scholarly journals CSIG-02. R-RAS SUBFAMILY PROTEINS ELICIT DISTINCT PHYSIOLOGIC EFFECTS AND PHOSPHOPROTEOME ALTERATIONS IN NEUROFIBROMIN-NULL MPNST CELLS

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii27-ii28
Author(s):  
Shannon Weber ◽  
Nicole Brossier ◽  
Amanda Prechtl ◽  
Stephanie Brosius ◽  
Stephen Barnes ◽  
...  
Keyword(s):  
Genetic Disorder ◽  
Neurofibromatosis Type ◽  
Dominant Negative ◽  
Spectrometric Analysis ◽  
Ras Proteins ◽  
Nerve Sheath Tumors ◽  
Peripheral Nerve Sheath Tumors ◽  
And Migration ◽  
The Impact

Abstract Loss of the Ras GTPase-activating protein neurofibromin promotes the development of aggressive spindle cell neoplasms known as Malignant Peripheral Nerve Sheath Tumors (MPNSTs) in patients with the genetic disorder neurofibromatosis type 1 (NF1). Currently, the available chemotherapeutic regimens and radiotherapy are ineffective against MPNSTs, so the prognosis for patients with these neoplasms is poor. Neurofibromin loss dysregulates multiple Ras proteins in the classic (H-Ras, N-Ras, K-Ras) and R-Ras (R-Ras, R-Ras2/TC21, R-Ras3/M-Ras) subfamilies. Consequently, it is unclear which Ras proteins or pathways regulated by these Ras proteins should be therapeutically targeted in MPNSTs. We have previously shown that classic Ras proteins drive MPNST cell proliferation and survival. However, the role(s) of the R-Ras subfamily of proteins in MPNSTs have not been elucidated. To determine how R-Ras proteins contribute to the pathogenesis of neurofibromin-null MPNSTs, we introduced dominant negative (DN) R-Ras mutants, which are pan-inhibitors of the R-Ras subfamily, into MPNST cells and assessed the impact of R-Ras subfamily inhibition on mitogenesis, migration and the phosphoproteome. A panel of MPNST cell lines (STS-26T, YST-1, ST88-14, 90–8, NMS2, NMS-PC, S462, T265-2c) was used. Methodologies utilized include immunoblotting, PCR, Transwell migration, 3H-thymidine incorporation, and mass spectrometric analysis of phosphoprotein-enriched specimens. We found that R-Ras and R-Ras2 are widely expressed and can be activated in neurofibromin-null MPNST cells. In contrast to classic Ras proteins, we found that R-Ras proteins drive MPNST both mitogenesis and migration. Using mass spectrometry-based phosphoproteomics, we identified thirteen protein networks that were regulated by DN R-Ras, including networks affecting cellular movement via effects on microtubules. We chose to further study changes in ROCK1 phosphorylation and found that R-Ras subfamily proteins function, at least in some part, through the same pathways as ROCK1. We conclude that R-Ras proteins promote tumorigenesis by regulating distinct signaling pathways that regulate MPNST mitogenesis and migration.

scholarly journals New Model Systems and the Development of Targeted Therapies for the Treatment of Neurofibromatosis Type 1-Associated Malignant Peripheral Nerve Sheath Tumors

Genes ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 477 ◽  
Author(s):  
Kyle B. Williams ◽  
David A. Largaespada
Keyword(s):  
Schwann Cell ◽  
Peripheral Nerve ◽  
Neurofibromatosis Type 1 ◽  
Single Agent ◽  
Neurofibromatosis Type ◽  
Mek Inhibitors ◽  
Nerve Sheath Tumors ◽  
Peripheral Nerve Sheath Tumors ◽  
Nerve Sheath

Neurofibromatosis Type 1 (NF1) is a common genetic disorder and cancer predisposition syndrome (1:3000 births) caused by mutations in the tumor suppressor gene NF1. NF1 encodes neurofibromin, a negative regulator of the Ras signaling pathway. Individuals with NF1 often develop benign tumors of the peripheral nervous system (neurofibromas), originating from the Schwann cell linage, some of which progress further to malignant peripheral nerve sheath tumors (MPNSTs). Treatment options for neurofibromas and MPNSTs are extremely limited, relying largely on surgical resection and cytotoxic chemotherapy. Identification of novel therapeutic targets in both benign neurofibromas and MPNSTs is critical for improved patient outcomes and quality of life. Recent clinical trials conducted in patients with NF1 for the treatment of symptomatic plexiform neurofibromas using inhibitors of the mitogen-activated protein kinase (MEK) have shown very promising results. However, MEK inhibitors do not work in all patients and have significant side effects. In addition, preliminary evidence suggests single agent use of MEK inhibitors for MPNST treatment will fail. Here, we describe the preclinical efforts that led to the identification of MEK inhibitors as promising therapeutics for the treatment of NF1-related neoplasia and possible reasons they lack single agent efficacy in the treatment of MPNSTs. In addition, we describe work to find targets other than MEK for treatment of MPNST. These have come from studies of RAS biochemistry, in vitro drug screening, forward genetic screens for Schwann cell tumors, and synthetic lethal screens in cells with oncogenic RAS gene mutations. Lastly, we discuss new approaches to exploit drug screening and synthetic lethality with NF1 loss of function mutations in human Schwann cells using CRISPR/Cas9 technology.

Imaging biomarkers for malignant peripheral nerve sheath tumors in neurofibromatosis type 1

Neurology ◽  
2019 ◽  
Vol 93 (11) ◽  
pp. e1076-e1084 ◽  
Author(s):  
Shivani Ahlawat ◽  
Jaishri O. Blakeley ◽  
Fausto J. Rodriguez ◽  
Laura M. Fayad
Keyword(s):  
Fdg Pet ◽  
Neurofibromatosis Type ◽  
Nerve Sheath Tumors ◽  
Peripheral Nerve Sheath Tumors ◽  
Pet Ct ◽  
Adc Values ◽  
Adc Mapping ◽  
Fdg Pet Ct

ObjectiveTo determine the utility of quantitative metrics obtained from fMRI using diffusion-weighted imaging (DWI)/apparent diffusion coefficient (ADC) mapping compared with metabolic (18F-fluorodeoxyglucose [FDG]-PET/CT) imaging in patients with neurofibromatosis type 1 (NF1) for the characterization of peripheral nerve sheath tumors (PNSTs) as benign or malignant.MethodsThis Institutional Review Board–approved, Health Insurance Portability and Accountability Act–compliant study retrospectively reviewed imaging of 55 PNSTs in 21 patients with NF1. Imaging included anatomic (unenhanced T1, fluid-sensitive, contrast-enhanced T1-weighted), functional DWI (b = 50, 400, 800 s/mm2) and ADC mapping, magnetic resonance sequences, and FDG-PET/CT imaging. Anatomic (size), functional (minimum ADC values), and metabolic (maximum standardized uptake values [SUVmax]) imaging characteristics were recorded. ADC values were correlated with SUVmax. With histologic correlation for all malignant PNSTs (MPNSTs) or clinical or imaging stability (>12 months) for benign lesions used as reference standards, diagnostic accuracy was calculated.ResultsOf 55 PNSTs, there were 19 (35%) malignant and 36 (65%) benign PNSTs. Benign PNSTs were overall smaller than MPNSTs (largest diameter 4.3 ± 1.3 vs 8.2 ± 3.3 cm, respectively, p = 0.014). Benign PNSTs had higher ADCmin (×10−3 mm2/s) than MPNSTs (1.6 ± 0.4 vs 0.6 ± 0.2, respectively, p < 0.0001) and lower SUVmax than MPNSTs (3.2 ± 1.8 vs 8 ± 3.9, p < 0.0001, respectively). ADCmin correlated inversely with SUVmax (correlation coefficient r = −0.0.58, p < 0.0001). Maintaining a sensitivity of 100% with threshold values of ADCmin ≤1 or SUVmax >3.2, DWI yielded a specificity of 94% while FDG-PET/CT offered a specificity of 83%.ConclusionsBoth quantitative metabolic imaging and functional imaging offer high sensitivity for the characterization of PNSTs in NF1; however, DWI/ADC mapping offers increased specificity and may be a more useful modality.Classification of evidenceThis study provides Class II evidence that for patients with NF1, MRI using DWI/ADC mapping accurately distinguishes malignant and benign PNSTs.

scholarly journals The impact of host immune cells on the development of neurofibromatosis type 1: The abnormal immune system provides an immune microenvironment for tumorigenesis

2019 ◽  
Vol 2 (Supplement_1) ◽  
pp. i33-i39
Author(s):  
Cheng-Jiang Wei ◽  
Shu-Chen Gu ◽  
Jie-Yi Ren ◽  
Yi-Hui Gu ◽  
Xiang-Wen Xu ◽  
...  
Keyword(s):  
Immune System ◽  
Immune Cells ◽  
Neurofibromatosis Type 1 ◽  
Immune Escape ◽  
Genetic Disorder ◽  
Neurofibromatosis Type ◽  
Complex Interactions ◽  
Nf1 Gene ◽  
The Impact

Abstract AbstractThe immune system plays an essential role in the development of tumors, which has been demonstrated in multiple types of cancers. Consistent with this, immunotherapies with targets that disrupt these mechanisms and turn the immune system against developing cancers have been proven effective. In neurofibromatosis type 1 (NF1), an autosomal dominant genetic disorder, the understanding of the complex interactions of the immune system is incomplete despite the discovery of the pivotal role of immune cells in the tumor microenvironment. Individuals with NF1 show a loss of the NF1 gene in nonneoplastic cells, including immune cells, and the aberrant immune system exhibits intriguing interactions with NF1. This review aims to provide an update on recent studies showing the bilateral influences of NF1 mutations on immune cells and how the abnormal immune system promotes the development of NF1 and NF1-related tumors. We then discuss the immune receptors major histocompatibility complex class I and II and the PD-L1 mechanism that shield NF1 from immunosurveillance and enable the immune escape of tumor tissues. Clarification of the latest understanding of the mechanisms underlying the effects of the abnormal immune system on promoting the development of NF1 will indicate potential future directions for further studies and new immunotherapies.

Neurofibromatosis-associated nerve sheath tumors

2006 ◽  
Vol 20 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Judith A. Murovic ◽  
Daniel H. Kim ◽  
David G. Kline
Keyword(s):  
Diagnostic Criteria ◽  
Current Literature ◽  
Neurofibromatosis Type 1 ◽  
Neurofibromatosis Type ◽  
Imaging Findings ◽  
Nerve Sheath Tumors ◽  
Peripheral Nerve Sheath Tumors ◽  
Examination Protocol ◽  
Nerve Sheath

In this paper the authors describe a patient with neurofibromatosis Type 1 (NF1) who presented with sequelae of this disease. They also review the current literature on NF1 and NF2 published between 2001 and 2005. The method used to obtain information for the case report consisted of a family member interview and a review of the patient's chart. For the literature review the authors used the search engine Ovid Medline to identify papers published on the topic between 2001 and 2005. Neurofibromatosis Type 1 appears in approximately one in 2500 to 4000 births, is caused by a defect on 17q11.2, and results in neurofibromin inactivation. The authors reviewed the current literature with regard to the following aspects of this disease: 1) diagnostic criteria for NF1; 2) criteria for other NF1-associated manifestations; 3) malignant peripheral nerve sheath tumors (PNSTs); 4) the examination protocol for a patient with an NF1-related NST; 5) imaging findings in patients with NF1; 6) other diagnostic studies; 7) surgical and adjuvant treatment for NSTs and malignant PNSTs; and 8) hormone receptors in NF1-related tumors. Pertinent illustrations are included. Neurofibromatosis Type 2 occurs much less frequently than NF1, that is, in one in 33,000 births. Mutations in NF2 occur on 22q12 and result in inactivation of the tumor suppressor merlin. The following data on this disease are presented: 1) diagnostic criteria for NF2; 2) criteria for other NF2 manifestations; 3) malignant PNSTs in patients with NF2; 4) examination protocol for the patient with NF2 who has an NST; and 5) imaging findings in patients with NF2. Relevant illustrations are included. It is important that neurosurgeons be aware of the sequelae of NF1 and NF2, because they may be called on to treat these conditions.

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