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: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:The MEK inhibitor selumetinib induces objective responses and provides clinical benefit in children with neurofibromatosis type 1 (NF1) and inoperable plexiform neurofibromas (PNs). To evaluate whether similar outcomes were possible in adult patients, in whom PN growth is generally slower than in pediatric patients, an open-label phase 2 study of selumetinib in adults with NF1 PNs was conducted. Correlative analysis included extraction of RNA followed by sequencing. Samples include paired specimens collected before and on treatment.
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: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:<p>Neurofibromatosis type 1 (NF1) is a common tumor-predisposition disorder due to germline mutations in the tumor suppressor gene <i>NF1</i>. A virtually pathognomonic finding of NF1 is the plexiform neurofibroma (PN), a benign, likely congenital tumor that arises from biallelic inactivation of <i>NF1</i>. PN can undergo transformation to a malignant peripheral nerve sheath tumor, an aggressive soft-tissue sarcoma. To better understand the non-<i>NF1</i> genetic contributions to PN pathogenesis, we performed whole-exome sequencing and genome-wide copy-number determination for 23 low-passage Schwann cell cultures established from surgical PN material with matching germline DNA. All resected tumors were derived from routine debulking surgeries. None of the tumors were considered at risk for malignant transformation at the time, <i>e.g.</i>, there was no pain or rapid growth. Deep (~500X) <i>NF1</i> exon sequencing was also conducted on tumor DNA. Non-<i>NF1</i> somatic mutation verification was performed using the Ampliseq/IonTorrent platform. We identified 100% of the germline <i>NF1</i> mutations and found somatic <i>NF1</i> inactivation in 74% of the PN. One individual with three PNs had different <i>NF1</i> somatic mutations in each tumor. The median number of somatic mutations per sample, including <i>NF1</i>, was one (range 0 - 8). <i>NF1</i> was the only gene that was recurrently somatically inactivated in multiple tumors. We found no recurrent non-<i>NF1</i> locus copy-number variation in PN. This is the first multi-sample whole-exome sequencing study of <i>NF1</i>-associated PN. Taken together with concurrent copy-number data, our comprehensive genetic analysis reveals the primacy of <i>NF1</i> loss as the driver of PN tumorigenesis.</p>
Project description:Malignant peripheral nerve sheath tumors (MPNSTs) are the leading cause of premature death for patients with Neurofibromatosis type 1 and no approved targeted therapies are available. Transformation from Nf1-null benign plexiform neurofibromas is driven by the loss of the Cdkn2a (Arf) locus. Here, genetically engineered mouse models with combined Nf1 flox/flox and Arf flox/flox alleles were used (crossed with Postn-Cre+ mice). Tissue from MPNSTs that form in the Nf1-/-;Arf-/- setting were used for mRNA sequencing and compared to benign plexiform neurofibroma tissue (Nf1-/- from Nf1 flox/flox; Postn-Cre+ mice, GSE213789) to identify transcriptome signatures from MPNST and compare them to benign plexiform neurofibroma.
Project description:Integration of single-nuclei RNA-sequencing and spatial transcriptomics defines the complex microenvironment of NF1-associated plexiform neurofibromas
Project description:To define alterations early in tumor formation, we studied nerve tumors in neurofibromatosis 1 (NF1), a tumor predisposition syndrome in which affected individuals develop plexiform neurofibroma (PN). These benign tumors are driven by NF1 loss in Schwann cells (SC). By comparing normal nerve cells to PN cells using single cell and bulk RNA sequencing, we identified changes in five SC populations, including a de novo Schwann cell progenitor-like population. Long after Nf1 loss, SC populations developed PN-specific expression of Dcn, Postn, and CD74, and showed dramatic expansion of immune and stromal cell populations; in human PN, immune and stromal cells comprised 90% of cells. Label transfer enabled verification of each SC population and predicted tumor unique patterns of cell-cell communication in each SC population. We identified PROS-AXL, FGF-FGFR, and MIF-CD74 and its effector pathway NFkB as deregulated in NF1 SC populations, including SCP-like cells. Each receptor-ligand pair was predicted to influence surrounding cells in mouse and human. These findings highlight remarkable changes in all PN cells driven by loss of NF1 in multiple types of SCs and identify therapeutic targets for PN.