scholarly journals Activation of MYC, a bona fide client of HSP90, contributes to intrinsic ibrutinib resistance in mantle cell lymphoma

2018 ◽  
Vol 2 (16) ◽  
pp. 2039-2051 ◽  
Author(s):  
Jimmy Lee ◽  
Liang Leo Zhang ◽  
Wenjun Wu ◽  
Hui Guo ◽  
Yan Li ◽  
...  
Keyword(s):  
Mantle Cell Lymphoma ◽  
Cell Lines ◽  
Cell Lymphoma ◽  
Resistant Cell ◽  
Intrinsic Resistance ◽  
Mantle Cell ◽  
Myc Gene ◽  
Bona Fide ◽  
Ibrutinib Resistance ◽  
Induced Apoptosis

Abstract The BTK inhibitor ibrutinib has demonstrated a remarkable therapeutic effect in mantle cell lymphoma (MCL). However, approximately one-third of patients do not respond to the drug initially. To identify the mechanisms underlying primary ibrutinib resistance in MCL, we analyzed the transcriptome changes in ibrutinib-sensitive and ibrutinib-resistant cell lines on ibrutinib treatment. We found that MYC gene signature was suppressed by ibrutinib in sensitive but not resistant cell lines. We demonstrated that MYC gene was structurally abnormal and MYC protein was overexpressed in MCL cells. Further, MYC knockdown with RNA interference inhibited cell growth in ibrutinib-sensitive as well as ibrutinib-resistant cells. We explored the possibility of inhibiting MYC through HSP90 inhibition. The chaperon protein is overexpressed in both cell lines and primary MCL cells from the patients. We demonstrated that MYC is a bona fide client of HSP90 in the context of MCL by both immunoprecipitation and chemical precipitation. Furthermore, inhibition of HSP90 using PU-H71 induced apoptosis and caused cell cycle arrest. PU-H71 also demonstrates strong and relatively specific inhibition of the MYC transcriptional program compared with other oncogenic pathways. In a MCL patient-derived xenograft model, the HSP90 inhibitor retards tumor growth and prolongs survival. Last, we showed that PU-H71 induced apoptosis and downregulated MYC protein in MCL cells derived from patients who were clinically resistant to ibrutinib. In conclusion, MYC activity underlies intrinsic resistance to ibrutinib in MCL. As a client protein of HSP90, MYC can be inhibited via PU-H71 to overcome primary ibrutinib resistance.

The Tak-1 Inhibitor AZ-Tak1 Inhibits XIAP, Activates Caspase-9, and Induces Apoptosis in Mantle Cell Lymphoma.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1692-1692 ◽  
Author(s):  
Daniela Buglio ◽  
Sangeetha Palakurthi ◽  
Katharine F. Byth ◽  
Anas Younes
Keyword(s):  
Mantle Cell Lymphoma ◽  
Cell Lines ◽  
Small Molecule ◽  
Cell Lymphoma ◽  
Small Molecule Inhibitor ◽  
Caspase 9 ◽  
Lymphoma Cells ◽  
Molecule Inhibitor ◽  
Mantle Cell ◽  
Induced Apoptosis

Abstract Abstract 1692 Poster Board I-718 Transforming growth factor-b-activated kinase 1 (TAK1) is a key regulator of NF-kB activation. TAK1 can be activated by a variety of pro-inflammatory cytokines and T and B cell receptors. Recent experiments demonstrated that deletion of TAK1 results in inactivation of both JNK and NF-kB signaling resulting in massive apoptotic death of hematopoietic cells in mice. In this study, we examined the expression pattern of TAK1 and its role as a potential therapeutic target for lymphoma. First, we examined TAK1 expression in a panel of lymphoid cell lines by western blot, and found it to be highly expressed in mantle cell lymphoma cell lines (Mino, SP53, and Jeko-1). These lines expressed relatively low levels of the tumor suppressor protein A20. Mino and SP53 expressed high level of p-p38. Subsequently, we investigated the in vitro activity of the novel TAK1 small molecule inhibitor AZ-Tak1 in these cell lines. AZ-Tak1 is a potent and a relatively selective inhibitor of TAK1 kinase activity, with an IC50 of 0.009 mM. It also inhibits Jak2 but at a much higher concentration (IC50=0.18 mM). AZ-Tak1 treatment decreased the level of p38 and ERK in mantle cell lymphoma cells, and induced apoptosis in a dose and time dependent manner, with an IC50 of 0.1-0.5 mM. Using the annexin-V and PI staining and FACS analysis, After 48 hours of incubation, AZ-Tak1 (0.1 mM) induced apoptosis in 28%, 34% and 86% of Mino, SP53, and Jeko cells, respectively, which was increased to 32%, 42%, and 86% when 0.5 mM concentration was used. Similar activity was also observed when primary mantle cell lymphoma cells were examined. Using pathway-specific protein arrays focusing on apoptosis, kinases, and transcription factors, AZ-Tak1 (0.5 mM) altered the level of several proteins that regulate cell growth and survival, especially members of the inhibitors of apoptosis (IAP) family. Specifically, AZ-Tak1 decreased the level of SMAC/DIABOLO and cytochrome –C in the mitochondria, which was associated with a decrease in the level of the anti-apoptotic protein X-linked IAP (XIAP) and activation of the intrinsic apoptotic pathway as evident by activation of caspase 9, cleavage of caspase 3, and induction of apoptosis. Furthermore, and consistant with its ability to inhibit Jak2 activity, AZ-Tak1 reduced STAT2 and STAT6 levels. AZ-Tak1 demonstrated no significant effect on bcl-2 family members. Finally, co-treatment with HDAC inhibitors demonstrated synergistic effect with low concentrations of AZ-Tak1. Collectively, our data demonstrate that targeting TAK1 by the small molecule inhibitor AZ-Tak1 induces cell death in mantle cell lymphoma by activating the intrinsic apoptosis pathway, suggesting that targeting TAK1 may have a therapeutic value for the treatment of mantle cell lymphoma. Disclosures Palakurthi: Astra Zeneca: Employment. Byth:Astra Zeneca : Employment.

scholarly journals Dual mTORC1/mTORC2 inhibition diminishes Akt activation and induces Puma-dependent apoptosis in lymphoid malignancies

Blood ◽  
2012 ◽  
Vol 119 (2) ◽  
pp. 476-487 ◽  
Author(s):  
Mamta Gupta ◽  
Andrea E. Wahner Hendrickson ◽  
Seong Seok Yun ◽  
Jing Jing Han ◽  
Paula A. Schneider ◽  
...  
Keyword(s):  
Mantle Cell Lymphoma ◽  
Cell Lines ◽  
Transcriptional Activation ◽  
Cell Lymphoma ◽  
Lymphocytic Leukemia ◽  
Clinical Samples ◽  
Lymphoid Malignancies ◽  
Mantle Cell ◽  
Induced Apoptosis

Abstract The mammalian target of rapamycin (mTOR) plays crucial roles in proliferative and antiapoptotic signaling in lymphoid malignancies. Rapamycin analogs, which are allosteric mTOR complex 1 (mTORC1) inhibitors, are active in mantle cell lymphoma and other lymphoid neoplasms, but responses are usually partial and short-lived. In the present study we compared the effects of rapamycin with the dual mTORC1/mTORC2 inhibitor OSI-027 in cell lines and clinical samples representing divers lymphoid malignancies. In contrast to rapamycin, OSI-027 markedly diminished proliferation and induced apoptosis in a variety of lymphoid cell lines and clinical samples, including specimens of B-cell acute lymphocytic leukemia (ALL), mantle cell lymphoma, marginal zone lymphoma and Sezary syndrome. Additional analysis demonstrated that OSI-027–induced apoptosis depended on transcriptional activation of the PUMA and BIM genes. Overexpression of Bcl-2, which neutralizes Puma and Bim, or loss of procaspase 9 diminished OSI-027–induced apoptosis in vitro. Moreover, OSI-027 inhibited phosphorylation of mTORC1 and mTORC2 substrates, up-regulated Puma, and induced regressions in Jeko xenografts. Collectively, these results not only identify a pathway that is critical for the cytotoxicity of dual mTORC1/mTORC2 inhibitors, but also suggest that simultaneously targeting mTORC1 and mTORC2 might be an effective anti-lymphoma strategy in vivo.

Targeting Oxphos Pathway Against Ibrutinib Resistance to Mantle Cell Lymphoma

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 290-290 ◽  
Author(s):  
Yang Liu ◽  
Taylor Bell ◽  
Hui Zhang ◽  
Yuting Sun ◽  
Carrie J Li ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Mantle Cell Lymphoma ◽  
Cell Lines ◽  
Research Funding ◽  
Cell Lymphoma ◽  
Gene Set Enrichment Analysis ◽  
Pdx Model ◽  
Mantle Cell ◽  
Ibrutinib Resistance

Abstract Background: Mantle cell lymphoma (MCL) is an aggressive B-cell malignancy that is initially responsive but ultimately relapses to frontline therapy. Ibrutinib, a first-in-class, once-daily, oral covalent inhibitor of Bruton's tyrosine kinase (BTK) has achieved 68% of overall response rate in relapsed/refractory mantle cell lymphoma (MCL) patients. However, the vast majority of MCL patients experience disease progression, demonstrating that standard-of-care approaches are failing and that a means for targeting ibrutinib resistant MCL is clinically needed. Our hypothesis is that the ibrutinib-resistant MCL may rely on the mitochondrial oxidative phosphorylation (OXPHOS) pathway to produce energy for tumor growth. In this study, we investigated the effects of IACS-010759, a small molecule mitochondrial complex I inhibitor discovered in MD Anderson Cancer Center which can block the OXPHOS pathway, to overcome ibrutinib resistance in MCL in vitro and in a patient-derived xenograft (PDX) model. Methods: The OXPHOS metabolic pathways were investigated by RNASeq in a panel of ibrutinib-sensitive and -resistant MCL samples. Cell growth inhibition assays were tested after 72-hour treatment with IACS-010759 in ibrutinib-resistant MCL cell lines, Z-138 and Maver-1, and ibrutinib-sensitive MCL cell lines, Rec-1, Mino, and Jeko-1, by CellTiter-Glo luminescent cell viability assay (Promega). Furthermore, an IBN-resistant MCL PDX model was established and the therapeutic effects and tolerability of IACS-010759 were investigated in the primary MCL-bearing PDX model. Results: We have done RNA sequencing (RNASeq) in 7 primary ibrutinib-resistant and 16 ibrutinib-sensitive MCL patient samples, and analyzed the data using Gene Set Enrichment Analysis (GSEA) software. The results demonstrated that the OXPHOS pathway was activated in the primary ibrutinib-resistant MCL cells but not ibrutinib-sensitive MCL cells. Based on the RNASeq data, we selected an OXPHOS inhibitor IACS-010759 to investigate its effects on both primary ibrutinib-resistant and ibrutinib-sensitive MCL cells in vitroand in PDX mice. IACS-010759 significantly inhibited cell proliferation in ibrutinib-resistant MCL cell lines, Z-138 and Maver-1, but not in ibrutinib-sensitive MCL cell lines, Rec-1, Mino, and Jeko-1, during a 72-hour incubation. Furthermore, the primary ibrutinib-resistant MCL PDX mice were administrated with 10 mg/kg IACS-10759 by oral gavage, for 28 days using a 5 on/2 off dosing schedule. Our data showed that IACS-010759 completely eradicated tumor growth in ibrutinib-resistant MCL PDX mice (n=5, p=0.045). All mice tolerated the treatment dose and no toxicity was found during 28 days of IACS-010759 treatment. Conclusions: The OXPHOS inhibitor IACS-010759 overcomes ibrutinib resistance both in vitro and in the PDX mouse model. The investigation of its mechanism-of-action is ongoing. IACS-010759 could have the potential for clinical use in ibrutinib-resistant relapsed/refractory MCL patients. Disclosures Wang: Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Asana BioSciences: Research Funding; Kite Pharma: Research Funding; Juno Therapeutics: Research Funding; Asana biosciences, Beigene, Celgene, Juno, Kite, Onyx, Pharmacyclics: Research Funding; Dava Oncology: Honoraria; BeiGene: Research Funding; Acerta: Consultancy, Research Funding.

scholarly journals Bryostatin analogue-induced apoptosis in mantle cell lymphoma cell lines

2012 ◽  
Vol 40 (8) ◽  
pp. 646-656.e2 ◽  
Author(s):  
Ana Lopez-Campistrous ◽  
Xiaohua Song ◽  
Adam J. Schrier ◽  
Paul A. Wender ◽  
Nancy A. Dower ◽  
...  
Keyword(s):  
Mantle Cell Lymphoma ◽  
Cell Lines ◽  
Cell Lymphoma ◽  
Lymphoma Cell ◽  
Mantle Cell Lymphoma Cell ◽  
Mantle Cell ◽  
Induced Apoptosis

Bortezomib Is Synergistic with Rituximab and Cyclophosphamide in Inducing Apoptosis of Mantle Cell Lymphoma Cells In Vitro and In Vivo.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4514-4514
Author(s):  
Liang Zhang ◽  
Yuankai Shi ◽  
Xiaohong Han ◽  
Jing Yang ◽  
Jianfei Qian ◽  
...  
Keyword(s):  
Mantle Cell Lymphoma ◽  
Tumor Cells ◽  
Cell Lines ◽  
Primary Tumor ◽  
Cell Lymphoma ◽  
Fixed Dose ◽  
Mantle Cell ◽  
Induced Apoptosis

Abstract Introduction: Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoma with poor clinical outcome. Although frontline therapy induces a high rate of complete remission, relapse is inevitable and new regimens are needed for relapsed MCL. The proteasome inhibitor bortezomib (BTZ) induces apoptosis and sensitizes MCL cells to chemotherapy in relapsed MCL, but as a single agent, response rate is low, duration of response is short and side effects are severe. Here we evaluated whether BTZ is additive or synergistic with cyclophosphamide (CTX) and rituximab (RTX). Material and Methods: Four human MCL cell lines SP53, MINO, Grant 519, and Jeko-1 and freshly isolated primary tumor cells from three MCL patients were treated with BTZ, CTX, RTX individually or in combination of RTX and CTX (RC), or BTZ plus RTX and CTX (BRC regimen). Cell proliferation and apoptosis were evaluated to determine if there was additive or synergistic effect of the BRC regimen. Western blot analysis was used to elucidate the molecular mechanism by which BTZ, RTX, CTX, RC and BRC induces apoptosis in MCL cells. In addition, in vivo experiments using severe combined immunodeficiency mice with human mantle cell lymphoma xenografts were performed to examine the in vivo efficacy of the regimen to control the growth of and eradicate MCL cells. Results: BTZ and CTX as single agents inhibited the growth of MCL cell lines in a dose-dependent manner (P < 0.01). The IC50 (inhibitory concentration at 50%) for BTZ and for CTX were between 10 and 20 nM and between 5 and 20 mM, respectively. Increasing doses of BTZ with a fixed dose of RTX (10 μg/mL) and CTX (10 mM) resulted in markedly synergistic growth inhibition of MCL cells (P < 0.01). The BRC regimen induced apoptosis in about 69.7% of MCL cell lines and 92.6% of primary tumor cells (P < 0.05 and P < 0.01, compared with those induced by BTZ, RTX, CTX or RC). Furthermore, western blotting analysis showed that BRC induced apoptosis earlier via activation and cleavage of caspases-8, -9, and -3, and PARP as compared with BTZ, RTX, CTX or RC. The pan-caspase inhibitor z-VAD-FMK completely blocked apoptosis induced by BRC. In vivo studies demonstrated that BRC regimen eradicated subcutaneous tumors in MCL-bearing SCID mice and significantly prolonged the long-term event-free survival up to 10 weeks in 70% of the mice, whereas all tumor-bearing mice receiving BTZ, RTX, CTX or RC or PBS (control) died of aggressive MCL within 6 weeks. Conclusion: Cytoreductive chemotherapy with both BTZ and anti-CD20 antibody effectively inhibited the growth and induced apoptosis of MCL cells in vitro and in vivo. Bortezomib-rituximab-cyclophosphamide (BRC) regimen may offer a better therapeutic modality for MCL patients. Thus, our data lay the basis for a clinical trial in relapsed MCL using the BRC combination treatment.

Inhibition of Tak-1 by AZ-Tak1 Impairs NF-κB Activation, Downregulates XIAP and Activates Caspase-9 Inducing Apoptosis In Mantle Cell lymphoma

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2852-2852 ◽  
Author(s):  
Daniela Buglio ◽  
Sangeetha Palakurti ◽  
Francisco Vega ◽  
Sattva S. Neelapu ◽  
Donald Berry ◽  
...  
Keyword(s):  
Cell Death ◽  
Mantle Cell Lymphoma ◽  
Cell Lines ◽  
Small Molecule ◽  
Cell Lymphoma ◽  
Small Molecule Inhibitor ◽  
Caspase 9 ◽  
Molecule Inhibitor ◽  
Mantle Cell ◽  
Induced Apoptosis

Abstract Abstract 2852 TGF-b-activated kinase 1 (TAK1), a member of the mitogen-activated protein kinase kinase kinase (MAPKKK) family, plays a key role in regulating inflammation, immunity, metabolism, and cell death in a variety of cell types. It is activated in response to a variety of cytokines, including tumor necrosis factor (TNF), TGF-b, and interleukin 1 (IL-1). Upon receptor binding, TAK1 binds to adaptor proteins, and subsequently phosphorylate downstream molecules leading to activation of p38MAPK, JNK, and NF-kB. In this study, we examined the expression pattern of TAK1 and its potential therapeutic role as a target for lymphoma. First, we examined TAK1 expression in a panel of lymphoid cell lines by western blot, and found it to be highly expressed in mantle cell lymphoma cell lines (Mino, SP53, and Jeko-1). In contrast, PBL from healthy donors had no expression of TAK1 protein. TAK1 was also highly expressed in primary lymph node sections of MCL compared with benign reactive lymph nodes. Subsequently, we investigated the in vitro activity of the novel TAK1 small molecule inhibitor AZ-Tak1 in these cell lines. AZ-Tak1 is a potent and a relatively selective inhibitor of TAK1 kinase activity, with an IC50 of 0.009 mM. AZ-Tak1 treatment decreased the level of p38 and ERK in mantle cell lymphoma cells, and induced apoptosis in a dose and time dependent manner, with an IC50 of 0.1–0.5 mM. Using the annexin-V and PI staining and FACS analysis, After 48 hours of incubation, AZ-Tak1 (0.1 mM) induced apoptosis in 28%, 34% and 86% of Mino, SP53, and Jeko cells, respectively, which was increased to 32%, 42%, and 86% when 0.5 mM concentration was used. Similar activity was also observed when TAK1 expression in MCL cells was downregulated by TAK1- specific SiRNA and when primary mantle cell lymphoma specimens were examined after treatment with AZ-Tak1 for 24h (300nM). Using pathway-specific protein arrays focusing on apoptosis, kinases, and transcription factors, AZ-Tak1 (0.5 mM) altered the level of several proteins that regulate cell growth and survival, especially members of the inhibitors of apoptosis (IAP) family. Specifically, nuclear NF-κB p65 levels were decreased, cytosolic levels of SMAC/DIABLO and cytochrome-C were increased in AZ-Tak1 treated cells, which were associated with a decrease in the level of the anti-apoptotic protein X-linked IAP (XIAP) and activation of the intrinsic apoptotic pathway as evident by activation of caspase 9, cleavage of caspase 3, and consequent cells apoptosis. Collectively, our data demonstrate that TAK1 is essential for MAPK and NF-κB activation. Inhibition of TAK1 by the small molecule inhibitor AZ-Tak1 or TAK1-SiRNA induces cell death in mantle cell lymphoma by activating the intrinsic apoptosis pathway, suggesting that targeting TAK1 may have a therapeutic value for the treatment of mantle cell lymphoma. Disclosures: No relevant conflicts of interest to declare.

The Multi-Kinase Inhibitor Sorafenib Blocks Migration, BCR Survival Signals, Protein Translation and Stroma-Mediated Bortezomib Resistance in Mantle Cell Lymphoma

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1647-1647
Author(s):  
Silvia Xargay-Torrent ◽  
Monica López-Guerra ◽  
Ifigènia Saborit-Villarroya ◽  
Laia Rosich ◽  
Alba Navarro ◽  
...  
Keyword(s):  
Cell Migration ◽  
Cyclin D1 ◽  
Mantle Cell Lymphoma ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Cell Lymphoma ◽  
Protein Translation ◽  
Multikinase Inhibitor ◽  
Mantle Cell ◽  
Induced Apoptosis

Abstract Abstract 1647 Mantle cell lymphoma (MCL) is an incurable B-lymphoid neoplasm harboring the t(11;14)(q13;q32) translocation which leads to the overexpression of cyclin D1, with the consequent cell cycle deregulation. Typically, MCL is characterized by bad prognosis and an aggressive course of the disease. Unfortunately, current therapies have shown limited efficacy and relapses occur early, thus our purpose was to evaluate the antitumoral properties of the multikinase inhibitor sorafenib in MCL. Sorafenib is an oral multikinase inhibitor that targets several cancer-specific pathways and directly affects tumor cell proliferation, cell survival and neovascularization. We analyzed the sensitivity to sorafenib in 9 MCL cell lines and 17 primary MCL cells by flow cytometry after annexin V staining. Sorafenib induced apoptosis in MCL cell lines with a mean LD50 of 11.5 ± 5.0 μM at 24 hours, while at 48 hours decreased to 7.1 ± 2.7 μM. In primary MCL cells, the mean LD50 was 13.0 ± 3.6 μM at 24 hours, while at 48 hours it notably decreased to 9.4 ± 3.4 μM. These data indicated that sorafenib exerted a time- and dose-dependent cytotoxic effect in MCL cells. Both in cell lines and primary MCL cells, sorafenib induces rapid dephosphorylation of the BCR (B-Cell Receptor)-associated tyrosine kinases, SYK and LYN, as well as of FAK, a downstream SRC target involved in focal adhesion. In line with this, we demonstrate a strong synergy when combining sorafenib with the SYK inhibitor, R406. In parallel, we show that sorafenib also blocks Mcl-1 and cyclin D1 translation, which promotes an unbalance between pro- and anti-apoptotic proteins and facilitates the release of Bax from cyclin D1. This process leads to the induction of the mitochondrial apoptotic pathway and caspase-dependent and independent mechanisms. Moreover, sorafenib inhibits MCL cell migration as well as actin polymerization in response to CXCL12. FAK siRNA-mediated knockdown partially prevents this inhibitory effect, indicating that FAK is a relevant target for the action of sorafenib in MCL cells. Importantly, this compound resensitizes MCL cells cocultured with bone marrow-derived stromal and follicular dendritic-like cells to bortezomib-induced apoptosis indicating that sorafenib was able to antagonize stroma-mediated resistance in MCL. In conclusion, we provide first evidence on the molecular mechanism of action of the multikinase inhibitor sorafenib in MCL. We propose that this compound inhibits cell migration and stroma-mediated bortezomib resistance by interfering BCR signaling and protein translation. All these results suggest that sorafenib, alone or in combination with bortezomib-based therapies, may represent a promising approach for the treatment of MCL patients. Research funding This work was supported by grants from Ministerio de Ciencia e Innovación (SAF 09/9503) and Redes Temáticas de Investigación Cooperativa de Cáncer from the Instituto de Salud Carlos III RED 2006-20-014 (D.C.). S.X-T. is a recipient of predoctoral fellowship from Ministerio de Ciencia e Innovación (FPU) and M.L-G. holds a contract from Fundación Científica de la Asociación Española contra el Cáncer. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Simultaneous Inhibition of BCL-2 and PI3K Signaling Overcomes Ibrutinib Resistance in Mantle Cell Lymphoma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2950-2950
Author(s):  
Haige Ye ◽  
Shengjian Huang ◽  
Dayoung Jung ◽  
Changying Jiang ◽  
Krystle Nomie ◽  
...  
Keyword(s):  
Cell Lines ◽  
Research Funding ◽  
Cell Lymphoma ◽  
Resistant Cell ◽  
Tumor Burden ◽  
Pi3k Signaling ◽  
Advisory Committees ◽  
Apoptotic Pathway ◽  
Mantle Cell ◽  
Ibrutinib Resistance

Abstract Background: Mantle cell lymphoma (MCL) is an aggressive B-cell malignancy that is initially responsive but ultimately relapses to frontline therapy. Ibrutinib, a first-in-class, once-daily, oral covalent inhibitor of Bruton's tyrosine kinase (BTK) has achieved a 68% overall response rate in relapsed/refractory MCL patients (Wang et al., NEJM, 2013). However, the vast majority of MCL patients experience disease progression; therefore, novel therapies to overcome ibrutinib resistance are urgently needed. Ibrutinib resistance is associated with the dysregulation of alternative signaling pathways such as the apoptotic pathway and PI3K/AKT signaling; therefore, combinatorial therapeutic strategies may prove fruitful in overcoming ibrutinib resistance via the blockade of these compensatory pathways. Based on the upregulation of the PI3K signaling pathway and the anti-apoptotic pathway in ibrutinib resistance, we co-inhibited both pathways with the dual PI3K-delta and -gamma inhibitor duvelisib and the BCL-2 inhibitor venetoclax to assess the ability of this combination to overcome ibrutinib resistance in MCL. Methods: Cell viability and apoptosis assays were conducted to assess the effects of venetoclax and duvelisib on 4 ibrutinib-resistant cell lines (Jeko BTK KD, Jeko-R, Z-138 and Maver-1) and 4 primary patient samples. We also confirmed the synergistic effect of this combination on two ibrutinib-resistant cell lines (Jeko BTK KD and Z-138) by western blotting. Aberrant protein expression between single agents and drug combination in Jeko BTK KD cells was detected using Reverse Phase Protein Array (RPPA) analysis with confirmation by western blotting. Cell migration of Jeko BTK KD cells was assessed. A Jeko-1 cell xenograft (which is resistant to ibrutinib in vivo) was established in NSG mice, and drug testing was performed in this model with tumor burden assessed viain vivo imaging. Results: We observed synergistic activity with the combination of venetoclax and duvelisib in 4 ibrutinib-resistant cell lines (Jeko BTK KD, 0.36; Jeko-R, 0.47; Z-138, 0.66; Maver-1, 0.41) and in 4 ibrutinib-resistant patient samples (PT1, 0.14; PT2, 0.43; PT3, 0.52; PT4, 0.41) by calculating the synergistic index (Ki value). We confirmed the synergistic effects of this combination by observing apoptosis at 72 hours post-treatment in Jeko BTK KD and Z-138 cells. Moreover, the combination of venetoclax and duvelisib synergistically reduced the cell migration of Jeko BTK KD cells. RPPA analysis of Z-138 MCL cells post-treatment demonstrated that multiple pathways, including the apoptotic pathway as well as the PI3K/AKT and BCR signaling pathways, were synergistically altered by venetoclax and duvelisib. Moreover, venetoclax and duvelisb synergistically reduced tumor burden in a Jeko-1 cell xenograft model resistant to ibrutinib. Conclusion: PI3K signaling and BCL-2-related pathways are activated in ibrutinib-resistant MCL cells, and targeting these pathways using a combinatorial approach may potentially overcome ibrutinib resistance. Disclosures Wang: AstraZeneca: Consultancy, Research Funding; Pharmacyclics: Honoraria, Research Funding; Novartis: Research Funding; MoreHealth: Consultancy; Juno: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma: Honoraria, Research Funding; Kite Pharma: Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Dava Oncology: Honoraria.

Carfilzomib Inhibits Constitutive NF-κB Activation in Mantle Cell Lymphoma B Cells and Leads to the Induction of Apoptosis

2017 ◽  
Vol 137 (2) ◽  
pp. 106-112 ◽  
Author(s):  
Yong-Li Zhang ◽  
Matthew Ho Zhi Guang ◽  
Hui-Qin Zhuo ◽  
Xiang-Hui Min ◽  
Qin Yao ◽  
...  
Keyword(s):  
Mantle Cell Lymphoma ◽  
Cell Lines ◽  
Mononuclear Cells ◽  
Cell Lymphoma ◽  
Dependent Manner ◽  
Mobility Shift ◽  
Peripheral Blood Mononuclear ◽  
Normal Peripheral Blood ◽  
Mantle Cell ◽  
Induced Apoptosis

Mantle cell lymphoma (MCL) remains incurable and new treatments are needed, especially in the relapsed/refractory setting. We therefore investigated the effects of carfilzomib, a novel, long-acting, second-generation proteasome inhibitor, in MCL cells. Eight established MCL cell lines and freshly isolated primary MCL cells were treated with carfilzomib. Cell proliferation was assessed by a 3H-thymidine incorporation assay. Cell apoptosis was evaluated by flow cytometry with annexin V and propidium iodide. Electrophoresis mobility shift (EMSA), Western blot, and luciferase assays were used to analyze NF-κB activation and related signaling proteins. Carfilzomib inhibited growth and induced apoptosis in both established MCL cell lines and freshly isolated primary MCL cells in a dose-dependent manner. In contrast, carfilzomib was less toxic to normal peripheral blood mononuclear cells from healthy individuals. The carfilzomib-induced apoptosis of MCL cells occurred in a caspase-dependent manner through both intrinsic and extrinsic caspase pathways. In addition, carfilzomib inhibited constitutive activation of the NF-κB signaling cascade, both in MCL cell lines and primary MCL cells, by completely blocking the phosphorylation of IκBα. Our results demonstrate that carfilzomib can induce growth arrest and apoptosis in MCL cells and that the mechanism may involve the NF-κB signaling pathway.

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