Genetic and epigenetic instability as an underlying driver of progression and aggressive behavior in IDH-mutant astrocytoma.

In recent years, the classification of adult-type diffuse gliomas has undergone a revolution, wherein specific molecular features now represent defining diagnostic criteria of IDH-wild-type glioblastomas, IDH-mutant astrocytomas, and IDH-mutant 1p/19q-codeleted oligodendrogliomas. With the introduction of the 2021 WHO CNS classification, additional molecular alterations are now integrated into the grading of these tumors, given equal weight to traditional histologic features. However, there remains a great deal of heterogeneity in patient outcome even within these established tumor subclassifications that is unexplained by currently codified molecular alterations, particularly in the IDH-mutant astrocytoma category. There is also significant intercellular genetic and epigenetic heterogeneity and plasticity with resulting phenotypic heterogeneity, making these tumors remarkably adaptable and robust, and presenting a significant barrier to the design of effective therapeutics. Herein, we review the mechanisms and consequences of genetic and epigenetic instability, including chromosomal instability (CIN), microsatellite instability (MSI)/mismatch repair (MMR) deficits, and epigenetic instability, in the underlying biology, tumorigenesis, and progression of IDH-mutant astrocytomas. We also discuss the contribution of recent high-resolution transcriptomics studies toward defining tumor heterogeneity with single-cell resolution. While intratumoral heterogeneity is a well-known feature of diffuse gliomas, the contribution of these various processes has only recently been considered as a potential driver of tumor aggressiveness. CIN has an independent, adverse effect on patient survival, similar to the effect of histologic grade and homozygous CDKN2A deletion, while MMR mutation is only associated with poor overall survival in univariate analysis but is highly correlated with higher histologic/molecular grade and other aggressive features. These forms of genomic instability, which may significantly affect the natural progression of these tumors, response to therapy, and ultimately clinical outcome for patients, are potentially measurable features which could aid in diagnosis, grading, prognosis, and development of personalized therapeutics.

Improved immunostaining of nanostructures and cells in human brain specimens through expansion-mediated protein decrowding.

Proteins are densely packed in cells and tissues, where they form complex nanostructures. Expansion microscopy (ExM) variants have been used to separate proteins from each other in preserved biospecimens, improving antibody access to epitopes. Here, we present an ExM variant, decrowding expansion pathology (dExPath), that can expand proteins away from each other in human brain pathology specimens, including formalin-fixed paraffin-embedded (FFPE) clinical specimens. Immunostaining of dExPath-expanded specimens reveals, with nanoscale precision, previously unobserved cellular structures, as well as more continuous patterns of staining. This enhanced molecular staining results in observation of previously invisible disease marker-positive cell populations in human glioma specimens, with potential implications for tumor aggressiveness. dExPath results in improved fluorescence signals even as it eliminates lipofuscin-associated autofluorescence. Thus, this form of expansion-mediated protein decrowding may, through improved epitope access for antibodies, render immunohistochemistry more powerful in clinical science and, perhaps, diagnosis.

CDKN2A mutations have equivalent prognostic significance to homozygous deletion in IDH-mutant astrocytoma.

Homozygous deletion of CDKN2A/B is currently considered a molecular signature for grade 4 in IDH-mutant astrocytomas, irrespective of tumor histomorphology. The 2021 WHO Classification of CNS Tumors does not currently include grading recommendations for histologically lower-grade (grade 2-3) IDH-mutant astrocytoma with CDKN2A mutation or other CDKN2A alterations, and little is currently known about the prognostic implications of these alternative CDKN2A inactivating mechanisms. To address this, we evaluated a cohort of institutional and publicly available IDH-mutant astrocytomas, 15 with pathogenic mutations in CDKN2A, 47 with homozygous CDKN2A deletion, and 401 with retained/wildtype CDKN2A. The IDH-mutant astrocytomas with mutant and deleted CDKN2A had significantly higher overall copy number variation compared to those with retained/wildtype CDKN2A, consistent with more aggressive behavior. Astrocytoma patients with CDKN2A mutation had significantly worse progression-free (p = 0.0025) and overall survival (p < 0.0001) compared to grade-matched patients with wildtype CDKN2A, but statistically equivalent progression-free survival and overall survival outcomes to patients with CDKN2A deletion. No significant survival difference was identified between CDKN2A mutant cases with or without loss of the second allele. These findings suggest that CDKN2A mutation has a detrimental effect on survival in otherwise lower-grade IDH-mutant astrocytomas, similar to homozygous CDKN2A deletion, and should be considered for future grading schemes.

DNA methylation of the promoter region at the CREB1 binding site is a mechanism for the epigenetic regulation of brain-specific PKMζ.

Protein kinase M zeta, PKMζ, is a brain enriched kinase with a well characterized role in Long-Term Potentiation (LTP), the activity-dependent strengthening of synapses involved in long-term memory formation. However, little is known about the molecular mechanisms that maintain the tissue specificity of this kinase. Here, we characterized the epigenetic factors, mainly DNA methylation, regulating PKMζ expression in the human brain. The PRKCZ gene has an upstream promoter regulating Protein kinase C ζ (PKCζ), and an internal promoter driving PKMζ expression. A demethylated region, including a canonical CREB binding site, situated at the internal promoter was only observed in human CNS tissues. The induction of site-specific hypermethylation of this region resulted in decreased CREB1 binding and downregulation of PKMζ expression. Noteworthy, CREB binding sites were absent in the upstream promoter of PRKCZ locus, suggesting a specific mechanism for regulating PKMζ expression. These observations were validated using a system of human neuronal differentiation from induced pluripotent stem cells (iPSCs). CREB1 binding at the internal promoter was detected only in differentiated neurons, where PKMζ is expressed. The same epigenetic mechanism in the context of CREB binding site was identified in other genes involved in neuronal differentiation and LTP. Additionally, aberrant DNA hypermethylation at the internal promoter was observed in cases of Alzheimer's disease, correlating with decreased expression of PKMζ in patient brains. Altogether, we present a conserved epigenetic mechanism regulating PKMζ expression and other genes enhanced in the CNS with possible implications in neuronal differentiation and Alzheimer's disease.

The extracellular matrix protein fibulin-3/EFEMP1 promotes pleural mesothelioma growth by activation of PI3K/Akt signaling.

Malignant pleural mesothelioma (MPM) is an aggressive tumor with poor prognosis and limited therapeutic options. The extracellular matrix protein fibulin-3/EFEMP1 accumulates in the pleural effusions of MPM patients and has been proposed as a prognostic biomarker of these tumors. However, it is entirely unknown whether fibulin-3 plays a functional role on MPM growth and progression. Here, we demonstrate that fibulin-3 is upregulated in MPM tissue, promotes the malignant behavior of MPM cells, and can be targeted to reduce tumor progression. Overexpression of fibulin-3 increased the viability, clonogenic capacity and invasion of mesothelial cells, whereas fibulin-3 knockdown decreased these phenotypic traits as well as chemoresistance in MPM cells. At the molecular level, fibulin-3 activated PI3K/Akt signaling and increased the expression of a PI3K-dependent gene signature associated with cell adhesion, motility, and invasion. These pro-tumoral effects of fibulin-3 on MPM cells were disrupted by PI3K inhibition as well as by a novel, function-blocking, anti-fibulin-3 chimeric antibody. Anti-fibulin-3 antibody therapy tested in two orthotopic models of MPM inhibited fibulin-3 signaling, resulting in decreased tumor cell proliferation, reduced tumor growth, and extended animal survival. Taken together, these results demonstrate for the first time that fibulin-3 is not only a prognostic factor of MPM but also a relevant molecular target in these tumors. Further development of anti-fibulin-3 approaches are proposed to increase early detection and therapeutic impact against MPM.

Alpha2beta1 Integrin Polymorphism in Diffuse Astrocytoma Patients.

Integrins are heterodimeric transmembrane glycoproteins resulting from the non-covalent association of an α and ß chain. The major integrin receptor for collagen/laminin, α2ß1 is expressed on a wide variety of cell types and plays an essential role in the adhesion of normal and tumor cells to the extracellular matrix. Integrin-triggered signaling pathways promote the invasion and survival of glioma cells by modifying the brain microenvironment. In this study, we investigated the association of a specific genetic polymorphism of integrin α2ß1 with the incidence of diffusely infiltrating astrocytoma and the progression of these tumors. Single-nucleotide polymorphism in intron 7 of the integrin ITGA2 gene was examined in 158 patients and 162 controls using polymerase chain reaction and restriction enzyme analysis. The ITGA2 genotype +/+ (with a BglII restriction site in both alleles) exhibited higher frequency in grade II astrocytoma compared to control (P = 0.02) whereas the genotype -/- (lacking the BglII site) correlated with the poorest survival rate (P = 0.04). In addition, in silico analyses of ITGA2 expression from low-grade gliomas (LGG, n = 515) and glioblastomas (GBM, n = 159) indicated that the higher expression of ITGA2 in LGG was associated with poor overall survival (P < 0.0001). However, the distribution of integrin ITGA2 BglII genotypes (+/+, +/-, -/-) was not significantly different between astrocytoma subgroups III and IV (P = 0.65, 0.24 and 0.33; 0.29, 0.48, 0.25, respectively) compared to control. These results suggest a narrow association between the presence of this SNP and indicate that further studies with larger samples are warranted to analyze the relation between tumor grade and overall survival, highlighting the importance of determining these polymorphisms for prognosis of astrocytomas.

Chromosomal instability in adult-type diffuse gliomas.

Chromosomal instability (CIN) is a fundamental property of cancer and a key underlying mechanism of tumorigenesis and malignant progression, and has been documented in a wide variety of cancers, including colorectal carcinoma with mutations in genes such as APC. Recent reports have demonstrated that CIN, driven in part by mutations in genes maintaining overall genomic stability, is found in subsets of adult-type diffusely infiltrating gliomas of all histologic and molecular grades, with resulting elevated overall copy number burden, chromothripsis, and poor clinical outcome. Still, relatively few studies have examined the effect of this process, due in part to the difficulty of routinely measuring CIN clinically. Herein, we review the underlying mechanisms of CIN, the relationship between chromosomal instability and malignancy, the prognostic significance and treatment potential in various cancers, systemic disease, and more specifically, in diffusely infiltrating glioma subtypes. While still in the early stages of discovery compared to other solid tumor types in which CIN is a known driver of malignancy, the presence of CIN as an early factor in gliomas may in part explain the ability of these tumors to develop resistance to standard therapy, while also providing a potential molecular target for future therapies.

Global DNA methylation profiling reveals chromosomal instability in IDH-mutant astrocytomas.

Diffusely infiltrating gliomas are among the most common central nervous system tumors in adults. Over the past decade, the subcategorization of these tumors has changed to include both traditional histologic features and more recently identified molecular factors. However, one molecular feature that has yet to be integrated is the presence/absence of chromosomal instability (CIN). Herein, we use global methylation profiling to evaluate a reference cohort of IDH-mutant astrocytomas with and without prior evidence of CIN (n = 42), and apply the resulting methylation-based characteristics to a larger test cohort of publicly-available IDH-mutant astrocytomas (n = 245). We demonstrate that IDH-mutant astrocytomas with evidence of CIN cluster separately from their chromosomally-stable counterparts. CIN cases were associated with higher initial histologic grade, altered expression patterns of genes related to CIN in other cancers, elevated initial total copy number burden, and significantly worse progression-free and overall survival. In addition, in a grade-for-grade analysis, patients with CIN-positive WHO grade 2 and 3 tumors had significantly worse survival. These results suggest that global methylation profiling can be used to discriminate between chromosomally stable and unstable IDH-mutant astrocytomas, and may therefore provide a reliable and cost-effective method for identifying gliomas with chromosomal instability and resultant poor clinical outcome.

Ko143 Reverses MDR in Glioblastoma via Deactivating P-Glycoprotein, Sensitizing a Resistant Phenotype to TMZ Treatment.

BACKGROUND/AIM: Over-expression of both P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP) has been associated with multidrug-resistance in glioblastoma (GBM). Though previously studied broad-spectrum inhibitors of drug efflux pumps have failed to progress in clinical studies due to in vivo toxicity, research into clinically viable targeted inhibitors is needed. This study evaluated the effects of Ko143, a non-toxic analog of fumitremorgin C, on temozolomide (TMZ) efficacy in resistant glioblastoma stem cells. MATERIALS AND METHODS: We used ATP-Glo assay to determine cell viabilities and flow cytometry to perform cell cycle analysis. Comparative gene expression was analysed through RT-qPCR. RESULTS: TMZ IC50 decreased 41.07% (p<0.01) in the resistant phenotype when delivered in combination with Ko143. Additionally, the TMZ-resistant phenotype (GBM146) displayed 44-fold greater P-gp expression than the TMZ-sensitive phenotype (GBM9) (p<0.01), yet a 0.6-fold lower BCRP expression. Ko143 potentiates TMZ efficacy and likely inhibits P-glycoprotein more potently than previously indicated. CONCLUSION: Further development of non-toxic, targeted inhibitors of drug efflux pumps for use in combinatorial chemotherapy may improve glioblastoma patient prognosis.

The scaffolding protein DLG5 promotes glioblastoma growth by controlling Sonic Hedgehog signaling in tumor stem cells.

BACKGROUND: Tumor invasion, a hallmark of malignant gliomas, involves reorganization of cell polarity and changes in the expression and distribution of scaffolding proteins associated with polarity complexes. The scaffolding proteins of the DLG family are usually downregulated in invasive tumors and regarded as tumor suppressors. Despite their important role in regulating neurodevelopmental signaling, the expression and functions of DLG proteins have remained almost entirely unexplored in malignant gliomas. METHODS: Western blot, immunohistochemistry, and analysis of gene expression were used to quantify DLG members in glioma specimens and cancer datasets. Over-expression and knockdown of DLG5, the highest-expressed DLG member in glioblastoma, were used to investigate its effects on tumor stem cells and tumor growth. qRT-PCR, Western blotting, and co-precipitation assays were used to investigate DLG5 signaling mechanisms. RESULTS: DLG5 was upregulated in malignant gliomas compared to other solid tumors, being the predominant DLG member in all glioblastoma molecular subtypes. DLG5 promoted glioblastoma stem cell invasion, viability, and self-renewal. Knockdown of this protein in vivo disrupted tumor formation and extended survival. At the molecular level, DLG5 regulated Sonic Hedgehog (Shh) signaling, making DLG5-deficient cells insensitive to Shh ligand. Loss of DLG5 increased the proteasomal degradation of Gli1, underlying the loss of Shh signaling and tumor stem cell sensitization. CONCLUSIONS: The high expression and pro-tumoral functions of DLG5 in glioblastoma, including its dominant regulation of Shh signaling in tumor stem cells, reveal a novel role for this protein that is strikingly different from its proposed tumor-suppressor role in other solid tumors.

Indisulam Reduces Viability and Regulates Apoptotic Gene Expression in Pediatric High-Grade Glioma Cells.

Pediatric high-grade glioma (pHGG) is one of the most aggressive brain tumors. Treatment includes surgery, radiotherapy, chemotherapy, or combination therapy in children older than 3−5 years of age. These devastating tumors are influenced by the hypoxic microenvironment that coordinatively increases the expression of carbonic anhydrases (CA9 and CA12) that are involved in pH regulation, metabolism, cell invasion, and resistance to therapy. The synthetic sulphonamide Indisulam is a potent inhibitor of CAs. The aim of this study was to evaluate the effects of Indisulam on CA9 and CA12 enzymes in pHGG cell lines. Our results indicated that, under hypoxia, the gene and protein expression of CA9 and CA12 are increased in pHGG cells. The functional effects of Indisulam on cell proliferation, clonogenic capacity, and apoptosis were measured in vitro. CA9 and CA12 gene and protein expression were analyzed by RT-PCR and western blot. The treatment with Indisulam significantly reduced cell proliferation (dose-time-dependent) and clonogenic capacity (p < 0.05) and potentiated the effect of apoptosis (p < 0.01). Indisulam promoted an imbalance in the anti-apoptotic BCL2 and pro-apoptotic BAX protein expression. Our results demonstrate that Indisulam contributes to apoptosis via imbalance of apoptotic proteins (BAX/BCL2) and suggests a potential to overcome chemotherapy resistance caused by the regulation these proteins.

Spatial progression and molecular heterogeneity of IDH-mutant glioblastoma determined by DNA methylation-based mapping.

Glioblastoma (GBM) is the most common malignant primary central nervous system (CNS) neoplasm in adults, and has an almost universally poor prognosis. Recently, an emphasis on genetic and epigenetic profiling has revealed a number of molecular features useful in the diagnostic and prognostic classification of GBM, advancing our understanding of the underlying features that make these tumors so aggressive and providing the rationale for the creation of better targeted therapeutics. One such method, DNA methylation profiling, has recently emerged as an important technique for the classification of CNS tumors, with diagnostic accuracy in some cases surpassing traditional methods. However, how DNA methylation profiles change with the course of the disease remains less understood. Here, we present a case of a 30-year-old male with primary IDH-mutant GBM with widespread recurrence and death two years later. Using unsupervised hierarchical clustering of methylation probes, we created a phylogenetic map to trace the tumor path as it spread from the initial biopsy site throughout the right hemisphere, across the corpus callosum to the contralateral hemisphere, and into the brainstem. We identified molecular divergence between the right and left hemisphere GBM samples marked by distinct copy number profile alterations, alterations in specific methylation sites, and regional loss of MGMT promoter methylation, providing a potential mechanism for treatment resistance in this case. In summary, this case both highlights the molecular diversity in GBM, and illustrates a novel use for methylation profiling in establishing a phylogenetic profile to allow for spatial mapping of tumor progression.

The Carbonic Anhydrase Inhibitor E7070 Sensitizes Glioblastoma Cells to Radio- and Chemotherapy and Reduces Tumor Growth.

Glioblastomas (GBMs), the most common and lethal primary brain tumor, show inherent infiltrative nature and high molecular heterogeneity that make complete surgical resection unfeasible and unresponsive to conventional adjuvant therapy. Due to their fast growth rate even under hypoxic and acidic conditions, GBM cells can conserve the intracellular pH at physiological range by overexpressing membrane-bound carbonic anhydrases (CAs). The synthetic sulfonamide E7070 is a potent inhibitor of CAs that harbors putative anticancer properties; however, this drug has still not been tested in GBMs. The present study aimed to evaluate the effects of E7070 on CA9 and CA12 enzymes in GBM cells as well as in the tumor cell growth, migration, invasion, and resistance to radiotherapy and chemotherapy. We found that E7070 treatment significantly reduced tumor cell growth and increased radio- and chemotherapy efficacy against GBM cells under hypoxia. Our data suggests that E7070 has therapeutic potential as a radio-chemo-sensitizing in drug-resistant GBMs, representing an attractive strategy to improve the adjuvant therapy. We showed that CA9 and CA12 represent potentially valuable therapeutic targets that should be further investigated as useful diagnostic and prognostic biomarkers for GBM tailored therapy.

Targeting glioblastoma using a novel peptide specific to a deglycosylated isoform of brevican.

Glioblastoma multiforme (GBM) is the most common and deadliest form of brain tumor and remains amongst the most difficult cancers to treat. Brevican (Bcan), a central nervous system (CNS)-specific extracellular matrix protein, is upregulated in high-grade glioma cells, including GBM. A Bcan isoform lacking most glycosylation, dg-Bcan, is found only in GBM tissues. Here, dg-Bcan is explored as a molecular target for GBM. In this study, we screened a d-peptide library to identify a small 8-amino acid dg-Bcan-Targeting Peptide (BTP) candidate, called BTP-7 that binds dg-Bcan with high affinity and specificity. BTP-7 is preferentially internalized by dg-Bcan-expressing patient-derived GBM cells. To demonstrate GBM targeting, we radiolabeled BTP-7 with 18F, a radioisotope of fluorine, and found increased radiotracer accumulation in intracranial GBM established in mice using positron emission tomography (PET) imaging. dg-Bcan is an attractive molecular target for GBM, and BTP-7 represents a promising lead candidate for further development into novel imaging agents and targeted therapeutics.

Molecular Signatures of Chromosomal Instability Correlate With Copy Number Variation Patterns and Patient Outcome in IDH-Mutant and IDH-Wildtype Astrocytomas.

Chromosomal instability due to mutations in genes guarding the stability of the genome is a well-known mechanism underlying tumorigenesis and malignant progression in numerous cancers. The effect of this process in gliomas is mostly unknown with relatively little research examining the effects of chromosomal instability on patient outcome and therapeutic efficacy, although studies have shown that overall/total copy number variation (CNV) is elevated in higher histologic grades and in cases with more rapid progression and shorter patient survival. Herein, we examine a 70-gene mRNA expression signature (CIN70), which has been previously shown to correlate tightly with chromosomal instability, in 2 independent cohorts of IDH-mutant astrocytomas (total n = 241), IDH-wildtype astrocytomas (n = 228), and oligodendrogliomas (n = 128). Our results show that CIN70 expression levels correlate with total CNV, as well as higher grade, progression-free survival, and overall survival in both IDH-mutant and IDH-wildtype astrocytomas. In oligodendrogliomas, these mRNA signatures correlate with total CNV but not consistently with clinical outcome. These data suggest that chromosomal instability is an underlying factor in aggressive behavior and progression of a subset of diffuse astrocytomas. In addition, chromosomal instability may in part explain the poor response of diffuse gliomas to treatment and may serve as a future therapeutic target.

Anaplastic Transformation in Myxopapillary Ependymoma: A Report of 2 Cases and Review of the Literature.

Myxopapillary ependymoma (MPE) is a relatively common neoplasm arising primarily in the filum terminale/lumbosacral region of the spinal cord. It is designated as a grade I tumor in the most recent WHO Classification of Tumours of the CNS, although aggressive clinical behavior can be observed, especially in cases arising in an extradural location. Anaplastic transformation in MPE is exceedingly rare with <20 examples reported in the English literature, and consensus on diagnostic features and definitive grading remain to be determined. Here, we present 2 cases of recurrent MPE with anaplastic features, both of which had histology consistent with conventional MPE as well as areas with significant atypia, frequent mitotic figures, elevated Ki-67 proliferation indices (>10%-50%), necrosis, and focal vascular proliferation. Targeted next-generation sequencing panels revealed no definitive pathogenic mutations or fusion proteins in either case. Copy number profiling, methylation profiling, and t-Distributed Stochastic Neighbor Embedding were performed to investigate the molecular characteristics of these tumors. To the best of our knowledge, these are the first reported cases of MPE with anaplastic features with methylation profiling data. In addition, we review the literature and discuss common histologic and molecular findings associated with anaplastic features in MPE.

Molecular Correlates of Long Survival in IDH-Wildtype Glioblastoma Cohorts.

IDH-wildtype glioblastoma is a relatively common malignant brain tumor in adults. These patients generally have dismal prognoses, although outliers with long survival have been noted in the literature. Recently, it has been reported that many histologically lower-grade IDH-wildtype astrocytomas have a similar clinical outcome to grade IV tumors, suggesting they may represent early or undersampled glioblastomas. cIMPACT-NOW 3 guidelines now recommend upgrading IDH-wildtype astrocytomas with certain molecular criteria (EGFR amplifications, chromosome 7 gain/10 loss, and/or TERT promoter mutations), establishing the concept of a "molecular grade IV" astrocytoma. In this report, we apply these cIMPACT-NOW 3 criteria to 2 independent glioblastoma cohorts, totaling 393 public database and institutional glioblastoma cases: 89 cases without any of the cIMPACT-NOW 3 criteria (GBM-C0) and 304 cases with one or more criteria (GBM-C1-3). In the GBM-C0 groups, there was a trend toward longer recurrence-free survival (median 12-17 vs 6-10 months), significantly longer overall survival (median 32-41 vs 15-18 months), younger age at initial diagnosis, and lower overall mutation burden compared to the GBM-C1-3 cohorts. These data suggest that while histologic features may not be ideal indicators of patient survival in IDH-wildtype astrocytomas, these 3 molecular features may also be important prognostic factors in IDH-wildtype glioblastoma.

The protein tyrosine phosphatase RPTPζ/phosphacan is critical for perineuronal net structure.

Perineuronal nets (PNNs) are conspicuous neuron-specific substructures within the extracellular matrix of the central nervous system that have generated an explosion of interest over the last decade. These reticulated structures appear to surround synapses on the cell bodies of a subset of the neurons in the central nervous system and play key roles in both developmental and adult-brain plasticity. Despite the interest in these structures and compelling demonstrations of their importance in regulating plasticity, their precise functional mechanisms remain elusive. The limited mechanistic understanding of PNNs is primarily because of an incomplete knowledge of their molecular composition and structure and a failure to identify PNN-specific targets. Thus, it has been challenging to precisely manipulate PNNs to rigorously investigate their function. Here, using mouse models and neuronal cultures, we demonstrate a role of receptor protein tyrosine phosphatase zeta (RPTPζ) in PNN structure. We found that in the absence of RPTPζ, the reticular structure of PNNs is lost and phenocopies the PNN structural abnormalities observed in tenascin-R knockout brains. Furthermore, we biochemically analyzed the contribution of RPTPζ to PNN formation and structure, which enabled us to generate a more detailed model for PNNs. We provide evidence for two distinct kinds of interactions of PNN components with the neuronal surface, one dependent on RPTPζ and the other requiring the glycosaminoglycan hyaluronan. We propose that these findings offer important insight into PNN structure and lay important groundwork for future strategies to specifically disrupt PNNs to precisely dissect their function.

Total copy number variation as a prognostic factor in adult astrocytoma subtypes.

Since the discovery that IDH1/2 mutations confer a significantly better prognosis in astrocytomas, much work has been done to identify other molecular signatures to help further stratify lower-grade astrocytomas and glioblastomas, with the goal of accurately predicting clinical outcome and identifying potentially targetable mutations. In the present study, we subclassify 135 astrocytomas (67 IDH-wildtype and 68 IDH-mutant) from The Cancer Genome Atlas dataset (TCGA) on the basis of grade, IDH-status, and the previously established prognostic factors, CDK4 amplification and CDKN2A/B deletion, within the IDH-mutant groups. We analyzed these groups for total copy number variation (CNV), total mutation burden, chromothripsis, specific mutations, and amplifications/deletions of specific genes/chromosomal regions. Herein, we demonstrate that across all of these tumor groups, total CNV level is a relatively consistent prognostic factor. We also identified a trend towards increased levels of chromothripsis in tumors with lower progression-free survival (PFS) and overall survival (OS) intervals. While no significant differences were identified in overall mutation load, we did identify a significantly higher number of cases with mutations in genes with functions related to maintaining genomic stability in groups with higher mean CNV and worse PFS and OS intervals, particularly in the IDH-mutant groups. Our data further support the case for total CNV level as a potential prognostic factor in astrocytomas, and suggest mutations in genes responsible for overall genomic instability as a possible underlying mechanism for some astrocytomas with poor clinical outcome.

Intramuscular delivery of replication-defective herpes simplex virus gives antigen expression in muscle syncytia and improved protection against pathogenic HSV-2 strains.

Herpes simplex virus 2 (HSV-2) is the leading cause of genital herpes and increases the risk of HIV infection, but there is no effective vaccine. A replication-defective HSV-2 mutant virus, dl5-29, is effective in animal models and has been in a phase I trial. Previous studies have shown that dl5-29 gives higher antibody responses and better protection when inoculated intramuscularly (IM) as compared with subcutaneously (SC). However, the basis for this effect has not been defined. We confirmed that IM inoculation of dl5-29 is more immunogenic and provides better protection than SC inoculation. IM inoculation of HSV-2 strains produced higher levels of a luciferase transgene than SC inoculation, as measured by intravital bioluminescence imaging. Intramuscular immunization also showed better protection against infection with a highly pathogenic African HSV-2, demonstrating that this single vaccine can be efficacious against HSV-2 strains from different geographic regions.