Persistent GDNF Expression 45 Months after Putaminal Infusion of AAV2-GDNF in a Patient with Parkinson's Disease.

OBJECTIVE: Gene therapy by convection-enhanced delivery of type 2 adeno-associated virus-glial cell derived neurotrophic factor (AAV2-GDNF) to the bilateral putamina seeks to increase GDNF gene expression and treat Parkinson's disease (PD). METHODS: A 63-year-old man with advanced PD received AAV2-GDNF in a clinical trial. He died from pneumonia after anterior cervical discectomy and fusion 45 months later. An autopsy included brain examination for GDNF transgene expression. Putaminal catecholamine concentrations were compared to in vivo 18F-Fluorodopa (18F-FDOPA) positron emission tomography (PET) scanning results before and 18 months after AAV2-GDNF infusion. RESULTS: Parkinsonian progression stabilized clinically. Postmortem neuropathology confirmed PD. Bilateral putaminal regions previously infused with AAV2-GDNF expressed the GDNF gene. Total putaminal dopamine was 1% of control, confirming the striatal dopaminergic deficiency suggested by baseline 18F-DOPA-PET scanning. Putaminal regions responded as expected to AAV2-GDNF. CONCLUSION: After AAV2-GDNF infusion, infused putaminal regions showed increased GDNF gene expression, tyrosine hydroxylase immunoreactive sprouting, catechol levels, and 18F-FDOPA-PET signal, suggesting the regenerative potential of AAV2-GDNF in PD. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Developmentally Arrested Basket/Stellate Cells in Postnatal Human Brain as Potential Tumor Cells of Origin for Cerebellar Hemangioblastoma in von Hippel-Lindau Patients.

von Hippel-Lindau (VHL) disease is an autosomal dominant hereditary cancer disorder caused by a germline mutation in the VHL tumor suppressor gene. Loss of the wild-type allele results in VHL deficiency and the potential formation of cerebellar hemangioblastomas, which resemble embryonic hemangioblast proliferation and differentiation processes. Multiple, microscopic, VHL-deficient precursors, termed developmentally arrested structural elements (DASEs), consistently involve the cerebellar molecular layer in VHL patients, indicating the tumor site of origin. Unlike hemangioblastomas, however, cerebellar DASEs do not express brachyury, a mesodermal marker for hemangioblasts. In this study, neuronal progenitors occupying the molecular layer were investigated as tumor cells of origin. By immunohistochemistry, cerebellar DASEs and hemangioblastomas lacked immunoreactivity with antibody ZIC1 (Zic family member 1), a granule cell progenitor marker with concordance from oligonucleotide RNA expression array analyses. Rather, cerebellar DASEs and hemangioblastomas were immunoreactive with antibody PAX2 (paired box 2), a marker of basket/stellate cell progenitors. VHL cerebellar cortices also revealed PAX2-positive cells in Purkinje and molecular layers, resembling the histological and molecular development of basket/stellate cells in postnatal non-VHL mouse and human cerebella. These data suggest that VHL deficiency can result in the developmental arrest of basket/stellate cells in the human cerebellum and that these PAX2-positive, initiated cells await another insult or signal to form DASEs and eventually, tumors.

Altered SYNJ2BP-mediated mitochondrial-ER contacts in motor neuron disease.

Synaptojanin 2 binding protein (SYNJ2BP) is an outer mitochondrial membrane protein with a cytosolic PDZ domain that functions as a cellular signaling hub. Few studies have evaluated its role in disease. Here we use induced pluripotent stem cell (iPSC)-derived motor neurons and post-mortem tissue from patients with two hereditary motor neuron diseases, spinal and bulbar muscular atrophy (SBMA) and amyotrophic lateral sclerosis type 4 (ALS4), and show that SYNJ2BP expression is increased in diseased motor neurons. Similarly, we show that SYNJ2BP expression increases in iPSC-derived motor neurons undergoing stress. Using proteomic analysis, we found that elevated SYNJ2BP alters the cellular distribution of mitochondria and increases mitochondrial-ER membrane contact sites. Furthermore, decreasing SYNJ2BP levels improves mitochondrial oxidative function in the diseased motor neurons. Together, our observations offer new insight into the molecular pathology of motor neuron disease and the role of SYNJ2BP in mitochondrial dysfunction.

GL261 luciferase-expressing cells elicit an anti-tumor immune response: an evaluation of murine glioma models.

Preclinical models that reliably recapitulate the immunosuppressive properties of human gliomas are essential to assess immune-based therapies. GL261 murine glioma cells are widely used as a syngeneic animal model of glioma, however, it has become common practice to transfect these cells with luciferase for fluorescent tumor tracking. The aim of this study was to compare the survival of mice injected with fluorescent or non-fluorescent GL261 cells and characterize the differences in their tumor microenvironment. Mice were intracranially implanted with GL261, GL261 Red-FLuc or GL261-Luc2 cells at varying doses. Cytokine profiles were evaluated by proteome microarray and Kaplan-Meier survival analysis was used to determine survival differences. Median survival for mice implanted with 5 × 104 GL261 cells was 18 to 21 days. The GL261 Red-FLuc implanted mice cells did not reach median survival at any tumor dose. Mice injected with 3 × 105 GL261-Luc2 cells reached median survival at 23 days. However, median survival was significantly prolonged to 37 days in mice implanted with 5 × 104 GL261-Luc2 cells. Additionally, proteomic analyses revealed significantly elevated inflammatory cytokines in the supernatants of the GL261 Red-FLuc cells and GL261-Luc2 cells. Our data suggest that GL261 Red-FLuc and GL261-Luc2 murine models elicit an anti-tumor immune response by increasing pro-inflammatory modulators.

Traumatic microbleeds suggest vascular injury and predict disability in traumatic brain injury.

Traumatic microbleeds are small foci of hypointensity seen on T2*-weighted MRI in patients following head trauma that have previously been considered a marker of axonal injury. The linear appearance and location of some traumatic microbleeds suggests a vascular origin. The aims of this study were to: (i) identify and characterize traumatic microbleeds in patients with acute traumatic brain injury; (ii) determine whether appearance of traumatic microbleeds predict clinical outcome; and (iii) describe the pathology underlying traumatic microbleeds in an index patient. Patients presenting to the emergency department following acute head trauma who received a head CT were enrolled within 48 h of injury and received a research MRI. Disability was defined using Glasgow Outcome Scale-Extended ≤6 at follow-up. All magnetic resonance images were interpreted prospectively and were used for subsequent analysis of traumatic microbleeds. Lesions on T2* MRI were stratified based on 'linear' streak-like or 'punctate' petechial-appearing traumatic microbleeds. The brain of an enrolled subject imaged acutely was procured following death for evaluation of traumatic microbleeds using MRI targeted pathology methods. Of the 439 patients enrolled over 78 months, 31% (134/439) had evidence of punctate and/or linear traumatic microbleeds on MRI. Severity of injury, mechanism of injury, and CT findings were associated with traumatic microbleeds on MRI. The presence of traumatic microbleeds was an independent predictor of disability (P < 0.05; odds ratio = 2.5). No differences were found between patients with punctate versus linear appearing microbleeds. Post-mortem imaging and histology revealed traumatic microbleed co-localization with iron-laden macrophages, predominately seen in perivascular space. Evidence of axonal injury was not observed in co-localized histopathological sections. Traumatic microbleeds were prevalent in the population studied and predictive of worse outcome. The source of traumatic microbleed signal on MRI appeared to be iron-laden macrophages in the perivascular space tracking a network of injured vessels. While axonal injury in association with traumatic microbleeds cannot be excluded, recognizing traumatic microbleeds as a form of traumatic vascular injury may aid in identifying patients who could benefit from new therapies targeting the injured vasculature and secondary injury to parenchyma.

Programmed Death Ligand 1 Is a Negative Prognostic Marker in Recurrent Isocitrate Dehydrogenase-Wildtype Glioblastoma.

BACKGROUND: Checkpoint inhibition has demonstrated clinical efficacy in a variety of solid tumors. Reports of programmed death ligand 1 (PD-L1) expression in glioblastoma are highly variable (ranging from 6% to 88%) and its role as a prognostic marker has yielded conflicting results. OBJECTIVE: To validate the prevalence and prognostic role of PD-L1 expression in a large cohort of diffuse gliomas according to the 2016 revised WHO classification. METHODS: Using tissue microarrays, we compared 5 PD-L1 monoclonal antibodies (n = 56) and validated expression (n = 183) using quantitative immunohistochemistry (IHC) and RNA in situ hybridization (RISH). Expression data from The Cancer Genome Atlas (TCGA) and published studies were compared with clinical outcome. Multiplexed immunophenotyping was used to identify PD-L1+ cell populations in post-treatment glioblastoma. RESULTS: Using a 5% cut-off, PD-L1 expression was significantly associated with a poor prognosis in both histologically defined (n = 125, log-rank P < .001) and recurrent isocitrate dehydrogenase (IDH)-wildtype glioblastoma (n = 60, log-rank P = .015). PD-L1 remained a significant negative prognosticator in Cox regression analysis (hazard ratio: 1.96, P = .021). Analysis of TCGA data confirmed decreased overall survival in recurrent non-glioma CpG island methylator phenotype (G-CIMP) glioblastoma (n = 12, log-rank P = .023), but not in glioblastoma as a group (n = 444, log-rank P = .135). PD-L1 RISH showed a significant correlation with IHC (P < .0001). PD-L1 was observed in the proliferating perivascular stem cell and immune niche of post-treatment glioblastoma. CONCLUSION: A 5% PD-L1 expression cut-off identified a subset of glioblastoma that is associated with a worse clinical outcome. This association remained significant within the newly defined IDH-wildtype classification. These findings could have implications for patient stratification in future clinical trials of PD-1/PD-L1 blockade.

Repurposing propranolol as an antitumor agent in von Hippel-Lindau disease.

OBJECTIVEVon Hippel-Lindau disease (VHL) is a tumor predisposition syndrome characterized by CNS hemangioblastomas (HBs) and clear cell renal cell carcinomas (RCCs) due to hypoxia-inducible factor activation (pseudohypoxia). Because of the lack of effective medical therapies for VHL, HBs and RCCs account for significant morbidity and mortality, ultimately necessitating numerous neurological and renal surgeries. Propranolol is an FDA-approved pan-beta adrenergic antagonist with antitumor effects against infantile hemangiomas (IHs) and possibly VHL HBs. Here, the authors investigated the antitumor efficacy of propranolol against pseudohypoxia-driven VHL-HBs and VHL-RCCs.METHODSPatient-derived VHL-associated HBs (VHL-HBs) or 786-O-VHL-/- RCC cells were treated with clinically relevant concentrations of propranolol in vitro and assessed with viability assays, flow cytometry, quantitative real-time polymerase chain reaction, and western blotting. In vivo confirmation of propranolol antitumor activity was confirmed in athymic nude mice bearing 786-O xenograft tumors. Lastly, patients enrolled in a VHL natural history study (NCT00005902) were analyzed for incidental propranolol intake. Propranolol activity against VHL-HBs was assessed retrospectively with volumetric HB growth kinetic analysis.RESULTSPropranolol decreased HB and RCC viability in vitro with IC50 (half maximal inhibitory concentration) values of 50 µM and 200 µM, respectively. Similar to prior reports in infantile hemangiomas, propranolol induced apoptosis and paradoxically increased VEGF-A mRNA expression in patient-derived VHL-HBs and 786-O cells. While intracellular VEGF protein levels were not affected by propranolol treatment, propranolol decreased HIF expression in 786-O cells (7.6-fold reduction, p < 0.005). Propranolol attenuated tumor progression compared with control (33% volume reduction at 7 days, p < 0.005) in 786-O xenografted tumor-bearing mice. Three patients (harboring 25 growing CNS HBs) started propranolol therapy during the longitudinal VHL-HB study. HBs in these patients tended to grow slower (median growth rate 27.1 mm3/year vs 13.3 mm3/year) during propranolol treatment (p < 0.0004).CONCLUSIONSPropranolol decreases VHL-HB and VHL-related RCC viability in vitro likely by modulation of VEGF expression and by inducing apoptosis. Propranolol abrogates 786-O xenograft tumor progression in vivo, and retrospective clinical data suggest that propranolol curtails HB growth. These results suggest that propranolol may play a role in the treatment of VHL-related tumors.

Pedunculopontine Nucleus Cholinergic Deficiency in Cervical Dystonia.

BACKGROUND: The etiology of cervical dystonia is unknown. Cholinergic abnormalities have been identified in dystonia animal models and human imaging studies. Some animal models have cholinergic neuronal loss in the striatum and increased acetylcholinesterase activity in the pedunculopontine nucleus. OBJECTIVES: The objective of this study was to determine the presence of cholinergic abnormalities in the putamen and pedunculopontine nucleus in cervical dystonia human brain donors. METHODS: Formalin-fixed brain tissues were obtained from 8 cervical dystonia and 7 age-matched control brains (controls). Pedunculopontine nucleus was available in only 6 cervical dystonia and 5 controls. Neurodegeneration was evaluated pathologically in the putamen, pedunculopontine nucleus, and other regions. Cholinergic neurons were detected using choline acetyltransferase immunohistochemistry in the putamen and pedunculopontine nucleus. Putaminal cholinergic neurons were quantified. A total of 6 cervical dystonia patients and 6 age-matched healthy controls underwent diffusion tensor imaging to determine if there were white matter microstructural abnormalities around the pedunculopontine nucleus. RESULTS: Decreased or absent choline acetyltransferase staining was identified in all 6 pedunculopontine nucleus samples in cervical dystonia. In contrast, strong choline acetyltransferase staining was present in 4 of 5 pedunculopontine nucleus controls. There were no differences in pedunculopontine nucleus diffusion tensor imaging between cervical dystonia and healthy controls. There was no difference in numbers of putaminal cholinergic neurons between cervical dystonia and controls. CONCLUSIONS: Our findings suggest that pedunculopontine nucleus choline acetyltransferase deficiency represents a functional cholinergic deficit in cervical dystonia. Structural lesions and confounding neurodegenerative processes were excluded by absence of neuronal loss, gliosis, diffusion tensor imaging abnormalities, and beta-amyloid, tau, and alpha-synuclein pathologies. © 2018 International Parkinson and Movement Disorder Society.

Corticotropin releasing hormone can selectively stimulate glucose uptake in corticotropinoma via glucose transporter 1.

BACKGROUND: Pre-operative detection of corticotropin (ACTH) secreting microadenomas causing Cushing's disease (CD) improves surgical outcomes. Current best magnetic resonance imaging fails to detect up to 40% of these microadenomas. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) is specific, but not sensitive in detecting corticotropinomas. Theoretically, secretagogue stimulation with corticotropin releasing hormone (CRH) could improve detection of adenomas with 18F-FDG PET. Previous attempts with simultaneous CRH stimulation have failed to demonstrate increased 18F-FDG uptake in corticotropinomas. We hypothesized that CRH stimulation leads to a delayed elevation in glucose uptake in corticotropinomas. METHODS: Clinical data was analyzed for efficacy of CRH in improving 18FDG-PET detection of corticotropinomas in CD. Glucose transporter 1 (GLUT1) immunoreactivity was performed on surgical specimens. Ex-vivo, viable cells from these tumors were tested for secretagogue effects (colorimetric glucose uptake), and for fate of intracellular glucose (glycolysis stress analysis). Validation of ex-vivo findings was performed with AtT-20 cells. RESULTS: CRH increased glucose uptake in human-derived corticotroph tumor cells and AtT-20, but not in normal murine or human corticotrophs (p < 0.0001). Continuous and intermittent (1 h) CRH exposure increased glucose uptake in AtT-20 with maximal effect at 4 h (p = 0.001). Similarly, CRH and 8-Br-cAMP led to robust GLUT1 upregulation and increased membrane translocation at 2 h, while fasentin suppressed baseline (p < 0.0001) and CRH-mediated glucose uptake. Expectedly, intra-operatively collected corticotropinomas demonstrated GLUT1 overexpression. Lastly, human derived corticotroph tumor cells demonstrated increased glycolysis and low glucose oxidation. CONCLUSION: Increased and delayed CRH-mediated glucose uptake differentially occurs in adenomatous corticotrophs. Delayed secretagogue-stimulated 18F-FDG PET could improve microadenoma detection.

Discovery of Aquaporin-1 and Aquaporin-4 Expression in an Intramedullary Spinal Cord Ependymal Cyst: Case Report.

BACKGROUND: Intramedullary ependymal cysts of the spinal cord are rare, benign, fluid-filled cysts usually situated along the ventral surface of the spinal cord. Only 32 cases have been reported since they were first described. Thus, owing to the rarity at which these cysts are encountered, their management and pathogenesis remain controversial. Whereas some investigators have advocated for cystosubarachnoid shunt placement for symptomatic ependymal cysts, others have argued for complete cyst resection or simple fenestration. Here we report the case of a 56-year-old female with a T11-T12 ependymal cyst that was successfully managed with cyst fenestration. We further investigated a potential pathological mechanism of cyst formation by performing immunohistochemistry to detect aquaporin expression in the cyst lining. CASE DESCRIPTION: A 56-year-old female was found to harbor an enlarging cystic lesion of the conus that was discovered on workup of progressive paraparesis and urinary incontinence. She had lower extremity weakness and progressive myelopathy. Thoracic laminectomy with cyst fenestration arrested her neurologic deterioration. Pathological analysis revealed an intramedullary ependymal cyst. Immunohistochemistry was subsequently performed for expression of aquaporin-1 and aquaporin-4. There was dense staining of the underlying neuropil with concurrent membranous staining pattern of the cyst lining. CONCLUSIONS: Intramedullary ependymal cysts are rare, cystic lesions of the spinal cord. Early cyst fenestration decompresses the cyst and prevents neurologic deterioration. Here we report for the first time that aquaporins are expressed in the cyst wall, which is consistent with a passive, osmotic pathogenic mechanism of cyst formation.

First insight into the somatic mutation burden of neurofibromatosis type 2-associated grade I and grade II meningiomas: a case report comprehensive genomic study of two cranial meningiomas with vastly different clinical presentation.

BACKGROUND: Neurofibromatosis type 2 (NF2) is a rare autosomal dominant nervous system tumor predisposition disorder caused by constitutive inactivation of one of the two copies of NF2. Meningiomas affect about one half of NF2 patients, and are associated with a higher disease burden. Currently, the somatic mutation landscape in NF2-associated meningiomas remains largely unexamined. CASE PRESENTATION: Here, we present an in-depth genomic study of benign and atypical meningiomas, both from a single NF2 patient. While the grade I tumor was asymptomatic, the grade II tumor exhibited an unusually high growth rate: expanding to 335 times its initial volume within one year. The genomes of both tumors were examined by whole-exome sequencing (WES) complemented with spectral karyotyping (SKY) and SNP-array copy-number analyses. To better understand the clonal composition of the atypical meningioma, the tumor was divided in four sections and each section was investigated independently. Both tumors had second copy inactivation of NF2, confirming the central role of the gene in meningioma formation. The genome of the benign tumor closely resembled that of a normal diploid cell and had only one other deleterious mutation (EPHB3). In contrast, the chromosomal architecture of the grade II tumor was highly re-arranged, yet uniform among all analyzed fragments, implying that this large and fast growing tumor was composed of relatively few clones. Besides multiple gains and losses, the grade II meningioma harbored numerous chromosomal translocations. WES analysis of the atypical tumor identified deleterious mutations in two genes: ADAMTSL3 and CAPN5 in all fragments, indicating that the mutations were present in the cell undergoing fast clonal expansion CONCLUSIONS: This is the first WES study of NF2-associated meningiomas. Besides second NF2 copy inactivation, we found low somatic burden in both tumors and high level of genomic instability in the atypical meningioma. Genomic instability resulting in altered gene dosage and compromised structural integrity of multiple genes may be the primary reason of the high growth rate for the grade II tumor. Further study of ADAMTSL3 and CAPN5 may lead to elucidation of their molecular implications in meningioma pathogenesis.

Somatostatin receptor expression on von Hippel-Lindau-associated hemangioblastomas offers novel therapeutic target.

Von Hippel-Lindau (VHL)-associated hemangioblastomas (VHL-HB) arise in the central nervous system (CNS), and are a leading cause of morbidity and mortality in VHL disease. Currently, surgical resection is the most effective way to manage symptomatic VHL-HBs. Surgically unresectable VHL-HBs or those in frail patients are challenging problems. Therapies targeting oncologic and vascular endothelial growth factor (VEGF) pathways have failed to demonstrate tumor control. Our experience and previous reports on VHL-HB avidity to somatostatin analogues suggested somatostatin receptor (SSTR) expression in VHL-HBs, offering an alternative therapeutic strategy. We explored this possibility by demonstrating consistent histologic expression of SSTR1, 2a, 4, and 5 in VHL-HBs. We found that somatostatin analogue octreotide induces apoptosis in VHL-HB stromal cells in a dose-dependent fashion by BAX - caspase-3 pathway unrelated to canonical VHL pathway. When administered to a patient with unresectable symptomatic suprasellar hemangioblastoma, octreotide resulted in tumor volume reduction, symptom stabilization, and tumor cytopenia on repeat 68Ga-DOTA-TATE positron emission tomography (PET) within 6 months, suggesting tumor infarction. We conclude that VHL-HBs harbor multiple SSTR subtypes that offer actionable chemo-therapeutic strategy for management of symptomatic, unresectable tumors by somatostatin analogue therapy.

Loss of Quiescence in von Hippel-Lindau Hemangioblastomas is Associated with Erythropoietin Signaling.

von Hippel-Lindau (VHL) patients develop multiple central nervous system hemangioblastomas (HB). Some HBs become symptomatic with exponential growth or cyst formation following long periods of quiescence. Understanding the factors underlying growth in hemangioblastoma may lead to better strategies to arrest or prevent tumor growth. In 5 VHL patients, we resected quiescent hemangioblastomas (Q-HB) that were en-route during surgical access to symptomatic hemangioblastomas (S-HB), for matched tumor analysis. Quantitative reverse transcriptase analysis demonstrated a 2-fold increase in EPO expression in all S-HB, while 4/5 showed either Hypoxia Inducible Factor-1α or 2α upregulation. Additionally, all S-HB had increased phosphorylated erythropoietin (EPO) receptor and phosphorylated STAT-5 relative to matched Q-HB, with increased phosphorylated JAK-2 largely confined to the stromal cells in clusters within the tumors. These findings suggest that Q-HB to S-HB conversion may be associated with an erythropoietin-signaling loop. Furthermore, we found that EPO is detectable in cyst fluid from S-HB (n = 14), while absent in CSF (n = 1). Additionally, S-HB presentation or S-HB resection does not result in discernible change in serum EPO or hemoglobin (n = 60). These observations suggest that the altered erythropoietin signaling is focal and suggests that studying modulation of erythropoietin receptor pathway may lead to strategies in preventing HB growth.

ZEB1 expression is increased in IDH1-mutant lower-grade gliomas.

Transcription factors that induce epithelial-mesenchymal transition (EMT) promote invasion, chemoresistance and a stem-cell phenotype in epithelial tumors, but their roles in central nervous system tumors are not well-understood. We hypothesized these transcription factors have a functional impact in grades II-III gliomas. Using the National Cancer Institute (NCI) Repository for Molecular Brain Neoplasia Data (REMBRANDT) and the Cancer Genome Atlas (TCGA) Lower-Grade Glioma (LGG) data, we determined the impact of EMT-promoting transcription factors (EMT-TFs) on overall survival in grades II-III gliomas, compared their expression across common genetic subtypes and subsequently validated these findings in a set of 31 tumors using quantitative real-time polymerase chain reaction (PCR) and immunohistochemistry. Increased expression of the gene coding for the transcriptional repressor Zinc Finger E box-binding Homeobox 1 (ZEB1) was associated with a significant increase in overall survival (OS) on Kaplan-Meier analysis. Genetic subtype analysis revealed that ZEB1 expression was relatively increased in IDH1/2-mutant gliomas, and IDH1/2-mutant gliomas expressed significantly lower levels of many ZEB1 transcriptional targets. Similarly, IDH1/2-mutant tumors expressed significantly higher levels of targets of microRNA 200C (MIR200C), a key regulator of ZEB1. In a validation study, ZEB1 mRNA was significantly increased in IDH1-mutant grades II-III gliomas, and ZEB1 protein expression was more pronounced in these tumors. Our findings demonstrate a novel relationship between IDH1/2 mutations and expression of ZEB1 and its transcriptional targets. Therapy targeting ZEB1-associated pathways may represent a novel therapeutic avenue for this class of tumors.

IDH mutations may not preclude distant, trans-tentorial spread in gliomas: a case report and review of the literature.

BACKGROUND: IDH mutations have been demonstrated to confer prolonged survival in patients suffering from gliomas, but the mechanisms underlying the improved prognosis are unclear. While some studies have attributed these observations to an enhanced sensitivity to genotoxic therapies, others have postulated that IDH-mutated gliomas exhibit less aggressive intrinsic biological behavior, including the propensity to invade distant sites. Although most gliomas recur local to the site of initial presentation, some tumors demonstrate distant recurrence, the vast majority of which involve the contralateral hemisphere. Trans-tentorial spread has been described once before, in which a supratentorial glioblastoma was reported to recur infratentorially in the cerebellum. CASE PRESENTATION: We describe a patient who underwent surgical resection, followed by adjuvant radiation and temozolomide of a World Health Organization (WHO) III anaplastic astrocytoma in the right temporal lobe, exhibiting an IDH1 (R132H) mutation. Twenty-two months after surgery, he developed a second lesion, located in the right cerebellum, suspicious for recurrent tumor versus radiation necrosis. A second surgery was performed, and pathology demonstrated recurrent tumor, consistent with IDH1-mutated anaplastic astrocytoma. CONCLUSIONS: This is the first example of trans-tentorial spread in an IDH-mutated glioma, suggesting that despite improved survival, IDH mutations may not preclude gliomas from exhibiting the ability to invade distant sites of the brain.

Notch receptor and effector expression in von Hippel-Lindau disease-associated central nervous system hemangioblastomas.

OBJECT: Central nervous system hemangioblastomas are the most common manifestation of von Hippel-Lindau (VHL) disease, an autosomal dominant tumor suppressor syndrome that results in loss of VHL protein function and continuous upregulation of hypoxia-inducible factors. These tumors are composed of neoplastic stromal cells and abundant vasculature. Stromal cells express markers consistent with multipotent embryonically arrested hemangioblasts, which are precursors for hematopoietic and vascular lineages. Notch receptors are transmembrane signaling molecules that regulate multiple developmental processes including hematopoiesis and vasculogenesis. To investigate the importance of notch signaling in the development of VHL disease-associated CNS hemangioblastomas, the authors examined the presence of the four notch receptors and downstream notch effectors in this setting. METHODS: The authors used surgical specimens obtained from confirmed VHL-associated hemangioblastomas. Immunohistochemical analysis for the four notch receptors and the downstream effectors was performed on formalin-fixed paraffin-embedded sections. Western blot analysis for HES1 was performed on frozen specimens. RESULTS: All four notch receptors are present in hemangioblastomas. NOTCH1 and NOTCH4 receptors were widely and prominently expressed in both the stromal and vascular cells, NOTCH2 receptor expression was limited to primarily stromal cells, and NOTCH3 receptor expression was limited to vascular cells. All 4 receptors displayed a nuclear presence. Immunohistochemical analysis also demonstrated that downstream notch effectors, HES1 and HES5, were uniformly expressed in tumor stromal and vascular cells, but HES3, HEY1, and HEY2 were not. Strong HES1 expression was confirmed by Western blot analysis. CONCLUSIONS: The presence of all four notch receptors and downstream effector molecules suggests that the notch signaling pathway plays a critical role in the maintenance of the undifferentiated pluripotent phenotype of these tumors and in the associated vascular response. Moreover, the prominent expression of notch receptors in VHL-associated CNS hemangioblastomas reveals a new and possibly potent therapeutic target.

Progression of epididymal maldevelopment into hamartoma-like neoplasia in VHL disease.

Inactivation of the von Hippel-Lindau (VHL) gene and activation of the hypoxia-inducible factor (HIF) in susceptible cells precedes formation of tumorlets and frank tumor in the epididymis of male VHL patients. We performed detailed histologic and molecular pathologic analysis of tumor-free epididymal tissues from VHL patients to obtain further insight into early epididymal tumorigenesis. Four epididymides from two VHL patients were serially sectioned to allow for three-dimensional visualization of morphologic changes. Areas of interest were genetically analyzed by tissue microdissection, immunohistochemistry for HIF and markers for mesonephric differentiation, and in situ hybridization for HIF downstream target vascular endothelial growth factor. Structural analysis of the epididymides revealed marked deviations from the regular anatomic structure resulting from impaired organogenesis. Selected efferent ductules were represented by disorganized mesonephric cells, and the maldeveloped mesonephric material was VHL-deficient by allelic deletion analysis. Furthermore, we observed maldeveloped mesonephric material near cystic structures, which were also VHL-deficient and were apparent derivatives of maldeveloped material. Finally, a subset of VHL-deficient cells was structurally integrated in regular efferent ductules; proliferation of intraductular VHL-deficient cells manifests itself as papillary growth into the ductular lumen. Furthermore, we clarify that that there is a pathogenetic continuum between microscopic tumorlets and formation of tumor. In multiple locations, three-dimensional reconstruction revealed papillary growth to extend deeply into ductular lumina, indicative of progression into early hamartoma-like neoplasia. We conclude epididymal tumorigenesis in VHL disease to occur in two distinct sequential steps: maldevelopment of VHL-deficient mesonephric cells, followed by neoplastic papillary proliferation.