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1.
J Clin Oncol ; : JCO2302175, 2024 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-38723212

RESUMO

PURPOSE: Allogeneic hematopoietic stem-cell transplantation (HSCT) is the only potentially curative treatment for patients with myelodysplastic syndromes (MDS). Several issues must be considered when evaluating the benefits and risks of HSCT for patients with MDS, with the timing of transplantation being a crucial question. Here, we aimed to develop and validate a decision support system to define the optimal timing of HSCT for patients with MDS on the basis of clinical and genomic information as provided by the Molecular International Prognostic Scoring System (IPSS-M). PATIENTS AND METHODS: We studied a retrospective population of 7,118 patients, stratified into training and validation cohorts. A decision strategy was built to estimate the average survival over an 8-year time horizon (restricted mean survival time [RMST]) for each combination of clinical and genomic covariates and to determine the optimal transplantation policy by comparing different strategies. RESULTS: Under an IPSS-M based policy, patients with either low and moderate-low risk benefited from a delayed transplantation policy, whereas in those belonging to moderately high-, high- and very high-risk categories, immediate transplantation was associated with a prolonged life expectancy (RMST). Modeling decision analysis on IPSS-M versus conventional Revised IPSS (IPSS-R) changed the transplantation policy in a significant proportion of patients (15% of patient candidate to be immediately transplanted under an IPSS-R-based policy would benefit from a delayed strategy by IPSS-M, whereas 19% of candidates to delayed transplantation by IPSS-R would benefit from immediate HSCT by IPSS-M), resulting in a significant gain-in-life expectancy under an IPSS-M-based policy (P = .001). CONCLUSION: These results provide evidence for the clinical relevance of including genomic features into the transplantation decision making process, allowing personalizing the hazards and effectiveness of HSCT in patients with MDS.

3.
JCO Clin Cancer Inform ; 7: e2300021, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37390377

RESUMO

PURPOSE: Synthetic data are artificial data generated without including any real patient information by an algorithm trained to learn the characteristics of a real source data set and became widely used to accelerate research in life sciences. We aimed to (1) apply generative artificial intelligence to build synthetic data in different hematologic neoplasms; (2) develop a synthetic validation framework to assess data fidelity and privacy preservability; and (3) test the capability of synthetic data to accelerate clinical/translational research in hematology. METHODS: A conditional generative adversarial network architecture was implemented to generate synthetic data. Use cases were myelodysplastic syndromes (MDS) and AML: 7,133 patients were included. A fully explainable validation framework was created to assess fidelity and privacy preservability of synthetic data. RESULTS: We generated MDS/AML synthetic cohorts (including information on clinical features, genomics, treatment, and outcomes) with high fidelity and privacy performances. This technology allowed resolution of lack/incomplete information and data augmentation. We then assessed the potential value of synthetic data on accelerating research in hematology. Starting from 944 patients with MDS available since 2014, we generated a 300% augmented synthetic cohort and anticipated the development of molecular classification and molecular scoring system obtained many years later from 2,043 to 2,957 real patients, respectively. Moreover, starting from 187 MDS treated with luspatercept into a clinical trial, we generated a synthetic cohort that recapitulated all the clinical end points of the study. Finally, we developed a website to enable clinicians generating high-quality synthetic data from an existing biobank of real patients. CONCLUSION: Synthetic data mimic real clinical-genomic features and outcomes, and anonymize patient information. The implementation of this technology allows to increase the scientific use and value of real data, thus accelerating precision medicine in hematology and the conduction of clinical trials.


Assuntos
Hematologia , Leucemia Mieloide Aguda , Humanos , Medicina de Precisão , Inteligência Artificial , Algoritmos
4.
J Clin Oncol ; 41(15): 2827-2842, 2023 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-36930857

RESUMO

PURPOSE: Myelodysplastic syndromes (MDS) are heterogeneous myeloid neoplasms in which a risk-adapted treatment strategy is needed. Recently, a new clinical-molecular prognostic model, the Molecular International Prognostic Scoring System (IPSS-M) was proposed to improve the prediction of clinical outcome of the currently available tool (Revised International Prognostic Scoring System [IPSS-R]). We aimed to provide an extensive validation of IPSS-M. METHODS: A total of 2,876 patients with primary MDS from the GenoMed4All consortium were retrospectively analyzed. RESULTS: IPSS-M improved prognostic discrimination across all clinical end points with respect to IPSS-R (concordance was 0.81 v 0.74 for overall survival and 0.89 v 0.76 for leukemia-free survival, respectively). This was true even in those patients without detectable gene mutations. Compared with the IPSS-R based stratification, the IPSS-M risk group changed in 46% of patients (23.6% and 22.4% of subjects were upstaged and downstaged, respectively).In patients treated with hematopoietic stem cell transplantation (HSCT), IPSS-M significantly improved the prediction of the risk of disease relapse and the probability of post-transplantation survival versus IPSS-R (concordance was 0.76 v 0.60 for overall survival and 0.89 v 0.70 for probability of relapse, respectively). In high-risk patients treated with hypomethylating agents (HMA), IPSS-M failed to stratify individual probability of response; response duration and probability of survival were inversely related to IPSS-M risk.Finally, we tested the accuracy in predicting IPSS-M when molecular information was missed and we defined a minimum set of 15 relevant genes associated with high performance of the score. CONCLUSION: IPSS-M improves MDS prognostication and might result in a more effective selection of candidates to HSCT. Additional factors other than gene mutations can be involved in determining HMA sensitivity. The definition of a minimum set of relevant genes may facilitate the clinical implementation of the score.


Assuntos
Síndromes Mielodisplásicas , Recidiva Local de Neoplasia , Humanos , Prognóstico , Estudos Retrospectivos , Síndromes Mielodisplásicas/diagnóstico , Síndromes Mielodisplásicas/genética , Síndromes Mielodisplásicas/terapia , Fatores de Risco
5.
J Clin Med ; 11(9)2022 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-35566719

RESUMO

Aims: To define the peculiar features of patients with the deletion of the chromosome 20 long arm (del20q), data from 69 patients with myelodysplastic syndromes (MDSs) and isolated del20q, followed by the Gruppo Romano-Laziale Sindromi Mielodisplastiche (GROM-L) and Ospedale Torrette of Ancona, were collected and compared with those of 502 MDS patients with normal karyotype (NK-MDS). Results: Compared to the NK-MDS group, patients with del20q at diagnosis were older (p = 0.020) and mainly male (p = 0.006). They also had a higher rate of bone marrow blast < 5% (p = 0.004), a higher proportion of low and int-1 risk according to IPSS score (p = 0.023), and lower median platelet (PLT) count (p < 0.001). To date, in the del20q cohort, 21 patients (30.4%) received no treatment, 42 (61.0%) were treated with erythropoiesis-stimulating agents (ESA), 3 (4.3%) with hypomethylating agents, and 3 (4.3%) with other treatments. Among 34 patients evaluable for response to ESA, 21 (61.7%) achieved stable erythroid response according to IWG 2006 criteria and 13 (38.2%) were resistant. Nine patients (13.0%) progressed to acute myeloid leukaemia (AML) after a median time from diagnosis of 28 months (IR 4.1−51.7). The median overall survival (OS) of the entire cohort was 60.6 months (95% CI 54.7−66.4). the 5-year cumulative OS was 55.9% (95% CI 40.6−71.2). Conclusion: According to our results, we hypothesize that MDSs with isolated del 20q may represent a distinct biological entity, with peculiar clinical and prognostic features. The physio-pathological mechanisms underlying the deletion of the chromosome 20 long arm are still unclear and warrant future molecular analysis.

6.
Blood ; 138(21): 2093-2105, 2021 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-34125889

RESUMO

Clonal hematopoiesis of indeterminate potential (CHIP) is associated with increased risk of cancers and inflammation-related diseases. This phenomenon becomes common in persons aged ≥80 years, in whom the implications of CHIP are not well defined. We performed a mutational screening in 1794 persons aged ≥80 years and investigated the relationships between CHIP and associated pathologies. Mutations were observed in one-third of persons aged ≥80 years and were associated with reduced survival. Mutations in JAK2 and splicing genes, multiple mutations (DNMT3A, TET2, and ASXL1 with additional genetic lesions), and variant allele frequency ≥0.096 had positive predictive value for myeloid neoplasms. Combining mutation profiles with abnormalities in red blood cell indices improved the ability of myeloid neoplasm prediction. On this basis, we defined a predictive model that identifies 3 risk groups with different probabilities of developing myeloid neoplasms. Mutations in DNMT3A, TET2, ASXL1, or JAK2 were associated with coronary heart disease and rheumatoid arthritis. Cytopenia was common in persons aged ≥80 years, with the underlying cause remaining unexplained in 30% of cases. Among individuals with unexplained cytopenia, the presence of highly specific mutation patterns was associated with myelodysplastic-like phenotype and a probability of survival comparable to that of myeloid neoplasms. Accordingly, 7.5% of subjects aged ≥80 years with cytopenia had presumptive evidence of myeloid neoplasm. In summary, specific mutational patterns define different risk of developing myeloid neoplasms vs inflammatory-associated diseases in persons aged ≥80 years. In individuals with unexplained cytopenia, mutational status may identify those subjects with presumptive evidence of myeloid neoplasms.


Assuntos
Hematopoiese Clonal , Mutação , Fatores Etários , Idoso de 80 Anos ou mais , Artrite Reumatoide/etiologia , Artrite Reumatoide/genética , Doença das Coronárias/etiologia , Doença das Coronárias/genética , Feminino , Humanos , Leucemia Mieloide/etiologia , Leucemia Mieloide/genética , Masculino , Síndromes Mielodisplásicas/etiologia , Síndromes Mielodisplásicas/genética
7.
J Clin Oncol ; 39(11): 1223-1233, 2021 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-33539200

RESUMO

PURPOSE: Recurrently mutated genes and chromosomal abnormalities have been identified in myelodysplastic syndromes (MDS). We aim to integrate these genomic features into disease classification and prognostication. METHODS: We retrospectively enrolled 2,043 patients. Using Bayesian networks and Dirichlet processes, we combined mutations in 47 genes with cytogenetic abnormalities to identify genetic associations and subgroups. Random-effects Cox proportional hazards multistate modeling was used for developing prognostic models. An independent validation on 318 cases was performed. RESULTS: We identify eight MDS groups (clusters) according to specific genomic features. In five groups, dominant genomic features include splicing gene mutations (SF3B1, SRSF2, and U2AF1) that occur early in disease history, determine specific phenotypes, and drive disease evolution. These groups display different prognosis (groups with SF3B1 mutations being associated with better survival). Specific co-mutation patterns account for clinical heterogeneity within SF3B1- and SRSF2-related MDS. MDS with complex karyotype and/or TP53 gene abnormalities and MDS with acute leukemia-like mutations show poorest prognosis. MDS with 5q deletion are clustered into two distinct groups according to the number of mutated genes and/or presence of TP53 mutations. By integrating 63 clinical and genomic variables, we define a novel prognostic model that generates personally tailored predictions of survival. The predicted and observed outcomes correlate well in internal cross-validation and in an independent external cohort. This model substantially improves predictive accuracy of currently available prognostic tools. We have created a Web portal that allows outcome predictions to be generated for user-defined constellations of genomic and clinical features. CONCLUSION: Genomic landscape in MDS reveals distinct subgroups associated with specific clinical features and discrete patterns of evolution, providing a proof of concept for next-generation disease classification and prognosis.


Assuntos
Genômica/métodos , Síndromes Mielodisplásicas/classificação , Feminino , Humanos , Masculino , Síndromes Mielodisplásicas/genética , Prognóstico , Estudos Retrospectivos
8.
Leuk Lymphoma ; 61(14): 3476-3483, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32870062

RESUMO

Prognostic role of chromosomal translocations (CT) in myelodysplasia (MDS) was retrospectively analyzed in 77 patients from GROM-L registry. Forty (51.9%) balanced, 28 (36.4%) unbalanced and 9 (11.7%) concomitant balanced and unbalanced CT were identified. Five-year overall survival (OS) of the entire cohort was 34.5% (CI 95% 22.5-46.5). Five-year OS of patients with unbalanced CT was significantly shorter than that of patients carrying balanced CT [22.3% (CI 95% 4.0-40.6) vs 44.0% (CI 95% 26.7-61.3) (p = 0.042)]. Five-year OS of patients with CT included in complex karyotype (CK) was significantly shorter than that of patients with isolated CT or CT with another abnormality [5.5% (CI 95% 0-15.7) vs 42.9% (CI 95% 21.3-64.5) and vs 4% (CI 95% 31.6-79.2) (p < 0.001)]. Presence of CT in MDS characterizes a more aggressive outcome only when associated with CK.


Assuntos
Síndromes Mielodisplásicas , Translocação Genética , Aberrações Cromossômicas , Humanos , Síndromes Mielodisplásicas/diagnóstico , Síndromes Mielodisplásicas/genética , Prognóstico , Estudos Retrospectivos
9.
Expert Opin Drug Saf ; 19(2): 187-204, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32005072

RESUMO

Introduction: A range of combination chemotherapy regimens are currently used in clinical practice. However, international antiemetic guidelines often only categorize the emetogenic potential of single agents rather than the emetogenicity of combination chemotherapy regimens. To manage the nausea and vomiting induced by antineoplastic combinations, guidelines suggest antiemetics that are appropriate for the component drug with the highest emetogenic potential. Furthermore, antiemetic guidelines generally do not consider the influence of other factors, including individual patient characteristics, on the emetic effects of cancer treatments. Similarly, the emetogenic potential of radiotherapy is stratified only according to the site of radiation, while other factors contributing to emetic risk are overlooked.Areas covered: An Expert Panel was convened to examine unresolved issues and summarize the current clinical research on managing nausea and vomiting associated with combination chemotherapy and radiotherapy.Expert opinion: The panel identified the incidence of nausea and vomiting induced by multi-drug combination therapies currently used to treat cancer at different anatomic sites and by radiotherapy in the presence of other risk factors. Based on these data and the clinical experience of panel members, several suggestions are made for a practical approach to prevent or manage nausea and vomiting due to chemotherapy regimens and radiation therapy.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Náusea/prevenção & controle , Radioterapia/efeitos adversos , Vômito/prevenção & controle , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Humanos , Incidência , Náusea/epidemiologia , Náusea/etiologia , Neoplasias/terapia , Guias de Prática Clínica como Assunto , Fatores de Risco , Vômito/epidemiologia , Vômito/etiologia
10.
Hematol Oncol ; 38(2): 189-196, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31891213

RESUMO

Pulmonary infections (PIs) are a major complication of patients with myelodysplastic syndromes (MDS). We retrospectively evaluated 234 MDS patients treated with azacytidine (AZA). The total number of AZA cycles was 2886 (median 8 cycles per patient). There were 111 episodes of PI (3.8% of AZA cycles) in 81 patients (34.6%). PIs were considered of fungal origin in 27 cases (24.3%), associated to bacteremia in 11 cases (9.9%), to influenza infection in two cases (1.8%) and of unknown origin in the remaining 71 cases (64.0%). Forty-five PI episodes were documented in cycles 1 to 4 of AZA (5.1% of 875 cycles) and the remaining 66 episodes beyond the fourth cycle (3.2% of 2011 cycles) (P = .017). Overall, a fungal PI was documented in 13/875 (1.5%) cycles 1 to 4 and in 13/2011 (0.6%) cycles beyond the fourth cycle (P = .001). A baseline chronic pulmonary disease was significantly associated to a higher risk of severe PIs. In the survival analysis, cases of PI in patients who progressed to acute leukemia (PAL) were excluded, in view of the predominant influence of PAL on the outcome of the patients. A PI unrelated to PAL documented during the first 4 AZA cycles was an independent factor predicting lower survival (OR, 2.13; 95% CI, 1.37-3.33; P = .001). In conclusion, PIs are common in MDS patients receiving AZA, in particular during the first cycles of treatment and are associated with an unfavorable outcome. The results of our study raise the issue of the need of a tailored infection prevention strategy.


Assuntos
Antimetabólitos Antineoplásicos/efeitos adversos , Azacitidina/efeitos adversos , Pulmão/microbiologia , Síndromes Mielodisplásicas/tratamento farmacológico , Infecções Respiratórias/etiologia , Idoso , Feminino , Seguimentos , Humanos , Pulmão/efeitos dos fármacos , Masculino , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/patologia , Prognóstico , Infecções Respiratórias/induzido quimicamente , Estudos Retrospectivos , Taxa de Sobrevida
12.
BMC Cancer ; 19(1): 50, 2019 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-30630459

RESUMO

BACKGROUND: Philadelphia (Ph) chromosome results from the reciprocal translocation t(9;22)(q34.1;q11.2) and is diagnostic for chronic myeloid leukemia (CML). However, this translocation is also found in acute lymphoid leukemia (ALL), as well as in rare cases of acute myeloid leukemias (AML). Most patients with CML harbor either the e13a2 or the e14a2 BCR-ABL fusion product, while a small subset of the cases expresses e1a2 or e19a2 transcripts. Moreover, several atypical BCR-ABL1 transcripts, beside the most common e1a2, e13a2 and e14a2, have been described, mainly in patients with CML. However, ALL and de novo AML may also carry BCR-ABL1 atypical transcripts which will confer a poor prognosis. CASE PRESENTATION: A 78-years old male was admitted at our hospital with clinical and laboratory features allowing to make the diagnosis of AML. No evidence of a preceding CML (splenomegaly or basophilia) was found. The karyotype on G-banded metaphases was 46,XY, t(9;22)(q34;q11). While the molecular analysis was ongoing, the patient started treatment based on hydroxyurea followed by 5-aza-2'-deoxycytidine. The molecular biology analysis revealed the simultaneous presence of the common p190 e1a2 and the rare e6a2 isoforms. Because of persistent pancytopenia and presence of blasts, according to the molecular data, he was then switched to tyrosine kinase inhibitors (TKIs) treatment. Nevertheless, after 2 months, the patient was still refractory to second line treatment dying because of a pulmonary infection. CONCLUSION: The atypical p190 e6a2 transcript seems to be associated in AML with aggressive disease. TKI therapy alone does not seem to control the disease. Prompt observations on these patients carrying rare BCR-ABL1 transcripts may help to establish optimal treatment approaches on these aggressive BCR-ABL1 phenotypes in different setting of patients.


Assuntos
Proteínas de Fusão bcr-abl/genética , Leucemia Mieloide Aguda/genética , Cromossomo Filadélfia , Adulto , Idoso , Medula Óssea/patologia , Feminino , Seguimentos , Humanos , Cariótipo , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/terapia , Masculino , Pessoa de Meia-Idade , Translocação Genética
13.
Leuk Res ; 76: 65-69, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30578958

RESUMO

Few data are available on the treatment with DFX in patients with transfusion dependent Ph- Myeloproliferative Neoplasms in fibrotic phase. Here we report 48MPNpatients and iron overload treated with DFX. Starting DFX dose was 20 mg/Kg in 23 patients, 15 mg/Kg in 20 patientsand 10 mg/Kg in 5 patients. After a median treatment of 27.6 months, 5 patients achieved ferritin<500 ng/ml, 11 < 1000 ng/ml and 3 a reduction >50% of basal ferritin with a global response rate of 41%. As to hematological improvement, 9/47 patients (19.1%) showed a persistent rise of Hb>1.5 g/dl, with disappearance of transfusion requirement in 6 cases. The median OS from DFX initiation in patients with chelation response was 61.0 months compared to 15.8 months in patients without chelation efficacy. Treatment with DFX is feasible and effective in MPN with iron overload and a hematological improvement can occur in a sizeable rate of patients.


Assuntos
Deferasirox/uso terapêutico , Quelantes de Ferro/uso terapêutico , Sobrecarga de Ferro/tratamento farmacológico , Sobrecarga de Ferro/etiologia , Transtornos Mieloproliferativos/complicações , Idoso , Biomarcadores , Deferasirox/administração & dosagem , Feminino , Ferritinas , Humanos , Ferro/metabolismo , Quelantes de Ferro/administração & dosagem , Sobrecarga de Ferro/metabolismo , Sobrecarga de Ferro/mortalidade , Masculino , Pessoa de Meia-Idade , Prognóstico , Resultado do Tratamento
14.
Arch Biochem Biophys ; 486(2): 103-10, 2009 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-19397888

RESUMO

Conjugated eicosapentaenoic acid (cEPA) has been found to have antitumor effects which has been ascribed to their ability to inhibit DNA topoisomerases and DNA polymerases. We here show that cEPA inhibits the catalytic activity of human topoisomerase I, but unlike camptothecin it does not stabilize the cleavable complex, indicating a different mechanism of action. cEPA inhibits topoisomerase by impeding the catalytic cleavage of the DNA substrate as demonstrated using specific oligonucleotide substrates, and prevents the stabilization of the cleavable complex by camptothecin. Preincubation of the inhibitor with the enzyme is required to obtain complete inhibition. Molecular docking simulations indicate that the preferred cEPA binding site is proximal to the active site with the carboxylic group strongly interacting with the positively charged K443 and K587. Taken together the results indicate that cEPA inhibitor does not prevent DNA binding but inhibits DNA cleavage, binding in a region close to the topoisomerase active site.


Assuntos
Camptotecina/farmacologia , Ácido Eicosapentaenoico/farmacologia , Inibidores da Topoisomerase , DNA/química , DNA/efeitos dos fármacos , DNA/genética , DNA Topoisomerases/química , DNA Topoisomerases/isolamento & purificação , Inibidores Enzimáticos/farmacologia , Humanos , Cinética , Modelos Moleculares , Conformação de Ácido Nucleico , Oligodesoxirribonucleotídeos/química , Oligodesoxirribonucleotídeos/metabolismo , Especificidade por Substrato
15.
Ital J Biochem ; 56(2): 110-4, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17722651

RESUMO

Eukaryotic topoisomerase I is an essential enzyme that regulates the changes in DNA topology, relaxing the superhelical tension associated with DNA replication, transcription and recombination. Human topoisomerase I is of significant medical interest being the only target of the antitumor drug camptothecin. The enzyme undergoes large conformational changes during its catalytic cycle and the knowedge of the degree of flexibility of the different regions provides an useful guide to the understanding of such movements. Molecular dynamics simulation is a well consolidated method for the investigation of structural and dynamic properties of proteins and nucleic acids and has been successfully applied to study the dynamical properties of the DNA-human topoisomerase complex. This review highlights some structural and dynamic properties of topoisomerase, obtained by MD simulations, that permits to explain the importance of flexibility in the modulation of the functional properties of the enzyme and in the transmission of communication between domains located far away one from each other.


Assuntos
Replicação do DNA/fisiologia , DNA Topoisomerases Tipo I/metabolismo , DNA Super-Helicoidal/metabolismo , Modelos Moleculares , Recombinação Genética/fisiologia , Transcrição Gênica/fisiologia , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Camptotecina/química , Camptotecina/farmacologia , Replicação do DNA/efeitos dos fármacos , DNA Topoisomerases Tipo I/química , DNA Super-Helicoidal/química , Humanos , Estrutura Terciária de Proteína , Recombinação Genética/efeitos dos fármacos , Relação Estrutura-Atividade , Inibidores da Topoisomerase I , Transcrição Gênica/efeitos dos fármacos
16.
FEBS J ; 273(16): 3650-62, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16911516

RESUMO

The NS2B-NS3 protease complex is essential for the replication of dengue virus, which is the etiologic agent of dengue and hemorrhagic fevers, diseases that are a burden for the tropical and subtropical areas of the world. The active form of the NS3 protease linked to the 40 residues of the NS2B cofactor shows highly flexible and disordered region(s) that are responsible for its high propensity to aggregate at the concentrations necessary for NMR spectroscopy studies or for crystallization. Limited proteolysis of this active form of the protease enabled us to obtain a folded and new essential form of the NS2B-NS3 protease complex. We found that the region from residues D50 to E80 of NS2B interacts directly and strongly with the NS3 protease domain. The proteolytic activity of the noncovalently binding complex was determined by a rapid and continuous fluorescence resonance energy transfer activity assay using a depsipeptide substrate. The new protein-cofactor complex obtained, encompassing the NS2B fragment (D50-E80) and the NS3 protease, shows proteolytic activity. The (1)H-(15)N-heteronuclear single quantum coherence spectrum of the isotopically enriched protein complex shows good cross-peak dispersion; this is indicative of a stable folded state. Our results significantly complement the X-ray structure of the NS2B-NS3pro complex published recently. Moreover, these results open the way to performing direct structural and interaction studies in solution on a new active NS2B-NS3pro complex with libraries of substrates and inhibitors in order to identify new drugs that prevent viral polyprotein processing.


Assuntos
Vírus da Dengue/enzimologia , Complexos Multiproteicos/metabolismo , Proteínas não Estruturais Virais/metabolismo , Sequência de Aminoácidos , Ativação Enzimática , Cinética , Dados de Sequência Molecular , Complexos Multiproteicos/química , Ressonância Magnética Nuclear Biomolecular , Dobramento de Proteína , RNA Helicases/química , RNA Helicases/metabolismo , Serina Endopeptidases/química , Serina Endopeptidases/metabolismo , Proteínas não Estruturais Virais/química
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