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Glassman KF, Brugge JS, Purchio AF, Kakach LT, Fuerst TR, Woods RM, Stover CK, Chunduru SK, Hincks JR, McKinlay MA, Nash CH, Pevear DC, Monath TP, Rice CM, Peters P. Biographical Feature: Marc S. Collett (23 May 1951-11 June 2022): the Battle against Viral Disease Has Lost a Valiant Warrior, and the World Has Lost a Splendid Human Being. J Virol 2023; 97:e0164322. [PMID: 36468860 PMCID: PMC9888289 DOI: 10.1128/jvi.01643-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022] Open
Affiliation(s)
| | - Joan S. Brugge
- Ludwig Center, Harvard Medical School, Harvard University, Boston, Massachusetts, USA
| | | | | | - Thomas R. Fuerst
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
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Haymaker C, Johnson DH, Murthy R, Bentebibel SE, Uemura MI, Hudgens CW, Safa H, James M, Andtbacka RHI, Johnson DB, Shaheen M, Davies MA, Rahimian S, Chunduru SK, Milton DR, Tetzlaff MT, Overwijk WW, Hwu P, Gabrail N, Agrawal S, Doolittle G, Puzanov I, Markowitz J, Bernatchez C, Diab A. Tilsotolimod with Ipilimumab Drives Tumor Responses in Anti-PD-1 Refractory Melanoma. Cancer Discov 2021; 11:1996-2013. [PMID: 33707233 PMCID: PMC8544022 DOI: 10.1158/2159-8290.cd-20-1546] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 02/08/2021] [Accepted: 03/09/2021] [Indexed: 11/16/2022]
Abstract
Many patients with advanced melanoma are resistant to immune checkpoint inhibition. In the ILLUMINATE-204 phase I/II trial, we assessed intratumoral tilsotolimod, an investigational Toll-like receptor 9 agonist, with systemic ipilimumab in patients with anti-PD-1- resistant advanced melanoma. In all patients, 48.4% experienced grade 3/4 treatment-emergent adverse events. The overall response rate at the recommended phase II dose of 8 mg was 22.4%, and an additional 49% of patients had stable disease. Responses in noninjected lesions and in patients expected to be resistant to ipilimumab monotherapy were observed. Rapid induction of a local IFNα gene signature, dendritic cell maturation and enhanced markers of antigen presentation, and T-cell clonal expansion correlated with clinical response. A phase III clinical trial with this combination (NCT03445533) is ongoing. SIGNIFICANCE: Despite recent developments in advanced melanoma therapies, most patients do not experience durable responses. Intratumoral tilsotolimod injection elicits a rapid, local type 1 IFN response and, in combination with ipilimumab, activates T cells to promote clinical activity, including in distant lesions and patients not expected to respond to ipilimumab alone.This article is highlighted in the In This Issue feature, p. 1861.
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Affiliation(s)
- Cara Haymaker
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Daniel H Johnson
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Ravi Murthy
- Department of Interventional Radiology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Salah-Eddine Bentebibel
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Marc I Uemura
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Courtney W Hudgens
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Houssein Safa
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Marihella James
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Robert H I Andtbacka
- Surgical Oncology Department of Surgery, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah
| | - Douglas B Johnson
- Division of Oncology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Montaser Shaheen
- Department of Medicine and Cancer Center, University of Arizona, Tucson, Arizona
| | - Michael A Davies
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | | | | | - Denái R Milton
- Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Michael T Tetzlaff
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Willem W Overwijk
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Patrick Hwu
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Nashat Gabrail
- Department of Oncology, Gabrail Cancer Center, Canton, Ohio
| | - Sudhir Agrawal
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Gary Doolittle
- Department of Oncology, University of Kansas Medical Center, Kansas City, Kansas
| | - Igor Puzanov
- Department of Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Joseph Markowitz
- Department of Cutaneous Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Chantale Bernatchez
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
| | - Adi Diab
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
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3
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Babiker HM, Subbiah V, Maguire O, Rahimian S, Minderman H, Haymaker CL, Bernatchez C, Borazanci E, Geib J, Chunduru SK, Anderson PM, Puzanov I, Diab A. Abstract 4062: Activation of innate and adaptive immunity using intratumoral tilsotolimod (IMO-2125) as monotherapy in patients with refractory solid tumors: a phase Ib study (ILLUMINATE-101). Cancer Res 2019. [DOI: 10.1158/1538-7445.am2019-4062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
While checkpoint inhibitor therapy has transformed treatment of multiple tumor types, many patients remain refractory. Tilsotolimod, a toll-like receptor 9 agonist, has been shown in preclinical models to activate plasmacytoid dendritic cells and increase T cell infiltration to the tumor microenvironment. Preliminary results of a phase 1/2 study suggested that intratumoral injection of tilsotolimod in combination with ipilimumab may revive an immune response in patients with immune checkpoint inhibitor-resistant metastatic melanoma. To further explore the role of tilsotolimod in modulating the tumor immune microenvironment, we conducted a Phase Ib monotherapy trial (ILLUMINATE-101). Adults with histologically or cytologically confirmed diagnosis of cancer not amenable to curative therapies received intratumoral tilsotolimod in doses escalating from 8 mg to 32 mg into a single lesion at weeks 1, 2, 3, 5, 8, and 11. Objectives of the dose evaluation portion included characterizing safety and pharmacokinetics, and evaluating alterations in the tumor microenvironment. Blood samples and tumor biopsies of injected and distal lesions were obtained at baseline and on treatment. Immune analyses included evaluation using Nanostring and/or flow cytometry of activation of the type 1 interferon (IFN) pathway, IFN gamma levels, activation of dendritic cell subsets, and changes in T cell status. As of November 7, 2018, 41 patients have been enrolled, including 38 patients into the dose evaluation portion and 3 patients into a melanoma expansion cohort. No dose-limiting toxicities or treatment-related adverse events have been observed. Within 24 hours, fresh tumor biopsies showed significant increases in IFN gamma levels, activation of the type 1 IFN pathway, induction of an antigen processing gene signature (a measure of the MHC class I antigen presentation pathway), and maturation of dendritic cells as measured by expression of HLA-DR (MHC class II), compared to pretreatment biopsies. Of 25 evaluable patients who received at least 1 dose of tilsotolimod and had at least 1 post-baseline disease assessment, 12 (48%) had a RECIST v1.1 disease assessment of stable disease. For patients with at least one disease assessment following documentation of stable disease (n=8), duration of stable disease ranged from 0.53 to 4.2+ months, with 3 patients ongoing. These results demonstrate that single agent tilsotolimod was well tolerated and induced robust alterations in the tumor microenvironment.
Citation Format: Hani M. Babiker, Vivek Subbiah, Orla Maguire, Shah Rahimian, Hans Minderman, Cara L. Haymaker, Chantale Bernatchez, Erkut Borazanci, James Geib, Srinivas K. Chunduru, Peter M. Anderson, Igor Puzanov, Adi Diab. Activation of innate and adaptive immunity using intratumoral tilsotolimod (IMO-2125) as monotherapy in patients with refractory solid tumors: a phase Ib study (ILLUMINATE-101) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4062.
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Affiliation(s)
| | - Vivek Subbiah
- 2University of Texas MD Anderson Cancer Center, Houston, TX
| | - Orla Maguire
- 3Roswell Park Comprehensive Cancer Center, Buffalo, NY
| | | | | | | | | | | | | | | | | | - Igor Puzanov
- 3Roswell Park Comprehensive Cancer Center, Buffalo, NY
| | - Adi Diab
- 2University of Texas MD Anderson Cancer Center, Houston, TX
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4
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Tanzer MC, Khan N, Rickard JA, Etemadi N, Lalaoui N, Spall SK, Hildebrand JM, Segal D, Miasari M, Chau D, Wong WL, McKinlay M, Chunduru SK, Benetatos CA, Condon SM, Vince JE, Herold MJ, Silke J. Combination of IAP antagonist and IFNγ activates novel caspase-10- and RIPK1-dependent cell death pathways. Cell Death Differ 2017; 24:481-491. [PMID: 28106882 DOI: 10.1038/cdd.2016.147] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 10/21/2016] [Accepted: 11/21/2016] [Indexed: 12/13/2022] Open
Abstract
Peptido-mimetic inhibitor of apoptosis protein (IAP) antagonists (Smac mimetics (SMs)) can kill tumour cells by depleting endogenous IAPs and thereby inducing tumour necrosis factor (TNF) production. We found that interferon-γ (IFNγ) synergises with SMs to kill cancer cells independently of TNF- and other cell death receptor signalling pathways. Surprisingly, CRISPR/Cas9 HT29 cells doubly deficient for caspase-8 and the necroptotic pathway mediators RIPK3 or MLKL were still sensitive to IFNγ/SM-induced killing. Triple CRISPR/Cas9-knockout HT29 cells lacking caspase-10 in addition to caspase-8 and RIPK3 or MLKL were resistant to IFNγ/SM killing. Caspase-8 and RIPK1 deficiency was, however, sufficient to protect cells from IFNγ/SM-induced cell death, implying a role for RIPK1 in the activation of caspase-10. These data show that RIPK1 and caspase-10 mediate cell death in HT29 cells when caspase-8-mediated apoptosis and necroptosis are blocked and help to clarify how SMs operate as chemotherapeutic agents.
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Affiliation(s)
- Maria C Tanzer
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - Nufail Khan
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - James A Rickard
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - Nima Etemadi
- Olivia Newton John Cancer Research Institute, Heidelberg, VIC 3084, Australia.,School of Cancer Medicine, La Trobe University, Melbourne, VIC 3084, Australia
| | - Najoua Lalaoui
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - Sukhdeep Kaur Spall
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - Joanne M Hildebrand
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - David Segal
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - Maria Miasari
- School of Cancer Medicine, La Trobe University, Melbourne, VIC 3084, Australia
| | - Diep Chau
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - WendyWei-Lynn Wong
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
| | - Mark McKinlay
- TetraLogic Pharmaceuticals Corporation, Malvern, PA 19355, USA
| | | | | | | | - James E Vince
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - Marco J Herold
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
| | - John Silke
- Cell Signalling and Cell Death, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC 3050, Australia
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5
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Mitsuuchi Y, Benetatos CA, Deng Y, Haimowitz T, Beck SC, Arnone MR, Kapoor GS, Seipel ME, Chunduru SK, McKinlay MA, Begley CG, Condon SM. Bivalent IAP antagonists, but not monovalent IAP antagonists, inhibit TNF-mediated NF- κB signaling by degrading TRAF2-associated cIAP1 in cancer cells. Cell Death Discov 2017; 3:16046. [PMID: 28149532 PMCID: PMC5238498 DOI: 10.1038/cddiscovery.2016.46] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 05/15/2016] [Indexed: 01/05/2023] Open
Abstract
The inhibitor of apoptosis (IAP) proteins have pivotal roles in cell proliferation and differentiation, and antagonizing IAPs in certain cancer cell lines results in induction of cell death. A variety of IAP antagonist compounds targeting the baculovirus IAP protein repeat 3 (BIR3) domain of cIAP1have advanced into clinical trials. Here we sought to compare and contrast the biochemical activities of selected monovalent and bivalent IAP antagonists with the intent of identifying functional differences between these two classes of IAP antagonist drug candidates. The anti-cellular IAP1 (cIAP1) and pro-apoptotic activities of monovalent IAP antagonists were increased by using a single covalent bond to combine the monovalent moieties at the P4 position. In addition, regardless of drug concentration, treatment with monovalent compounds resulted in consistently higher levels of residual cIAP1 compared with that seen following bivalent compound treatment. We found that the remaining residual cIAP1 following monovalent compound treatment was predominantly tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2)-associated cIAP1. As a consequence, bivalent compounds were more effective at inhibiting TNF-induced activation of p65/NF-κB compared with monovalent compounds. Moreover, extension of the linker chain at the P4 position of bivalent compounds resulted in a decreased ability to degrade TRAF2-associated cIAP1 in a manner similar to monovalent compounds. This result implied that specific bivalent IAP antagonists but not monovalent compounds were capable of inducing formation of a cIAP1 E3 ubiquitin ligase complex with the capacity to effectively degrade TRAF2-associated cIAP1. These results further suggested that only certain bivalent IAP antagonists are preferred for the targeting of TNF-dependent signaling for the treatment of cancer or infectious diseases.
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Affiliation(s)
- Y Mitsuuchi
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - C A Benetatos
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - Y Deng
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - T Haimowitz
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - S C Beck
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - M R Arnone
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - G S Kapoor
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - M E Seipel
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - S K Chunduru
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - M A McKinlay
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - C G Begley
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
| | - S M Condon
- TetraLogic Pharmaceuticals Corporation , 343 Phoenixville Pike, Malvern, PA 19355, USA
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6
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Kapoor GS, Benetatos CA, Mitsuuchi Y, Neiman EM, Yu G, Mckinlay MA, Burns J, Silke J, Condon SM, Chunduru SK. Abstract 2278: The SMAC-mimetic birinapant regulates autocrine TNF production by caspase-8:RIPK1 complex via p38MAPK pathway. Cancer Res 2014. [DOI: 10.1158/1538-7445.am2014-2278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Birinapant (TL32711), a SMAC-mimetic currently in clinical trials, antagonizes multiple members of the inhibitor of apoptosis (IAP) protein family to promote apoptosis in cancer cells through the formation of a caspase-8:RIPK1 complex and induction of autocrine tumor necrosis factor (TNF). Evidently, birinapant-resistant cells do not produce TNF upon drug treatment. However, the mechanism by which birinapant-sensitive cells produce TNF is not clear. Owing to the fact that mitogen-activated protein kinases (MAPKs) regulate a variety of cellular processes, we explored the role of MAPKs in birinapant-induced TNF production. Western blot analyses on a panel of birinapant-sensitive (SK-OV-3, EVSA-T, TOV-21G: all with an IC50 < 200nM) and birinapant-resistant (IGROV-1, HCT116, WIDR & SK-MEL-28: all with an IC50 > 10μM) cell lines showed that birinapant induced rapid and robust phosphorylation of p38MAPK in sensitive cells, which corresponded to increased TNF production as assessed by ELISA. However, resistant cells were not affected at multiple time points. The p38MAPK inhibitor, LY2228820, reduced the levels of birinapant-induced TNF (2-fold with 5nM birinapant after 24h) in birinapant-sensitive cancer cells (SK-OV-3), whereas inhibitors of Erk1/2 (PD98059) and JNK (SP600125) had no effect on TNF production. Interestingly, RNAi-mediated inhibition of p38α (MAPK14) isoform significantly inhibited birinapant-induced TNF production (∼3-fold with 5nM birinapant after 24h) in SK-OV-3 cells while inhibition of p38β (MAPK11) isoform upregulated TNF production (∼3-fold), suggesting that there may be a balance between p38MAPK isoforms to regulate TNF production. Pharmacological and RNAi-mediated inhibition of RIPK1 and caspase-8 activities in SK-OV-3 cells resulted in reduced birinapant-induced p38MAPK phosphorylation and TNF production. Furthermore, commercially available pooled siRNAs targeting different isoforms of cFLIP, a catalytically-inactive homologue of caspase-8, upregulated p38MAPK phosphorylation (∼4-fold) and TNF production (∼8 to 26-fold) in birinapant-resistant cancer cell lines (T24, HT1376 & IGROV-1), and conferred differential sensitivity to the drug treatment (T24-IC50: 7nM; HT1376-IC50: >10nM; IGROV-1-IC50: >1μM). Experiments involving cFLIP long (cFLIP-L) and short (cFLIP-S) isoform-specific siRNAs showed that inhibition of cFLIP-L, but not cFLIP-S, in T24 & HT1376 cells induced p38MAPK phosphorylation and TNF production, and conferred sensitivity to birinapant. However, the combined inhibition of cFLIP-L and cFLIP-S in IGROV-1 cells was required to induce p38MAPK phosphorylation, TNF production and apoptosis. Collectively, these observations indicate that birinapant-induced autocrine TNF production is triggered by the activation of the caspase-8/RIPK1/p38MAPK axis, and that cFLIP isoforms may confer a context-dependent negative regulatory effect.
Citation Format: Gurpreet Singh Kapoor, Christopher A. Benetatos, Yasuhiro Mitsuuchi, Eric M. Neiman, Guangyao Yu, Mark A. Mckinlay, Jennifer Burns, John Silke, Stephen M. Condon, Srinivas K. Chunduru. The SMAC-mimetic birinapant regulates autocrine TNF production by caspase-8:RIPK1 complex via p38MAPK pathway. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2278. doi:10.1158/1538-7445.AM2014-2278
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Affiliation(s)
| | | | | | | | | | | | | | - John Silke
- 2The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
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7
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Gray CM, McCorkell KA, Chunduru SK, McKinlay MA, May MJ. Negative feedback regulation of NF-κB-inducing kinase is proteasome-dependent but does not require cellular inhibitors of apoptosis. Biochem Biophys Res Commun 2014; 450:341-6. [PMID: 24942881 PMCID: PMC4107106 DOI: 10.1016/j.bbrc.2014.05.122] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 05/25/2014] [Indexed: 11/16/2022]
Abstract
Non-canonical NF-κB signaling is controlled by the precise regulation of NF-κB inducing kinase (NIK) stability. NIK is constitutively ubiquitylated by cellular inhibitor of apoptosis (cIAP) proteins 1 and 2, leading to its complete proteasomal degradation in resting cells. Following stimulation, cIAP-mediated ubiquitylation of NIK ceases and NIK is stabilized, allowing for inhibitor of κB kinase (IKK)α activation and non-canonical NF-κB signaling. Non-canonical NF-κB signaling is terminated by feedback phosphorylation of NIK by IKKα that promotes NIK degradation; however, the mechanism of active NIK protein turnover remains unknown. To address this question, we established a strategy to precisely distinguish between basal degradation of newly synthesized endogenous NIK and induced active NIK in stimulated cells. Using this approach, we found that IKKα-mediated degradation of signal-induced activated NIK occurs through the proteasome. To determine whether cIAP1 or cIAP2 play a role in active NIK turnover, we utilized a Smac mimetic (GT13072), which promotes degradation of these E3 ubiquitin ligases. As expected, GT13072 stabilized NIK in resting cells. However, loss of the cIAPs did not inhibit proteasome-dependent turnover of signal-induced NIK showing that unlike the basal regulatory mechanism, active NIK turnover is independent of cIAP1 and cIAP2. Our results therefore establish that the negative feedback control of IKKα-mediated NIK turnover occurs via a novel proteasome-dependent and cIAP-independent mechanism.
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Affiliation(s)
- Carolyn M Gray
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, 3800 Spruce Street, Philadelphia, PA 19104, United States
| | - Kelly A McCorkell
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, 3800 Spruce Street, Philadelphia, PA 19104, United States
| | - Srinivas K Chunduru
- PKPD Biosciences, 717 Constitution Drive, Suite 104, Exton, PA 19341, United States
| | - Mark A McKinlay
- Task Force for Global Health, 325 Swanton Way, Decatur, GA 30030, United States
| | - Michael J May
- Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, 3800 Spruce Street, Philadelphia, PA 19104, United States; Mari Lowe Center for Comparative Oncology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, United States.
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Condon SM, Mitsuuchi Y, Deng Y, LaPorte MG, Rippin SR, Haimowitz T, Alexander MD, Kumar PT, Hendi MS, Lee YH, Benetatos CA, Yu G, Kapoor GS, Neiman E, Seipel ME, Burns JM, Graham MA, McKinlay MA, Li X, Wang J, Shi Y, Feltham R, Bettjeman B, Cumming MH, Vince JE, Khan N, Silke J, Day CL, Chunduru SK. Birinapant, a smac-mimetic with improved tolerability for the treatment of solid tumors and hematological malignancies. J Med Chem 2014; 57:3666-77. [PMID: 24684347 DOI: 10.1021/jm500176w] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Birinapant (1) is a second-generation bivalent antagonist of IAP proteins that is currently undergoing clinical development for the treatment of cancer. Using a range of assays that evaluated cIAP1 stability and oligomeric state, we demonstrated that 1 stabilized the cIAP1-BUCR (BIR3-UBA-CARD-RING) dimer and promoted autoubiquitylation of cIAP1 in vitro. Smac-mimetic 1-induced loss of cIAPs correlated with inhibition of TNF-mediated NF-κB activation, caspase activation, and tumor cell killing. Many first-generation Smac-mimetics such as compound A (2) were poorly tolerated. Notably, animals that lack functional cIAP1, cIAP2, and XIAP are not viable, and 2 mimicked features of triple IAP knockout cells in vitro. The improved tolerability of 1 was associated with (i) decreased potency against cIAP2 and affinity for XIAP BIR3 and (ii) decreased ability to inhibit XIAP-dependent signaling pathways. The P2' position of 1 was critical to this differential activity, and this improved tolerability has allowed 1 to proceed into clinical studies.
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Affiliation(s)
- Stephen M Condon
- TetraLogic Pharmaceuticals, Inc. , 343 Phoenixville Pike, Malvern, Pennsylvania 19355, United States
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9
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Benetatos CA, Mitsuuchi Y, Burns JM, Neiman EM, Condon SM, Yu G, Seipel ME, Kapoor GS, Laporte MG, Rippin SR, Deng Y, Hendi MS, Tirunahari PK, Lee YH, Haimowitz T, Alexander MD, Graham MA, Weng D, Shi Y, McKinlay MA, Chunduru SK. Birinapant (TL32711), a bivalent SMAC mimetic, targets TRAF2-associated cIAPs, abrogates TNF-induced NF-κB activation, and is active in patient-derived xenograft models. Mol Cancer Ther 2014; 13:867-79. [PMID: 24563541 DOI: 10.1158/1535-7163.mct-13-0798] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The acquisition of apoptosis resistance is a fundamental event in cancer development. Among the mechanisms used by cancer cells to evade apoptosis is the dysregulation of inhibitor of apoptosis (IAP) proteins. The activity of the IAPs is regulated by endogenous IAP antagonists such as SMAC (also termed DIABLO). Antagonism of IAP proteins by SMAC occurs via binding of the N-terminal tetrapeptide (AVPI) of SMAC to selected BIR domains of the IAPs. Small molecule compounds that mimic the AVPI motif of SMAC have been designed to overcome IAP-mediated apoptosis resistance of cancer cells. Here, we report the preclinical characterization of birinapant (TL32711), a bivalent SMAC-mimetic compound currently in clinical trials for the treatment of cancer. Birinapant bound to the BIR3 domains of cIAP1, cIAP2, XIAP, and the BIR domain of ML-IAP in vitro and induced the autoubiquitylation and proteasomal degradation of cIAP1 and cIAP2 in intact cells, which resulted in formation of a RIPK1:caspase-8 complex, caspase-8 activation, and induction of tumor cell death. Birinapant preferentially targeted the TRAF2-associated cIAP1 and cIAP2 with subsequent inhibition of TNF-induced NF-κB activation. The activity of a variety of chemotherapeutic cancer drugs was potentiated by birinapant both in a TNF-dependent or TNF-independent manner. Tumor growth in multiple primary patient-derived xenotransplant models was inhibited by birinapant at well-tolerated doses. These results support the therapeutic combination of birinapant with multiple chemotherapies, in particular, those therapies that can induce TNF secretion.
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Affiliation(s)
- Christopher A Benetatos
- Authors' Affiliations: TetraLogic Pharmaceuticals, 343 Phoenixville Pike, Malvern, Pennsylvania; and Tsinghua University School of Medicine, Beijing, China
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Neiman EM, Benetatos CA, Kapoor GS, Mitsuuchi Y, McKinlay MA, Seipel ME, Yu G, Condon SM, Chunduru SK. Abstract 5302: Characterization of tumor cell lines resistant to birinapant, a novel bivalent smac mimetic. Cancer Res 2013. [DOI: 10.1158/1538-7445.am2013-5302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Acquired resistance to cancer therapies remains a major therapeutic challenge. Identification of resistance mechanisms and biomarkers of acquired resistance are important for management of patients with drug refractory tumors. The present study was aimed to understand the potential mechanism(s) of acquired resistance to birinapant (TL32711), a bivalent Smac Mimetic (SM), currently in clinical trials for the treatment of solid and hematological malignancies. We generated SM resistant cell lines from four tumor cell lines (SKOV-3, EFM192A, EVSA-T and MDA-MB-231) which were initially sensitive to birinapant. Resistant variants of each cell line were resistant to 10μM concentration of birinapant, equivalent to 1000-10,000x IC50 values. Variants were also cross-resistant to other, structurally diverse, SM compounds suggesting common mechanisms of resistance. Sensitivity to birinapant in combination with TRAIL and TNF was also measured. These experiments revealed a range of sensitivity among the resistant variants. In order to identify changes which occurred during development of resistance, total mRNAs were extracted from SM sensitive cell lines and their resistant variants and were subjected to gene expression analyses using commercially available apoptosis pathway real-time PCR arrays. Preliminary data analysis identified several candidate genes that were down- or up-regulated in the SM resistant cell line relative to their sensitive counterparts. Three of four SM-resistant subclones exhibited decreased expression of genes including NAIP, BCL2A1, DAPK1, TNF, cFLIP, Smac, and TNFSF10 or increased expression of BCL2L2, or BAK1 (Table 1).
Table 1 - Resistant cell line gene expression changes Cell Line EVSA-T EFM192A MDA-MB-231 SKOV-3 Gene Fold change from sensitive NAIP −1.60 −6.95 −42.07 −31.4 BCL2A1 ND −6.30 −11.37 −55.61 DAPK1 −3.09 −4.86 −189.2 −2.80 TNF 1.39 −3.27 −8.41 −70.71 cFLAR (cFLIP) −1.17 −3.25 −3.02 −6.64 DIABLO (Smac) −2.31 −2.27 −2.53 −3.52 TNFSF10 (TRAIL) −3.38 −1.46 −17.95 −67.64 BCL2L2 4.94 5.75 1.43 3.46 BAK1 3.92 14.15 1.66 4.65
Identification of genes modulated during acquired resistance provides a starting point for the discovery of novel biomarkers that may explain mechanism(s) of acquired resistance, and could potentially be exploited to achieve maximum anti-tumor response with birinapant as a single agent or in combination with other treatment regimens.
Citation Format: Eric M. Neiman, Christopher A. Benetatos, Gurpreet S. Kapoor, Yasuhiro Mitsuuchi, Mark A. McKinlay, Martin E. Seipel, Guangyao Yu, Stephen M. Condon, Srinivas K. Chunduru. Characterization of tumor cell lines resistant to birinapant, a novel bivalent smac mimetic. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5302. doi:10.1158/1538-7445.AM2013-5302
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Krepler C, Chunduru SK, Halloran MB, He X, Xiao M, Vultur A, Villanueva J, Mitsuuchi Y, Neiman EM, Benetatos C, Nathanson KL, Amaravadi RK, Pehamberger H, McKinlay M, Herlyn M. The novel SMAC mimetic birinapant exhibits potent activity against human melanoma cells. Clin Cancer Res 2013; 19:1784-94. [PMID: 23403634 DOI: 10.1158/1078-0432.ccr-12-2518] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE Inhibitor of apoptosis proteins (IAP) promote cancer cell survival and confer resistance to therapy. We report on the ability of second mitochondria-derived activator of caspases mimetic, birinapant, which acts as antagonist to cIAP1 and cIAP2, to restore the sensitivity to apoptotic stimuli such as TNF-α in melanomas. EXPERIMENTAL DESIGN Seventeen melanoma cell lines, representing five major genetic subgroups of cutaneous melanoma, were treated with birinapant as a single agent or in combination with TNF-α. Effects on cell viability, target inhibition, and initiation of apoptosis were assessed and findings were validated in 2-dimensional (2D), 3D spheroid, and in vivo xenograft models. RESULTS When birinapant was combined with TNF-α, strong combination activity, that is, neither compound was effective individually but the combination was highly effective, was observed in 12 of 18 cell lines. This response was conserved in spheroid models, whereas in vivo birinapant inhibited tumor growth without adding TNF-α in in vitro resistant cell lines. Birinapant combined with TNF-α inhibited the growth of a melanoma cell line with acquired resistance to BRAF inhibition to the same extent as in the parental cell line. CONCLUSIONS Birinapant in combination with TNF-α exhibits a strong antimelanoma effect in vitro. Birinapant as a single agent shows in vivo antitumor activity, even if cells are resistant to single agent therapy in vitro. Birinapant in combination with TNF-α is effective in a melanoma cell line with acquired resistance to BRAF inhibitors.
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Affiliation(s)
- Clemens Krepler
- Tumor Microenvironment and Metastasis Program, The Wistar Institute, Philadelphia, PA 19104, USA
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Jackson RW, LaPorte MG, Herbertz T, Draper TL, Gaboury JA, Rippin SR, Patel R, Chunduru SK, Benetatos CA, Young DC, Burns CJ, Condon SM. The discovery and structure–activity relationships of pyrano[3,4-b]indole-based inhibitors of hepatitis C virus NS5B polymerase. Bioorg Med Chem Lett 2011; 21:3227-31. [DOI: 10.1016/j.bmcl.2011.04.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 04/11/2011] [Accepted: 04/12/2011] [Indexed: 10/21/2022]
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Krepler C, Chunduru SK, He X, Gimotty PA, Vultur A, Villanueva J, Herlyn M. Abstract 5480: Effect of the Smac mimetic TL32711 in combination with TRAIL or TNF alpha on a panel of melanoma cell lines. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-5480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Although major advances have been made recently in the treatment of malignant melanoma, it remains an incurable disease when not surgically excised at a very early stage. This is due to the development of resistance to targeted compounds currently being tested in patients. In addition, the genetic heterogeneity of melanoma often limits the effects of those therapies to specific subsets of patients. New targets that are exploitable in multiple genetic subgroups of melanoma and that can overcome resistance are therefore still urgently needed. IAP's (inhibitor of apoptosis proteins) have been described as major players in conferring resistance to therapy by blocking the apoptotic cascade in a high percentage of melanomas. Thus, the sensitivity to apoptotic stimuli, such as TNF alpha or TRAIL, could be restored in melanomas using the novel Smac (second mitochondria-derived activator of caspases) mimetic, TL32711. A panel of patient-derived human melanoma cell lines was clustered according to mutational status, representing all major genetic subgroups of cutaneous melanoma. Cells were treated with TL32711 as a single agent or in combination with TRAIL or TNF-α for 72h. Cell viability was assessed by MTS assay. Target inhibition and initiation of apoptosis were also evaluated. To more accurately predict in vivo efficacy, cells were grown as three dimensional spheroids in a collagen matrix and treated as described above. Treatment effects on spheroids were assessed through confocal microscopy using live/ dead immune fluorescent staining, as well as alamar blue cell viability assay for objective quantification.We observed that seventeen out of eighteen cell lines tested were resistant to TL32711 as a single agent in vitro, even at high doses of the compound. Similarly, treatment with TRAIL or TNF-α alone did not show any significant increase in apoptosis. However, when TL32711 was combined with either TRAIL or TNF-α, a strong synergistic activity was observed in twelve out of eighteen cell lines at low doses, resulting in a dramatic increase in cell death of adherent and three dimensional cultures (spheroids). In all treated cell lines, degradation of the target IAP proteins was observed. However, only in sensitive cell lines, activation of apoptotic cascade was observed.In conclusion, the Smac mimetic TL32711 exhibits strong synergistic activity in combination with TRAIL or TNF-α leading to apoptosis in the majority of the genetically diverse cell lines tested. Since TNF-α and TRAIL are present in a high percentage of melanoma tumors in vivo, single agent activity of TL32711 may be observed in vivo.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5480. doi:10.1158/1538-7445.AM2011-5480
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Affiliation(s)
| | | | - Xu He
- 1The Wistar Institute, Philadelphia, PA
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Amaravadi RK, Schilder RJ, Dy GK, Ma WW, Fetterly GJ, Weng DE, Graham MA, Burns JM, Chunduru SK, Condon SM, McKinlay MA, Adjei AA. Abstract LB-406: Phase 1 study of the Smac mimetic TL32711 in adult subjects with advanced solid tumors and lymphoma to evaluate safety, pharmacokinetics, pharmacodynamics, and antitumor activity. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-lb-406] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Introduction: TL32711 is a small molecule Smac mimetic that potently and specifically antagonizes inhibitor of apoptosis proteins (IAPs), resulting in caspase-dependent apoptosis and inactivation of NF-kB signaling. In preclinical studies, single agent tumor regression was observed for multiple tumor types and potent anti-tumor activity was observed when TL32711 was combined with specific chemotherapies and death receptor ligands. This first-in-human study assesses the safety, pharmacokinetic (PK), and pharmacodynamic (PD) profile and anti-tumor activity of single agent TL32711.
Methods: Using a standard 3+3 dose escalation design, subjects with refractory solid tumors and lymphoma received weekly intravenous TL32711 for 3 weeks on/ 1 week off, with disease assessment every 2 cycles. PK analysis was conducted using an intensive sampling approach. PD assays included measurement of cIAP1 and cIAP2 levels in lysates from serially collected PBMC and tumor tissue, serum levels of cleaved cytokeratin-18 (CK-18, requiring activated caspase-3) and activated caspase-3/7.
Results: 27 patients were treated at doses 0.18–26 mg/m2 over 9 cohorts. TL32711 was well-tolerated, with no dose-limiting toxicities. Toxicities included reversible grade 2 lymphocytopenia and grade 1 rash at ≥11.5 mg/m2. TL32711 exhibited dose-proportional, uniform, non-accumulating PK, with a mean β-phase half-life of 35 hrs. Doses ≥2.88 mg/m2 achieved an AUC0-∞ exposure sufficient for single agent activity in preclinical tumor models. At doses ≥1.44 mg/m2, cIAP1 levels were suppressed >80% within 24 hrs and after 1 week >50% suppression was maintained. Based on PBMC drug levels, actual and predicted cIAP1 suppression was well-correlated. A dose-dependent increase in serum levels of cleaved CK-18 and activated caspase-3/7 was observed in patients treated at doses ≥2.88 mg/m2. At 11.5 mg/m2, > 90% cIAP1 suppression, increased activated caspase-8, and PARP cleavage in tumor lysates were observed in a tumor biopsy from a melanoma patient with progressive disease prior to TL32711, with stable disease after 2 cycles. One colon cancer subject with progressive disease after prior therapies, at 0.36 mg/m2 demonstrated tumor shrinkage in radiographic lesions, serum CEA decline, and elevated serum caspase-3/7. One colon cancer subject at 17.2 mg/m2 demonstrated serum CEA decline, elevated serum caspase-3/7, and a large photopenic lesion in a metastatic lesion within the first cycle.
Conclusions: TL32711 is well-tolerated, has dose-proportional PK, and demonstrates potent and sustained target inhibition and apoptotic pathway activation in tumor and surrogate tissues. Preliminary evidence of antitumor activity was observed in colon cancer and melanoma. Updated results of final dose escalation cohorts will be presented.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-406. doi:10.1158/1538-7445.AM2011-LB-406
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Affiliation(s)
| | | | | | - Wen W. Ma
- 3Roswell Park Cancer Institute, Buffalo, NY
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Feltham R, Bettjeman B, Budhidarmo R, Mace PD, Shirley S, Condon SM, Chunduru SK, McKinlay MA, Vaux DL, Silke J, Day CL. Smac mimetics activate the E3 ligase activity of cIAP1 protein by promoting RING domain dimerization. J Biol Chem 2011; 286:17015-28. [PMID: 21393245 DOI: 10.1074/jbc.m111.222919] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The inhibitor of apoptosis (IAP) proteins are important ubiquitin E3 ligases that regulate cell survival and oncogenesis. The cIAP1 and cIAP2 paralogs bear three N-terminal baculoviral IAP repeat (BIR) domains and a C-terminal E3 ligase RING domain. IAP antagonist compounds, also known as Smac mimetics, bind the BIR domains of IAPs and trigger rapid RING-dependent autoubiquitylation, but the mechanism is unknown. We show that RING dimerization is essential for the E3 ligase activity of cIAP1 and cIAP2 because monomeric RING mutants could not interact with the ubiquitin-charged E2 enzyme and were resistant to Smac mimetic-induced autoubiquitylation. Unexpectedly, the BIR domains inhibited cIAP1 RING dimerization, and cIAP1 existed predominantly as an inactive monomer. However, addition of either mono- or bivalent Smac mimetics relieved this inhibition, thereby allowing dimer formation and promoting E3 ligase activation. In contrast, the cIAP2 dimer was more stable, had higher intrinsic E3 ligase activity, and was not highly activated by Smac mimetics. These results explain how Smac mimetics promote rapid destruction of cIAP1 and suggest mechanisms for activating cIAP1 in other pathways.
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Affiliation(s)
- Rebecca Feltham
- Department of Biochemistry, La Trobe University, Victoria 3086, Australia
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LaPorte MG, Draper TL, Miller LE, Blackledge CW, Leister LK, Amparo E, Hussey AR, Young DC, Chunduru SK, Benetatos CA, Rhodes G, Gopalsamy A, Herbertz T, Burns CJ, Condon SM. The discovery and structure–activity relationships of pyrano[3,4-b]indole based inhibitors of hepatitis C virus NS5B polymerase. Bioorg Med Chem Lett 2010; 20:2968-73. [DOI: 10.1016/j.bmcl.2010.03.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 03/01/2010] [Indexed: 10/21/2022]
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Jinesh GG, Chunduru SK, Kamat AM. Abstract LB-30: Smac mimetic sensitizes antitumor activity of bacillus Calmette-Guerin stimulated neutrophils against bladder cancer cells. Cancer Res 2010. [DOI: 10.1158/1538-7445.am10-lb-30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Bacillus Calmette-Guerin (BCG) is the current gold standard therapy for bladder cancer. It is believed to work via recruitment of neutrophils to the tumor microenvironment and releasing cytokines, specifically TRAIL. However, BCG mediated therapy is hampered by relapse and resistance problems indicating the need for alternative or combination therapeutic options. Smac mimetics provide an alternative platform to rescue cells from TRAIL resistance by circumventing the IAP mediated inhibition of caspases. Herein we show that the KU-7 and RT4v6 bladder cancer cell lines are resistant to cell death with BCG stimulated neutrophils alone in vitro but a Smac mimetic kills bladder cancer cells in combination with BCG stimulated neutrophils. The sensitization of bladder cancer cells to Smac mimetic and BCG stimulated neutrophils is associated with the dowregulation of cIAP2 and cIAP1. TNF-α, TRAIL or Smac mimetic compound could not induce significant cell death as single agents in these cell lines, where as Smac mimetic compound in combination with TNF-α or TRAIL induced potent and massive cell death supporting our hypothesis. Our results suggest that Smac mimetics present a viable mechanism based approach to combination therapy with BCG for bladder cancer.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-30.
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Vince JE, Chau D, Callus B, Wong WWL, Hawkins CJ, Schneider P, McKinlay M, Benetatos CA, Condon SM, Chunduru SK, Yeoh G, Brink R, Vaux DL, Silke J. TWEAK-FN14 signaling induces lysosomal degradation of a cIAP1–TRAF2 complex to sensitize tumor cells to TNFα. J Exp Med 2008. [DOI: 10.1084/jem2058oia18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Vince JE, Chau D, Callus B, Wong WWL, Hawkins CJ, Schneider P, McKinlay M, Benetatos CA, Condon SM, Chunduru SK, Yeoh G, Brink R, Vaux DL, Silke J. TWEAK-FN14 signaling induces lysosomal degradation of a cIAP1-TRAF2 complex to sensitize tumor cells to TNFalpha. ACTA ACUST UNITED AC 2008; 182:171-84. [PMID: 18606850 PMCID: PMC2447903 DOI: 10.1083/jcb.200801010] [Citation(s) in RCA: 211] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Synthetic inhibitor of apoptosis (IAP) antagonists induce degradation of IAP proteins such as cellular IAP1 (cIAP1), activate nuclear factor κB (NF-κB) signaling, and sensitize cells to tumor necrosis factor α (TNFα). The physiological relevance of these discoveries to cIAP1 function remains undetermined. We show that upon ligand binding, the TNF superfamily receptor FN14 recruits a cIAP1–Tnf receptor-associated factor 2 (TRAF2) complex. Unlike IAP antagonists that cause rapid proteasomal degradation of cIAP1, signaling by FN14 promotes the lysosomal degradation of cIAP1–TRAF2 in a cIAP1-dependent manner. TNF-like weak inducer of apoptosis (TWEAK)/FN14 signaling nevertheless promotes the same noncanonical NF-κB signaling elicited by IAP antagonists and, in sensitive cells, the same autocrine TNFα-induced death occurs. TWEAK-induced loss of the cIAP1–TRAF2 complex sensitizes immortalized and minimally passaged tumor cells to TNFα-induced death, whereas primary cells remain resistant. Conversely, cIAP1–TRAF2 complex overexpression limits FN14 signaling and protects tumor cells from TWEAK-induced TNFα sensitization. Lysosomal degradation of cIAP1–TRAF2 by TWEAK/FN14 therefore critically alters the balance of life/death signals emanating from TNF-R1 in immortalized cells.
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Affiliation(s)
- James E Vince
- Department of Biochemistry, La Trobe University, Kingsbury Drive, Melbourne, VIC 3086, Australia
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Vince JE, Wong WWL, Khan N, Feltham R, Chau D, Ahmed AU, Benetatos CA, Chunduru SK, Condon SM, McKinlay M, Brink R, Leverkus M, Tergaonkar V, Schneider P, Callus BA, Koentgen F, Vaux DL, Silke J. IAP antagonists target cIAP1 to induce TNFalpha-dependent apoptosis. Cell 2008; 131:682-93. [PMID: 18022363 DOI: 10.1016/j.cell.2007.10.037] [Citation(s) in RCA: 986] [Impact Index Per Article: 61.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 09/19/2007] [Accepted: 10/22/2007] [Indexed: 11/17/2022]
Abstract
XIAP prevents apoptosis by binding to and inhibiting caspases, and this inhibition can be relieved by IAP antagonists, such as Smac/DIABLO. IAP antagonist compounds (IACs) have therefore been designed to inhibit XIAP to kill tumor cells. Because XIAP inhibits postmitochondrial caspases, caspase 8 inhibitors should not block killing by IACs. Instead, we show that apoptosis caused by an IAC is blocked by the caspase 8 inhibitor crmA and that IAP antagonists activate NF-kappaB signaling via inhibtion of cIAP1. In sensitive tumor lines, IAP antagonist induced NF-kappaB-stimulated production of TNFalpha that killed cells in an autocrine fashion. Inhibition of NF-kappaB reduced TNFalpha production, and blocking NF-kappaB activation or TNFalpha allowed tumor cells to survive IAC-induced apoptosis. Cells treated with an IAC, or those in which cIAP1 was deleted, became sensitive to apoptosis induced by exogenous TNFalpha, suggesting novel uses of these compounds in treating cancer.
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Affiliation(s)
- James E Vince
- Department of Biochemistry, La Trobe University, Kingsbury Drive, Melbourne, VIC 3086, Australia
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21
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Howe AYM, Cheng H, Thompson I, Chunduru SK, Herrmann S, O'Connell J, Agarwal A, Chopra R, Del Vecchio AM. Molecular mechanism of a thumb domain hepatitis C virus nonnucleoside RNA-dependent RNA polymerase inhibitor. Antimicrob Agents Chemother 2006; 50:4103-13. [PMID: 16940072 PMCID: PMC1693979 DOI: 10.1128/aac.00365-06] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
A new pyranoindole class of small-molecule inhibitors was studied to understand viral resistance and elucidate the mechanism of inhibition in hepatitis C virus (HCV) replication. HCV replicon variants less susceptible to inhibition by the pyranoindoles were selected in Huh-7 hepatoma cells. Variant replicons contained clusters of mutations in the NS5B polymerase gene corresponding to the drug-binding pocket on the surface of the thumb domain identified by X-ray crystallography. An additional cluster of mutations present in part of a unique beta-hairpin loop was also identified. The mutations were characterized by using recombinant replicon variants engineered with the corresponding amino acid substitutions. A single mutation (L419M or M423V), located at the pyranoindole-binding site, resulted in an 8- to 10-fold more resistant replicon, while a combination mutant (T19P, M71V, A338V, M423V, A442T) showed a 17-fold increase in drug resistance. The results of a competition experiment with purified NS5B enzyme with GTP showed that the inhibitory activity of the pyranoindole inhibitor was not affected by GTP at concentrations up to 250 microM. Following de novo initiation, the presence of a pyranoindole inhibitor resulted in the accumulation of a five-nucleotide oligomer, with a concomitant decrease in higher-molecular-weight products. The results of these studies have confirmed that pyranoindoles target the NS5B polymerase through interactions at the thumb domain. This inhibition is independent of GTP concentrations and is likely mediated by an allosteric blockade introduced by the inhibitor during the transition to RNA elongation after the formation of an initiation complex.
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MESH Headings
- Amino Acid Substitution
- Binding Sites
- Binding, Competitive
- Cell Line, Tumor
- Crystallography, X-Ray
- Drug Resistance, Viral/genetics
- Enzyme Inhibitors/chemistry
- Enzyme Inhibitors/pharmacology
- Genes, Viral
- Genetic Engineering
- Genetic Variation
- Guanosine Triphosphate/metabolism
- Hepacivirus/drug effects
- Hepacivirus/enzymology
- Hepacivirus/genetics
- Humans
- Models, Molecular
- Mutation
- Protein Binding
- Protein Structure, Tertiary
- RNA, Viral/genetics
- RNA-Dependent RNA Polymerase/antagonists & inhibitors
- Recombination, Genetic
- Replicon/genetics
- Selection, Genetic
- Viral Nonstructural Proteins/antagonists & inhibitors
- Viral Nonstructural Proteins/genetics
- Virus Replication
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Affiliation(s)
- Anita Y M Howe
- Infectious Diseases, Wyeth Research, 500 Arcola Road, Collegeville, PA 19426, USA.
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Laporte MG, Lessen TA, Leister L, Cebzanov D, Amparo E, Faust C, Ortlip D, Bailey TR, Nitz TJ, Chunduru SK, Young DC, Burns CJ. Tetrahydrobenzothiophene inhibitors of hepatitis C virus NS5B polymerase. Bioorg Med Chem Lett 2006; 16:100-3. [PMID: 16260131 DOI: 10.1016/j.bmcl.2005.09.047] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 09/15/2005] [Accepted: 09/16/2005] [Indexed: 12/09/2022]
Abstract
A novel series of selective HCV NS5B RNA dependent RNA polymerase inhibitors has been disclosed. These compounds contain an appropriately substituted tetrahydrobenzothiophene scaffold. This communication will detail the SAR and activities of this series.
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Affiliation(s)
- M G Laporte
- ViroPharma Incorporated, 397 Eagleview Boulevard, Exton, PA 19341, USA.
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23
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Howe AYM, Bloom J, Baldick CJ, Benetatos CA, Cheng H, Christensen JS, Chunduru SK, Coburn GA, Feld B, Gopalsamy A, Gorczyca WP, Herrmann S, Johann S, Jiang X, Kimberland ML, Krisnamurthy G, Olson M, Orlowski M, Swanberg S, Thompson I, Thorn M, Del Vecchio A, Young DC, van Zeijl M, Ellingboe JW, Upeslacis J, Collett M, Mansour TS, O'Connell JF. Novel nonnucleoside inhibitor of hepatitis C virus RNA-dependent RNA polymerase. Antimicrob Agents Chemother 2005; 48:4813-21. [PMID: 15561861 PMCID: PMC529219 DOI: 10.1128/aac.48.12.4813-4821.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel nonnucleoside inhibitor of hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp), [(1R)-5-cyano-8-methyl-1-propyl-1,3,4,9-tetrahydropyano[3,4-b]indol-1-yl] acetic acid (HCV-371), was discovered through high-throughput screening followed by chemical optimization. HCV-371 displayed broad inhibitory activities against the NS5B RdRp enzyme, with 50% inhibitory concentrations ranging from 0.3 to 1.8 microM for 90% of the isolates derived from HCV genotypes 1a, 1b, and 3a. HCV-371 showed no inhibitory activity against a panel of human polymerases, including mitochondrial DNA polymerase gamma, and other unrelated viral polymerases, demonstrating its specificity for the HCV polymerase. A single administration of HCV-371 to cells containing the HCV subgenomic replicon for 3 days resulted in a dose-dependent reduction of the steady-state levels of viral RNA and protein. Multiple treatments with HCV-371 for 16 days led to a >3-log10 reduction in the HCV RNA level. In comparison, multiple treatments with a similar inhibitory dose of alpha interferon resulted in a 2-log10 reduction of the viral RNA level. In addition, treatment of cells with a combination of HCV-371 and pegylated alpha interferon resulted in an additive antiviral activity. Within the effective antiviral concentrations of HCV-371, there was no effect on cell viability and metabolism. The intracellular antiviral specificity of HCV-371 was demonstrated by its lack of activity in cells infected with several DNA or RNA viruses. Fluorescence binding studies show that HCV-371 binds the NS5B with an apparent dissociation constant of 150 nM, leading to high selectivity and lack of cytotoxicity in the antiviral assays.
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Affiliation(s)
- Anita Y M Howe
- Infectious Diseases Wyeth Research, Pearl River, New York 10965, USA.
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24
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Baginski SG, Pevear DC, Seipel M, Sun SC, Benetatos CA, Chunduru SK, Rice CM, Collett MS. Mechanism of action of a pestivirus antiviral compound. Proc Natl Acad Sci U S A 2000; 97:7981-6. [PMID: 10869440 PMCID: PMC16656 DOI: 10.1073/pnas.140220397] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We report here the discovery of a small molecule inhibitor of pestivirus replication. The compound, designated VP32947, inhibits the replication of bovine viral diarrhea virus (BVDV) in cell culture at a 50% inhibitory concentration of approximately 20 nM. VP32947 inhibits both cytopathic and noncytopathic pestiviruses, including isolates of BVDV-1, BVDV-2, border disease virus, and classical swine fever virus. However, the compound shows no activity against viruses from unrelated virus groups. Time of drug addition studies indicated that VP32947 acts after virus adsorption and penetration and before virus assembly and release. Analysis of viral macromolecular synthesis showed VP32947 had no effect on viral protein synthesis or polyprotein processing but did inhibit viral RNA synthesis. To identify the molecular target of VP32947, we isolated drug-resistant (DR) variants of BVDV-1 in cell culture. Sequence analysis of the complete genomic RNA of two DR variants revealed a single common amino acid change located within the coding region of the NS5B protein, the viral RNA-dependent RNA polymerase. When this single amino acid change was introduced into an infectious clone of drug-sensitive wild-type (WT) BVDV-1, replication of the resulting virus was resistant to VP32947. The RNA-dependent RNA polymerase activity of the NS5B proteins derived from WT and DR viruses expressed and purified from recombinant baculovirus-infected insect cells confirmed the drug sensitivity of the WT enzyme and the drug resistance of the DR enzyme. This work formally validates NS5B as a target for antiviral drug discovery and development. The utility of VP32947 and similar compounds for the control of pestivirus diseases, and for hepatitis C virus drug discovery efforts, is discussed.
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Affiliation(s)
- S G Baginski
- Washington University, Department of Molecular Microbiology, St. Louis, MO 63110, USA
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25
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Chunduru SK, Sutherland RM, Stewart GA, Doms RW, Paterson Y. Exploitation of the Vbeta8.2 T cell receptor in protection against experimental autoimmune encephalomyelitis using a live vaccinia virus vector. The Journal of Immunology 1996. [DOI: 10.4049/jimmunol.156.12.4940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
This study takes advantage of the predominant usage of Vbeta8.2 by the TCRs of encephalitogenic T cells specific for myelin basic protein. Vaccinia virus recombinants expressing Vbeta8.2 (VVbeta8.2) 8.2) and Vbeta3 (VVbeta 3) proteins were constructed, and their abilities to confer protection against experimental autoimmune encephalomyelitis (EAE) induction in H-2u mice were examined. Mice immunized with VVbeta8.2 developed very mild EAE by comparison with mice that were vaccinated with VVbeta3, which developed severe clinical symptoms. This reduction in EAE correlated with a diminished T cell proliferative response to myelin basic protein in the mice that received VVbeta8.2 compared with that in mice receiving VVbeta3.
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Affiliation(s)
- S K Chunduru
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - R M Sutherland
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - G A Stewart
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - R W Doms
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Y Paterson
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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26
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Chunduru SK, Sutherland RM, Stewart GA, Doms RW, Paterson Y. Exploitation of the Vbeta8.2 T cell receptor in protection against experimental autoimmune encephalomyelitis using a live vaccinia virus vector. J Immunol 1996; 156:4940-5. [PMID: 8648145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This study takes advantage of the predominant usage of Vbeta8.2 by the TCRs of encephalitogenic T cells specific for myelin basic protein. Vaccinia virus recombinants expressing Vbeta8.2 (VVbeta8.2) 8.2) and Vbeta3 (VVbeta 3) proteins were constructed, and their abilities to confer protection against experimental autoimmune encephalomyelitis (EAE) induction in H-2u mice were examined. Mice immunized with VVbeta8.2 developed very mild EAE by comparison with mice that were vaccinated with VVbeta3, which developed severe clinical symptoms. This reduction in EAE correlated with a diminished T cell proliferative response to myelin basic protein in the mice that received VVbeta8.2 compared with that in mice receiving VVbeta3.
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Affiliation(s)
- S K Chunduru
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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27
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Spencer HT, Sorrentino BP, Pui CH, Chunduru SK, Sleep SE, Blakley RL. Mutations in the gene for human dihydrofolate reductase: an unlikely cause of clinical relapse in pediatric leukemia after therapy with methotrexate. Leukemia 1996; 10:439-46. [PMID: 8642859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Resistance to methotrexate (MTX) in some sublines of mammalian cells is reported to be due to one of the following amino acid substitutions in dihydrofolate reductase (DHFR) that lower inhibition by MTX: Gly15 to Trp, Leu22 to Arg or Phe or Phe31 to Trp or Ser. We have produced variants of human DHFR (hDHFR) with these substitutions by directed mutagenesis. Recombinant hDHFR variants expressed in Escherichia coli have greatly decreased inhibition by MTX, but decreased catalytic efficiency, and in one case decreased stability. When a retroviral vector encoding wild-type (wt) hDHFR or one of these variants was introduced into murine fibroblasts or bone marrow progenitors, modest protection from MTX was conferred, even by wt. Relapsed pediatric patients with acute lymphoblastic leukemia who have received multiple courses of high-dose MTX seem most likely to develop such MTX resistance. cDNA was reverse transcribed from blast mRNA from 17 of these patients. However, upon amplification and sequencing of DHFR cDNA, no resistance mutation was found. The explanation for this probably lies in the need for considerable gene amplification to offset lowered catalytic efficiency, and the need for two-base changes for most substitutions, both of which are probably infrequent events.
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Affiliation(s)
- H T Spencer
- Department of Molecular Pharmacology, St Jude Children's Research Hospital, Memphis, Tennessee, USA
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28
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Lewis WS, Cody V, Galitsky N, Luft JR, Pangborn W, Chunduru SK, Spencer HT, Appleman JR, Blakley RL. Methotrexate-resistant variants of human dihydrofolate reductase with substitutions of leucine 22. Kinetics, crystallography, and potential as selectable markers. J Biol Chem 1995; 270:5057-64. [PMID: 7890613 DOI: 10.1074/jbc.270.10.5057] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Although substitution of tyrosine, phenylalanine, tryptophan, or arginine for leucine 22 in human dihydrofolate reductase greatly slows hydride transfer, there is little loss in overall activity (kcat) at pH 7.65 (except for the arginine 22 variant), but Km for dihydrofolate and NADPH are increased significantly. The greatest effect, decreased binding of methotrexate to the enzyme-NADPH complex by 740- to 28,000-fold due to a large increase in the rate of methotrexate dissociation, makes these variants suitable to act as selectable markers. Affinities for four other inhibitors are also greatly decreased. Binding of methotrexate to apoenzyme is decreased much less (decreases as much as 120-fold), binding of tetrahydrofolate is decreased as much as 23-fold, and binding of dihydrofolate is decreased little or increased. Crystal structures of ternary complexes of three of the variants show that the mutations cause little perturbation of the protein backbone, of side chains of other active site residues, or of bound inhibitor. The largest structural deviations occur in the ternary complex of the arginine variant at residues 21-27 and in the orientation of the methotrexate. Tyrosine 22 and arginine 22 relieve short contacts to methotrexate and NADPH by occupying low probability conformations, but this is unnecessary for phenylalanine 22 in the piritrexim complex.
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Affiliation(s)
- W S Lewis
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101
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29
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Chunduru SK, Cody V, Luft JR, Pangborn W, Appleman JR, Blakley RL. Methotrexate-resistant variants of human dihydrofolate reductase. Effects of Phe31 substitutions. J Biol Chem 1994; 269:9547-55. [PMID: 8144541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Substitution of glycine or alanine for phenylalanine 31 in human dihydrofolate reductase produces variants that are inhibited less by methotrexate (MTX) than the previously reported serine variant. The 100 times decrease in MTX affinity for the glycine variant is due to slower binding, and to inability of the initial complex to isomerize to a nondissociating conformer. A polar group at position 31 is unnecessary for resistance, but residues larger than serine confer no resistance. The glycine variant best fulfills criteria for gene therapy: low Km for H2folate, high kcat, and good stability. Although kcat is unaltered by these mutations, the rate of hydride transfer is greatly decreased. Presteady-state measurements have enabled a complete catalytic scheme to be constructed for the glycine variant that predicts observed steady-state behavior. The crystal structures of inhibitor complexes of the serine, alanine, and glycine mutants and of the wild-type enzyme show that the mutations cause little perturbation of the protein backbone, of side chains of residues at the active site, or of the bound inhibitor. A molecule of bound water occupies the space vacated by the phenyl group.
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Affiliation(s)
- S K Chunduru
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101
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30
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Chunduru SK, Appleman JR, Blakley RL. Activity of human DNA polymerases alpha and beta with 2-chloro-2'-deoxyadenosine 5'-triphosphate as a substrate and quantitative effects of incorporation on chain extension. Arch Biochem Biophys 1993; 302:19-30. [PMID: 8470896 DOI: 10.1006/abbi.1993.1175] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
When 2-chloro-2'-deoxyadenosine 5'-triphosphate (CldATP) is incorporated into DNA by human polymerases alpha and beta (Hpol alpha, Hpol beta) the rate of chain extension decreases. In the present study primer extension has been quantitated by estimating the concentration of each successive oligonucleotide product at a series of time points. This has permitted calculation of pseudo-first-order rate constants for successive nucleotide additions to primer. By this method it has been shown that rate constants for CldATP addition are 79-100% of those for dATP in the case of Hpol alpha, and 26-153% with Hpol beta. The concentrations of CldATP for half maximum velocity is 0.6 microM for Hpol alpha, and 6 microM for Hpol beta, each about twice the value for dATP. Thus, CldATP is a good substrate for both enzymes but is more efficiently used by Hpol alpha. Addition of a single analogue residue by Hpol beta to any of seven primers decreases the rate constant for addition of the next nucleotide to 2-7% of that after dAMP addition and further extension is negligible. Consecutive additions of analogue residues by Hpol alpha progressively decrease the rate of subsequent extension, and after five consecutive additions extension virtually terminates. These effects probably make a major contribution to the cytotoxicity of chlorodeoxyadenosine and its therapeutic usefulness as an antileukemic agent.
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Affiliation(s)
- S K Chunduru
- Department of Biochemical and Clinical Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38101
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31
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Chunduru SK, Appleman JR, Blakley RL. Kinetic investigation of methotrexate resistant human dihydrofolate reductase (hDHFR) mutants at Phe31. Adv Exp Med Biol 1993; 338:507-10. [PMID: 8304168 DOI: 10.1007/978-1-4615-2960-6_102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- S K Chunduru
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, TN 38101
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32
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Blakley RL, Appleman JR, Chunduru SK, Nakano T, Lewis WS, Harris SE. Mutations of human dihydrofolate reductase causing decreased inhibition by methotrexate. Adv Exp Med Biol 1993; 338:473-9. [PMID: 8304162 DOI: 10.1007/978-1-4615-2960-6_96] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- R L Blakley
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, TN 38101
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33
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Mrachko GT, Chunduru SK, Calvo KC. The pH dependence of the kinetic parameters of ketol acid reductoisomerase indicates a proton shuttle mechanism for alkyl migration. Arch Biochem Biophys 1992; 294:446-53. [PMID: 1567200 DOI: 10.1016/0003-9861(92)90710-e] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The enzyme ketol acid reductoisomerase catalyzes the second common reaction in the biosynthesis of the branched chain amino acids. The reaction is complex as an alkyl migration and a ketone reduction apparently occur as separate steps during the conversion of acetolactate to 2,3-dihydroxy-3-methylbutyrate. This paper reports on the pH dependence of the kinetic parameters of the enzyme. The pH variation of log(V/K) for acetolactate was fit to an equation describing a bell-shaped curve, indicating an acid and a base catalyst for the reaction. In the reverse direction, V/K for 2,3-dihydroxy-3-methylbutyrate is constant over the pH range 8 to 10 and decreases below pH 8 with the ionization of two catalytic groups. The pH dependence of the V/K values for reduction of the kinetically competent intermediate and analogs of this intermediate are also described by a bell-shaped curve. The pH dependence of the V/K for alkyl migration of this intermediate indicates a single base catalyst for this reaction. We observe no deuterium kinetic isotope effect on V or V/K for the reaction of acetolactate at any pH. We observe a pH-dependent kinetic isotope effect on V/K for the reduction of the intermediate, the magnitude of which is metal ion dependent. Larger KIE's are observed in the presence of Mn2+ as opposed to Mg2+. In the reverse reaction there is a pH-dependent kinetic isotope effect on V/K. Based on the pH dependence of the kinetic parameters and the kinetic isotope effects, we propose a base-catalyzed proton shuttle mechanism for the alkyl migration reaction followed by an acid-assisted ketone reduction by NADPH.
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Affiliation(s)
- G T Mrachko
- Department of Chemistry, University of Akron, Ohio 44325-3601
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34
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Abstract
Ketol acid reductoisomerase is an enzyme of the branched-chain amino acid biosynthetic pathway. It catalyzes two separate reactions: an acetoin rearrangement and a reduction. This paper reports on the purification of the enzyme from a recombinant Escherichia coli and on the steady-state kinetics of the enzyme. The kinetics of the reaction were determined for the forward and reverse reaction by using the appropriate chiral substrates. At saturating metal ion concentrations the mechanism follows an ordered pathway where NADPH binds before acetolactate. The product of the rearrangement of acetolactate, 3-hydroxy-3-methyl-2-oxobutyrate, is shown to be kinetically competent as an intermediate in the enzyme-catalyzed reaction. Starting with acetolactate, Mg2+ is the only divalent metal ion that will support enzyme catalysis. For the reduction of 3-hydroxy-3-methyl-2-oxobutyrate, Mn2+ is catalytically active. Product and dead-end inhibition studies indicate that the binding of metal ion and NADPH occurs randomly. In the forward reaction direction, the deuterium kinetic isotope effect on V/K is 1.07 when acetolactate is the substrate and 1.39 when 3-hydroxy-3-methyl-2-oxobutyrate is the substrate.
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Affiliation(s)
- S K Chunduru
- Department of Chemistry, University of Akron, Ohio 44325
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