukemia 1 (MCL-1), and c-MYC, and activation of the activating transcription factor 6 (ATF-6), inositol-requiring enzyme 1 (IRE-1), and protein kinase RNA-like endoplasmic reticulum (ER) kinase (PERK) arms of the ER stress response pathway, as well as oxidative stress. UAE inhibition showed comparable activity against otherwise isogenic cell lines with wild-type (WT) or deleted p53 despite induction of TP53 signaling in WT cells. Notably, TAK-243 overcame resistance to conventional drugs and novel agents in cell-line models, including bortezomib and carfilzomib resistance, and showed activity against primary cells from relapsed/refractory myeloma patients. In addition, TAK-243 showed strong synergy with a number of antimyeloma agents, including doxorubicin, melphalan, and panobinostat as measured by low combination indices. Finally, TAK-243 was active against a number of in vivo myeloma models in association with activation of ER stress. Taken together, the data support the conclusion that UAE inhibition could be an attractive strategy to move forward to the clinic for patients with relapsed and/or refractory multiple myeloma.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2019
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 10
    Online Resource
    Online Resource
    American Society of Hematology ; 2013
    In:  Blood Vol. 122, No. 21 ( 2013-11-15), p. 3499-3499
    In: Blood, American Society of Hematology, Vol. 122, No. 21 ( 2013-11-15), p. 3499-3499
    Abstract: Thalidomide (THAL), and the IMiDs® immunomodulatory agents lenalidomide (LEN), and pomalidomide (POM) are all approved for use in multiple myeloma (MM) either as single agents, or in combination with dexamethasone (DEX). Despite the enhanced efficacy of these novel agents, concern has arisen as to the increased incidence of secondary primary malignancies (SPM). For example, the IFM 2005-002 trial reported cases of lymphoblastic leukemia and Hodgkin’s disease (HD) following LEN use (Attal, Lauwers-Cances et al. 2012) in MM patients on maintenance therapy. Also, a recent case report described a MM patient who developed HD who had been treated with salvage therapy containing THAL(Chim, Choi et al. 2013), and two publications reported EBV reactivation in MM patients treated with LEN (Kneppers, van der Holt et al. 2011; Kroger, Zabelina et al. 2013). As HD is causally linked to EBV, this raises the question as to whether the IMiDs reactivate latent EBV infection in normal memory B-cells, and thereby increase the risk of EBV-related malignancies. To this end, we have investigated the ability of the IMiD’s to induce reactivation of latently infected B-cell lines. Methods A panel of latently infected EBV-positive B-cell lines including Burkitt’s lymphoma (BL) cells and lymphoblastoid cell lines (LCL) were treated with either LEN, THAL or POM, and the status of the EBV lytic cycle was evaluated using in vitro and in vivo models. Results Treatment of BL and LCL cell lines with physiological concentrations of IMiDs (1-5 μM) induced the immediate early gene BZLF1 and the early gene BMRF1. Interestingly, the ability to induce EBV reactivation was in their potency order (i.e. POM 〉 LEN 〉 THAL). The IMiD’s also induced lytic cell death, as an LCL carrying a BZLF1-deleted EBV, which is incapable of undergoing a lytic cycle, showed no change in cell viability, compared to wild-type cells which had increased cell death. The addition of the nucleoside analogue ganciclovir (GCV) enhanced the cytotoxic effect of LEN and POM alone in BL cells lines. An in vivo xenograft model of BL demonstrated that the combination of LEN and GCV was highly efficacious at suppressing tumor cell growth, thus confirming the ability of LEN to stimulate the EBV-lytic life cycle. The ability to induce EBV reactivation was directly related to the stimulation of phosphatidylinositol-3 kinase (PI3K) signaling, which was completely blockaded by the PI3K-δ inhibitor, CAL101. The combination of LEN with either, DEX or rituximab, induced increased BMRF1 compared to the LEN alone. Conclusions The IMiD class of drugs has a potent ability to reactivate the lytic cycle in B-cells latently infected with EBV. We hypothesize that the IMiD’s reactivate latently infected resting memory B cells through enhancing PI3K signaling. This reactivation may be further potentiated when the IMiDs are used in combination with rituximab or DEX, which may simultaneously enhance the EBV lytic cycle and suppress the host immune response. These findings suggest the possibility that immunocompromised patients who receive IMiDs should be monitored for evidence of EBV reactivation. Also, this may suggest a mechanism by which patients may develop EBV-associated SPM, an effect which is similar to the methotrexate induced EBV-positive lymphomas seen in rheumatoid arthritis patients (Feng, Cohen et al. 2004). References Attal, M., V. Lauwers-Cances, et al. (2012). “Lenalidomide maintenance after stem-cell transplantation for multiple myeloma.” The New England journal of medicine 366(19): 1782-1791. Chim, C. S., P. T. Choi, et al. (2013). “Hodgkin's lymphoma as a second cancer in multiple myeloma never exposed to lenalidomide.” Annals of hematology 92(6): 855-857. Feng, W. H., J. I. Cohen, et al. (2004). “Reactivation of latent Epstein-Barr virus by methotrexate: a potential contributor to methotrexate-associated lymphomas.” Journal of the National Cancer Institute 96(22): 1691-1702. Kneppers, E., B. van der Holt, et al. (2011). “Lenalidomide maintenance after nonmyeloablative allogeneic stem cell transplantation in multiple myeloma is not feasible: results of the HOVON 76 Trial.” Blood 118(9): 2413-2419. Kroger, N., T. Zabelina, et al. (2013). “Toxicity-reduced, myeloablative allograft followed by lenalidomide maintenance as salvage therapy for refractory/relapsed myeloma patients.” Bone marrow transplantation 48(3): 403-407. Disclosures: Orlowski: Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Resverlogix: Research Funding; Array Biopharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Merck: Membership on an entity’s Board of Directors or advisory committees.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2013
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...