RESUMO
Neurofibromatosis type 1 (NF1), an autosomal dominant genetic disorder, is caused by mutations in the NF1 gene, which encodes the GTPase-activating protein neurofibromin. The pathogenesis of the tumor progression of benign plexiform neurofibromas (PNs) and malignant peripheral nerve sheath tumors (MPNSTs) remain unclear. Here, we found that interferon-induced transmembrane protein 1 (IFITM1) was downregulated in MPNST tissues compared to those in PN tissues from patients with NF1. Overexpression of IFITM1 in NF1-associated MPNST cells resulted in a significant decrease in Ras activation (GTP-Ras) and downstream extracellular regulatory kinase 1/2 (ERK1/2) phosphorylation, whereas downregulation of IFITM1 via treatment with small interfering RNA in normal Schwann cells had the opposite result, indicating that expression levels of IFITM1 are closely associated with tumor progression in NF1. Treatment of MPNST cells with interferon-gamma (IFN-γ) significantly augmented the expression of IFITM1, thereby leading to a decrease in Ras and ERK1/2 activation. Despite the small number of patient samples, these findings may potentially provide a new target for chemotherapy in patients with NF1-associated MPNSTs. In xenograft mice injected with MPNST cells, IFN-γ treatment successfully suppressed tumor progression with increased IFITM1 expression and decreased Ras and ERK1/2 activation in tumor tissues. Collectively, these results suggest that IFITM1 is closely involved in MPNST pathogenesis and that IFN-γ is a good candidate for the therapeutic treatment of MPNSTs in NF1.
Assuntos
Antígenos de Diferenciação , Neoplasias de Bainha Neural , Neurofibromatose 1 , Humanos , Animais , Neurofibromatose 1/metabolismo , Neurofibromatose 1/genética , Neurofibromatose 1/patologia , Neurofibromatose 1/complicações , Camundongos , Neoplasias de Bainha Neural/metabolismo , Neoplasias de Bainha Neural/genética , Neoplasias de Bainha Neural/patologia , Linhagem Celular Tumoral , Antígenos de Diferenciação/metabolismo , Antígenos de Diferenciação/genética , Regulação para Baixo , Feminino , Regulação Neoplásica da Expressão Gênica , Masculino , Interferon gama/metabolismo , Sistema de Sinalização das MAP Quinases , Proteínas ras/metabolismo , Proteínas ras/genética , Neurofibromina 1/genética , Neurofibromina 1/metabolismo , AdultoRESUMO
Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder that is caused by a mutation in the NF1 gene, which is located on chromosome 17q11.2, which encodes for a protein known as "Neurofibromin", which acts as an inhibitor of oncogene RAS. This gene mutation causes tumours to grow on nerves which results in other systemic abnormalities such as skin changes, bone and eye abnormalities, hormonal imbalances, and diversity in achievement of puberty with neurologic complications. NF1 has a wide variety of associations in context with puberty. It is important to determine the cause of precocious and delayed puberty in order to establish an early treatment plan, to lead a successful prognosis, and decrease complications. The case reports of two patients presenting with dichotomous pubertal variation in association with NF1 are presented.
Assuntos
Neurofibromatose 1 , Humanos , Neurofibromatose 1/genética , Neurofibromatose 1/complicações , Neurofibromatose 1/diagnóstico , Masculino , Adolescente , Feminino , Criança , Puberdade Precoce/etiologia , Puberdade Precoce/diagnóstico , Puberdade Tardia/etiologia , Puberdade Tardia/diagnóstico , PuberdadeRESUMO
Plexiform neurofibromas (PNFs) are a prevalent and severe phenotype associated with NF1, characterized by a high teratogenic rate and potential for malignant transformation. The growth and recurrence of PNFs are attributed to aberrant proliferation and migration of Nf1-deficient Schwann cells. Protein tyrosine phosphatase receptor S (PTPRS) is believed to modulate cell migration and invasion by inhibiting the EMT process in NF1-derived malignant peripheral nerve sheath tumors. Nevertheless, the specific role of PTPRS in NF1-derived PNFs remains to be elucidated. The study utilized the GEO database and tissue microarray to illustrate a decrease in PTPRS expression in PNF tissues, linked to tumor recurrence. Furthermore, the down- and over-expression of PTPRS in Nf1-deficient Schwann cell lines resulted in the changes of cell migration and EMT processes. Additionally, RTK assay and WB showed that PTPRS knockdown can promote EGFR expression and phosphorylation. The restoration of EMT processes disrupted by alterations in PTPRS levels in Schwann cells can be achieved through EGFR knockdown and EGFR inhibitor. Moreover, high EGFR expression has been significantly correlated with poor prognosis. These findings underscore the potential role of PTPRS as a tumor suppressor in the recurrence of PNF via the regulation of EGFR-mediated EMT processes, suggesting potential targets for future clinical interventions.
Assuntos
Movimento Celular , Transição Epitelial-Mesenquimal , Receptores ErbB , Neurofibroma Plexiforme , Células de Schwann , Humanos , Linhagem Celular Tumoral , Receptores ErbB/metabolismo , Receptores ErbB/genética , Regulação Neoplásica da Expressão Gênica , Recidiva Local de Neoplasia/patologia , Recidiva Local de Neoplasia/genética , Neurofibroma Plexiforme/patologia , Neurofibroma Plexiforme/genética , Neurofibroma Plexiforme/metabolismo , Neurofibromatose 1/genética , Neurofibromatose 1/metabolismo , Neurofibromatose 1/patologia , Neurofibromina 1/genética , Neurofibromina 1/metabolismo , Fosforilação , Proteínas Tirosina Fosfatases Classe 2 Semelhantes a Receptores/genética , Proteínas Tirosina Fosfatases Classe 2 Semelhantes a Receptores/metabolismo , Células de Schwann/metabolismo , Células de Schwann/patologia , Transdução de SinaisRESUMO
Neurofibromatosis type 1 (NF1) is a human genetic disorder caused by variants in the NF1 gene. Plexiform neurofibromas, one of many NF1 manifestations, are benign peripheral nerve sheath tumors occurring in up to 50% of NF1 patients. A substantial fraction of NF1 pathogenetic variants are nonsense mutations, which result in the synthesis of truncated non-functional NF1 protein (neurofibromin). To date, no therapeutics have restored neurofibromin expression or addressed the consequences of this protein's absence in NF1 nonsense mutation patients, but nonsense suppression is a potential approach to the problem. Ataluren is a small molecule drug that has been shown to stimulate functional nonsense codon readthrough in several models of nonsense mutation diseases, as well as in Duchenne muscular dystrophy patients. To test ataluren's potential applicability in nonsense mutation NF1 patients, we evaluated its therapeutic effects using three treatment regimens in a previously established NF1 patient-derived (c.2041C > T; p.Arg681X) nonsense mutation mouse model. Collectively, our experiments indicate that: i) ataluren appeared to slow the growth of neurofibromas and alleviate some paralysis phenotypes, ii) female Nf1-nonsense mutation mice manifested more severe paralysis and neurofibroma phenotypes than male mice, iii) ataluren doses with apparent effectiveness were lower in female mice than in male mice, and iv) age factors also influenced ataluren's effectiveness.
Assuntos
Códon sem Sentido , Modelos Animais de Doenças , Neurofibromatose 1 , Neurofibromina 1 , Animais , Códon sem Sentido/efeitos dos fármacos , Camundongos , Masculino , Feminino , Neurofibromatose 1/genética , Neurofibromatose 1/tratamento farmacológico , Neurofibromina 1/genética , Oxidiazóis/farmacologia , Oxidiazóis/uso terapêutico , Humanos , Camundongos Endogâmicos C57BL , Camundongos TransgênicosRESUMO
PURPOSE: Early detection of neurofibromatosis type 1 (NF1)-associated peripheral nerve sheath tumors (PNST) informs clinical decision-making, enabling early definitive treatment and potentially averting deadly outcomes. In this study, we describe a cell-free DNA (cfDNA) fragmentomic approach that distinguishes nonmalignant, premalignant, and malignant forms of PNST in the cancer predisposition syndrome, NF1. EXPERIMENTAL DESIGN: cfDNA was isolated from plasma samples of a novel cohort of 101 patients with NF1 and 21 healthy controls and underwent whole-genome sequencing. We investigated diagnosis-specific signatures of copy-number alterations with in silico size selection as well as fragment profiles. Fragmentomics were analyzed using complementary feature types: bin-wise fragment size ratios, end motifs, and fragment non-negative matrix factorization signatures. RESULTS: The novel cohort of patients with NF1 validated that our previous cfDNA copy-number alteration-based approach identifies malignant PNST (MPNST) but cannot distinguish between benign and premalignant states. Fragmentomic methods were able to differentiate premalignant states including atypical neurofibromas (AN). Fragmentomics also adjudicated AN cases suspicious for MPNST, correctly diagnosing samples noninvasively, which could have informed clinical management. CONCLUSIONS: Novel cfDNA fragmentomic signatures distinguish AN from benign plexiform neurofibromas and MPNST, enabling more precise clinical diagnosis and management. This study pioneers the early detection of malignant and premalignant PNST in NF1 and provides a blueprint for decentralizing noninvasive cancer surveillance in hereditary cancer predisposition syndromes.
Assuntos
Biomarcadores Tumorais , Ácidos Nucleicos Livres , Variações do Número de Cópias de DNA , Detecção Precoce de Câncer , Humanos , Detecção Precoce de Câncer/métodos , Ácidos Nucleicos Livres/genética , Ácidos Nucleicos Livres/sangue , Feminino , Masculino , Adulto , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/sangue , Pessoa de Meia-Idade , Neurofibromatose 1/genética , Neurofibromatose 1/diagnóstico , Lesões Pré-Cancerosas/genética , Lesões Pré-Cancerosas/diagnóstico , Lesões Pré-Cancerosas/sangue , Lesões Pré-Cancerosas/patologia , Neoplasias do Sistema Nervoso Periférico/genética , Neoplasias do Sistema Nervoso Periférico/diagnóstico , Neoplasias do Sistema Nervoso Periférico/patologia , Adulto Jovem , Adolescente , Sequenciamento Completo do Genoma/métodos , Idoso , Criança , Neoplasias de Bainha Neural/genética , Neoplasias de Bainha Neural/diagnóstico , Neoplasias de Bainha Neural/patologia , Neoplasias de Bainha Neural/sangueRESUMO
OBJECTIVES: To investigate the clinical and genetic features in a cohort of Chinese families with neurofibromatosis type 1 (NF1). METHODS: The clinical information of 21 patients with NF1 in 10 families was retrospectively analyzed. To broaden the genetic spectrum of NF1, multiplex ligation-dependent probe amplification analysis was performed first, followed by the whole-exome sequencing, in order to identify pathogenic or potentially pathogenic variants of NF1 gene in 10 unrelated Chinese families. RESULTS: Nine different NF1 variants were identified in all 10 families. Of these, 7 were known pathogenic variants and included the exon 1 deletion, exons 1-58 deletion, c.5401C>T (p.Q1801*), c.2291-2A>C, c.484C>T (p.Q162*), c.4922G>A (p.W1641*) and c.1019_1020del (p.S340Cfs*25). The 2 novel variants were c.5197T>C (p.S1733P) and c.783_797delinsC (p.K261Nfs*25). The p.S1733P variant was classified as a variant of uncertain significance, while p.K261Nfs*25 was classified as pathogenic. Hence, the positive detection rate of NF1 variants was 100% (10/10). While the truncating variants were responsible for 60.0% (6/10) of the cases, the splicing variant was responsible for 10% (1/10) of the cases. CONCLUSION: We identified 2 novel heterozygous variants (c.5197T>C and c.783_797delinsC) in the NF1 gene, which broadens the genetic spectrum of the NF1 gene.
Assuntos
Povo Asiático , Neurofibromatose 1 , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem , Povo Asiático/genética , China , População do Leste Asiático , Família , Mutação , Neurofibromatose 1/genética , Neurofibromina 1/genética , Linhagem , Estudos RetrospectivosRESUMO
Neurofibromatosis type 1, a genetic disorder caused by pathogenic germline variations in NF1, predisposes individuals to the development of tumors, including cutaneous and plexiform neurofibromas (CNs and PNs), optic gliomas, astrocytomas, juvenile myelomonocytic leukemia, high-grade gliomas and malignant peripheral nerve sheath tumors (MPNSTs), which are chemotherapy- and radiation-resistant sarcomas with poor survival. Loss of NF1 also occurs in sporadic tumors, such as glioblastoma (GBM), melanoma, breast, ovarian and lung cancers. We performed a high-throughput screen for compounds that were synthetic lethal with NF1 loss, which identified several leads, including the small molecule Y102. Treatment of cells with Y102 perturbed autophagy, mitophagy and lysosome positioning in NF1-deficient cells. A dual proteomics approach identified BLOC-one-related complex (BORC), which is required for lysosome positioning and trafficking, as a potential target of Y102. Knockdown of a BORC subunit using siRNA recapitulated the phenotypes observed with Y102 treatment. Our findings demonstrate that BORC might be a promising therapeutic target for NF1-deficient tumors.
Assuntos
Lisossomos , Neurofibromina 1 , Humanos , Lisossomos/metabolismo , Neurofibromina 1/genética , Neurofibromina 1/metabolismo , Neurofibromatose 1/metabolismo , Neurofibromatose 1/genética , Neurofibromatose 1/patologia , Autofagia/efeitos dos fármacos , Mutações Sintéticas Letais , Transporte Proteico/efeitos dos fármacosRESUMO
The neurofibromatosis type 1 (NF1) RASopathy is associated with persistent fibrotic nonunions (pseudarthrosis) in human and mouse skeletal tissue. Here, we performed spatial transcriptomics to define the molecular signatures occurring during normal endochondral healing following fracture in mice. Within the control fracture callus, we observed spatially restricted activation of morphogenetic pathways, such as TGF-ß, WNT, and BMP. To investigate the molecular mechanisms contributing to Nf1-deficient delayed fracture healing, we performed spatial transcriptomic analysis on a Postn-cre;Nf1fl/- (Nf1Postn) fracture callus. Transcriptional analyses, subsequently confirmed through phospho-SMAD1/5/8 immunohistochemistry, demonstrated a lack of BMP pathway induction in Nf1Postn mice. To gain further insight into the human condition, we performed spatial transcriptomic analysis of fracture pseudarthrosis tissue from a patient with NF1. Analyses detected increased MAPK signaling at the fibrocartilaginous-osseus junction. Similar to that in the Nf1Postn fracture, BMP pathway activation was absent within the pseudarthrosis tissue. Our results demonstrate the feasibility of delineating the molecular and tissue-specific heterogeneity inherent in complex regenerative processes, such as fracture healing, and reconstructing phase transitions representing endochondral bone formation in vivo. Furthermore, our results provide in situ molecular evidence of impaired BMP signaling underlying NF1 pseudarthrosis, potentially informing the clinical relevance of off-label BMP2 as a therapeutic intervention.
Assuntos
Proteínas Morfogenéticas Ósseas , Consolidação da Fratura , Neurofibromatose 1 , Pseudoartrose , Transdução de Sinais , Transcriptoma , Animais , Pseudoartrose/metabolismo , Pseudoartrose/genética , Camundongos , Humanos , Proteínas Morfogenéticas Ósseas/metabolismo , Proteínas Morfogenéticas Ósseas/genética , Neurofibromatose 1/genética , Neurofibromatose 1/metabolismo , Neurofibromatose 1/complicações , Neurofibromatose 1/patologia , Consolidação da Fratura/genética , Fraturas Ósseas/metabolismo , Fraturas Ósseas/genética , Modelos Animais de Doenças , Neurofibromina 1/genética , Neurofibromina 1/metabolismo , Perfilação da Expressão GênicaRESUMO
Neurofibromatosis type 1 (NF1) is a genetic disorder caused by mutations in the NF1 gene. This disorder shows nearly complete penetrance and high phenotypic variability. We used the whole-exome sequencing technique to identify mutations in 32 NF1 cases from 22 Iranian families. A total of 31 variants, including 30 point mutations and one large deletion, were detected. In eight cases, variants were inherited, while they were sporadic in the remaining. Seven novel variants, including c.5576 T > G, c.6658_6659insC, c.2322dupT, c.92_93insAA, c.4360C > T, c.3814C > T, and c.4565_4566delinsC, were identified. The current study is the largest in terms of the sample size of Iranian NF1 cases with identified mutations. The results can broaden the spectrum of NF1 mutations and facilitate the process of genetic counseling in the affected families.
Assuntos
Sequenciamento do Exoma , Genes da Neurofibromatose 1 , Neurofibromatose 1 , Neurofibromina 1 , Humanos , Irã (Geográfico) , Neurofibromatose 1/genética , Neurofibromina 1/genética , Feminino , Masculino , Criança , Linhagem , Adulto , Mutação Puntual , Mutação , Adolescente , Pré-Escolar , Adulto Jovem , Análise Mutacional de DNA , Deleção de SequênciaRESUMO
Encephalocraniocutaneous lipomatosis (ECCL) is a sporadic congenital condition characterised by ocular, cutaneous and central nervous system involvement. Mosaic activating variants in FGFR1 and KRAS have been reported in several individuals with this syndrome. We report on a patient with neurofibromatosis type 1 (NF1) with a germline pathogenic variant in the NF1 gene and an ECCL phenotype, suggesting ECCL to be part of a spectrum of malformations associated with NF1 pathogenic variants. An anatomical hemispherectomy was performed for intractable epilepsy. Through genetic analysis of blood, cerebral tissue and giant cell lesions in both jaws, we identified the germline NF1 pathogenic variant in all samples and a second-hit pathogenic NF1 variant in cerebral tissue and both giant cell lesions. Both NF1 variants were located on different alleles resulting in somatic mosaicism for a biallelic NF1 inactivation originating in early embryogenesis (second-hit mosaicism or Happle type 2 mosaicism). The biallelic deficit in NF1 in the left hemicranium explains the severe localised, congenital abnormality in this patient. Identical first and second-hit variants in a giant cell lesion of both upper and lower jaws provide confirmatory evidence for an early embryonic second hit involving at least the neural crest. We suggest that the ECCL phenotype may be part of a spectrum of congenital problems associated with mosaic NF1 nullisomy originating during early embryogenesis. The biallelic NF1 inactivation during early embryogenesis mimics the severe activation of the RAS-MAPK pathway seen in ECCL caused by embryonic mosaic activating FGFR1 and KRAS variants in the cranial region. We propose that distinct mechanisms of mosaicism can cause the ECCL phenotype through convergence on the RAS-MAPK pathway.
Assuntos
Lipomatose , Mosaicismo , Síndromes Neurocutâneas , Neurofibromina 1 , Fenótipo , Humanos , Lipomatose/genética , Lipomatose/patologia , Síndromes Neurocutâneas/genética , Síndromes Neurocutâneas/patologia , Neurofibromina 1/genética , Alelos , Neurofibromatose 1/genética , Neurofibromatose 1/patologia , Feminino , Masculino , Mutação em Linhagem Germinativa/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , OftalmopatiasRESUMO
Neurofibromatosis Type 1 (NF1) is caused by loss of function variants in the NF1 gene. Most patients with NF1 develop skin lesions called cutaneous neurofibromas (cNFs). Currently the only approved therapeutic for NF1 is selumetinib, a mitogen -activated protein kinase (MEK) inhibitor. The purpose of this study was to analyze the transcriptome of cNF tumors before and on selumetinib treatment to understand both tumor composition and response. We obtained biopsy sets of tumors both pre- and on- selumetinib treatment from the same individuals and were able to collect sets from four separate individuals. We sequenced mRNA from 5844 nuclei and identified 30,442 genes in the untreated group and sequenced 5701 nuclei and identified 30,127 genes in the selumetinib treated group. We identified and quantified distinct populations of cells (Schwann cells, fibroblasts, pericytes, myeloid cells, melanocytes, keratinocytes, and two populations of endothelial cells). While we anticipated that cell proportions might change with treatment, we did not identify any one cell population that changed significantly, likely due to an inherent level of variability between tumors. We also evaluated differential gene expression based on drug treatment in each cell type. Ingenuity pathway analysis (IPA) was also used to identify pathways that differ on treatment. As anticipated, we identified a significant decrease in ERK/MAPK signaling in cells including Schwann cells but most specifically in myeloid cells. Interestingly, there is a significant decrease in opioid signaling in myeloid and endothelial cells; this downward trend is also observed in Schwann cells and fibroblasts. Cell communication was assessed by RNA velocity, Scriabin, and CellChat analyses which indicated that Schwann cells and fibroblasts have dramatically altered cell states defined by specific gene expression signatures following treatment (RNA velocity). There are dramatic changes in receptor-ligand pairs following treatment (Scriabin), and robust intercellular signaling between virtually all cell types associated with extracellular matrix (ECM) pathways (Collagen, Laminin, Fibronectin, and Nectin) is downregulated after treatment. These response specific gene signatures and interaction pathways could provide clues for understanding treatment outcomes or inform future therapies.
Assuntos
Benzimidazóis , Matriz Extracelular , Células de Schwann , Transdução de Sinais , Neoplasias Cutâneas , Humanos , Células de Schwann/efeitos dos fármacos , Células de Schwann/metabolismo , Células de Schwann/patologia , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/tratamento farmacológico , Neoplasias Cutâneas/patologia , Benzimidazóis/farmacologia , Matriz Extracelular/metabolismo , Matriz Extracelular/efeitos dos fármacos , Matriz Extracelular/genética , Transdução de Sinais/efeitos dos fármacos , Neurofibroma/genética , Neurofibroma/tratamento farmacológico , Neurofibroma/metabolismo , Neurofibroma/patologia , Feminino , Masculino , RNA-Seq , Pessoa de Meia-Idade , Adulto , Neurofibromatose 1/genética , Neurofibromatose 1/tratamento farmacológico , Neurofibromatose 1/patologia , Inibidores de Proteínas Quinases/farmacologia , Transcriptoma/efeitos dos fármacosRESUMO
Neurofibromatosis Type I (NF1) is a rare genetic disorder. NF1 patients frequently develop a benign tumor in peripheral nerve plexuses called plexiform neurofibroma. In the past two decades, tissue-specific Nf1 knockout mouse models were developed using commercially available tissue-specific Cre recombinase and the Nf1 flox mice to mimic neurofibroma development. However, these models develop para-spinal neurofibroma, recapitulating a rare type of neurofibroma found in NF1 patients. The NPcis mouse model developed a malignant version of neurofibroma called malignant peripheral nerve sheath tumor (MPNST) within 3 to 6 months but intriguingly without apparent benign precursor lesion. Here, we revisited the NPcis model and discovered that about 20% display clinical signs similar to Nf1 tissue-specific knockout mice models. However, a systematic histological analysis could not explain the clinical signs we observed although we noticed lesions reminiscent of a neurofibroma in a peripheral nerve, a cutaneous neurofibroma, and para-spinal neurofibroma on rare occasions in NPcis mice. We also observed that 10% of the mice developed a malignant peripheral nerve sheath tumor (MPNST) spontaneously, coinciding with their earring tag identification. Strikingly, half of the sciatic nerves from NPcis mice developed plexiform neurofibroma within 1-6 months when intentionally injured. Thus, we provided a procedure to turn the widely used NPcis sarcoma model into a model recapitulating plexiform neurofibroma.
Assuntos
Modelos Animais de Doenças , Neurofibroma Plexiforme , Animais , Neurofibroma Plexiforme/patologia , Camundongos , Nervo Isquiático/patologia , Camundongos Knockout , Neurofibromatose 1/patologia , Neurofibromatose 1/genética , Neurofibromina 1/genéticaRESUMO
NF1 microdeletion syndrome, accounting for 5-11% of NF1 patients, is caused by a deletion in the NF1 region and it is generally characterized by a severe phenotype. Although 70% of NF1 microdeletion patients presents the same 1.4 Mb type-I deletion, some patients may show additional clinical features. Therefore, the contribution of several pathogenic mechanisms, besides haploinsufficiency of some genes within the deletion interval, is expected and needs to be defined. We investigated an altered expression of deletion flanking genes by qPCR in patients with type-1 NF1 deletion, compared to healthy donors, possibly contributing to the clinical traits of NF1 microdeletion syndrome. In addition, the 1.4-Mb deletion leads to changes in the 3D chromatin structure in the 17q11.2 region. Specifically, this deletion alters DNA-DNA interactions in the regions flanking the breakpoints, as demonstrated by our 4C-seq analysis. This alteration likely causes position effect on the expression of deletion flanking genes.Interestingly, 4C-seq analysis revealed that in microdeletion patients, an interaction was established between the RHOT1 promoter and the SLC6A4 gene, which showed increased expression. We performed NGS on putative modifier genes, and identified two "likely pathogenic" rare variants in RAS pathway, possibly contributing to incidental phenotypic features.This study provides new insights into understanding the pathogenesis of NF1 microdeletion syndrome and suggests a novel pathomechanism that contributes to the expression phenotype in addition to haploinsufficiency of genes located within the deletion.This is a pivotal approach that can be applied to unravel microdeletion syndromes, improving precision medicine, prognosis and patients' follow-up.
Assuntos
Deleção Cromossômica , Epigênese Genética , Haploinsuficiência , Neurofibromatose 1 , Humanos , Neurofibromatose 1/genética , Feminino , Masculino , Neurofibromina 1/genética , Cromossomos Humanos Par 17/genética , Fenótipo , Criança , Regiões Promotoras GenéticasRESUMO
Neurofibromatosis type 1 (NF1) is a complex genetic disorder that affects a range of tissues including muscle and bone. Recent preclinical and clinical studies have shown that Nf1 deficiency in muscle causes metabolic changes resulting in intramyocellular lipid accumulation and muscle weakness. These can be subsequently rescued by dietary interventions aimed at modulating lipid availability and metabolism. It was speculated that the modified diet may rescue defects in cortical bone as NF1 deficiency has been reported to affect genes involved with lipid metabolism. Bone specimens were analyzed from wild type control mice as well as Nf1Prx1-/- (limb-targeted Nf1 knockout mice) fed standard chow versus a range of modified chows hypothesized to influence lipid metabolism. Mice were fed from 4 weeks to 12 weeks of age. MicroCT analysis was performed on the cortical bone to examine standard parameters (bone volume, tissue mineral density, cortical thickness) and specific porosity measures (closed pores corresponding to osteocyte lacunae, and larger open pores). Nf1Prx1-/- bones were found to have inferior bone properties to wild type bones, with a 4-fold increase in the porosity attributed to open pores. These measures were rescued by dietary interventions including a L-carnitine + medium-chain fatty acid supplemented chow previously shown to improve muscle histology function. Histological staining visualized these changes in bone porosity. These data support the concept that lipid metabolism may have a mechanistic impact on bone porosity and quality in NF1.
Assuntos
Modelos Animais de Doenças , Camundongos Knockout , Neurofibromatose 1 , Animais , Neurofibromatose 1/dietoterapia , Neurofibromatose 1/patologia , Neurofibromatose 1/metabolismo , Neurofibromatose 1/genética , Camundongos , Fenótipo , Neurofibromina 1/genética , Neurofibromina 1/metabolismo , Porosidade , Osso e Ossos/metabolismo , Osso e Ossos/patologia , Metabolismo dos Lipídeos , Microtomografia por Raio-X , Masculino , Densidade Óssea , DietaRESUMO
Optic pathway gliomas (OPGs) are most predominant pilocytic astrocytomas, which are typically diagnosed within the first decade of life. The majority of affected children with OPGs also present with neurofibromatosis type 1 (NF1), the most common tumor predisposition syndrome. OPGs in individuals with NF1 primarily affect the optic pathway and lead to visual disturbance. However, it is challenging to assess risk in asymptomatic patients without valid biomarkers. On the other hand, for symptomatic patients, there is still no effective treatment to prevent or recover vision loss. Therefore, this review summarizes current knowledge regarding the pathogenesis of NF1-associated OPGs (NF1-OPGs) from preclinical studies to seek potential prognostic markers and therapeutic targets. First, the loss of the NF1 gene activates 3 distinct Ras effector pathways, including the PI3K/AKT/mTOR pathway, the MEK/ERK pathway, and the cAMP pathway, which mediate glioma tumorigenesis. Meanwhile, non-neoplastic cells from the tumor microenvironment (microglia, T cells, neurons, etc.) also contribute to gliomagenesis via various soluble factors. Subsequently, we investigated potential genetic risk factors, molecularly targeted therapies, and neuroprotective strategies for tumor prevention and vision recovery. Last, potential directions and promising preclinical models of NF1-OPGs are presented for further research. On the whole, NF1-OPGs develop as a result of the interaction between glioma cells and the tumor microenvironment. Developing effective treatments require a better understanding of tumor molecular characteristics, as well as multistage interventions targeting both neoplastic cells and non-neoplastic cells.
Assuntos
Neurofibromatose 1 , Glioma do Nervo Óptico , Humanos , Neurofibromatose 1/complicações , Neurofibromatose 1/genética , Glioma do Nervo Óptico/terapia , Glioma do Nervo Óptico/genética , Fatores de Risco , Animais , Neurofibromina 1/genética , Neoplasias do Nervo Óptico/terapia , Neoplasias do Nervo Óptico/genéticaRESUMO
Individuals with neurofibromatosis type 1, an autosomal dominant neurogenetic and tumor predisposition syndrome, are susceptible to developing low-grade glioma and less commonly high-grade glioma. These gliomas exhibit loss of the neurofibromin gene [neurofibromin type 1 (NF1)], and 10% to 15% of sporadic high-grade gliomas have somatic NF1 alterations. Loss of NF1 leads to hyperactive RAS signaling, creating opportunity given the established efficacy of MEK inhibitors in plexiform neurofibromas and some individuals with low-grade glioma. We observed that NF1-deficient glioblastoma neurospheres were sensitive to the combination of an MEK inhibitor (mirdametinib) with irradiation, as evidenced by synergistic inhibition of cell growth, colony formation, and increased cell death. In contrast, NF1-intact neurospheres were not sensitive to the combination, despite complete ERK pathway inhibition. No neurosphere lines exhibited enhanced sensitivity to temozolomide combined with mirdametinib. Mirdametinib decreased transcription of homologous recombination genes and RAD51 foci, associated with DNA damage repair, in sensitive models. Heterotopic xenograft models displayed synergistic growth inhibition to mirdametinib combined with irradiation in NF1-deficient glioma xenografts but not in those with intact NF1. In sensitive models, benefits were observed at least 3 weeks beyond the completion of treatment, including sustained phosphor-ERK inhibition on immunoblot and decreased Ki-67 expression. These observations demonstrate synergistic activity between mirdametinib and irradiation in NF1-deficient glioma models and may have clinical implications for patients with gliomas that harbor germline or somatic NF1 alterations.
Assuntos
Glioblastoma , Neurofibromina 1 , Ensaios Antitumorais Modelo de Xenoenxerto , Humanos , Glioblastoma/patologia , Glioblastoma/radioterapia , Glioblastoma/genética , Glioblastoma/tratamento farmacológico , Animais , Camundongos , Neurofibromina 1/genética , Neurofibromina 1/deficiência , Linhagem Celular Tumoral , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Proliferação de Células/efeitos dos fármacos , Benzamidas/farmacologia , Benzamidas/uso terapêutico , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/genética , Neurofibromatose 1/genética , Neurofibromatose 1/tratamento farmacológico , Difenilamina/análogos & derivadosAssuntos
Cromossomos Humanos Par 17 , Humanos , Feminino , Gravidez , Adulto , Cromossomos Humanos Par 17/genética , Duplicação Cromossômica/genética , Diagnóstico Pré-Natal/métodos , Neurofibromina 1/genética , Ultrassonografia Pré-Natal , Heterozigoto , Neurofibromatose 1/genética , Neurofibromatose 1/diagnósticoRESUMO
Neurofibromatosis type 1 (NF1) is an autosomal dominant disease with complete penetrance, most commonly known to affect the skin and eyes. Although lung involvement in the form of cysts and bullae occurs in up to 20% of adults, the seemingly intuitive association of NF1 and spontaneous pneumothorax is not widely recognised among clinicians. Here, we report the second case of recurring spontaneous pneumothorax in the context of NF1 with a confirmed molecular diagnosis. In both cases, the NF1 variants featured a premature stop codon in the C-terminal protein domain. Interestingly, our patient had mild skin symptoms, suggesting that spontaneous pneumothorax may not be correlated with cutaneous disease severity. More genotype-phenotype correlation studies are needed for NF1 in general and for its link to spontaneous pneumothorax in particular.