Deregulated microRNAs in neurofibromatosis type 1 derived malignant peripheral nerve sheath tumors

Altered Expressions of NF1 and NF1-Related microRNAs as Biomarkers in the Diagnosis of Undifferentiated Pleomorphic Sarcoma

Objective: Undifferentiated pleomorphic sarcoma (UPS) is a highly malignant, aggressive, and pleomorphic subtype of soft tissue sarcoma in adults. However, UPS is difficult to be diagnosed due to the lack of specific morphological and immunophenotypic features. Here, we aimed to identify new biomarkers for the diagnosis of UPS.

Methods: The mRNA and protein expression of neurofibromin 1 (NF1) in 68 pairs of UPS and adjacent normal tissues were detected by qRT-PCR and immunohistochemistry, and the correlation between the NF1 protein expression and clinicopathological characteristics was analyzed. Then, differentially expressed microRNAs (DE miRNAs) were identified between the UPS tumor tissue and matched adjacent normal tissue using Hisep sequencing, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG). The DE miRNAs of the regulating NF1 gene were also identified using the TargetScan and miRanda databases and validated by qRT-PCR.

Results: Compared with the adjacent normal tissue, both mRNA and protein expressions of NF1 in the UPS tumor tissue were significantly decreased, and the positive rate of NF1 protein was associated with the tumor size, metastasis, and recurrence. A total of 125 known DE miRNAs were identified from the screened miRNAs based on | log₂(Fold Change) ≥5 and p-value < 0.05 (A total of 82 upregulated and 43 downregulated DE miRNAs in the UPS tissue). Target genes regulated by the DE miRNAs were enriched in pathways of metabolisms, RNA degradation, PI3K-Akt, and Rap1 pathway. In total, 11 miRNAs which were predicted to regulate the NF1 gene were screened. After verification, the relative expressions of hsa-miR-199a-3p and hsa-miR-34a-5p were increased and decreased in the UPS tumor tissue compared with those in the adjacent normal tissue, respectively.

Conclusion: NF1 and NF1-related microRNAs including hsa-miR-199a-3p and hsa-miR-34a-5p may be novel biomarkers in the diagnosis of undifferentiated pleomorphic sarcoma (UPS).

MicroRNAs in neural crest development and neurocristopathies

The neural crest (NC) is a vertebrate-specific migratory population of multipotent stem cells that originate during late gastrulation in the region between the neural and non-neural ectoderm. This population of cells give rise to a range of derivatives, such as melanocytes, neurons, chondrocytes, chromaffin cells, and osteoblasts. Because of this, failure of NC development can cause a variety of pathologies, often syndromic, that are globally called neurocristopathies. Many genes are known to be involved in NC development, but not all of them have been identified. In recent years, attention has moved from protein-coding genes to non-coding genes, such as microRNAs (miRNA). There is increasing evidence that these non-coding RNAs are playing roles during embryogenesis by regulating the expression of protein-coding genes. In this review, we give an introduction to miRNAs in general and then focus on some miRNAs that may be involved in NC development and neurocristopathies. This new direction of research will give geneticists, clinicians, and molecular biologists more tools to help patients affected by neurocristopathies, as well as broadening our understanding of NC biology.

Neurofibromin and suppression of tumorigenesis: beyond the GAP

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disease and one of the most common inherited tumor predisposition syndromes, affecting 1 in 3000 individuals worldwide. The NF1 gene encodes neurofibromin, a large protein with RAS GTP-ase activating (RAS-GAP) activity, and loss of NF1 results in increased RAS signaling. Neurofibromin contains many other domains, and there is considerable evidence that these domains play a role in some manifestations of NF1. Investigating the role of these domains as well as the various signaling pathways that neurofibromin regulates and interacts with will provide a better understanding of how neurofibromin acts to suppress tumor development and potentially open new therapeutic avenues. In this review, we discuss what is known about the structure of neurofibromin, its interactions with other proteins and signaling pathways, its role in development and differentiation, and its function as a tumor suppressor. Finally, we discuss the latest research on potential therapeutics for neurofibromin-deficient neoplasms.

The clinical course and role of surgery in pediatric malignant peripheral nerve sheath tumors: a database study

OBJECTIVE

Malignant peripheral nerve sheath tumors (MPNSTs) are rare tumors found throughout the body, with their clinical course in children still not completely understood. Correspondingly, this study aimed to determine survival outcomes and specific clinical predictors of survival in this population from a large national database.

METHODS

All patients with MPNSTs aged ≤ 18 years in the US National Cancer Database (NCDB) between 2005 and 2016 were retrospectively reviewed. Data were summarized, and overall survival was modeled using Kaplan-Meier and Cox regression analyses.

RESULTS

A total of 251 pediatric patients with MPNSTs (132 [53%] females and 119 [47%] males) were identified; the mean age at diagnosis was 13.1 years (range 1-18 years). There were 84 (33%) MPNSTs located in the extremities, 127 (51%) were smaller than 1 cm, and 22 (9%) had metastasis at the time of diagnosis. In terms of treatment, surgery was pursued in 187 patients (74%), chemotherapy in 116 patients (46%), and radiation therapy in 129 patients (61%). The 5-year overall survival rate was estimated at 52% (95% CI 45%-59%), with a median survival of 64 months (range 36-136 months). Multivariate regression revealed that older age (HR 1.10, p < 0.01), metastases at the time of diagnosis (HR 2.14, p = 0.01), and undergoing biopsy only (HR 2.98, p < 0.01) significantly and independently predicted a shorter overall survival. Chemotherapy and radiation therapy were not statistically significant.

CONCLUSIONS

In this study, the authors found that older patient age, tumor metastases at the time of diagnosis, and undergoing only biopsy significantly and independently predicted poorer outcomes. Only approximately half of patients survived to 5 years. These results have shown a clear survival benefit in pursuing maximal safe resection in pediatric patients with MPNSTs. As such, judicious workup with meticulous resection by an expert team should be considered the standard of care for these tumors in children.

Pharmacological Approaches in Neurofibromatosis Type 1-Associated Nervous System Tumors

Simple Summary

Neurofibromatosis type 1 (NF1) is a common cancer predisposition genetic disease that is associated with significant morbidity and mortality. In this literature review, we discuss the major pathways in the nervous system that are affected by NF1, tumors that are associated with NF1, drugs that target these pathways, and genetic models of NF1. We also summarize the latest updates from clinical trials that are evaluating pharmacological agents to treat these tumors and discuss the efforts that are being made to cure the disease in the future

Abstract

Neurofibromatosis type 1 is an autosomal dominant genetic disease and a common tumor predisposition syndrome that affects 1 in 3000 to 4000 patients in the USA. Although studies have been conducted to better understand and manage this disease, the underlying pathogenesis of neurofibromatosis type 1 has not been completely elucidated, and this disease is still associated with significant morbidity and mortality. Treatment options are limited to surgery with chemotherapy for tumors in cases of malignant transformation. In this review, we summarize the advances in the development of targeted pharmacological interventions for neurofibromatosis type 1 and related conditions.

Pathogenic noncoding variants in the neurofibromatosis and schwannomatosis predisposition genes

Neurofibromatosis type 1 (NF1), type 2 (NF2), and schwannomatosis are a group of autosomal dominant disorders that predispose to the development of nerve sheath tumors. Pathogenic variants (PVs) that cause NF1 and NF2 are located in the NF1 and NF2 loci, respectively. To date, most variants associated with schwannomatosis have been identified in the SMARCB1 and LZTR1 genes, and a missense variant in the DGCR8 gene was recently reported to predispose to schwannomas. In spite of the high detection rate for PVs in NF1 and NF2 (over 90% of non-mosaic germline variants can be identified by routine genetic screening) underlying PVs for a proportion of clinical cases remain undetected. A higher proportion of non-NF2 schwannomatosis cases have no detected PV, with PVs currently only identified in around 70%-86% of familial cases and 30%-40% of non-NF2 sporadic schwannomatosis cases. A number of variants of uncertain significance have been observed for each disorder, many of them located in noncoding, regulatory, or intergenic regions. Here we summarize noncoding variants in this group of genes and discuss their established or potential role in the pathogenesis of NF1, NF2, and schwannomatosis.

Review and update in the diagnosis of peripheral nerve sheath tumors

PURPOSE OF REVIEW

Although tumors with nerve sheath differentiation are vast, the main clinically significant problems faced by the pathologist are the separation of malignant peripheral nerve sheath tumors (MPNSTs) from histologic mimics, the diagnosis of neurofibromatous neoplasms with atypical features, and the separation of cutaneous neurofibromatous neoplasms from melanoma. This review briefly discusses a variety of common nerve sheath tumors and summarizes recent advances on these diagnostic fronts.

RECENT FINDINGS

Much of recent work has focused on abnormalities in polycomb repressive complex 2, and the ways in which these abnormalities may be exploited in the diagnosis of MPNSTs. Progress has been made in the diagnostic and clinical understanding of atypical neurofibromatous neoplasms and low-grade MPNSTs. A number of reports have explored the diagnostic distinction between cutaneous neurofibroma and melanoma.

SUMMARY

New discoveries show promise in the diagnosis of peripheral nerve sheath tumors, but challenges - old and new - remain.