Project description:Neurofibromatosis type 1 (NF1) is a genetic disorder that leads to the formation of cutaneous neurofibromas (cNFs), benign nerve sheath tumors that develop in the skin and significantly impact patients’ quality of life. cNF development begins with bi-allelic NF1 loss in Schwann cell (SC) lineage, followed by the recruitment of a complex tumor microenvironment consisting of fibroblasts, immune cells, blood vessels, axons and a dense extracellular matrix. Despite their high prevalence and clinical impact, the molecular mechanisms underlying cNF formation remain poorly understood. Here, we used an Nf1 knockout (Nf1-KO) mouse model, combined with immuno-histochemistry and single-cell transcriptomics, to explore the mechanisms driving cNF development. Our findings revealed that mutant SCs accumulate in the skin of young mice weeks before cNF onset. However, these cells remain quiescent until triggered by skin trauma, which induces their proliferation and the rapid formation of cNFs. Using a trauma-induced Nf1-KO model with scRNAseq, we conceived a transcriptomic atlas of growing and mature cNFs, as well as adjacent, seemingly healthy skin. This analysis identified a population of non-myelinating Aquaporin1highNestinlow SCs as the likely cells of origin for cNFs. These cells overexpress genes involved in axon growth and guidance, potentially driving the abnormal innervation observed in cNFs from both mice and patients. Additionally, we found that tumor SCs, along with dermal and/or epineurial fibroblasts and pericytes, overexpress collagen-encoding genes, contributing to the extensive fibrosis characteristic of cNFs. Notably, all of these cells exhibit high expression of Periostin and Tenascin C, key extracellular matrix components, highlighting them as novel therapeutic targets for cNF treatment.
Project description:22 plexiform neurofibromas from 18 unrelated neurofibromatosis-type 1 patients were screened with a high resolution array-CGH. Each PNF DNA (somatic tumor DNA) was individually hybridized on Agilent whole human genome 244K microarrays (Platform GPL4091) using the matched genomic constitutional DNA (lymphocytes DNA) from the corresponding patient as reference, in order to detect tumor-specific aberrations. NF1-associated plexiform neurofibromas DNA vs. constitutional DNA
Project description:Malignant peripheral nerve sheath tumors (MPNST) are aggressive cancers that occur spontaneously (sporadic MPNST) or from pre-existing, benign plexiform neurofibromas in neurofibromatosis type 1 (NF1) patients. MPNSTs metastasize easily, are resistant to therapeutic intervention and are frequently fatal. The molecular changes underlying the transition to malignancy in the NF1 setting are incompletely understood. Here we investigate the involvement of microRNAs in this process. Using an RT-PCR platform microRNA expression profiles were determined from a unique series of archival paired samples of plexiform neurofibroma and MPNST. At least 90 differentially expressed microRNAs (p<0.025; FDR<10%) were identified between the paired samples. Most microRNAs (91%) were found downregulated and 9% of the microRNAs were upregulated in MPNST. Based on the fold changes and statistical significance three downregulated microRNAs (let-7b-5p, miR-143-3p, miR-145-5p) and two upregulated microRNAs (miR135b-5p and miR-889-3p) were selected for further functional characterization. Their expression levels were validated in a relevant cell line panel and a series of unpaired fresh frozen tumor samples containing plexiform neurofibromas, atypical neurofibromas and MPNSTs. As part of the validation process we also determined and analyzed microRNA expression profiles of sporadic MPNSTs observing that microRNA expression discriminates NF1-associated and sporadic MPNSTs emphasizing their different etiologies. The involvement of microRNAs in tumorigenesis and cancer progression was examined in NF1-derived MPNST cell lines through modulating microRNA levels by transient transfection of microRNA mimics or inhibitors. The effects of microRNAs on cellular proliferation, migration, invasion and Wnt/ẞ-catenin signaling were determined. Our findings indicate that, some of the selected microRNAs affect migratory and invasive capabilities and Wnt signaling activity. It was observed that the functional effects upon microRNA modulation are distinct in different cell lines. From our study we conclude that miRNAs play essential regulatory roles in MPNST facilitating tumor progression.
Project description:Patients carrying an inactive NF1 allele develop tumours of Schwann cell origin called neurofibromas (NFs). Genetically engineered mouse models have significantly enriched our understanding of plexiform forms of NFs (pNFs). However, this has not been the case for cutaneous neurofibromas (cNFs), observed in all NF1 patients, as no previous model recapitulates their development. Here, we show that conditional Nf1 inactivation in Prss56-positive boundary cap cells leads to bona fide pNFs and cNFs. This work identifies subepidermal glia as a likely candidate for the cellular origin of cNFs, and provides insights on disease mechanisms, revealing a long, multistep pathological process in which inflammation play pivotal role. This new mouse model is an important asset for future clinical and therapeutic investigations of NF1-associated neurofibromas.
Project description:22 plexiform neurofibromas from 18 unrelated neurofibromatosis-type 1 patients were screened with a high resolution array-CGH. Each PNF DNA (somatic tumor DNA) was individually hybridized on Agilent whole human genome 244K microarrays (Platform GPL4091) using the matched genomic constitutional DNA (lymphocytes DNA) from the corresponding patient as reference, in order to detect tumor-specific aberrations.
Project description:Neurofibromatosis 1 (NF1) is a genetic, neurocutaneous syndrome caused by a mutation in the gene encoding neurofibromin. Individuals with NF1 develop growths that define the NF1 phenotype, including Lisch nodules, cafe-au-lait spots, and neurofibromas. However, more than 50% of individuals with NF1 have cognitive deficits, such as learning disorders and attention deficit/hyperactive disorder that are neuroanatomically unrelated to the neurofibromas. The purpose of this study is to determine the molecular basis of the neurodevelopmental changes that result from the primary gene mutation using a mouse model of NF. These mice are heterozygous for the Nf1 gene (NF+/-), and develop learning and memory difficulties that mimic humans, but do not develop tumors. By applying the technique of gene expression profiling to both NF+/- and control mice, we expect get a "genetic fingerprint" of 12,000 RNA molecules expressed in different parts of the brain during development. Comparison of the "genetic fingerprints" in these mice during development may help us identify key molecular changes that eventually result in cognitive deficits. Such an understanding of the molecular changes triggered by the primary gene mutation may eventually lead to treatments that prevent the cognitive deficits in NF1. Keywords: other
Project description:Neurofibromatosis type 1 (NF1) (MIM#162200) is a relatively frequent genetic condition that predisposes to tumor formation. The main types of tumors occurring in NF1 patients are cutaneous and subcutaneous neurofibromas, plexiform neurofibromas, optic pathway gliomas, and malignant peripheral nerve sheath tumors. To search for somatic mutations in cutaneous (dermal) neurofibromas, whole-exome sequencing (WES) was performed on seven spatially separated tumors and two reference tissues (blood and unaffected skin) from a single NF1 patient. Validation of WES findings was done using routine Sanger sequencing or Sequenom IPlex SNP genotyping. Exome sequencing confirmed the existence of a known familial splice-site mutation NM_000267.3:c.3113+1G>A in exon 23 of NF1 gene (HGMD ID CS951480) in blood, unaffected skin, and all tumor samples. In five out of seven analyzed tumors, we additionally detected second-hit mutations in the NF1 gene. Four of them were novel and one was previously observed. Each mutation was distinct, demonstrating the independent origin of each tumor. Only in two of seven tumors we detected an additional somatic mutation that was not associated with NF1. Our study demonstrated that somatic mutations of NF1 are likely the main drivers of cutaneous tumor formation. The study provides evidence for the rareness of single base pair level alterations in the exomes of benign NF1 cutaneous tumors.
Project description:The skin manifestations of neurofibromatosis 1 significantly reduce health-related quality-of-life. However, data on the utility of existing surveys in capturing neurofibromatosis 1 skin treatment outcomes are lacking. This quantitative study examined the relationship between clinician-rated severity and visibility and patient-rated itch and quality-of-life (QoL) to (1) establish baseline levels of skin- and condition-specific-related QoL, itch, depression and anxiety; (2) identify patient concerns to inform the development and evaluation of skin interventions; and (3) compare the sensitivity of different QoL measures. Validated scales included Skindex-29, Dermatology Life Quality Index (DLQI), Neurofibromatosis 1-adult quality-of-life (NF1-AdQOL) questionnaire, and the Hospital Anxiety and Depression Scale (HADS). We recruited 100 participants (response rate: 95%). Of these, 42% reported itch and 23% had probable clinical anxiety. Our cohort had higher levels of anxiety and total HADS scores compared to a control population. Using multivariate regression analysis, increasing visibility significantly predicted poorer QoL using the Skindex-29, NF1-AdQOL, and DLQI (p < 0.05); and itch significantly predicted worse QoL in Skindex-29 and NF1-AdQOL (p < 0.05). The highest mean scoring questions in Skindex-29 and NF1-AdQOL concerned worry about worsening skin disease and embarrassment. The highest mean scoring questions in DLQI were regarding itch, pain, and embarrassment. Items asking specifically about cutaneous neurofibromas (cNF) scored higher than comparable skin-specific questions (t-test p value <0.05). In summary, this study provides insights into the factors contributing to impaired QoL, anxiety, and mood in NF1 patients with cutaneous neurofibromas. Key factors identified for use in cNF measures include visibility, itch, anxiety, embarrassment, fears of worsening skin disease, and cNF-specific questions.
Project description:Understanding biological pathways critical for common neurofibromatosis type 1 (NF1) peripheral nerve tumors is essential, as tumor biomarkers, prognostic factors and therapeutics are all lacking. We used gene expression profiling to define transcriptional changes between primary normal Schwann cells (n = 10), NF1-derived primary benign neurofibroma Schwann cells (n = 22), malignant peripheral nerve sheath tumor (MPNST) cell lines (n = 13), benign neurofibromas (n = 26) and MPNST (n = 6). Dermal and plexiform neurofibromas were indistinguishable. A prominent theme in the analysis was aberrant differentiation. Neurofibromas repressed gene programs normally active in Schwann cell precursors and immature Schwann cells. MPNST signatures strongly differed; genes upregulated in the sarcomas were significantly enriched for genes activated in neural crest cells. We validated differential expression of 82 genes including the neural crest transcription factor SOX9 and SOX9 predicted targets. SOX9 immunoreactivity was robust in neurofibroma and MPSNT tissue sections and targeting SOX9 - strongly expressed in NF1-related tumors - caused MPNST cell death. SOX9 is a biomarker of neurofibroma and MPNST, and possibly a therapeutic target in NF1. Keywords: tumor stage 86 microarrays, consisting of 77 samples and 9 batch reference samples: NHSC (10), dNFSC (11), pNFSC (11), MPNST cell lines (13), dNF (13), pNF (13), MPNST (6)