In this study, we report that the leucine-rich domain (LRD) of neurofibromin inhibits invasion of human glioblastoma cells without affecting their proliferation.
A recent genome-wide analysis has shown frequent NF1 gene alterations in the mesenchymal subtype of a glioblastoma; however, little is known about clinicopathological features of glioblastomas in NF1 patients (NF1 glioblastomas).We analyzed four NF1 glioblastomas.
Mutation of <i>NF1</i> or loss of the NF1 protein is also observed in glioblastoma, lung adenocarcinoma, and ovarian cancer among other sporadic cancers.
Using RNAseq data from The Cancer Genome Atlas (TCGA), we trained an ensemble of 500 logistic regression classifiers that integrates mutation status with whole transcriptomes to predict NF1 inactivation in glioblastoma (GBM).
Specifically, we demonstrate that neurofibromin, phosphorylated on Ser2808, a residue adjacent to a nuclear localization signal in the C-terminal domain (CTD), by Protein Kinase C-epsilon (PKC-ε), accumulates in a Ran-dependent manner and through binding to lamin in the nucleus at G2 in glioblastoma cells.
Tumors with NF1/Ch17 loss were predominantly adult GBM (4/5); lacked EGFR amplification (0/4), strong p53 immunolabeling (1/5), or IDH1 (R132H) protein expression (0/5); but expressed the mesenchymal marker podoplanin in 4/5.
Thus, neurofibromin-deficient glioblastoma and mouse fibroblasts are enriched in Rac1-GTP, p-Pak1, p-LIMK1 and p-cofilin, with all proteins exhibiting decreased expression upon expression of NF1(1-1163) polypeptide.
However, no methylation was found at the NF1 promoter region in PA. To rule out that silencing of NF1 by promoter methylation is restricted to higher-grade astrocytomas, 15 pediatric WHO II degree and IV degree astrocytomas were analyzed: 12 astrocytomas II and 3 glioblastomas displayed no NF1 promoter methylation.