Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

L-Asparaginase (l-ASP), a bacterial enzyme used since the 1970s to treat acute lymphoblastic leukemia, selectively starves cells that cannot synthesize sufficient asparagine for their own needs. Molecular profiling of the NCI-60 cancer cell lines using five different microarray platforms showed strong negative correlations of asparagine synthetase (ASNS) expression and DNA copy number with sensitivity to l-ASP in the leukemia and ovarian cancer cell subsets. To assess whether the ovarian relationship is causal, we used RNA interference to silence ASNS in three ovarian lines and observed 4- to 5-fold potentiation of sensitivity to l-ASP with two of the lines. For OVCAR-8, the line that expresses the least ASNS, the potentiation was >500-fold. Significantly, that potentiation was >700-fold in the multidrug-resistant derivative OVCAR-8/ADR, showing that the causal relationship between ASNS expression and l-ASP activity survives development of classical multidrug resistance. Tissue microarrays confirmed low ASNS expression in a subset of clinical ovarian cancers as well as other tumor types. Overall, this pharmacogenomic/pharmacoproteomic study suggests the use of l-ASP for treatment of a subset of ovarian cancers (and perhaps other tumor types), with ASNS as a biomarker for patient selection.
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PMID:Asparagine synthetase as a causal, predictive biomarker for L-asparaginase activity in ovarian cancer cells. 1708 36

The L-asparaginases from Escherichia coli and Erwinia chrysanthemi are effective drugs that have been used in the treatment of acute childhood lymphoblastic leukaemia for over 30 years. However, despite their therapeutic potential, they can cause serious side effects as a consequence of their intrinsic glutaminase activity, which leads to L-glutamine depletion in the blood. Consequently, new asparaginases with low glutaminase activity, fewer side effects and high activity towards L-asparagine are highly desirable as better alternatives in cancer therapy. L-Asparaginase from Helicobacter pylori was overexpressed in E. coli and purified for structural studies. The enzyme was crystallized at pH 7.0 in the presence of 16-19%(w/v) PEG 4000 and 0.1 M magnesium formate. Data were collected to 1.6 A resolution at 100 K from a single crystal at a synchrotron-radiation source. The crystals belong to space group I222, with unit-cell parameters a = 63.6, b = 94.9, c = 100.2 A and one molecule of L-asparaginase in the asymmetric unit. Elucidation of the crystal structure will provide insight into the active site of the enzyme and a better understanding of the structure-activity relationship in L-asparaginases.
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PMID:Expression, purification and crystallization of Helicobacter pylori L-asparaginase. 1867 46

L-Asparaginase (L-ASP) is an enzyme drug that has been an asset to leukemia treatment regimens for four decades. Variability in its clinical efficacy, however, has prompted the search for biomarkers capable of distinguishing responders from non-responders. In that regard, the NCI-60 cell line panel has served as a biomarker discovery platform and has led to the identification of a correlation between L-ASP efficacy and asparagine synthetase (ASNS) expression in cultured cells. The presence of that correlation in the ovarian subpanel of the NCI-60 has made a case for repositioning L-ASP to ovarian cancer. This review presents an overview of the biomarker development process, summarizes the efforts that have been invested thus far in developing ASNS as a biomarker for ovarian cancer treatment, highlights the role of RNAi and the limitations of the NCI-60 in that process, and addresses important considerations for next steps in the development of ASNS as a predictive biomarker.
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PMID:Asparagine synthetase: a new potential biomarker in ovarian cancer. 1920

The incidence of pancreatitis in patients with haematopoetic neoplasms who are treated with L-asparaginase is fom 2 to 24%. In majority of cases the pancreatitis is oedematous and self-limiting. Acute haemorrhagic or necrotizing pancreatitis caused by L-asparaginase is rare but potentially life-threatening complication. We present 2 cases of acute pancreatitis in children aged 2 and 4 years. They were diagnosed to have acute lymphoblastic leukaemia and were treated according to the ALLLIC BFM 2002 protocol. Acute pancreatitis developed in these children after induction therapy and was followed by formation of a pseudocyst. In both cases the diagnosis of this complication was made directly after phase I of the protocol I (after eighth dose of L-Asparaginase). In the first case the course of acute pancreatitis was mild. Normalization of the amylase levels occurred after 7 days and the diagnosis of post inflammatory cyst was made 15 days after the first signs of the disease. But thereafter, during the additional complication (pneumonia with Pseudomonas aeruginosa bacteriemia) the pancreatic cyst became infected. In the second case acute pancreatitis had a severe course and the child required treatment in the Intensive Care Unit for 21 days. The cyst was diagnosed after 20 days from the beginning of symptoms. The surgical procedure, applied in both cases was internal drainage by anastomosis of the cyst with the back wall of the stomach. Antileukaemic treatment was recommenced after 6-8 weeks when complications resolved. Currently both children are well and remain in haematological remission and continue maintenance chemotherapy.
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PMID:[Acute pancreatitis during chemotherapy of acute lymphoblastic leukaemia complicated with pseudocyst]. 1953 25

A 30-year-old manufacturing process for the biologic product L-asparaginase from the plant pathogen Erwinia chrysanthemi was rigorously qualified and validated, with a high level of agreement between validation data and the 6-year process database. L-Asparaginase exists in its native state as a tetrameric protein and is used as a chemotherapeutic agent in the treatment regimen for Acute Lymphoblastic Leukaemia (ALL). The manufacturing process involves fermentation of the production organism, extraction and purification of the L-asparaginase to make drug substance (DS), and finally formulation and lyophilisation to generate drug product (DP). The extensive manufacturing experience with the product was used to establish ranges for all process parameters and product quality attributes. The product and in-process intermediates were rigorously characterised, and new assays, such as size-exclusion and reversed-phase UPLC, were developed, validated, and used to analyse several pre-validation batches. Finally, three prospective process validation batches were manufactured and product quality data generated using both the existing and the new analytical methods. These data demonstrated the process to be robust, highly reproducible and consistent, and the validation was successful, contributing to the granting of an FDA product license in November, 2011.
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PMID:Validation of a 30-year-old process for the manufacture of L-asparaginase from Erwinia chrysanthemi. 2290 65

L-Asparaginase (ASNase) is important for the treatment of childhood acute lymphoblastic leukemia. ASNase sensitivity has been shown to correlate with the asparagine synthetase (ASNS) protein content in acute lymphoblastic leukemia cell lines. However, there have been few studies to determine ASNS protein levels in human leukemias, since no appropriate monoclonal antibody is available for such quantitative analysis. In this study, we report the generation of anti-ASNS monoclonal antibodies, which are applicable to flow cytometry and enzyme-linked immunosorbent assay. These monoclonal antibodies should provide a valuable tool for the quantification of ASNS protein level and estimation of ASNase-resistance in leukemia cells.
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PMID:Evaluation of the asparagine synthetase level in leukemia cells by monoclonal antibodies. 2309 98

L-Asparaginase-II from Escherichia coli (EcA) is a central component in the treatment of acute lymphoblastic leukemia (ALL). However, the therapeutic efficacy of EcA is limited due to immunogenicity and a short half-life in the patient. Here, we performed rational mutagenesis to obtain EcA variants with a potential to improve ALL treatment. Several variants, especially W66Y and Y176F, killed the ALL cells more efficiently than did wild-type EcA (WT-EcA), although nonleukemic peripheral blood monocytes were not affected. Several assays, including Western blotting, annexin-V/propidium iodide binding, comet, and micronuclei assays, showed that the reduction in viability of leukemic cells is due to the increase in caspase-3, cytochrome c release, poly(ADP-ribose) polymerase activation, down-regulation of anti-apoptotic protein Bcl-XL, an arrest of the cell cycle at the G0/G1 phase, and eventually apoptosis. Both W66Y and Y176F induced significantly more apoptosis in lymphocytes derived from ALL patients. In addition, Y176F and Y176S exhibited greatly decreased glutaminase activity, whereas K288S/Y176F, a variant mutated in one of the immunodominant epitopes, showed reduced antigenicity. Further in vivo immunogenicity studies in mice showed that K288S/Y176F was 10-fold less immunogenic as compared with WT-EcA. Moreover, sera obtained from WT-EcA immunized mice and ALL patients who were given asparaginase therapy for several weeks recognized the K288S/Y176F mutant significantly less than the WT-EcA. Further mechanistic studies revealed that W66Y, Y176F, and K288S/Y176F rapidly depleted asparagine and also down-regulated the transcription of asparagine synthetase as compared with WT-EcA. These highly desirable attributes of these variants could significantly advance asparaginase therapy of leukemia in the future.
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PMID:Mutations in subunit interface and B-cell epitopes improve antileukemic activities of Escherichia coli asparaginase-II: evaluation of immunogenicity in mice. 2429 77

L-Asparaginase (EC3.5.1.1) is an enzyme, which is used for treatment of acute lymphoblastic leukaemia (ALL) and other related blood cancers from a long time. This enzyme selectively hydrolyzes the extracellular amino acid L-asparagine into L-aspartate and ammonia, leading to nutritional deficiencies, protein synthesis inhibition, and ultimately death of lymphoblastic cells by apoptosis. Currently, bacterial asparaginases are used for treatment purpose but offers scepticism due to a number of toxicities, including thrombosis, pancreatitis, hyperglycemia, and hepatotoxicity. Resistance towards bacterial asparaginase is another major disadvantage during cancer management. This situation attracted attention of researchers towards alternative sources of L-asparaginase, including plants and fungi. Present article discusses about potential of L-asparaginase as an anticancer agent, its mechanism of action, and adverse effects related to current asparaginase formulations. This article also provides an outlook for recent developments in L-asparaginase discovery from alternative sources and their potential as a less toxic alternative to current formulations.
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PMID:Recent developments in L-asparaginase discovery and its potential as anticancer agent. 2563 Jun 63

Protein therapeutics, particularly of heterologous origin are shown to elicit immunogenic responses which result in adverse allergic reactions in spite of their promising clinical benefit. L-Asparaginase is one such well known chemotherapeutic agent that has enhanced the survival rates to 90 % in the treatment of acute lymphoblastic leukaemia for past 30 years. But the use of this enzyme is accompanied by hypersensitive reactions ranging from allergy to anaphylactic shock which have a drastic influence in treatment outcomes. Numerous attempts have been made to minimize the problems of immunogenicity, which remained as a major bottleneck in the treatment protocols. Conjugating the enzyme L- Asparaginase with PEG was successful as it has reduced the complications in therapy and frequency of injections (dosages), and thus became prominent in reducing the immunogenicity up to a certain extent. Keeping the bottlenecks in consideration during the development of therapeutics, the present study concentrates on engineering of protein as an alternative to the PEGylated enzyme, having reduced immunogenicity as an inbuilt character of protein by using in silico approaches. L-Asparaginase from Escherichia coli and Pectobacterium carotovorum were selected for the present study. The methodology consists of (i) locating the B and CD4+ T cell epitopes of enzyme by in silico tools (ii) generating point mutations of these epitopes to alter or reduce the immunogenicity of protein (iii) generating enzyme models by molecular modelling (iv) assessing the binding affinity of the substrate with L-Asparaginase variants by in silico docking methods using Autodock 4.2 and (v) validating the mutated model for stability by molecular dynamics simulation studies using Gromacs.
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PMID:Studies on Deimmunization of Antileukaemic L-Asparaginase to have Reduced Clinical Immunogenicity--An in silico Approach. 2574 72

L-Asparaginase (ASNase) is a front-line chemotherapy for acute lymphoblastic leukemia (ALL), which acts by deaminating asparagine and glutamine. To evaluate the importance of glutaminase activity, we exploited a recently developed mutant of Helicobacter pylori ASNase (dm HpA), with amino acid substitutions M121C/T169M. The mutant form has the same asparaginase activity as wild-type but lacks glutaminase activity. Wild-type and dm HpA were compared with the clinically used ASNases from Escherichia coli (l-ASP) and Erwinia chrysanthemi (ERWase). Asparaginase activity was similar for all isoforms, while glutaminase activity followed the rank order: ERWase>l-ASP>wild-type HpA>dm HpA. Cytotoxic efficacy of ASNases was tested on 11 human leukemia cell lines and two patient-derived ALL samples. Two cell lines which we had previously shown to be asparagine-dependent were equally sensitive to the asparaginase isoforms. The other nine lines and the two patient-derived samples were more sensitive to isoforms with higher glutaminase activities. ERWase was overall the most effective ASNase on all cell lines tested whereas dm HpA, having the lowest glutaminase activity, was the least effective. These data demonstrate that asparaginase activity alone may not be sufficient for ASNase cytotoxicity, and that glutaminase activity may be required for full anti-leukemic efficacy.
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PMID:Glutaminase activity determines cytotoxicity of L-asparaginases on most leukemia cell lines. 2594 Oct 2


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