1
|
Ning D, Xue J, Lou X, Shao R, Liu Y, Chen G. Transforming toxins into treatments: the revolutionary role of α-amanitin in cancer therapy. Arch Toxicol 2024; 98:1705-1716. [PMID: 38555326 DOI: 10.1007/s00204-024-03727-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 03/07/2024] [Indexed: 04/02/2024]
Abstract
Amanita phalloides is the primary species responsible for fatal mushroom poisoning, as its main toxin, α-amanitin, irreversibly and potently inhibits eukaryotic RNA polymerase II (RNAP II), leading to cell death. There is no specific antidote for α-amanitin, which hinders its clinical application. However, with the advancement of precision medicine in oncology, including the development of antibody-drug conjugates (ADCs), the potential value of various toxic small molecules has been explored. These ADCs ingeniously combine the targeting precision of antibodies with the cytotoxicity of small-molecule payloads to precisely kill tumor cells. We searched PubMed for studies in this area using these MeSH terms "Amanitins, Alpha-Amanitin, Therapeutic use, Immunotherapy, Immunoconjugates, Antibodies" and did not limit the time interval. Recent studies have conducted preclinical experiments on ADCs based on α-amanitin, showing promising therapeutic effects and good tolerance in primates. The current challenges include the not fully understood toxicological mechanism of α-amanitin and the lack of clinical studies to evaluate the therapeutic efficacy of ADCs developed based on α-amanitin. In this article, we will discuss the role and therapeutic efficacy of α-amanitin as an effective payload in ADCs for the treatment of various cancers, providing background information for the research and application strategies of current and future drugs.
Collapse
Affiliation(s)
- Deyuan Ning
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - Jinfang Xue
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - Xiran Lou
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - Ruifei Shao
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - Yu Liu
- Medical School, Kunming University of Science and Technology, Kunming, China
| | - Guobing Chen
- Department of Emergency Medicine, The First People's Hospital of Yunnan Province, No 157 Jinbi Road, Xishan District, Kunming, 650032, China.
| |
Collapse
|
2
|
Abstract
Cancer drugs are broadly classified into two categories: cytotoxic chemotherapies and targeted therapies that specifically modulate the activity of one or more proteins involved in cancer. Major advances have been achieved in targeted cancer therapies in the past few decades, which is ascribed to the increasing understanding of molecular mechanisms for cancer initiation and progression. Consequently, monoclonal antibodies and small molecules have been developed to interfere with a specific molecular oncogenic target. Targeting gain-of-function mutations, in general, has been productive. However, it has been a major challenge to use standard pharmacologic approaches to target loss-of-function mutations of tumor suppressor genes. Novel approaches, including synthetic lethality and collateral vulnerability screens, are now being developed to target gene defects in p53, PTEN, and BRCA1/2. Here, we review and summarize the recent findings in cancer genomics, drug development, and molecular cancer biology, which show promise in targeting tumor suppressors in cancer therapeutics.
Collapse
Affiliation(s)
- Yunhua Liu
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Xiaoxiao Hu
- State Key Laboratory for Chemo/Bio Sensing and Chemometrics, College of Biology, Hunan University, Changsha, China
| | - Cecil Han
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Liana Wang
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Xinna Zhang
- Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Xiaoming He
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Xiongbin Lu
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| |
Collapse
|
3
|
Liu Y, Zhang X, Han C, Wan G, Huang X, Ivan C, Jiang D, Rodriguez-Aguayo C, Lopez-Berestein G, Rao PH, Maru DM, Pahl A, He X, Sood AK, Ellis LM, Anderl J, Lu X. TP53 loss creates therapeutic vulnerability in colorectal cancer. Nature 2015; 520:697-701. [PMID: 25901683 PMCID: PMC4417759 DOI: 10.1038/nature14418] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 03/17/2015] [Indexed: 12/26/2022]
Abstract
TP53, a well-known tumour suppressor gene that encodes p53, is frequently inactivated by mutation or deletion in most human tumours. A tremendous effort has been made to restore p53 activity in cancer therapies. However, no effective p53-based therapy has been successfully translated into clinical cancer treatment owing to the complexity of p53 signalling. Here we demonstrate that genomic deletion of TP53 frequently encompasses essential neighbouring genes, rendering cancer cells with hemizygous TP53 deletion vulnerable to further suppression of such genes. POLR2A is identified as such a gene that is almost always co-deleted with TP53 in human cancers. It encodes the largest and catalytic subunit of the RNA polymerase II complex, which is specifically inhibited by α-amanitin. Our analysis of The Cancer Genome Atlas (TCGA) and Cancer Cell Line Encyclopedia (CCLE) databases reveals that POLR2A expression levels are tightly correlated with its gene copy numbers in human colorectal cancer. Suppression of POLR2A with α-amanitin or small interfering RNAs selectively inhibits the proliferation, survival and tumorigenic potential of colorectal cancer cells with hemizygous TP53 loss in a p53-independent manner. Previous clinical applications of α-amanitin have been limited owing to its liver toxicity. However, we found that α-amanitin-based antibody-drug conjugates are highly effective therapeutic agents with reduced toxicity. Here we show that low doses of α-amanitin-conjugated anti-epithelial cell adhesion molecule (EpCAM) antibody lead to complete tumour regression in mouse models of human colorectal cancer with hemizygous deletion of POLR2A. We anticipate that inhibiting POLR2A will be a new therapeutic approach for human cancers containing such common genomic alterations.
Collapse
Affiliation(s)
- Yunhua Liu
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Xinna Zhang
- Department of Gynaecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Center for RNA Interference and Non-coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Cecil Han
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Guohui Wan
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Xingxu Huang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Cristina Ivan
- Department of Gynaecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Center for RNA Interference and Non-coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Dahai Jiang
- Department of Gynaecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Center for RNA Interference and Non-coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Cristian Rodriguez-Aguayo
- Center for RNA Interference and Non-coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Gabriel Lopez-Berestein
- Center for RNA Interference and Non-coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Pulivarthi H. Rao
- Department of Paediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Dipen M. Maru
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Andreas Pahl
- Heidelberg Pharma GmbH, Ladenburg 68526, Germany
| | - Xiaoming He
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio 43210, USA
| | - Anil K. Sood
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Department of Gynaecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Center for RNA Interference and Non-coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Lee M. Ellis
- Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Jan Anderl
- Heidelberg Pharma GmbH, Ladenburg 68526, Germany
| | - Xiongbin Lu
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
- Center for RNA Interference and Non-coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| |
Collapse
|
4
|
Fiume L, Manerba M, Di Stefano G. Albumin-drug conjugates in the treatment of hepatic disorders. Expert Opin Drug Deliv 2014; 11:1203-17. [PMID: 24773257 DOI: 10.1517/17425247.2014.913567] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION This review deals with the use of serum albumin (SA) as a carrier for the selective delivery of drugs to liver cells. AREAS COVERED The synthesis and properties of the SA conjugates prepared to enhance the performance of the drugs used in the treatment of viral hepatitis, hepatocellular carcinoma (HCC), liver micrometastases and hepatic fibrosis are reported. EXPERT OPINION Studies in humans and laboratory animals demonstrated the capacity of SA conjugates to accomplish a liver targeting of the drugs, but at the same time underscored their limits and drawbacks, which can explain why to date these complexes did not reach a practical application. The major drawback is the need of administration by intravenous route, which prevents long-term daily treatments as required by some liver pathologies, such as chronic virus hepatitis and fibrosis. At present, only a conjugate carrying doxorubicin and addressed to the treatment of HCC showed in laboratory animals a solid potentiality to improve the value of the coupled drug. In the future, conjugation to SA could remain a successful strategy to permit the administration of drugs with rapid resolutive effects inside liver cells without causing severe extrahepatic adverse reactions.
Collapse
Affiliation(s)
- Luigi Fiume
- University of Bologna, Department of Experimental, Diagnostic and Specialty Medicine , via San Giacomo 14 - 20126 Bologna , Italy +39 0512094700 ; +39 0512094746 ;
| | | | | |
Collapse
|
5
|
Moldenhauer G, Salnikov AV, Lüttgau S, Herr I, Anderl J, Faulstich H. Therapeutic potential of amanitin-conjugated anti-epithelial cell adhesion molecule monoclonal antibody against pancreatic carcinoma. J Natl Cancer Inst 2012; 104:622-34. [PMID: 22457476 DOI: 10.1093/jnci/djs140] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Human epithelial cell adhesion molecule (EpCAM) is overexpressed in many cancers. Anti-EpCAM antibodies have shown promise in preclinical studies, but showed no tumor regression in a recent phase II clinical trial. Therefore, we generated a novel anti-EpCAM antibody-drug conjugate and assessed whether it showed enhanced antitumor effects. METHODS Chemical cross-linking was conducted to covalently conjugate α-amanitin, a toxin known to inhibit DNA transcription, with chiHEA125, a chimerized anti-EpCAM monoclonal antibody, to generate the antibody-drug conjugate α-amanitin-glutarate-chiHEA125 (chiHEA125-Ama). Antiproliferative activity of chiHEA125-Ama was tested in human pancreatic (BxPc-3 and Capan-1), colorectal (Colo205), breast (MCF-7), and bile duct (OZ) cancer cell lines in vitro using [(3)H]-thymidine incorporation assay. Antitumor activity of chiHEA125-Ama was assessed in vivo in immunocompromised mice bearing subcutaneous human BxPc-3 pancreatic carcinoma xenograft tumors (n = 66 mice). Cell proliferation and apoptosis were evaluated in xenograft tumors by immunohistochemistry. All statistical tests were two-sided. RESULTS In all cell lines, chiHEA125-Ama reduced cell proliferation (mean half maximal inhibitory concentration [IC(50)] = 2.5 × 10(-10) to 5.4 × 10(-12) M). A single dose of chiHEA125-Ama inhibited BxPc-3 xenograft tumor growth (chiHEA125 [control, n = 4 mice] vs. chiHEA125-Ama [n = 6 mice], dose of 15 mg/kg with respect to IgG and 50 μg/kg with respect to α-amanitin, mean relative increase in tumor volume on day 16 = 884% vs. -79%, difference = 963%, 95% CI = 582% to 1344%, P = .019). Two higher doses of chiHEA125-Ama (100 μg/kg with respect to α-amanitin), administered 1 week apart (n = 10 mice per group), led to complete tumor regression in nine of 10 (90%) mice compared with chiHEA125, during the observation period of 16 days; increased apoptosis and reduced cell proliferation were observed in mice treated with chiHEA125-Ama. CONCLUSION This preclinical study suggests that anti-EpCAM antibody conjugates with α-amanitin have the potential to be highly effective therapeutic agents for pancreatic carcinomas and various EpCAM-expressing malignancies.
Collapse
Affiliation(s)
- Gerhard Moldenhauer
- Department of Translational Immunology (D015), German Cancer Research Center, Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
| | | | | | | | | | | |
Collapse
|
6
|
Maurer HH, Schmitt CJ, Weber AA, Kraemer T. Validated electrospray liquid chromatographic-mass spectrometric assay for the determination of the mushroom toxins alpha- and beta-amanitin in urine after immunoaffinity extraction. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2000; 748:125-35. [PMID: 11092592 DOI: 10.1016/s0378-4347(00)00270-x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Specific detection of amanitins in body fluids is necessary for an early diagnosis of an intoxication with amanita mushrooms. In this paper, a liquid chromatographic-mass spectrometric assay after immunoaffinity extraction (IAE-LC-MS) is described for the determination of alpha- and beta-amanitin in urine. The method has been validated according to the criteria established by the Journal of Chromatography B. The assay was found to be selective. The calibration curves for alpha- and beta-amanitin were linear from 5 to 75 ng/ml. Intra- and inter-day accuracy and precision were inside the required limits. Amatoxins in frozen urine samples or immunoaffinity extracts were stable for more than 6 months, and the IAE columns could be used more than fifty times without remarkable loss in performance. LOD for alpha- and beta-amanitin was 2.5 ng/ml and LOQ for both was 5.0 ng/ml. The absolute recoveries of alpha- and beta-amanitin were 63% and 58% for the low quality control and 61% and 57% for the high quality control. The absolute recovery for the internal standard gamma-amanitin methyl ether at 25 ng/ml was 60%. The analysis of 5 authentic urine samples from patients intoxicated by amanita mushrooms showed a good correlation between the results measured by radioimmunoassay and the IAE-LC-MS assay. A partial validation showed that the assay was also suitable for plasma analysis.
Collapse
Affiliation(s)
- H H Maurer
- Department of Toxicology, Institute of Pharmacology and Toxicology, University of Saarland, Homburg (Saar), Germany.
| | | | | | | |
Collapse
|
7
|
Baumann K, Zanotti G, Faulstich H. A beta-turn in alpha-amanitin is the most important structural feature for binding to RNA polymerase II and three monoclonal antibodies. Protein Sci 1994; 3:750-6. [PMID: 8061605 PMCID: PMC2142721 DOI: 10.1002/pro.5560030504] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Four amatoxin-binding proteins with KD values in the nanomolar range, 3 monoclonal antibodies and RNA polymerase II, were studied with respect to their affinities to 24 alpha-amanitin derivatives with modified side chains. From KD values we estimated the amounts of binding energy that single side chains of the amatoxins contribute to complex formation. Ile6, previously identified by X-ray analysis to be part of a beta-turn (Kostansek EC, Lipscomb WN, Yocum RR, Thiessen WE, 1978, Biochemistry 17:3790-3795) proved to be of outstanding importance in all complexes. Replacement of the isoleucine with alanine reduced the affinity to all binding proteins to < 1%, suggesting a strong hydrophobic interaction. A strong effect was also seen when Gly5 was replaced with alanine, suggesting that the absence of a side chain in proximity to the beta-turn is likewise important. In addition to the beta-turn, each of the proteins showed at least 2 other points of strong contact formed by hydrogen bonds. Donors are the indole NH of 6'-hydroxy-Trp4 and OH of hydroxy-Pro2 and dihydroxy-Ile3. All the antibodies, but not RNA polymerase II, recognized the indole nucleus of 6'-hydroxy-Trp4. The geometric arrangement of the 4 strongest contact points suggests that the amatoxin binding site is different in each of the 4 proteins, except for the 2 antibodies raised in the same animal. Here, most of the contact points were identical but differed in strength of interaction. The method of structural analysis presented in this study is useful for identifying contact sites in complexes of proteins with peptides of rigid conformation. Furthermore, the method complements X-ray data by providing information on the amount of binding energy contributed by single structural elements.
Collapse
Affiliation(s)
- K Baumann
- Max-Planck-Institut für medizinische Forschung, Heidelberg, Germany
| | | | | |
Collapse
|
8
|
|
9
|
Akhlynina TV, Rosenkranz AA, Jans DA, Gulak PV, Serebryakova NV, Sobolev AS. The use of internalizable derivatives of chlorin E6 for increasing its photosensitizing activity. Photochem Photobiol 1993; 58:45-8. [PMID: 8378431 DOI: 10.1111/j.1751-1097.1993.tb04901.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Experiments with human hepatoma PLC/PRF/5 cells and human embryo skin fibroblasts involving the use of three different tests (colony formation, Trypan blue exclusion, labeled thymidine incorporation) have demonstrated a significantly higher photosensitizing activity of chlorin e6 conjugates with internalizable ligands as compared to that of chlorin e6 itself. Receptor-mediated internalization of chlorin e6 conjugates ensures a greater photosensitization of cells than binding of those conjugates to cell surface receptors. The suitability of such conjugates that permit the delivery of a photosensitizer to sensitive intracellular targets is discussed.
Collapse
Affiliation(s)
- T V Akhlynina
- Russian Research Center of Molecular Diagnostics and Therapy, Moscow
| | | | | | | | | | | |
Collapse
|
10
|
Baumann K, Münter K, Faulstich H. Identification of structural features involved in binding of alpha-amanitin to a monoclonal antibody. Biochemistry 1993; 32:4043-50. [PMID: 8471612 DOI: 10.1021/bi00066a027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Twenty-four derivatives of the cyclic octapeptide alpha-amanitin were assayed for their affinities to the monoclonal antibody beta A1/1. The derivatives were of natural, semisynthetic, and synthetic origin and had KD values ranging from 2 nM to > 70 microM. In the majority of the derivatives the chemical modifications had no detectable influence on the overall shape of the double-ring peptide. Given this condition, binding factors could be calculated from KD values of the amatoxin derivatives, which were valid for all amatoxins for estimating the contribution made by single structures to complex formation. The complex between alpha-amanitin and the immunoglobulin involves at least eight sites of contact. Four of them are responsible for strong interactions: (1) the OH group of hydroxyproline2 (binding factor 413), (2) the lipophilic side chain of isoleucine6 (binding factor 131), (3) the -CH2- moiety of the adjacent glycine5 or the absence of a side chain in this position (binding factor 361), and (4) the proton at the indole nitrogen of hydroxytryptophan4 (binding factor 140). The residual four interactions are hydrogen bonds of lower strength corresponding to binding factors of 1.5-8. The key role of the unique conformation of the amatoxins in determining their binding properties was shown by two amatoxin derivatives in which changes in the conformation were associated with virtually complete loss of affinity. For all amatoxin derivatives with conformations similar or identical to that of alpha-amanitin, we found empirical evidence that those structures of the peptide involved in binding make their contributions virtually independent of each other. It is a consequence of this rule that structural features that cooperate in binding could be characterized by the numerical product of their binding factors.
Collapse
Affiliation(s)
- K Baumann
- Max-Planck-Institut für medizinische Forschung, Heidelberg, Germany
| | | | | |
Collapse
|
11
|
Abstract
Pharmacokinetic studies have provided new insights into human Amanita poisoning, but it appears to be impossible to treat this intoxication by immunotherapy. New synthetic analogs have revealed structure-activity relationships that were unknown so far. The main toxin, alpha-amanitin, is in constant use as a tool in molecular biology and in biological research. First experiments have been reported in which amanitin bound to polymers could be internalized into tumor cells via a receptor-mediated endocytosis.
Collapse
Affiliation(s)
- T Wieland
- Max-Planck-Institut für Medizinische Forschung, Heidelberg, Germany
| | | |
Collapse
|
12
|
Mullersman JE, Preston JF. Amatoxins bearing amino and carboxyl groups prepared by selective alteration of the aldehyde generated by periodate oxidation of methylated alpha-amanitin. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1991; 37:544-51. [PMID: 1655668 DOI: 10.1111/j.1399-3011.1991.tb00773.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Amatoxins are cyclic peptides which can be purified from the carpophores of various mushroom species. Since they were first recognized as potent inhibitors of the nuclear RNA polymerases of most eukaryotes these peptides have served as important tools in the study of transcription. The presence of unusual amino acid residues in these peptides has provided opportunities to attempt a variety of semisynthetic modifications. We describe several new amatoxin derivatives that were prepared by selective modification of an aldehyde group which can be generated by periodate oxidation of 6'-O-methyl-alpha-amanitin. The derivatives which resulted from sodium cyanoborohydride-mediated coupling to the toxin of ammonia, glycine, and L-proline exhibited Ki values for calf thymus RNA polymerase II of 1.7 x 10(-7) M, 2.5 x 10(-7) M and 7.0 x 10(-6) M, respectively. Treatment of the aldehyde with sodium chlorite or hydroxylamine-O-sulfonic acid converted the amanitin aldehyde to the corresponding carboxyl or nitrile compounds with Ki values of 1.0 x 10(-7) M and 3.0 x 10(-9) M, respectively. Difficulties which were encountered in the preparation of these derivatives are discussed relative to peculiarities in the chemical behavior of the amanitin aldehyde.
Collapse
Affiliation(s)
- J E Mullersman
- Department of Microbiology and Cell Science, University of Florida, Gainesville
| | | |
Collapse
|
13
|
Akhlynina TV, Gulak PV, Serebryakova NV, Rozenkrants AA, Sobolev AS. Photodynamic action of concanavalin A-chlorin conjugate e6 on human fibroblasts. Bull Exp Biol Med 1990. [DOI: 10.1007/bf00841665] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
14
|
Faulstich H, Kirchner K, Derenzini M. Strongly enhanced toxicity of the mushroom toxin alpha-amanitin by an amatoxin-specific Fab or monoclonal antibody. Toxicon 1988; 26:491-9. [PMID: 3188055 DOI: 10.1016/0041-0101(88)90188-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A monoclonal antibody, with high affinity against the mushroom toxin alpha-amanitin, was prepared. Administration of the Fab fragment of the monoclonal antibody to mice caused a 50-fold increase in alpha-amanitin toxicity. Electron micrographs showed normal appearance of hepatocytes but typical, amanitin-induced lesions in cells of the proximal convoluted tubules of the kidney. The pronounced nephrotoxicity is mainly explained by glomerular filtration and tubular reabsorption of the Fab-amatoxin complex and, to a lesser extent, of the immunoglobulin-amatoxin complex, which is still c. Twice as toxic as free alpha-amanitin. To our knowledge this is the first reported case where immunoglobulins or their fragments enhance rather than decrease the activity of a toxin. Accordingly, immunotherapy of Amanita mushroom poisoning in humans does not appear promising.
Collapse
Affiliation(s)
- H Faulstich
- Max-Planck-Institut für Medizinische Forschung, Heidelberg, F.R.G
| | | | | |
Collapse
|
15
|
Andres RY, Frei W. [125I]amatoxin and anti-amatoxin for radioimmunoassay prepared by a novel approach: chemical and structural considerations. Toxicon 1987; 25:915-22. [PMID: 3433302 DOI: 10.1016/0041-0101(87)90153-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A novel approach for the production of [125I]amatoxin and anti-amanitin is described. The antigen and the starting material for Bolton Hunter iodination is prepared by periodic acid oxidation of the gamma-delta-dihydroxy-isoleucine side chain of alpha-amanitin followed by reductive amination. The antigen seems to be of low apparent toxicity. Chemical, spectroscopic and immunological evidence suggests that the hapten has a secondary structure similar to alpha-amanitin, but a modified tryptophanyl ring system. The establishment of a clinically useful iodinated radioimmunoassay system is possible, because the ring system seems to be of limited immunological importance.
Collapse
Affiliation(s)
- R Y Andres
- Swiss Federal Institute for Reactor Research, Wuerenlingen
| | | |
Collapse
|
16
|
Fiume L, Bassi B, Busi C, Mattioli A, Spinosa G. Drug targeting in antiviral chemotherapy. A chemically stable conjugate of 9-beta-D-arabinofuranosyl-adenine 5'-monophosphate with lactosaminated albumin accomplishes a selective delivery of the drug to liver cells. Biochem Pharmacol 1986; 35:967-72. [PMID: 2420334 DOI: 10.1016/0006-2952(86)90084-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
With the aim of improving the chemotherapeutic index of 9-beta-D-arabinofuranosyl-adenine 5' monophosphate (ara-AMP) in the treatment of chronic hepatitis B, this drug was conjugated with lactosaminated serum albumin (L-SA), a neoglycoprotein which only enters into hepatocytes. We used a L-SA-ara-AMP conjugate which, in contrast to those previously employed, has the advantage of remaining soluble after lyophilization. We found in mice that: (I) this new conjugate was quite stable in the bloodstream where only a small part of ara-AMP was released; (II) after administration of the conjugate labelled in the drug moiety both acid insoluble and soluble radioactivities were several times higher in liver than in other organs; (III) in mice with Ectromelia virus hepatitis, the conjugate inhibited virus DNA synthesis in liver without affecting cellular DNA synthesis in intestine and bone marrow; (IV) the conjugate did not display any recognizable sign of acute toxicity even at doses several fold higher than those pharmacologically active; and (V) when prepared with homologous albumin it was not immunogenic.
Collapse
|