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Knödler M, Buyel JF. Plant-made immunotoxin building blocks: A roadmap for producing therapeutic antibody-toxin fusions. Biotechnol Adv 2021; 47:107683. [PMID: 33373687 DOI: 10.1016/j.biotechadv.2020.107683] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 12/07/2020] [Accepted: 12/20/2020] [Indexed: 12/16/2022]
Abstract
Molecular farming in plants is an emerging platform for the production of pharmaceutical proteins, and host species such as tobacco are now becoming competitive with commercially established production hosts based on bacteria and mammalian cell lines. The range of recombinant therapeutic proteins produced in plants includes replacement enzymes, vaccines and monoclonal antibodies (mAbs). But plants can also be used to manufacture toxins, such as the mistletoe lectin viscumin, providing an opportunity to express active antibody-toxin fusion proteins, so-called recombinant immunotoxins (RITs). Mammalian production systems are currently used to produce antibody-drug conjugates (ADCs), which require the separate expression and purification of each component followed by a complex and hazardous coupling procedure. In contrast, RITs made in plants are expressed in a single step and could therefore reduce production and purification costs. The costs can be reduced further if subcellular compartments that accumulate large quantities of the stable protein are identified and optimal plant growth conditions are selected. In this review, we first provide an overview of the current state of RIT production in plants before discussing the three key components of RITs in detail. The specificity-defining domain (often an antibody) binds cancer cells, including solid tumors and hematological malignancies. The toxin provides the means to kill target cells. Toxins from different species with different modes of action can be used for this purpose. Finally, the linker spaces the two other components to ensure they adopt a stable, functional conformation, and may also promote toxin release inside the cell. Given the diversity of these components, we extract broad principles that can be used as recommendations for the development of effective RITs. Future research should focus on such proteins to exploit the advantages of plants as efficient production platforms for targeted anti-cancer therapeutics.
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Affiliation(s)
- M Knödler
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, Aachen 52074, Germany; Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, Aachen 52074, Germany.
| | - J F Buyel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, Aachen 52074, Germany; Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, Aachen 52074, Germany.
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Ben Abdessamad I, Bouhlel I, Chekir-Ghedira L, Krifa M. Antitumor Effect of Bryonia dioïca Methanol Extract: In Vitro and In Vivo Study. Nutr Cancer 2019; 72:747-756. [PMID: 31460802 DOI: 10.1080/01635581.2019.1654528] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Aim: A large number of plant-derived products have been approved for the treatment of numerous types of cancer, and these products have also shown to reduce the effects of metastatic cancer. The aim of this study is to evaluate the anticancer effects of a methanolic extract of Bryonia dioïca root (M extract) against B16F10 melanoma cancer cells in vitro as well as in vivo.Results: It was shown to induce apoptosis, in vitro, and to inhibit cell growth by arresting cell cycle progression in SubG1 phase. Mice bearing the melanoma cells were used to confirm any in vivo effectiveness of the M extract as an antitumor promoting agent. In mice dosed with 50 mg M/kg/d (for 28 days), tumor weight was inhibited by 65.03% compared to that in mice that did not receive the product. Our results demonstrate on the one hand, that this inhibition was accompanied by a drastic decrease regulation of complex FAK, Src, ERK, p130Cas and paxillin. On the other hand, it was marked by a measurable decrease of the metastatic descent in the lungs.Conclusions: These effects could be ascribed to the presence of bryoniosides and cucurbitacins such as cucurbitacin A and cucurbitacin G in M extract.
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Affiliation(s)
- Imen Ben Abdessamad
- Research Unit Bioactive Natural Products and Biotechnology, Faculty of Pharmacy of Monastir, University of Monastir, Monastir, Tunisia.,Department of Biochemistry, General Medicine Faculty of Monastir, Monastir, Tunisia
| | - Ines Bouhlel
- Research Unit Bioactive Natural Products and Biotechnology, Faculty of Pharmacy of Monastir, University of Monastir, Monastir, Tunisia.,Department of Biochemistry, General Medicine Faculty of Monastir, Monastir, Tunisia
| | - Leila Chekir-Ghedira
- Research Unit Bioactive Natural Products and Biotechnology, Faculty of Pharmacy of Monastir, University of Monastir, Monastir, Tunisia.,Department of Biochemistry, General Medicine Faculty of Monastir, Monastir, Tunisia
| | - Mounira Krifa
- Research Unit Bioactive Natural Products and Biotechnology, Faculty of Pharmacy of Monastir, University of Monastir, Monastir, Tunisia.,Department of Biochemistry, General Medicine Faculty of Monastir, Monastir, Tunisia
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Bracker M, Dinkelbach F, Weingart O, Kleinschmidt M. Impact of fluorination on the photophysics of the flavin chromophore: a quantum chemical perspective. Phys Chem Chem Phys 2019; 21:9912-9923. [DOI: 10.1039/c9cp00805e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
10-Methylisoalloxazine (MIA) and its fluorinated derivatives (6-9F-MIA) were investigated by means of quantum chemistry, looking into the influence of fluorination on fluorescence, absorption and inter-system crossing (ISC) in vacuum and in aqueous solution.
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Affiliation(s)
- Mario Bracker
- Institut für Theoretische Chemie und Computerchemie
- Heinrich-Heine-Universität Düsseldorf
- 40225 Düsseldorf
- Germany
| | - Fabian Dinkelbach
- Institut für Theoretische Chemie und Computerchemie
- Heinrich-Heine-Universität Düsseldorf
- 40225 Düsseldorf
- Germany
| | - Oliver Weingart
- Institut für Theoretische Chemie und Computerchemie
- Heinrich-Heine-Universität Düsseldorf
- 40225 Düsseldorf
- Germany
| | - Martin Kleinschmidt
- Institut für Theoretische Chemie und Computerchemie
- Heinrich-Heine-Universität Düsseldorf
- 40225 Düsseldorf
- Germany
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Atanackovic D, Radhakrishnan SV, Bhardwaj N, Luetkens T. Chimeric Antigen Receptor (CAR) therapy for multiple myeloma. Br J Haematol 2016; 172:685-98. [DOI: 10.1111/bjh.13889] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Djordje Atanackovic
- Multiple Myeloma Program, Hematology and Hematologic Malignancies; University of Utah/Huntsman Cancer Institute; Salt Lake City UT USA
| | - Sabarinath V. Radhakrishnan
- Multiple Myeloma Program, Hematology and Hematologic Malignancies; University of Utah/Huntsman Cancer Institute; Salt Lake City UT USA
| | - Neelam Bhardwaj
- Multiple Myeloma Program, Hematology and Hematologic Malignancies; University of Utah/Huntsman Cancer Institute; Salt Lake City UT USA
| | - Tim Luetkens
- Multiple Myeloma Program, Hematology and Hematologic Malignancies; University of Utah/Huntsman Cancer Institute; Salt Lake City UT USA
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Lorberboum-Galski H. Human toxin-based recombinant immunotoxins/chimeric proteins as a drug delivery system for targeted treatment of human diseases. Expert Opin Drug Deliv 2011; 8:605-21. [PMID: 21453191 DOI: 10.1517/17425247.2011.566269] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION The development of specific immunosuppressive reagents remains the major goal in the treatment of human diseases. One such approach is the use of recombinant immunotoxins/chimeric proteins, composed of targeting and killing moieties, fused at the cDNA level. Most of these 'magic bullets' use bacterial or plant toxins to induce cell death. These toxins are extremely potent, but they also cause severe toxicity and systemic side effects that limit the maximal doses given to patients. Moreover, being of non-human origin, they are highly immunogenic, and the resulting neutralizing antibody production impairs their efficacy. AREAS COVERED This review describes recombinant immunotoxins/chimeric proteins composed of the classical delivering, cell-targeting molecules, fused to highly cytotoxic human proteins capable of generating an intense apoptotic response within the target cell. This review focuses on the new 'Human Killing Moieties' of these targeted proteins and describes recent progress in the development of these promising molecules. EXPERT OPINION Human toxin-based immunotoxins/chimeric proteins for the targeted delivery of drugs are still in their early stages of development. However, they are certain to advance in the very near future to become an extra weapon in the everlasting war against human diseases, mainly cancer.
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Affiliation(s)
- Haya Lorberboum-Galski
- The Hebrew University, Institute for Medical Research - Israel-Canada, Department of Biochemistry and Molecular Biology, Faculty of Medicine, Jerusalem 91120, Israel.
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Shapira S, Shapira A, Starr A, Kazanov D, Kraus S, Benhar I, Arber N. An immunoconjugate of anti-CD24 and Pseudomonas exotoxin selectively kills human colorectal tumors in mice. Gastroenterology 2011; 140:935-46. [PMID: 21147107 DOI: 10.1053/j.gastro.2010.12.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 11/25/2010] [Accepted: 12/02/2010] [Indexed: 01/17/2023]
Abstract
BACKGROUND & AIMS Effective and selective treatment options are needed for patients with colorectal cancer (CRC). The CD24 mucin-like glycoprotein is overexpressed in CRCs; monoclonal antibodies (mAbs) against CD24 inhibit tumor cell growth in vitro and in vivo. Based on the tumor-specific expression of CD24, we investigated the potential of anti-CD24 SWA11 mAb, to deliver a cytotoxic agent into CRC cells. METHODS We conjugated SWA11 to a Pseudomonas exotoxin derivative (PE38) via an Fc-binding ZZ domain from Staphylococcal protein A (which binds the Fc domain of mouse IgG2a immunoglobulins) to generate the immunotoxin SWA11-ZZ-PE38; IgG-ZZ-PE38 was used as control. Human HT-29 and COLO320 (CD24-positive) and HCT116 (CD24-negative) CRC cell lines were assayed for immunotoxin binding, cytotoxicity, viability, and apoptosis. Toxicity and antitumor efficacy were tested in mice. RESULTS The immunotoxin preserved the affinity and specificity of SWA11, bound and selectively killed CD24-expressing CRC cells via apoptosis. IC(50) values ranged from 20 to 50 ng/mL-several orders of magnitude lower than that of the mAb alone. The immunotoxins were not toxic to mice at the maximum dose of 0.75 mg/kg. Growth of HT-29 xenograft tumors was significantly reduced in mice given SWA11-ZZ-PE38 (by 78%) compared to untreated mice. CONCLUSIONS Anti-CD24 SWA11 mAb can deliver a PE exotoxin derivative to CRC cells and cause them to undergo apoptosis, without toxicity to normal tissues. This immunotoxin might be developed as a therapeutic treatment for patients with CRC.
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Affiliation(s)
- Shiran Shapira
- The Integrated Cancer Prevention Center, Tel Aviv, Israel
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Kreitman RJ. Recombinant immunotoxins containing truncated bacterial toxins for the treatment of hematologic malignancies. BioDrugs 2009; 23:1-13. [PMID: 19344187 DOI: 10.2165/00063030-200923010-00001] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Immunotoxins are molecules that contain a protein toxin and a ligand that is either an antibody or a growth factor. The ligand binds to a target cell antigen, and the target cell internalizes the immunotoxin, allowing the toxin to migrate to the cytoplasm where it can kill the cell. In the case of recombinant immunotoxins, the ligand and toxin are encoded in DNA that is then expressed in bacteria, and the purified immunotoxin contains the ligand and toxin fused together. Among the most active recombinant immunotoxins clinically tested are those that are targeted to hematologic malignancies. One agent, containing human interleukin-2 and truncated diphtheria toxin (denileukin diftitox), has been approved for use in cutaneous T-cell lymphoma, and has shown activity in other hematologic malignancies, including leukemias and lymphomas. Diphtheria toxin has also been targeted by other ligands, including granulocyte-macrophage colony-stimulating factor and interleukin-3, to target myelogenous leukemia cells. Single-chain antibodies containing variable heavy and light antibody domains have been fused to truncated Pseudomonas exotoxin to target lymphomas and lymphocytic leukemias. Recombinant immunotoxins anti-Tac(Fv)-PE38 (LMB-2), targeting CD25, and RFB4(dsFv)-PE38 (BL22, CAT-3888), targeting CD22, have each been tested in patients. Major responses have been observed after failure of standard chemotherapy. The most successful application of recombinant immunotoxins today is in hairy cell leukemia, where BL22 has induced complete remissions in most patients who were previously treated with optimal chemotherapy.
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Affiliation(s)
- Robert J Kreitman
- Clinical Immunotherapy Section, Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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Houtenbos I, Santegoets S, Westers TM, Waisfisz Q, Kipriyanov S, Denkers F, Scheper RJ, de Gruijl TD, Ossenkoppele GJ, van de Loosdrecht AA. The novel bispecific diabody CD40CD28 strengthens leukaemic dendritic cell-induced T-cell reactivity. Br J Haematol 2008; 142:273-83. [DOI: 10.1111/j.1365-2141.2008.06990.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Abstract
Immunotoxins are proteins that contain a toxin along with an antibody or growth factor that binds specifically to target cells. Nearly all protein toxins work by enzymatically inhibiting protein synthesis. For the immunotoxin to work, it must bind to and be internalized by the target cells, and the enzymatic fragment of the toxin must translocate to the cytosol. Once in the cytosol, 1 molecule is capable of killing a cell, making immunotoxins some of the most potent killing agents. Various plant and bacterial toxins have been genetically fused or chemically conjugated to ligands that bind to cancer cells. Among the most active clinically are those that bind to hematologic tumors. At present, only 1 agent, which contains human interleukin-2 and truncated diphtheria toxin, is approved for use in cutaneous T-cell lymphoma. Another, containing an anti-CD22 Fv and truncated Pseudomonas exotoxin, has induced complete remissions in a high proportion of cases of hairy-cell leukemia. Refinement of existing immunotoxins and development of new immunotoxins are underway to improve the treatment of cancer.
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Affiliation(s)
- Robert J Kreitman
- Clinical Immunotherapy Section, Laboratory of Molecular Biology, Centers for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Building 37, Room 5124B, Bethesda, MD 20892-4255, USA.
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Chatterjee M, Chakraborty T, Tassone P. Multiple myeloma: monoclonal antibodies-based immunotherapeutic strategies and targeted radiotherapy. Eur J Cancer 2006; 42:1640-52. [PMID: 16797969 DOI: 10.1016/j.ejca.2006.02.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Accepted: 02/22/2006] [Indexed: 02/08/2023]
Abstract
Multiple myeloma (MM) is an incurable B-cell malignancy of terminally differentiated plasma cells. Besides conventional treatments, several targeted therapies are emerging for MM. We review recent developments in monoclonal antibodies (MoAbs) and (radio)immunoconjugates-based targeted immunotherapeutic (serotherapies) strategies, as well as skeletal targeted radiotherapy (STR) in MM. MoAbs-based strategies include the targeting of cytokines and their receptors as well as toxins, drugs or radionuclide delivery to MM cells. Both targeted radioimmunotherapy (RIT) and STR have proved efficient in the treatment of radiosensitive tumours. We conclude that there is a need for more mechanistic investigations of drug action to identify novel therapeutic targets in myeloma cells, as well as in the bone marrow microenvironment.
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Affiliation(s)
- Malay Chatterjee
- Department of Pharmaceutical Technology, Division of Biochemistry, Jadavpur University, Calcutta, West-Bengal 700 032, India.
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Kreitman RJ. Recombinant toxins in haematologic malignancies and solid tumours. Expert Opin Investig Drugs 2005; 7:1405-27. [PMID: 15992040 DOI: 10.1517/13543784.7.9.1405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Recombinant toxins constitute a new modality for the treatment of cancer, since they target cells displaying specific surface-receptors or antigens. They are fusion proteins, which contain toxin and ligand regions, and are produced in Escherichia coli. The ligand may be a growth factor or a fragment of an antibody, and the toxin is usually one of the two bacterial toxins: Pseudomonas exotoxin and diphtheria toxin. Compared to the earlier generation chemical conjugates of ligands and toxins, recombinant toxins have many advantages, including homogeneity with respect to the connection between the ligand and toxin, ease and yield of production and small size. A variety of chemotherapy-resistant haematologic and solid tumours have been targeted with recombinant toxins, and clinical trials with many of them have recently demonstrated their effectiveness. Moreover, their unwanted toxic effects are different from those of most chemotherapeutic agents, supporting the expectation that they can be combined with existing modalities to improve the clinical resources available to treat cancer in humans.
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Affiliation(s)
- R J Kreitman
- Division of Cancer Biology, National Cancer Institute, National Institutes of Health, 37/4B27, 37 Convent Drive, MSC 4255, Bethesda, MD 20892, USA
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Abstract
Patients with chemotherapy relapsed or refractory hematologic malignancies may be effectively treated with allogeneic or autologous stem cell transplants. However, many patients cannot be transplanted due to age, comorbidities, or lack of suitable donors. Further, a fraction of patients relapse post-transplant. Novel therapeutic agents that can kill multidrug-resistant malignant stem cells and are not myelosuppressive are needed. One class of such agents is immunotoxins. Immunotoxins consist of cell-selective ligands covalently linked to peptide toxins. The ligand delivers the molecule to specific cell surface receptors on malignant cells. The toxin triggers cell death either by reaching the cytosol and catalytically inactivating vital cell processes or by modifying the tumor cell surface membrane. We have synthesized immunotoxins for therapy of chemoresistant hematologic diseases. In this review, we will detail the synthesis of a number of these drugs and describe their preclinical and clinical activity. Several of these agents have shown dramatic antitumor effects in patients with hematologic neoplasms, and one immunotoxin has been approved for use by the US Food and Drug Administration (FDA). Over the next several decades, a growing number of these agents should reach the clinic.
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Affiliation(s)
- Arthur E Frankel
- Wake Forest University School of Medicine, Winston-Salem, NC, USA
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Brandão JG, Scheper RJ, Lougheed SM, Curiel DT, Tillman BW, Gerritsen WR, van den Eertwegh AJM, Pinedo HM, Haisma HJ, de Gruijl TD. CD40-targeted adenoviral gene transfer to dendritic cells through the use of a novel bispecific single-chain Fv antibody enhances cytotoxic T cell activation. Vaccine 2003; 21:2268-72. [PMID: 12744857 DOI: 10.1016/s0264-410x(03)00050-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Adenoviral (Ad) transduction of dendritic cells (DC) is a promising vaccination strategy. However, clinical applicability of Ad vectors is hampered by the necessity to use high titers of infectious Ad particles for efficient DC transduction. Here, we report on the production of a bacterially expressed bispecific conjugate, consisting of a fusion of recombinant single-chain (sc) mAb Fv fragments, which bind and neutralize the Ad fiber knob (through the S11 mAb scFv) and retarget Ad to CD40 on the DC surface (through the G28-5 mAb scFv). We show that this bispecific scFv fusion protein significantly enhances transduction efficiency of monocyte-derived DC (MoDC), reduces the amount of virus needed for a given level of transduction, and increases the ability of MoDC to activate CTL in an antigen specific manner. This single-component conjugate may prove to be a valuable immunotherapeutic tool for the targeting of Ad to DC in vivo.
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Affiliation(s)
- Joana G Brandão
- Department of Pathology, VU University Medical Center, PO Box 7057, 1007 Amsterdam MB, The Netherlands
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Frleta D, Demian D, Wade WF. Class II-targeted antigen is superior to CD40-targeted antigen at stimulating humoral responses in vivo. Int Immunopharmacol 2001; 1:265-75. [PMID: 11360928 DOI: 10.1016/s1567-5769(00)00032-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We examined the efficacy of using monoclonal antibodies to target antigen (avidin) to different surface molecules expressed on antigen presenting cells (APC). In particular, we targeted CD40 to test whether the "adjuvant" properties of CD40 signaling combined with targeted antigen would result in enhanced serologic responses. We targeted avidin to class II as a positive control and to CD11c as a negative control. These surface proteins represent an ensemble of surface molecules that signal upon ligation and that are expressed on professional APC, in particular dendritic cells (DC). We observed that targeting class II molecules on APC was superior to targeting CD40, or CD11c. However, CD40 and CD11c could function as targets for antigen bound monoclonal antibodies under certain conditions. Interestingly, inclusion of anti-CD40 mAb with the targeting anti-class II-targeted antigens negatively affects humoral response, suggesting that CD40 signaling under certain conditions may suppress processing and/or presentation of targeted antigen.
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Affiliation(s)
- D Frleta
- Department of Microbiology, Dartmouth Medical School, Lebanon, NH 03756, USA
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Francisco JA, Siegall CB. Single-chain immunotoxins targeted to CD40 for the treatment of human B-lineage hematologic malignancies. Leuk Lymphoma 1998; 30:237-45. [PMID: 9713956 DOI: 10.3109/10428199809057537] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Immunotoxins, in chemical conjugate form, have shown limited efficacy in clinical trials in patients with hematologic malignancies. Single-chain immunotoxins (SCIT) provide for enhanced therapeutic efficacy over chemical conjugate forms without additional toxicity and thus may result in improved antitumor activity. We have evaluated two SCITs targeted to CD40, a receptor expressed on most B-lineage hematologic malignancies, for the treatment of non-Hodgkin's lymphoma and multiple myeloma. Both SCITs, G28-5 sFv-PE40 and BD1-G28-5 sFv, were highly potent and specifically cytotoxic against non-Hodgkin's lymphoma and multiple myeloma cell lines. G28-5 sFv-PE40 has proven to be efficacious in SCID mice bearing human non-Hodgkin's lymphoma and multiple myeloma xenografts. Antitumor activity has also been noted in preliminary studies using BD1-G28-5 sFv in non-Hodgkin's lymphoma models. The data presented here indicate that these agents should be considered for use in clinical trials in patients with refractive non-Hodgkin's lymphoma, multiple myeloma and other CD40-expressing hematologic malignancies.
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Affiliation(s)
- J A Francisco
- Molecular Immunology Department, Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, WA 98121, USA
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Fryxell DK, Gawlak SL, Dodge RW, Siegall CB. Identification of a specific tyrosine residue in Bryodin 1 distinct from the active site but required for full catalytic and cytotoxic activity. Protein Sci 1998; 7:318-24. [PMID: 9521107 PMCID: PMC2143931 DOI: 10.1002/pro.5560070211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Bryodin 1 (BD1) is a type I ribosome-inactivating protein (RIP) with low inherent animal toxicity. It has been cloned recently and the recombinant protein (rBD1) has been produced and crystallized. To gain insight into the relationship of rBD1 structure and function, we investigated the role of sequences in a region (residues 128-156) that exhibits homology with membrane interactive sequences and is not part of the enzymatically defined active site. Progressive deletions representing alpha-helical tums within these residues were generated; mutant rBD1 proteins were expressed in Escherichia coli and demonstrated increasing losses of enzymatic activity. Point mutations were also generated within this region to replace Y140, Y141, and Y142 with either alanine or lysine. Mutants at position 140 or 142 retained full enzymatic activity, whereas A141 and K141 mutants were >19-fold less potent. In cytotoxicity assays, the rBD1 point mutants at Y141 were >80-fold less potent than either rBD1 or mutants at residues 140 or 142. However, when introduced into the anti-CD40 single-chain immunotoxin rBD1-G28-5 sFv, the A140 and A141 point mutations led to decreased cytotoxicity toward CD40 positive cell lines. These data indicate that Y141 plays an important role in the enzymatic activity of BD1 and that Y140, although not essential for catalytic activity, is required for full BD1 function. Because residues 140 and 141 are distinct from residues implicit in the active site, they may be involved in ribosomal and/or membrane interactions or in intracellular trafficking of the toxin and immunotoxin.
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Affiliation(s)
- D K Fryxell
- Molecular Immunology Department, Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, Washington 98121, USA
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