Normal Schwann Cells Research Articles

Calebin-A induced death of malignant peripheral nerve sheath tumor cells by activation of histone acetyltransferase

BackgroundNeurofibromatosis type 1 (NF1) is one of the most common hereditary neurocutaneous disorders. The malignant peripheral nerve sheath tumor (MPNST), transformed from NF1 related plexiform neurofibroma, is a rapidly growing and highly invasive tumor. No effective chemotherapeutic agent is currently available. Calebin-A is a derivative from turmeric Curcuma longa. Given the anti-inflammatory and anticancer potentials of curcumin, whether Calebin-A also had the tumoricidal effect upon MPNST cells is still elusive. PurposeTo determine whether Calebin-A has the potential for anti-MPNST effect. MethodsThe MTT and FACS analysis of normal Schwann (HSC) and MPNST cells have been employed to determine the tumoricidal effect of Calebin-A. The expression of the signal pathway molecules was assessed by Western blotting. The CHIP with quantitative PCR assay was performed to quantify the promoter DNA binding to acetylated histone 3 (acetyl H3). The enzyme activities of histone acetyltransferase (HAT) and deacetylase (HDAC) have been evaluated by commercial kits. The measurements of tumor size of the xenograft mouse model were also performed. ResultsCalebin-A inhibited the proliferation of MPNST and primary neurofibroma cells in a dose-dependent manner. The flow cytometry analysis of the MPNST cells after treatment of 25 μm of Calebin-A demonstrated an increase of population in the G0/G1 phase but decrease in G2/M phase. Before treatment, the expression of Axl, Tyro3, and acetyl H3 was significantly higher in MPNST cells when compared to HSC. The expression of phosphorylated-AKT, -ERK1/2, survivin, hTERT, and acetyl H3 proteins were reduced after treatment. The CHIP assay shows the promoter DNA copies of survivin (BRIC5) and hTERT genes are significantly reduced post-treatment. The enzyme activity of HAT was significantly reduced, but not that of HDAC. Two HAT inhibitors, epigallocatechin-3-gallate (EGCG) and anacardic acid (AA) have also demonstrated a significant inhibitory effect on MPNST cells. Finally, the measurements of tumor size showed a significant reduction of the xenograft tumors after treatment of Calebin-A. ConclusionBoth in vitro and in vivo studies showed Calebin-A could inhibit the proliferation of MPNST with suppression of survivin and hTERT. The reduced expression of these two factors might be through the epigenetic histone modification resulting from the decreased activity of HAT.

Tonic ATP-mediated growth suppression in peripheral nerve glia requires arrestin-PP2 and is evaded in NF1

Normal Schwann cells (SCs) are quiescent in adult nerves, when ATP is released from the nerve in an activity dependent manner. We find that suppressing nerve activity in adult nerves causes SC to enter the cell cycle. In vitro, ATP activates the SC G-protein coupled receptor (GPCR) P2Y2. Downstream of P2Y2, β-arrestin-mediated signaling results in PP2-mediated de-phosphorylation of AKT, and PP2 activity is required for SC growth suppression. NF1 deficient SC show reduced growth suppression by ATP, and are resistant to the effects of β-arrestin-mediated signaling, including PP2-mediated de-phosphorylation of AKT. In patients with the disorder Neurofibromatosis type 1, NF1 mutant SCs proliferate and form SC tumors called neurofibromas. Elevating ATP levels in vivo reduced neurofibroma cell proliferation. Thus, the low proliferation characteristic of differentiated adult peripheral nerve may require ongoing, nerve activity-dependent, ATP. Additionally, we identify a mechanism through which NF1 SCs may evade growth suppression in nerve tumors.

218 - Tyrosine nitration regulates signaling pathways involved in Neurofibromatosis type 2-associated Schwannoma growth

Neurofibromatosis type 2 (NF2) is a genetic disorder of the nervous system caused by inactivation of the merlin tumor suppressor gene. NF2 patients develop bilateral vestibular schwannomas (VS) and other nervous system tumors throughout their life for which there is no effective drug treatment. Production of the oxidant peroxynitrite occurs in pathological conditions and leads to tyrosine (Tyr) nitration of proteins. Although Tyr nitration is found in multiple tumor types, its role in tumorigenesis is unknown. We discovered that VS and human merlin-deficient (MD) Schwann cells show significantly increased levels of peroxynitrite and Tyr nitration compared to normal Schwann cells. Notably, prevention of tyrosine nitration selectively decreases MD-Schwann cell survival. Our goal is to identify nitrated proteins that support VS growth as new potential tumor-specific therapeutic targets, enabling the development of safe pharmacological strategies for NF2 schwannomas. This is the first focused effort to determine the signaling pathways regulated by tyrosine nitration in pathological conditions. By performing immunoprecipitations using a polyclonal anti-nitrotyrosine antibody followed by mass spectrometry analysis and western blot, we identified a limited number of proteins endogenously nitrated in VS from NF2 patients, and in mouse and human MD-Schwann cells. A group of the identified proteins play a role in pathways that are dysregulated in NF2. Further, using complementary phospho-kinase arrays, we found that prevention of tyrosine nitration using urate and edaravone has an impact on several of these key signaling pathways. The identification of the specific nitrated proteins that promote schwannoma growth could provide exceptional novel targets for the treatment of NF2 and possibly other tumors of the nervous system as well. Supported by DoD, NRP, NIA W81XWH-17-1-0409 (to MCF).

A proteasome-resistant fragment of NIK mediates oncogenic NF-κB signaling in schwannomas.

Schwannomas are common, highly morbid and medically untreatable tumors that can arise in patients with germ line as well as somatic mutations in neurofibromatosis type 2 (NF2). These mutations most commonly result in the loss of function of the NF2-encoded protein, Merlin. Little is known about how Merlin functions endogenously as a tumor suppressor and how its loss leads to oncogenic transformation in Schwann cells (SCs). Here, we identify nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-inducing kinase (NIK) as a potential drug target driving NF-κB signaling and Merlin-deficient schwannoma genesis. Using a genomic approach to profile aberrant tumor signaling pathways, we describe multiple upregulated NF-κB signaling elements in human and murine schwannomas, leading us to identify a caspase-cleaved, proteasome-resistant NIK kinase domain fragment that amplifies pathogenic NF-κB signaling. Lentiviral-mediated transduction of this NIK fragment into normal SCs promotes proliferation, survival, and adhesion while inducing schwannoma formation in a novel in vivo orthotopic transplant model. Furthermore, we describe an NF-κB-potentiated hepatocyte growth factor (HGF) to MET proto-oncogene receptor tyrosine kinase (c-Met) autocrine feed-forward loop promoting SC proliferation. These innovative studies identify a novel signaling axis underlying schwannoma formation, revealing new and potentially druggable schwannoma vulnerabilities with future therapeutic potential.

Fluorescent Detection of Merlin-deficient Schwann Cells and Primary Human Vestibular Schwannoma Cells Using Sodium Fluorescein.

Merlin-deficient Schwann cells (MD-SC) and primary human vestibular schwannoma (VS) cells exhibit selective uptake of sodium-fluorescein (SF), allowing for fluorescent detection and improved visualization of tumor cells, when compared with Schwann cells (SC). SF is a fluorescent compound used for fluorescence-guided resection of gliomas. The utility of SF for VS surgery has not been assessed. Mouse MD-SCs and rat SCs were cultured on 96-well plates at different cell densities and treated with SF at several drug concentrations and durations. Relative fluorescence units (RFU) were measured using a fluorometer to determine optimal treatment parameters in vitro. Subsequently, a four-point Likert scale for fluorescence visualization of pelleted cells was created and validated. Blinded observers rated SF-treated primary human VS and SC cultures, which were developed from deidentified specimens obtained from live and cadaveric donors, respectively. In contrast to SCs that showed low levels of fluorescence, MD-SCs demonstrated dose-dependent increases in RFUs when treated with incremental dosages of SF as well as longer treatment and fluorescent excitation times. In addition, RFUs were higher at greater MD-SC densities. The Likert scale for fluorescence visualization was validated using nine blinded observers and there were excellent inter- and intrarater reliabilities (intraclass coefficients of 0.989 and >0.858, respectively). Using the Likert scale, human VS treated with SF received higher scores than human SCs (p < 0.001). Mouse MD-SC and human VS cells demonstrate preferential uptake of SF when compared with normal primary SCs. Observers detected differences in fluorescence using the validated Likert scale. Further investigations into the utility of SF-guidance in VS surgery are warranted.

ITRAQ-based proteomics profiling of Schwann cells before and after peripheral nerve injury.

Objective(s):Schwann cells (SCs) have a wide range of applications as seed cells in the treatment of nerve injury during transplantation. However, there has been no report yet on kinds of proteomics changes that occur in Schwann cells before and after peripheral nerve injury.Materials and Methods: Activated Schwann cells (ASCs) and normal Schwann cells (NSCs) were obtained from adult Wistar rat sciatic nerves. After immunofluorescence identification, we identified differentially expressed proteins in the ASCs and NSCs using isobaric tags for relative and absolute quantitation (iTRAQ) combined with high-resolution Orbitrap liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). In addition, all the differentially expressed proteins were analyzed by Gene ontology (GO) analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis. Finally, several differentially expressed proteins were selected for Western blot verification.Results:A total of 122 differentially expressed proteins in ASCs and NSCs were screened. GO analysis suggested that these different proteins are likely to accumulate in the cytoplasm and are associated with single-multicellular organism processes. The KEGG pathway analysis suggested that proteins related to purine metabolism were significantly enriched. The expression of Transmembrane glycoprotein NMB (GPNMB), Ectonucleotide pyrophosphatase/phosphodiesterase family member 3 (ENPP3), and other proteins were consistent with the proteomics data obtained by Western blot analysis. Conclusion:GPNMB, ENPP3, GFPT2, and other proteins may play an important role in the repair of peripheral nerve injury. This study may provide new insights into changes in SCs after peripheral nerve injury.

Abstract 2084: Reprogramming the epigenome as an effective treatment option for neurofibromatosis1 associated malignant peripheral nerve sheath tumors

Abstract Neurofibromatosis type 1 (NF1) is common, occurring in 1 in 3000 live births, and results in skin pigmentation and the growth of tumors along nerves in the skin, brain, and other parts of the body. It arises from a mutated and non-functional tumor suppressor gene NF1. Tumors of the peripheral nerves, called neurofibromas and of the main eye nerve, called optic glioma, are debilitating and deadly. Epigenetic mechanisms have been shown to play an important role in the progression of neurofibromas to malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs with polycomb repressive complex 2 (PRC2) loss showed complete loss of trimethylation at lysine 27 of histone H3 (H3K27me3). We hypothesized that owing to the loss of this repressive complex PRC2, there is an overexpression of genes related to tumorigenesis in MPNSTs because of reciprocal gain of the activation marks such as trimethylation at lysine 4 of histone H3 (H3K4me3) and acetylation of lysine 27 of histone H3 (H3K27Ac) at their promoters. Using RT-PCR, we observed an increase in the expression of candidate oncogenes genes PAX2, FOXN4, IGF2 and TLX1 in NF1 associated MPNST cell line ST88-14 versus the normal Schwann cells and normal human fibroblasts. Western blots using purified histones revealed that there was an increase in the expression of H3K4me3, H3K9me2, H3K18Ac and H3K27Ac. Recently, aqueous extracts of Ocimum Sanctum has been used as investigational cancer preventive drug. We wanted to know the effects of extracts of O. Sanctum on MPNST cell line ST88-14. Treatment of ST88-14 cells with the hydrophilic fraction of methanolic extract of Ocimum Sanctum (OSHP-1) not only showed a dose dependent decrease in the above histone marks but also showed an increase in the expression of N-CAM 140KD, characteristic of mature Schwann cells, in addition to a significant decline in proliferation. Further evaluation of the nuclear extracts showed that OSHP-1 treatment increased the expression of HDAC2, a component of NuRD complex and decreased that of lysine acetyl transferase 7 (KAT7) in a dose dependent manner suggesting that both HDAC2 and KAT7 may be responsible for the decrease in the acetylation of H3K27Ac and therefore reversal of the tumorigenic MPNSTs to a differentiated Schwann cell phenotype. Chromatin immunoprecipitation (ChIP) data revealed H3K27Ac occupancy on candidate genes (PAX2, FOXN4, IGF2 and TLX1) promoters was reduced by OSHP-1 treatment. In conclusion, OSHP-1 reprograms the epigenome and may be an effective treatment option for NF1 associated MPNSTs. Citation Format: Chandra S. Mayanil, Mariam M. Khan, Vineet Mohanty, Raj Kumar, Guifa Xi, Shunsuke Ichi, Bal Ram Singh, Barbara Mania-Farnell, Tadanori Tomita. Reprogramming the epigenome as an effective treatment option for neurofibromatosis1 associated malignant peripheral nerve sheath tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2084.

Schwann cells regulate sensory neuron gene expression before and after peripheral nerve injury.

Sensory neurons in the PNS demonstrate substantial capacity for regeneration following injury. Recent studies have identified changes in the transcriptome of sensory neurons, which are instrumental for axon regeneration. The role of Schwann cells (SCs) in mediating these changes remains undefined. We tested the hypothesis that SCs regulate expression of genes in sensory neurons before and after PNS injury by comparing mice in which LDL Receptor-related Protein-1 (LRP1) is deleted in SCs (scLRP1-/- mice) with wild-type (scLRP1+/+ ) littermates. LRP1 is an endocytic and cell-signaling receptor that is necessary for normal SC function and the SC response to nerve injury. scLRP1-/- mice represent a characterized model in which the SC response to nerve injury is abnormal. Adult DRG neurons, isolated from scLRP1-/- mice, with or without a conditioning nerve lesion, demonstrated increased neurite outgrowth when cultured ex vivo, compared with neurons from wild-type mice. Following sciatic nerve crush injury, nerve regeneration was accelerated in vivo in scLRP1-/- mice. These results were explained by transcriptional activation of RAGs in DRG neurons in scLRP1-/- mice prior to nerve injury. Although the presence of abnormal SCs in scLRP1-/- mice primed DRG neurons for repair, nerve regeneration in scLRP1-/- mice resulted in abnormalities in ultrastructure, principally in Remak bundles, and with the onset of neuropathic pain. These results demonstrate the importance of SCs in controlling RAG expression by neurons and the potential for this process to cause chronic pain when abnormal. The SC may represent an important target for preventing pain following PNS injury.

A murine model of Charcot-Marie-Tooth disease 4F reveals a role for the C-terminus of periaxin in the formation and stabilization of Cajal bands

Charcot-Marie-Tooth (CMT) disease comprises up to 80 monogenic inherited neuropathies of the peripheral nervous system (PNS) that collectively result in demyelination and axon degeneration. The majority of CMT disease is primarily either dysmyelinating or demyelinating in which mutations affect the ability of Schwann cells to either assemble or stabilize peripheral nerve myelin. CMT4F is a recessive demyelinating form of the disease caused by mutations in the Periaxin ( PRX) gene . Periaxin (Prx) interacts with Dystrophin Related Protein 2 (Drp2) in an adhesion complex with the laminin receptor Dystroglycan (Dag). In mice the Prx/Drp2/Dag complex assembles adhesive domains at the interface between the abaxonal surface of the myelin sheath and the cytoplasmic surface of the Schwann cell plasma membrane. Assembly of these appositions causes the formation of cytoplasmic channels called Cajal bands beneath the surface of the Schwann cell plasma membrane. Loss of either Periaxin or Drp2 disrupts the appositions and causes CMT in both mouse and man. In a mouse model of CMT4F, complete loss of Periaxin first prevents normal Schwann cell elongation resulting in abnormally short internodal distances which can reduce nerve conduction velocity, and subsequently precipitates demyelination. Distinct functional domains responsible for Periaxin homodimerization and interaction with Drp2 to form the Prx/Drp2/Dag complex have been identified at the N-terminus of Periaxin. However, CMT4F can also be caused by a mutation that results in the truncation of Periaxin at the extreme C-terminus with the loss of 391 amino acids. By modelling this in mice, we show that loss of the C-terminus of Periaxin results in a surprising reduction in Drp2. This would be predicted to cause the observed instability of both appositions and myelin, and contribute significantly to the clinical phenotype in CMT4F.

A murine model of Charcot-Marie-Tooth disease 4F reveals a role for the C-terminus of periaxin in the formation and stabilization of Cajal bands.

Charcot-Marie-Tooth (CMT) disease comprises up to 80 monogenic inherited neuropathies of the peripheral nervous system (PNS) that collectively result in demyelination and axon degeneration. The majority of CMT disease is primarily either dysmyelinating or demyelinating in which mutations affect the ability of Schwann cells to either assemble or stabilize peripheral nerve myelin. CMT4F is a recessive demyelinating form of the disease caused by mutations in the Periaxin ( PRX) gene . Periaxin (Prx) interacts with Dystrophin Related Protein 2 (Drp2) in an adhesion complex with the laminin receptor Dystroglycan (Dag). In mice the Prx/Drp2/Dag complex assembles adhesive domains at the interface between the abaxonal surface of the myelin sheath and the cytoplasmic surface of the Schwann cell plasma membrane. Assembly of these appositions causes the formation of cytoplasmic channels called Cajal bands beneath the surface of the Schwann cell plasma membrane. Loss of either Periaxin or Drp2 disrupts the appositions and causes CMT in both mouse and man. In a mouse model of CMT4F, complete loss of Periaxin first prevents normal Schwann cell elongation resulting in abnormally short internodal distances which can reduce nerve conduction velocity, and subsequently precipitates demyelination. Distinct functional domains responsible for Periaxin homodimerization and interaction with Drp2 to form the Prx/Drp2/Dag complex have been identified at the N-terminus of Periaxin. However, CMT4F can also be caused by a mutation that results in the truncation of Periaxin at the extreme C-terminus with the loss of 391 amino acids. By modelling this in mice, we show that loss of the C-terminus of Periaxin results in a surprising reduction in Drp2. This would be predicted to cause the observed instability of both appositions and myelin, and contribute significantly to the clinical phenotype in CMT4F.

Analyzing the DNA methylation differentiation of proliferation associated genes between activated Schwann cell and normal Schwann cell

Analyzing the DNA methylation differentiation of proliferation associated genes between activated Schwann cell and normal Schwann cell

Drug sensitivity and resistance testing identifies PLK1 inhibitors and gemcitabine as potent drugs for malignant peripheral nerve sheath tumors.

Patients with malignant peripheral nerve sheath tumor (MPNST), a rare soft tissue cancer associated with loss of the tumor suppressor neurofibromin (NF1), have poor prognosis and typically respond poorly to adjuvant therapy. We evaluated the effect of 299 clinical and investigational compounds on seven MPNST cell lines, two primary cultures of human Schwann cells, and five normal bone marrow aspirates, to identify potent drugs for MPNST treatment with few side effects. Top hits included Polo‐like kinase 1 (PLK1) inhibitors (volasertib and BI2536) and the fluoronucleoside gemcitabine, which were validated in orthogonal assays measuring viability, cytotoxicity, and apoptosis. DNA copy number, gene expression, and protein expression were determined for the cell lines to assess pharmacogenomic relationships. MPNST cells were more sensitive to BI2536 and gemcitabine compared to a reference set of 94 cancer cell lines. PLK1,RRM1, and RRM2 mRNA levels were increased in MPNST compared to benign neurofibroma tissue, and the protein level of PLK1 was increased in the MPNST cell lines compared to normal Schwann cells, indicating an increased dependence on these drug targets in malignant cells. Furthermore, we observed an association between increased mRNA expression of PLK1,RRM1, and RRM2 in patient samples and worse disease outcome, suggesting a selective benefit from inhibition of these genes in the most aggressive tumors.

KIR2DL5 mutation and loss underlies sporadic dermal neurofibroma pathogenesis and growth.

Dermal neurofibromas (DNFs) are benign peripheral nerve sheath tumors thought to originate from Schwann cell progenitors. These tumors represent one of the hallmarks of the neurofibromatosis type 1 (NF1) tumor predisposition syndrome, where they can number in the thousands. While NF1-DNFs arise due to mutations in the NF1 gene, the vast majority of DNFs occur sporadically (sp-DNFs), where the genetic etiology is currently unknown. Herein, we employed whole-exome sequencing of sp-DNFs to identify a recurrent mutation in the KIR2DL5 gene, which codes for a protein suppressor of natural killer (NK) cell activity. While the function of KIR2DL5 outside of the immune system is unknown, we identified a KIR2DL5N173D mutation in three of nine sp-DNFs, resulting in loss of KIR2DL5 protein expression. In contrast, two of these subjects had unrelated tumors, which retained KIR2DL5 protein expression. Moreover, loss of KIR2DL5 expression was demonstrated in 15 of 45 independently-identified sp-DNFs. Consistent with its potential role as a negative growth regulator important for neurofibroma maintenance, ectopic KIR2DL5N173D expression in normal human Schwann cells resulted in reduced KIR2DL5 expression and increased cell proliferation. Similarly, KIR2DL5 short hairpin RNA knockdown (KD) decreased KIR2DL5 protein levels and increased cell proliferation, as well as correlated with PDGFRβ and downstream RAS/AKT/mTOR hyperactivation. Importantly, inhibition of PDGFRβ or AKT/mTOR activity in KIR2DL5-KD human Schwann cells reduced proliferation to control levels. Collectively, these findings establish KIR2DL5 as a new Schwann cell growth regulator relevant to sp-DNF pathogenesis, which links sporadic and NF1-associated DNFs through RAS pathway hyperactivation.

OS08.7 The somatic landscape of Schwannoma

AbstractTo date, clinical trials for schwannomas, which are common cranial and spinal nerve tumors, have generated dismal results. This is largely due to a lack of fully understanding the somatic alterations that occur in schwannoma. To gain a comprehensive molecular understanding of Schwannoma, we performed an integrative multiplatform analysis to determine the genetic landscape of sporadic schwannomas. Exome sequence analysis with validation by targeted DNA-sequencing of 125 samples uncovered, in addition to expected NF2 disruption, recurrent mutations in ARID1A, ARID1B and DDR1. Genome wide methylation profiling revealed that schwannomas consists of two molecular subgroups with unique gene signatures and anatomical location. RNA sequencing revealed a recurrent in-frame gene fusion on chromosome 10q in 12/125 (10%) cases involving two gene partners, SH3PXD2A and HTRA1. Further genomic analysis identified the mechanism to be from a balanced 19Mb chromosomal inversion. The presence of the fusion was associated with male gender predominance, occurring in one out of every six men with schwannoma. Expression of the fusion in both schwannomas and normal schwann cells resulted in elevated phosphorylated-ERK, increased proliferation, increased invasion and resulted in the formation of in vivo xenografts. Furthermore, the fusion increased cell invasion and enhanced protease activity. Targeting of the MEK/ERK pathway was effective in fusion-positive Schwann cells, suggesting a possible therapeutic approach for this subset of tumors.

An inflammatory gene signature distinguishes neurofibroma Schwann cells and macrophages from cells in the normal peripheral nervous system

Neurofibromas are benign peripheral nerve tumors driven by NF1 loss in Schwann cells (SCs). Macrophages are abundant in neurofibromas, and macrophage targeted interventions may have therapeutic potential in these tumors. We generated gene expression data from fluorescence-activated cell sorted (FACS) SCs and macrophages from wild-type and mutant nerve and neurofibroma to identify candidate pathways involved in SC-macrophage cross-talk. While in 1-month-old Nf1 mutant nerve neither SCs nor macrophages significantly differed from their normal counterparts, both macrophages and SCs showed significantly altered cytokine gene expression in neurofibromas. Computationally reconstructed SC-macrophage molecular networks were enriched for inflammation-associated pathways. We verified that neurofibroma SC conditioned medium contains macrophage chemo-attractants including colony stimulation factor 1 (CSF1). Network analysis confirmed previously implicated pathways and predict novel paracrine and autocrine loops involving cytokines, chemokines, and growth factors. Network analysis also predicted a central role for decreased type-I interferon signaling. We validated type-I interferon expression in neurofibroma by protein profiling, and show that treatment of neurofibroma-bearing mice with polyethylene glycolyated (PEGylated) type-I interferon-α2b reduces the expression of many cytokines overexpressed in neurofibroma. These studies reveal numerous potential targetable interactions between Nf1 mutant SCs and macrophages for further analyses.

Comparison of DNA Methylation in Schwann Cells before and after Peripheral Nerve Injury in Rats.

This study aims to find the difference of genomewide DNA methylation in Schwann cells (SCs) before and after peripheral nerve system (PNS) injury by Methylated DNA Immunoprecipitation Sequencing (MeDIP-Seq) and seek meaningful differentially methylated genes related to repairment of injured PNS. SCs harvested from sciatic nerve were named as activated Schwann cells (ASCs), and the ones harvested from brachial plexus were named as normal Schwann cells (NSCs). Genomic DNA of ASCs and NSCs were isolated and MeDIP-Seq was conducted. Differentially methylated genes and regions were discovered and analyzed by bioinformatic methods. MeDIP-Seq analysis showed methylation differences were identified between ASCs and NSCs. The distribution of differentially methylated regions (DMRs) peaks in different components of genome was mainly located in distal intergenic regions. GO and KEGG analysis of these methylated genes were also conducted. The expression patterns of hypermethylated genes (Dgcr8, Zeb2, Dixdc1, Sox2, and Shh) and hypomethylated genes (Gpr126, Birc2) detected by qRT-PCR were opposite to the MeDIP analysis data with significance (p < 0.05), which proved MeDIP analysis data were real and believable. Our data serve as a basis for understanding the injury-induced epigenetic changes in SCs and the foundation for further studies on repair of PNS injury.

Schwann cells induce cancer cell dispersion and invasion.

Nerves enable cancer progression, as cancers have been shown to extend along nerves through the process of perineural invasion, which carries a poor prognosis. Furthermore, the innervation of some cancers promotes growth and metastases. It remains unclear, however, how nerves mechanistically contribute to cancer progression. Here, we demonstrated that Schwann cells promote cancer invasion through direct cancer cell contact. Histological evaluation of murine and human cancer specimens with perineural invasion uncovered a subpopulation of Schwann cells that associates with cancer cells. Coculture of cancer cells with dorsal root ganglion extracts revealed that Schwann cells direct cancer cells to migrate toward nerves and promote invasion in a contact-dependent manner. Upon contact, Schwann cells induced the formation of cancer cell protrusions in their direction and intercalated between the cancer cells, leading to cancer cell dispersion. The formation of these processes was dependent on Schwann cell expression of neural cell adhesion molecule 1 (NCAM1) and ultimately promoted perineural invasion. Moreover, NCAM1-deficient mice showed decreased neural invasion and less paralysis. Such Schwann cell behavior reflects normal Schwann cell programs that are typically activated in nerve repair but are instead exploited by cancer cells to promote perineural invasion and cancer progression.

Oncolytic measles virus as a novel therapy for malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors (MPNSTs) are devastating soft tissue sarcomas that can arise sporadically or in association with neurofibromatosis type I, have a poor prognosis, and have limited treatment options. Oncolytic measles virus therapy has been demonstrated to have significant antitumor properties in a number of different cancers, but the oncolytic potential of a MV Edmonston (MVEdm) vaccine strain engineered to express the human sodium iodide symporter (MV-NIS) on MPNST has not previously been evaluated. MPNST cell lines were found to highly express CD46, a cellular receptor required for measles viral entry, on their cell surface. After in vitro MV-NIS infection, MPNST cell lines showed significant cytopathic effect (CPE), while normal Schwann cells were less susceptible to CPE. Virus localization and distribution could be monitored by imaging of I-125 uptake. Local administration of MV-NIS into MPNST-derived tumors resulted in significant regression of tumor and improved survival. These results demonstrate feasibility of oncolytic measles virus therapy for MPNST patients and the possibility of a novel treatment for patients with NF1 tumors.

Upregulation of galectin-3 in immortalized Schwann cells IFRS1 under diabetic conditions

A spontaneously immortalized adult Fischer rat Schwann cell line IFRS1 retains the characteristic features of normal Schwann cells, and can be a useful tool for the study of diabetic neuropathy. In the present study, we examined the effects of high glucose and 3-deoxyglucosone (3-DG) on the viability and the protein expression of advanced glycation endproducts (AGE)-binding proteins, such as galectin-3 (GAL-3) and receptor for AGE (RAGE) in IFRS1 cells. Exposure to 30mM of glucose or 0.2mM of 3-DG for 7 days failed to impair the IFRS1 cell viability, but significantly upregulated the expression of GAL-3. The same exposure tended to increase the expression of RAGE, but the changes were not significant. The high glucose-induced upregulation of GAL-3 was attenuated by cotreatment with 0.2mM of an anti-glycated agent aminoguanidine or 20nM of an anti-oxidant trans-resveratrol. In addition, treatment of IFRS1 cells with 1μg/ml of recombinant GAL-3 for 48h resulted in the upregulation of B-cell lymphoma 2 (Bcl-2) and the downregulation of 4-hydroxynonenal (4HNE). These findings suggest the involvement of GAL-3 in the glycation and oxidative stress under diabetic conditions and its cytoprotective role in Schwann cells.

Abstract 2770: MGAT5B expression in malignant peripheral nerve sheath tumors and RAS-mutated tumors promote maturation of tyrosine kinase receptors through a PI3K/AKT/MGAT5B mechanism

Abstract Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas that occur either sporadically or in patients with Neurofibromatosis type I. Surgery is the main stay of treatment, however, due to the invasive growth, propensity to metastasis, limited sensitivity to chemotherapy and radiation therapy, 5-year survival rates is only 20%-50%. Recent studies have identified several altered intracellular signal transduction cascades and deregulated expression of kinase receptors in MPNSTs, posing the possibility of personalized, targeted therapeutics for these diseases. Kinase receptors depend on the glycosylation for stabilization, maturation, transport onto the cell surface, phosphorylation and activation. Aberrant glycosylation to stabilize the expression of kinase receptors on the cell surface is associated with many cancers. The appropriate and accurate modification of glycans to proteins mainly depends on the action of highly specific and precisely located enzymes known as glycosyltransferases and glycosidases in different tissues and cells. In this report, we found that glycoproteins were highly expressed in MPNST cell lines compared with normal Schwann cells (NSC). We used the Human Glycosylation PCR Array to profile the expression of 84 key genes encoding enzymes that regulate protein glycosylation. We did not identify any change in glycosidase mRNA expression levels, whereas multiple glycosyltransferases (B4GALT5, FUT8, MGAT3, MGAT4A, MGAT5, MGAT5B, GALNT13, GALNT14, POMT1, ST8SIA2) were overexpressed in different MPNST cell lines. This is especially true for MGAT5B, a glycosyltransferase that promotes N-linked or O-linked protein glycosylation, which was highly expressed in all MPNST cell lines, many MPNST clinical specimens, as well as colon and pancreatic cancer cell lines with K-ras mutations. Exogenous expression of K-ras (G12V) significantly upregulated MGAT5B expression to promote glycosylation of several tyrosine kinase receptors, whereas knockdown of MGAT5B significantly inhibited the glycosylation and phosphorylation of these kinase receptors. Moreover, we found AKT interacted with and phosphorylated Ser192 in MGAT5B to promote MGAT5B transport from the cytoplasm to the Golgi apparatus. Mutated MGAT5BS192A protein stayed in the cytoplasm significantly attenuated experimental lung tumor metastasis in vivo. Furthermore treatment of MPNST cells with the PI3K inhibitor Ly294002 inhibited MGAT5B glycosyltransferase activity to attenuate glycosylation and phosphorylation of tyrosine kinase receptors. Taken together, these data suggest that RAS-mediated MGAT5B expression plays a critical role in promoting glycosylation of many kinase receptors. Targeting MGAT5B-mediated protein glycosylation may open a new therapeutic window for the treatment of MPNSTs and RAS-related malignancies. Citation Format: Quansheng Zhu, Hui Shang, Yechun Song, Yi Zhang, Raphael Pollock, Steven Hsesheng Lin. MGAT5B expression in malignant peripheral nerve sheath tumors and RAS-mutated tumors promote maturation of tyrosine kinase receptors through a PI3K/AKT/MGAT5B mechanism. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2770. doi:10.1158/1538-7445.AM2014-2770