Expression of Protein SOX9 in Biliary Atresia.

OBJECTIVES: Biliary atresia (BA) is still an enigmatic disease. Deeper knowledge of its pathophysiology could help develop better treatments. SOX9 regulates bile duct development, liver regeneration and fibrosis; therefore, it could be determinant in characterizing BA liver damage. Aim: To study if there is a SOX9 expression pattern in liver biopsies from BA patients. METHODS: Liver biopsies from BA patients (group BA), from age-matched infants without primary hepatic disease (group Control), and from patients with other liver conditions (group OLC) were compared. Expression of SOX9 was checked for: amount, intensity of immunoreaction, localization within ductular structures, perifibrotic epithelial cells, and lobular cells. The scores were added to create a scale from 0 to 11 that allowed group comparison. SOX9 Scale and liver survival were also looked for a correlation. RESULTS: All BA cases had a score >4, while all controls scored <4. OLC livers scored 1 to 8 (3.5 ±â€Š2.0) (P < 0.001 between all groups). A cut-off at 4 had 100% sensitivity and 88.24% specificity to differentiate BA from Controls and from OLC (area under receiver operating characteristic curve: 0.9989 (95% confidence interval: 0.9964-1.000). Strong expression of SOX9 was observed mainly in the nuclei of proliferated ductules of portal spaces and fibrotic bridges. SOX9 Scale score could not be related to liver survival in this study. CONCLUSION: In BA livers, SOX9 is mainly expressed in reactive ductular epithelium, following a pattern significantly different from that seen in non-BA patients; thus, SOX9 Scale may have a role in the diagnosis of BA.

EORTC SPECTA-AYA: A unique molecular profiling platform for adolescents and young adults with cancer in Europe.

For most adolescent and young adult (AYA) cancers, age-specific molecular features are poorly understood. EORTC-SPECTA, an academic translational research infrastructure for biomaterial collection, will explicitly recruit AYA patients and will therefore collect empirical data to bridge the molecular gap between pediatric and adult oncology. The initial pilot study, activated in February 2019 across Europe, will recruit 100 AYA patients (aged 12-29 years) with newly diagnosed or relapsed high-grade gliomas and high-grade bone and soft tissue sarcomas. The primary objective of the pilot is to determine feasibility and recruitment rates. Formalin-fixed tumor tissue and whole blood from study participants will be prospectively collected with clinical data and stored centrally at the Integrated BioBank of Luxembourg. Whole exome sequencing of matched tumor and blood, and tumor RNA sequencing and DNA methylation profiling will be performed at the German Cancer Research Center, Heidelberg, Germany. Virtual central pathology review of scanned diagnostic slides will be undertaken by an international expert panel, and diagnostic material returned to the participating centers. A multidisciplinary molecular tumor board will release a clinically validated report to referring clinicians within 4-6 weeks after biopsy. SPECTA-AYA constitutes a major opportunity to gain knowledge about the tumor biology of this unique age group. It incorporates notable innovative aspects: AYA specificity, pan-European academic collaboration, centralized biobanking, comprehensive molecular profiling and virtual central pathology review, among others. SPECTA-AYA will help untangle the tumor particularities of AYAs with cancer and aims to improve their access to novel drugs and personalized medicine.

Midline Cervical Cleft: An Anatomical Finding and a Proposal for a New Approach.

Congenital midline cervical cleft is a rare malformation. Typical case shows an area of hypotrophic skin, a cranial nipple-like structure, and a caudal blind sinus. Cervical extension is limited. Relapse of the retraction is common following cutaneous z-plasty. The aim of this study is to describe the radiological, surgical, and histological findings of the 4 cases treated in our center in the last 8 years and communicate the finding of a contractile structure, anterior to the platysma, composed by striated muscle, figure not previously described. This distinct muscular band is responsible for neck retraction. Removal of this releases cervical tension and is essential to avoid the relapse.

Prognostic value of stem cell markers in glioblastoma.

Background/Context: Glioblastoma (GB) is the most common primary brain tumour in adults and it is associated with a high mortality rate. According to the stem cell theory, the growth, relapse and treatment response of GB is determined by the stem cell subpopulation present in the tumour. Objective: Our aim is to study the prognostic value of stem cell markers (CD44, Nestin, Olig2 and SOX2) in a series of homogeneously treated GBs. Material and methods: We study 280 GBs treated with STUPP acheme with a histologican review of the cases and TMA with a máximum of 4 spots for each case. Each slide was immunohistochemically stained and Reading. We compared the immunohistochemical results with survival tme. Results: Only SOX2 immunoexpression (IE) excedding 10% of the tumour cells was found to be related to good survival (p= 0.037) in univariate analysis. However, amultivariate analysis indicate the age, surgery and MGMT promotes methylation but no SOX2 IE are prognostic factors. Conclusions: We conclude the immunohistochemical studies of stem cell markers in GB are not useful for predicting prognosis in daily practice.

Management in chordoid glioma: Avoiding the pitfalls in this rare and challenging entity.

Chordoid glioma (CG) of the third ventricle is an unusual neoplasm of glial nature, which is almost exclusively located in the anterior wall of the third ventricle, in close relation with the hypothalamus. Magnetic resonance images show CG as a suprasellar, hypo- to isointense mass, homogeneously enhancing after the administration of gadolinium. Since its description in 1998 by Brat et al., approximately 85 cases have been reported. Some of its pathological features are under discussion and its histological origin still remains unclear. In this study, we present a patient having this rare entity. We review the management of CG reported in literature. We also studied its pathological features, the postoperative mortality and morbidity related to radical surgical resection, and the implemented adjuvant therapies. Due to its classical clinical features and its close resemblance to other lesions in the region, it is an entity unlikely to be suspected prior to its histological diagnosis. Despite the benign nature of this tumor, the clinical outcome might be poor. Its treatment may represent a real challenge because it involves critical anatomical areas, leading to high postoperative morbidity and mortality rates. An initial minimally invasive management and adjuvant therapies, such as radiosurgery, in case of symptomatic recurrences, can be effective handling strategies.

KINFix--A formalin-free non-commercial fixative optimized for histological, immunohistochemical and molecular analyses of neurosurgical tissue specimens.

An optimal fixative should ideally combine the advantages of formalin fixation and freezing, allowing for good preservation of histology and molecular components, easy handling and storage, lack of toxicity, and low costs. Most of these criteria are fulfilled by ethanol-based solutions, and due to our good experience with the commercial RCL2 fixative, reflected by our published single-center trial, we initiated a multicenter ring trial. However, during its course, RCL2 was discontinued on the market. Therefore, we created our own agent, KINFix, composed of the same main constituents as RCL2, and employed it in our laboratory with similar results. Here we present our evaluation of the three fixatives formalin, RCL2, and KINFix from the perspective of histopathology as well as nucleic acid and protein analyses in comparison to fresh frozen tissues together with the multicenter ring trial data for RCL2. We observe that RCL2 and KINFix offer comparable histomorphology and superior template for molecular analyses than formalin. Moreover, KINFix as freely available fixative might overcome some of the difficulties related to the commercial agents. Therefore, we conclude that KINFix might be an attractive complement to formalin in tissue processing and advocate its use in neuropathological practice.

Impact on prognosis of the regional distribution of MGMT methylation with respect to the CpG island methylator phenotype and age in glioma patients.

Clinical and molecular prognostic factors in gliomas include age, IDH mutation, the glioma CpG island methylator phenotype (G-CIMP+) and promoter methylation of the O(6)-methylguanine DNA-methyltransferase (MGMT) gene. Among these markers, a predictive value was reported in glioblastomas (GBM) for MGMT promoter methylation, in particular in elderly GBM patients. In this study, methylation data from 46 glioma samples with the Illumina 450K platform were obtained and extended using external data to include a total of 247 glioma samples. Methylation analysis of the whole MGMT gene with this platform revealed two strongly survival-associated CpG regions within the promoter and the gene body, which were confirmed in a reported dataset of high grade-gliomas. Methylation at the promoter (CpG 25, cg12981137 and the prognostic model MGMT-STP27) and at the gene body CpG 165 (cg07933035), were significantly associated with better overall survival, and strongly correlated with G-CIMP+ status. In this series, the prognostic value of MGMT methylation at the promoter was not observed in G-CIMP- cases, although around 50 % of them were MGMT-methylated. These results were also obtained in an homogeneously-treated series of chemoradiated G-CIMP- GBMs analyzed by MSP and qMSP, and confirmed in a reported pyrosequencing-analyzed series of gliomas. Interestingly, in contrast to the MGMT promoter, gene body methylation was of prognostic value in G-CIMP-patients older than 65 years. Our study highlights the relevance of the prognostic value of the different regions of methylation throughout the MGMT gene that could be affected by specific G-CIMP profiles and age groups.

Prominent EMA 'dots' in tumour-induced Bergmann gliosis.

AIMS: To describe an unusual pattern of epithelial membrane antigen (EMA) immunoreactivity in highly proliferative human Bergmann glia. METHODS AND RESULTS: An immunohistochemical study was performed of postmortem cerebellar tissue from 18 adult patients with cerebellar damage of various aetiologies and 15 biopsies of diverse adult and paediatric cerebellar tumours. We observed marked proliferation of Bergmann glia with unusual prominent dot-like cytoplasmic EMA immunoreactivity in a case with extensive leptomeningeal sarcomatosis. Similar staining was not observed in association with other types of cerebellar pathology, except for other neoplastic conditions, such as leptomeningeal carcinomatosis, adult medulloblastoma, and pilocytic astrocytoma in children. At an ultrastructural level, the index case showed prominent endoplasmic reticulum with some intermediate filaments and lipofuscin granules, but no structures related to cilia or microvilli were observed. CONCLUSIONS: We consider that prominent EMA dots in Bergmann glia might represent excessive activation induced by an overlying leptomeningeal tumour that stimulates the expression of early developmental antigens. This observation suggests modulation of the glial phenotype when exposed to a neoplastic microenvironment that, in turn, might influence the regenerative potential of Bergmann glia.

Multiple organ involvement by alpha-synuclein pathology in Lewy body disorders.

Lewy body (LB) diseases are characterized by alpha-synuclein (AS) aggregates in the central nervous system (CNS). Involvement of the peripheral autonomic nervous system (pANS) is increasingly recognized, although less studied. The aim of this study was to systematically analyze the distribution and severity of AS pathology in the CNS and pANS. Detailed postmortem histopathological study of brain and peripheral tissues from 28 brain bank donors (10 with Parkinson's disease [PD], 5 with dementia with LB [DLB], and 13 with non-LB diseases including atypical parkinsonism and non-LB dementia). AS aggregates were found in the pANS of all 15 LB disease cases (PD, DLB) in stellate and sympathetic ganglia (100%), vagus nerve (86.7%), gastrointestinal tract (86.7%), adrenal gland and/or surrounding fat (53.3%), heart (100%), and genitourinary tract (13.3%), as well as in 1 case of incidental Lewy body disease (iLBD). A craniocaudal gradient of AS burden in sympathetic chain and gastrointestinal tract was observed. DLB cases showed higher amounts of CNS AS aggregates than PD cases, but this was not the case in the pANS. No pANS AS aggregates were detected in Alzheimer's disease (AD) cases with or without CNS AS aggregates. All pathologically confirmed LB disease cases including 1 case of iLBD had AS aggregates in the pANS with a craniocaudal gradient of pathology burden in sympathetic chain and gastrointestinal tract. AS was not detected in the pANS of any AD case. These findings may help in the search of peripheral AS aggregates in vivo for the early diagnosis of PD.

Flanagan's condensed protocol for neurodegenerative diseases. Implementation in a clinical autopsy setting with partial supervision of a neuropathologist.

The Condensed Protocol (CP) was originally developed for the evaluation of Alzheimer's Disease (AD) and other neurodegenerative diseases as a workable alternative to the complex and costly established autopsy guidelines. The study objective is to examine the degree of implementation of the CP in the pathology department of a third level university hospital in a period of 5 years. Clinical autopsies performed between 2016 and 2021 on patients aged 65 years or over and did not require a specific neuropathological examination were reviewed. Histological screening and staging of neurodegenerative diseases was performed using the original immunohistochemical stains. Out of 255 autopsies, 204 met the inclusion criteria and 190 could be reviewed. The CP was applied to 99 cases; histological signs of neurodegenerative disease were observed in 92. Sampling errors were detected in 59 cases. Immunohistochemical studies were performed in 68 cases. The diseases identified were: 31 cases of AD (12 low grade; 19 intermediate), 18 amyloid angiopathy, 15 primary age-related tauopathy, 6 argyrophilic grain disease, 3 progressive supranuclear palsy, 1 Lewy body disease (of 22 cases), and 2 limbic-predominant age TDP43 encephalopathy (of 5 cases). In 30 out of 83 cases, there was more severe vascular pathology in complete sections of frontal cortex and lentiform nucleus. The CP allows reliable detection and staging of AD and related neurodegenerative diseases in clinical autopsies. However, supervision by a neuropathologist seems necessary for a fully successful implementation of the CP in a clinical hospital setting.

Immunopathology of autoantibody-associated encephalitides: clues for pathogenesis.

Classical paraneoplastic encephalitis syndromes with 'onconeural' antibodies directed to intracellular antigens, and the recently described paraneoplastic or non-paraneoplastic encephalitides and antibodies against both neural surface antigens (voltage-gated potassium channel-complexes, N-methyl-d-aspartate receptors) and intracellular antigens (glutamic acid decarboxylase-65), constitute an increasingly recognized group of immune-mediated brain diseases. Evidence for specific immune mechanisms, however, is scarce. Here, we report qualitative and quantitative immunopathology in brain tissue (biopsy or autopsy material) of 17 cases with encephalitis and antibodies to either intracellular (Hu, Ma2, glutamic acid decarboxylase) or surface antigenic targets (voltage-gated potassium channel-complex or N-methyl-d-aspartate receptors). We hypothesized that the encephalitides with antibodies against intracellular antigens (intracellular antigen-onconeural and intracellular antigen-glutamic acid decarboxylase groups) would show neurodegeneration mediated by T cell cytotoxicity and the encephalitides with antibodies against surface antigens would be antibody-mediated and would show less T cell involvement. We found a higher CD8/CD3 ratio and more frequent appositions of granzyme-B(+) cytotoxic T cells to neurons, with associated neuronal loss, in the intracellular antigen-onconeural group (anti-Hu and anti-Ma2 cases) compared to the patients with surface antigens (anti-N-methyl-d-aspartate receptors and anti-voltage-gated potassium channel complex cases). One of the glutamic acid decarboxylase antibody encephalitis cases (intracellular antigen-glutamic acid decarboxylase group) showed multiple appositions of GrB-positive T cells to neurons. Generally, however, the glutamic acid decarboxylase antibody cases showed less intense inflammation and also had relatively low CD8/CD3 ratios compared with the intracellular antigen-onconeural cases. Conversely, we found complement C9neo deposition on neurons associated with acute neuronal cell death in the surface antigen group only, specifically in the voltage-gated potassium channel-complex antibody patients. N-methyl-d-aspartate receptors-antibody cases showed no evidence of antibody and complement-mediated tissue injury and were distinguished from all other encephalitides by the absence of clear neuronal pathology and a low density of inflammatory cells. Although tissue samples varied in location and in the stage of disease, our findings strongly support a central role for T cell-mediated neuronal cytotoxicity in encephalitides with antibodies against intracellular antigens. In voltage-gated potassium channel-complex encephalitis, a subset of the surface antigen antibody encephalitides, an antibody- and complement-mediated immune response appears to be responsible for neuronal loss and cerebral atrophy; the apparent absence of these mechanisms in N-methyl-d-aspartate receptors antibody encephalitis is intriguing and requires further study.

Atypical neuropathological sCJD-MM phenotype with abundant white matter Kuru-type plaques sparing the cerebellar cortex.

We describe an atypical neuropatholgical phenotype of sporadic Creutzfeldt-Jakob disease (sCJD) in a 64-year-old man presenting with a 5-month history of rapidly progressive dementia, comprising behavioral disturbances, memory complaints, disorientation and language alterations. MRI showed diffuse atrophy and hyperintensities in parietal, occipital, temporal and frontal cortices and left caudate nucleus on T2-weighted and fluid-attenuated inversion recovery images. No typical EEG alterations were observed. Repeated 14-3-3 assay was positive after a first negative test. Neuropathology showed classical CJD changes with small cortical foci of large confluent vacuoles and relatively well-preserved cerebellar cortex. The most striking feature was the presence of abundant Kuru-type plaques in both cerebral cortex and subcortical white matter. Sparse Kuru-type plaques were also seen in cerebellum, although only in white matter. Immunohistochemistry showed, in addition to unicentric plaques, diffuse synaptic and patchy perivacuolar, as well as plaque-like and periaxonal pathological prion protein deposits (PrP(res) ). Western blot studies demonstrated the co-occurrence of PrP(res) types 1 and 2 in frontal cortex and a relatively weak type 2 signal in cerebellum. PRNP genotyping revealed methionine homozygosity at codon 129 and excluded mutations. This case shows a previously undescribed combination of histopathological features which preclude its classification according to the current phenotypic and molecular sCJD classification. The observation demonstrates that Kuru-type amyloid plaques mainly involving the cerebral white matter may also occur in sCJD cases with short clinical course and the co-existence of PrP(res) types 1 and 2. This case further highlights the complexity of the correlations between histopathological phenotype and PrP(res) isotype in prion diseases.

Gal-1 Expression Analysis in the GLIOCAT Multicenter Study: Role as a Prognostic Factor and an Immune-Suppressive Biomarker.

Glioblastoma (GBM) is the most frequent primary malignant brain tumor and has a dismal prognosis. Unfortunately, despite the recent revolution of immune checkpoint inhibitors in many solid tumors, these have not shown a benefit in overall survival in GBM patients. Therefore, new potential treatment targets as well as diagnostic, prognostic, and/or predictive biomarkers are needed to improve outcomes in this population. The ß-galactoside binding protein Galectin-1 (Gal-1) is a protein with a wide range of pro-tumor functions such as proliferation, invasion, angiogenesis, and immune suppression. Here, we evaluated Gal-1 expression by immunohistochemistry in a homogenously treated cohort of GBM (the GLIOCAT project) and correlated its expression with clinical and molecular data. We observed that Gal-1 is a negative prognostic factor in GBM. Interestingly, we observed higher levels of Gal-1 expression in the mesenchymal/classical subtypes compared to the less aggressive proneural subtype. We also observed a Gal-1 expression correlation with immune suppressive signatures of CD4 T-cells and macrophages, as well as with several GBM established biomarkers, including SHC1, PD-L1, PAX2, MEOX2, YKL-40, TCIRG1, YWHAG, OLIG2, SOX2, Ki-67, and SOX11. Moreover, Gal-1 levels were significantly lower in grade 4 IDH-1 mutant astrocytomas, which have a better prognosis. Our results confirm the role of Gal-1 as a prognostic factor and also suggest its value as an immune-suppressive biomarker in GBM.

Post-mortem neuropathologic examination of a 6-case series of CAR T-cell treated patients.

Introduction: Chimeric antigen receptor (CAR) T-cell therapy is a promising immunotherapy for the treatment of refractory hematopoietic malignancies. Adverse events are common, and neurotoxicity is one of the most important. However, the physiopathology is unknown and neuropathologic information is scarce. Materials and methods: Post-mortem examination of 6 brains from patients that underwent CAR T-cell therapy from 2017 to 2022. In all cases, polymerase chain reaction (PCR) in paraffin blocks for the detection of CAR T cells was performed. Results: Two patients died of hematologic progression, while the others died of cytokine release syndrome, lung infection, encephalomyelitis, and acute liver failure. Two out of 6 presented neurological symptoms, one with extracranial malignancy progression and the other with encephalomyelitis. The neuropathology of the latter showed severe perivascular and interstitial lymphocytic infiltration, predominantly CD8+, together with a diffuse interstitial histiocytic infiltration, affecting mainly the spinal cord, midbrain, and hippocampus, and a diffuse gliosis of basal ganglia, hippocampus, and brainstem. Microbiological studies were negative for neurotropic viruses, and PCR failed to detect CAR T -cells. Another case without detectable neurological signs showed cortical and subcortical gliosis due to acute hypoxic-ischemic damage. The remaining 4 cases only showed a mild patchy gliosis and microglial activation, and CAR T cells were detected by PCR only in one of them. Conclusions: In this series of patients that died after CAR T-cell therapy, we predominantly found non-specific or minimal neuropathological changes. CAR T-cell related toxicity may not be the only cause of neurological symptoms, and the autopsy could detect additional pathological findings.

Glioblastoma TCGA Mesenchymal and IGS 23 Tumors are Identifiable by IHC and have an Immune-phenotype Indicating a Potential Benefit from Immunotherapy.

PURPOSE: Molecular subtype classifications in glioblastoma may detect therapy sensitivities. IHC would potentially allow the identification of molecular subtypes in routine clinical practice. EXPERIMENTAL DESIGN: Formalin-fixed, paraffin-embedded tumor samples of 124 uniformly treated, newly diagnosed patients with glioblastoma were submitted to RNA sequencing, IHC, and immune-phenotyping to identify differences in molecular subtypes associated with treatment sensitivities. RESULTS: We detected high molecular and IHC overlapping of the The Cancer Genome Atlas (TCGA) mesenchymal subtype with instrinsic glioma subtypes (IGS) cluster 23 and of the TCGA classical subtype with IGS cluster 18. IHC patterns, gene fusion profiles, and immune-phenotypes varied across subtypes. IHC revealed that the TCGA classical subtype was identified by high expression of EGFR and low expression of PTEN, while the mesenchymal subtype was identified by low expression of SOX2 and high expression of two antibodies, SHC1 and TCIRG1, selected on the basis of RNA differential transcriptomic expression. The proneural subtype was identified by frequent positive IDH1 expression and high Olig2 and Ki67 expression. Immune-phenotyping showed that mesenchymal and IGS 23 tumors exhibited a higher positive effector cell score, a higher negative suppressor cell score, and lower levels of immune checkpoint molecules. The cell-type deconvolution analysis revealed that these tumors are highly enriched in M2 macrophages, resting memory CD4+ T cells, and activated dendritic cells, indicating that they may be ideal candidates for immunotherapy, especially with anti-M2 and/or dendritic cell vaccination. CONCLUSIONS: There is a subset of tumors, frequently classified as mesenchymal or IGS cluster 23, that may be identified with IHC and could well be optimal candidates for immunotherapy.

Novel genomic alterations and mechanisms associated with tumor progression in oligodendroglioma and mixed oligoastrocytoma.

Combined 1p/19q deletions are very prevalent in oligodendrogliomas (OGs) and, to a lesser extent, in oligoastrocytomas (OAs). These losses are associated with responsiveness to therapy. Using array-based comparative genomic hybridization, we screened for recurrent genomic alterations in OG and oligoastrocytoma subtypes on chromosome 19. Concomitant 1p/19q loss was detected in most of the tumors with allelic loss, but array-based comparative genomic hybridization revealed some tumors to have unrelated 1p/19q arm losses, suggesting alternative mechanisms of loss to that related to the reported t(1;19) translocation. Analyses of 1p/19q loss by fluorescence in situ hybridization and loss of heterozygosity assays and correlations of genomic data with the Ki-67 proliferation marker were also performed. Four 1q (or 19p) and 2 1p (or 19q) fluorescence in situ hybridization probe signals together with homozygosity of the 1p/19q microsatellites suggested a hypothetical mechanism of genome duplication consecutive to the loss of the derivative chromosome der(1p;19q) from the t(1;19)(1q;19p) translocation. This genome duplication was frequent in high-grade OGs and was strongly correlated with Ki-67 expression; thus, it could be related to tumor progression. Finally, in addition to the frequent 1p/19q loss, we report a novel 17q amplified region in OGs with BIRC5 as one of the possible candidate target genes of the amplicon.

A Comparison of RNA-Seq Results from Paired Formalin-Fixed Paraffin-Embedded and Fresh-Frozen Glioblastoma Tissue Samples.

The molecular classification of glioblastoma (GBM) based on gene expression might better explain outcome and response to treatment than clinical factors. Whole transcriptome sequencing using next-generation sequencing platforms is rapidly becoming accepted as a tool for measuring gene expression for both research and clinical use. Fresh frozen (FF) tissue specimens of GBM are difficult to obtain since tumor tissue obtained at surgery is often scarce and necrotic and diagnosis is prioritized over freezing. After diagnosis, leftover tissue is usually stored as formalin-fixed paraffin-embedded (FFPE) tissue. However, RNA from FFPE tissues is usually degraded, which could hamper gene expression analysis. We compared RNA-Seq data obtained from matched pairs of FF and FFPE GBM specimens. Only three FFPE out of eleven FFPE-FF matched samples yielded informative results. Several quality-control measurements showed that RNA from FFPE samples was highly degraded but maintained transcriptomic similarities to RNA from FF samples. Certain issues regarding mutation analysis and subtype prediction were detected. Nevertheless, our results suggest that RNA-Seq of FFPE GBM specimens provides reliable gene expression data that can be used in molecular studies of GBM if the RNA is sufficiently preserved.

GPR56/ADGRG1 Inhibits Mesenchymal Differentiation and Radioresistance in Glioblastoma.

A mesenchymal transition occurs both during the natural evolution of glioblastoma (GBM) and in response to therapy. Here, we report that the adhesion G-protein-coupled receptor, GPR56/ADGRG1, inhibits GBM mesenchymal differentiation and radioresistance. GPR56 is enriched in proneural and classical GBMs and is lost during their transition toward a mesenchymal subtype. GPR56 loss of function promotes mesenchymal differentiation and radioresistance of glioma initiating cells both in vitro and in vivo. Accordingly, a low GPR56-associated signature is prognostic of a poor outcome in GBM patients even within non-G-CIMP GBMs. Mechanistically, we reveal GPR56 as an inhibitor of the nuclear factor kappa B (NF-κB) signaling pathway, thereby providing the rationale by which this receptor prevents mesenchymal differentiation and radioresistance. A pan-cancer analysis suggests that GPR56 might be an inhibitor of the mesenchymal transition across multiple tumor types beyond GBM.