RESUMO
Microbial specialized metabolite biosynthetic gene clusters (SMBGCs) are a formidable source of natural products of pharmaceutical interest. With the multiplication of genomic data available, very efficient bioinformatic tools for automatic SMBGC detection have been developed. Nevertheless, most of these tools identify SMBGCs based on sequence similarity with enzymes typically involved in specialised metabolism and thus may miss SMBGCs coding for undercharacterised enzymes. Here we present Synteruptor (https://bioi2.i2bc.paris-saclay.fr/synteruptor), a program that identifies genomic islands, known to be enriched in SMBGCs, in the genomes of closely related species. With this tool, we identified a SMBGC in the genome of Streptomyces ambofaciens ATCC23877, undetected by antiSMASH versions prior to antiSMASH 5, and experimentally demonstrated that it directs the biosynthesis of two metabolites, one of which was identified as sphydrofuran. Synteruptor is also a valuable resource for the delineation of individual SMBGCs within antiSMASH regions that may encompass multiple clusters, and for refining the boundaries of these SMBGCs.
RESUMO
Metronomic chemotherapy-based combinations have received interest for relapsed/refractory malignancies. Preclinical and clinical studies showed activity of metronomic etoposide and axitinib. We report our retrospective experience in six children treated with axitinib and metronomic etoposide for refractory/relapsed brain tumors as an "off-label" combination. Three patients with medulloblastoma experienced partial response; one patient with atypical teratoid rhabdoid tumor (ATRT) displays an ongoing stable disease (12 months); two patients with medulloblastoma had progressive disease. Grade 3-4 toxicities were observed in two patients (thrombocytopenia, anemia, diarrhea, fatigue). The axitinib-etoposide combination shows signals of efficacy in heavily pretreated patients with relapsed/refractory brain tumors. These results were based on real-world observation and will need formal evaluation in a phase I/II trial.
Assuntos
Administração Metronômica , Protocolos de Quimioterapia Combinada Antineoplásica , Axitinibe , Neoplasias Encefálicas , Etoposídeo , Recidiva Local de Neoplasia , Humanos , Masculino , Estudos Retrospectivos , Feminino , Etoposídeo/administração & dosagem , Etoposídeo/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Criança , Axitinibe/uso terapêutico , Axitinibe/administração & dosagem , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/patologia , Pré-Escolar , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/patologia , Adolescente , Administração Oral , Seguimentos , Prognóstico , LactenteRESUMO
PURPOSE: MRI is the main imaging modality for pediatric brain tumors, but amino acid PET can provide additional information. Simultaneous PET-MRI acquisition allows to fully assess the tumor and lower the radiation exposure. Although symptomatic posterior fossa tumors are typically resected, the patient management is evolving and will benefit from an improved preoperative tumor characterization. We aimed to explore, in children with newly diagnosed posterior fossa tumor, the complementarity of the information provided by amino acid PET and MRI parameters and the correlation to histopathological results. PATIENTS AND METHODS: Children with a newly diagnosed posterior fossa tumor prospectively underwent a preoperative 11 C-methionine (MET) PET-MRI. Images were assessed visually and semiquantitatively. Using correlation, minimum apparent diffusion coefficient (ADC min ) and contrast enhancement were compared with MET SUV max . The diameter of the enhancing lesions was compared with metabolic tumoral volume. Lesions were classified according to the 2021 World Health Organization (WHO) classification. RESULTS: Ten children were included 4 pilocytic astrocytomas, 2 medulloblastomas, 1 ganglioglioma, 1 central nervous system embryonal tumor, and 1 schwannoma. All lesions showed visually increased MET uptake. A negative moderate correlation was found between ADC min and SUV max values ( r = -0.39). Mean SUV max was 3.8 (range, 3.3-4.2) in WHO grade 4 versus 2.5 (range, 1.7-3.0) in WHO grade 1 lesions. A positive moderate correlation was found between metabolic tumoral volume and diameter values ( r = 0.34). There was no correlation between SUV max and contrast enhancement intensity ( r = -0.15). CONCLUSIONS: Preoperative 11 C-MET PET and MRI could provide complementary information to characterize pediatric infratentorial tumors.
Assuntos
Neoplasias Encefálicas , Neoplasias Cerebelares , Neoplasias Infratentoriais , Meduloblastoma , Criança , Humanos , Metionina , Fluordesoxiglucose F18 , Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons/métodos , Imagem de Difusão por Ressonância Magnética/métodos , Racemetionina , Neoplasias Encefálicas/diagnóstico por imagem , AminoácidosRESUMO
The BMP pathway is one of the major signaling pathways in embryonic development, ontogeny and homeostasis, identified many years ago by pioneers in developmental biology. Evidence of the deregulation of its activity has also emerged in many cancers, with complex and sometimes opposing effects. Recently, its role has been suspected in Diffuse Midline Gliomas (DMG), among which Diffuse Intrinsic Pontine Gliomas (DIPG) are one of the most complex challenges in pediatric oncology. Genomic sequencing has led to understanding part of their molecular etiology, with the identification of histone H3 mutations in a large proportion of patients. The epigenetic remodeling associated with these genetic alterations has also been precisely described, creating a permissive context for oncogenic transcriptional program activation. This review aims to describe the new findings about the involvement of BMP pathway activation in these tumors, placing their appearance in a developmental context. Targeting the oncogenic synergy resulting from this pathway activation in an H3K27M context could offer new therapeutic perspectives based on targeting treatment-resistant cell states.
Assuntos
Glioma Pontino Intrínseco Difuso , Glioma , Humanos , Criança , Glioma/metabolismo , Histonas/metabolismo , Glioma Pontino Intrínseco Difuso/genética , Glioma Pontino Intrínseco Difuso/metabolismo , Glioma Pontino Intrínseco Difuso/patologia , Mutação , Transdução de Sinais , Proteínas Morfogenéticas Ósseas/metabolismoRESUMO
The linear chromosome of Streptomyces exhibits a highly compartmentalized structure with a conserved central region flanked by variable arms. As double strand break (DSB) repair mechanisms play a crucial role in shaping the genome plasticity of Streptomyces, we investigated the role of EndoMS/NucS, a recently characterized endonuclease involved in a non-canonical mismatch repair (MMR) mechanism in archaea and actinobacteria, that singularly corrects mismatches by creating a DSB. We showed that Streptomyces mutants lacking NucS display a marked colonial phenotype and a drastic increase in spontaneous mutation rate. In vitro biochemical assays revealed that NucS cooperates with the replication clamp to efficiently cleave G/T, G/G and T/T mismatched DNA by producing DSBs. These findings are consistent with the transition-shifted mutational spectrum observed in the mutant strains and reveal that NucS-dependent MMR specific task is to eliminate G/T mismatches generated by the DNA polymerase during replication. Interestingly, our data unveil a crescent-shaped distribution of the transition frequency from the replication origin towards the chromosomal ends, shedding light on a possible link between NucS-mediated DSBs and Streptomyces genome evolution.
Assuntos
Cromossomos Bacterianos , Reparo de Erro de Pareamento de DNA , Endonucleases , Streptomyces , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Pareamento Incorreto de Bases , Cromossomos Bacterianos/genética , Quebras de DNA de Cadeia Dupla , Reparo de Erro de Pareamento de DNA/genética , Replicação do DNA/genética , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Endodesoxirribonucleases/metabolismo , Endodesoxirribonucleases/genética , Endonucleases/genética , Endonucleases/metabolismo , Mutação , Taxa de Mutação , Streptomyces/genética , Streptomyces/enzimologiaRESUMO
BACKGROUND: This multicenter Phase I study (NCT03585465) evaluated nivolumab in combination with 3 metronomic chemotherapy (MC) regimens in children with refractory/relapsing solid tumors. OBJECTIVES: To evaluate the feasibility and safety of the three regimens METHODS: Patients aged < 18 years were enrolled. Nivolumab was combined with cyclophosphamide and vinblastine (arm A), capecitabine (arm B), or cyclophosphamide, vinblastine and capecitabine (arm C). Arm A and B were allocated sequentially. Arm C opened only if A and B were deemed safe. Dose-limiting toxicities (DLTs) were evaluated over the first two cycles. Patients were evaluable if they received > 2 cycles and > 70% of the planned dose. POPULATION: Sixteen patients were enrolled, 3 in arm A, 6 in arm B, and 7 in arm C. Median age was 11.5 years (range, 5-19). Patients previously received a median of 3.5 (range, 1-4) lines of systemic treatment, 14 patients had surgery and 11 had radiotherapy. RESULTS: Median number of cycles was 2 (1-24), median treatment duration was 56 days (18-714). In arm C, median number of cycles was 4 with median treatment duration of 95 days. No DLT was observed. Grade 3 adverse events (AE) and serious AE were observed in 8 patients (50%) and 1 patient (6%), respectively, over the first 2 cycles. No grade 4 AE occurred. The 6-month PFS and OS were 12% and 44%, respectively, in the whole population. Prolonged stable disease was observed in a high-grade glioma and an atypical teratoid rhabdoid tumor. CONCLUSION: Arm C appears safe. A randomized phase II trial evaluating the addition of nivolumab to the triple MC is ongoing.