Edjah K. Nduom, Chunzhang Yang, Marsha J. Merrill, Zhengping Zhuang, and Russell R. Lonser
The astrocytic contribution to the blood-brain barrier (BBB) in metastatic and primary malignant brain tumors is not well understood. To better understand the vascular properties associated with metastatic and primary malignant brain tumors, the authors systematically analyzed the astrocytic component of the BBB in brain neoplasms.
Twelve patients who underwent resection of metastatic or primary brain neoplasms (4 metastatic lesions, 2 low-grade astrocytomas, 2 anaplastic astrocytomas, and 4 glioblastoma multiforme) were included. Clinical, MRI, operative, histopathological and immunohistochemical (glial fibrillary acidic protein [GFAP], CD31, and aquaporin 4 [AQ4]) findings were analyzed.
Intratumoral regions of MRI enhancement corresponded with breakdown of the normal astrocyte–endothelial cell relationship in the BBB in metastatic deposits and malignant gliomas. Metastases demonstrated lack of perivascular GFAP and AQ4 on CD31-positive intratumoral vessels. At the metastasis-brain interface, normalization of GFAP and AQ4 staining associated with intraparenchymal vessels was observed. Intratumoral vasculature in enhancing regions of high-grade gliomas revealed gaps in GFAP and AQ4 staining consistent with disintegration of the normal astrocyte–endothelial cell association in the BBB. Intratumoral vasculature in low-grade and nonenhancing regions of high-grade gliomas maintained the normal astrocyte–endothelial cell relationship seen in an intact BBB, with GFAP- and AQ4-positive glial processes that were uniformly associated with the CD31-positive vasculature.
Regions of MRI enhancement in metastatic and primary malignancies correspond to areas of breakdown of the physiological astrocyte–endothelial cell relationship of the BBB, including loss of normal perivascular astrocytic architecture on GFAP and AQ4 immunohistochemistry. Nonenhancing areas are associated with preservation of the normal astrocyte–endothelial cell relationship of the intact BBB.
Lance S. Governale, Alexander O. Vortmeyer, Zhengping Zhuang, and Edward H. Oldfield
✓ Meningioma has been included in the constellation of tumors associated with von Hippel—Lindau (VHL) disease in previously published reports. It is unclear whether these tumors are an uncommon component of VHL disease or are more readily detected in these patients because of the frequency with which they undergo central nervous system imaging as part of the routine management of VHL disease. The authors report the case of a patient with VHL disease in whom a progressively enlarging supratentorial mass developed and was diagnosed as a hemangioblastoma because of its appearance on serial magnetic resonance images. At surgery the tumor displayed the typical features of a meningioma and was given the histological diagnosis of fibrous meningioma. Single-stranded conformational polymorphism analysis of the tumor DNA revealed a loss of heterozygosity at the neurofibromatosis Type 2 gene locus, known to be associated with sporadically occurring meningiomas. Despite this finding, the VHL gene locus on the allele from the patient's unaffected parent was normal. Thus it is unlikely that the occurrence of this patient's fibrous meningioma was associated with underlying VHL disease. Given the high frequency of neuroimaging sessions in patients with VHL disease, some supratentorial lesions that have been given radiological diagnoses of hemangioblastomas may be incidental meningiomas.
Shuyu Hao, Christopher S. Hong, Jie Feng, Chunzhang Yang, Prashant Chittiboina, Junting Zhang, and Zhengping Zhuang
Maffucci syndrome is a rare disease characterized by multiple enchondromas and soft-tissue hemangiomas. Additionally, neuroendocrine tumors including pituitary adenomas have been described in these patients. The underlying genetic etiology lies in somatic mosaicism of mutations in isocitrate dehydrogenase 1 (IDH1) or isocitrate dehydrogenase 2 (IDH2). This report describes a patient with Maffucci syndrome who presented with intracranial tumors of the skull base and suprasellar region. The patient underwent resection of both intracranial tumors, revealing histopathological diagnoses of chondrosarcoma and pituitary adenoma. DNA sequencing of the tumors was performed to identify common IDH1/2 mutations. Clinical, radiological, and biochemical assessments were performed. Genotypic studies used standard Sanger sequencing in conjunction with a target-specific peptide nucleic acid to detect IDH1 mutations in tumor tissues. DNA sequencing demonstrated identical IDH1 mutations (c.394C > T) in both tumors.
To the authors’ knowledge, this report provides the first genetic evidence for the inclusion of pituitary adenomas among tumors characterizing Maffucci syndrome. In patients who are newly diagnosed with Maffucci syndrome, it is appropriate to monitor for development of pituitary pathology and neuroendocrine dysfunction.
Matthew J. Shepard, Alejandro Bugarini, Nancy A. Edwards, Jie Lu, Qi Zhang, Tianxia Wu, Zhengping Zhuang, and Prashant Chittiboina
Von 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.
Patient-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.
Propranolol 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).
Propranolol 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.
Robert J. Weil, Zhengping Zhuang, Svetlana Pack, Shimareet Kumar, Lee Helman, Brian G. Fuller, Crystall L. Mackall, and Edward H. Oldfield
✓ Molecular biological techniques have begun to transform modern medicine. These techniques have shown promise in the pathological diagnosis of difficult or uncommon tumors. Accurate molecular diagnosis of the small round-cell tumors, for example, is especially important because divergent therapies may be required to eradicate such disparate lesions as neuroblastoma, lymphoma, rhabdomyosarcoma, central primitive neuroectodermal tumors/medulloblastoma, or Ewing sarcoma (ES). The authors present an unusual case of a primary, extraosseous ES arising from the intramedullary spinal cord, in which molecular studies were required for specific diagnosis and therapeutic guidance.
Robert J. Weil, Alexander O. Vortmeyer, Zhengping Zhuang, Svetlana D. Pack, Nicholas Theodore, Robert K. Erickson, and Edward H. Oldfield
✓ Hemangioblastomas of the central nervous system (CNS) may occur sporadically or in association with von Hippel—Lindau (VHL) syndrome. The authors present four patients with no family history or clinical evidence of VHL syndrome in whom extensive, progressive, en plaque coating of the brainstem and spinal cord with hemangioblastomas developed 1 to 8 years after complete resection of a solitary cerebellar hemangioblastoma.
Analysis included detailed physical, biochemical, radiological, and pathological examinations in all four patients, combined with family pedigree analysis. In addition, a detailed investigation of the VHL gene was undertaken. Allelic loss, comparative genomic hybridization (CGH), single-stranded conformational polymorphism screening, CpG island methylation status, and X chromosome inactivation clonality analyses were performed. Although there was no evidence of germline alterations in the VHL gene on clinical and radiological examination or in the family history (all four patients) or analysis of peripheral blood (three patients), somatic deletion of one copy of the VHL gene occurred in these tumors. These findings indicate that the multiple, separate deposits of tumors were likely derived from a single clone. Results of CGH indicate that one or several additional genes are probably involved in the malignant behavior of the hemangioblastomas in these patients. Furthermore, the malignant biological and clinical behavior of these tumors, in which multiple sites of subarachnoid dissemination developed 1 to 8 years after initial complete resection, followed by progressive tumor growth and death of the patients, occurred despite a histological appearance typical of benign hemangioblastomas.
Malignant hemangioblastomatosis developed 1 to 8 years after resection of an isolated cerebellar hemangioblastoma. Alterations of the VHL gene may be permissive in this setting, but other genes are likely to be the source of the novel biological and clinical presentation of the disseminated hemangioblastomas in these patients. This appears to represent a novel condition in which the product of one or more mutations in several genes permits malignant tumor behavior despite retention of a benign histological picture, a circumstance previously not recognized in CNS tumors.
Dueng-Yuan Hueng and Huey-Kang Sytwu
Russell R. Lonser, John A. Butman, Kristin Huntoon, Ashok R. Asthagiri, Tianxia Wu, Kamran D. Bakhtian, Emily Y. Chew, Zhengping Zhuang, W. Marston Linehan, and Edward H. Oldfield
The tumors most frequently associated with von Hippel-Lindau (VHL) disease are hemangioblastomas. While they are associated with significant neurological impairment and mortality, their natural history and optimal management have not been fully defined.
Patients with VHL were enrolled in a prospective study designed to define the natural history of CNS hemangioblastomas. In the present analysis, serial imaging, laboratory, genetic, and clinical data were evaluated in those with at least 2 years of follow-up data.
At study entrance 225 patients (111 males, 114 females) harbored 1921 CNS hemangioblastomas in the supratentorial compartment (21 tumors [1%]), cerebellum (865 [45%]), brainstem (129 [7%]), spinal cord (689 [36%]), cauda equina (212 [11%]), and nerve roots (5 [0.3%]; follow-up 15,819 hemangioblastoma-years). Increased tumor burden was associated with partial deletions in the VHL gene (p = 0.005) and male sex (p = 0.002). Hemangioblastoma development (median 0.3 new tumors/year) was associated with younger age (p < 0.0001) and more tumors at study entrance (p < 0.0001). While 1278 hemangioblastomas (51%) did not grow, 1227 hemangioblastomas (49%) grew in a saltatory (886 [72%]), linear (76 [6%]), or exponential (264 [22%]) pattern. Faster tumor growth was associated with male sex (p = 0.001), symptomatic tumors (p < 0.0001), and tumors associated with cysts (p < 0.0001). Location-dependent tumor size was the primary predictor of eventual symptom formation (159 symptomatic tumors [6.3%]; area under the curve > 0.9).
Central nervous system hemangioblastoma burden in VHL is associated with partial germline deletions and male sex. Unpredictable growth of hemangioblastomas compromises assessment of nonsurgical therapies. The judicious treatment of symptom-producing hemangioblastomas, while avoiding unnecessary treatment of asymptomatic tumors that may not progress, can provide clinical stability. Clinical trial registration no.: NCT00005902 (ClinicalTrials.gov).
Jie Lu, Zhengping Zhuang, Debbie K. Song, Gautam U. Mehta, Barbara Ikejiri, Harry Mushlin, Deric M. Park, and Russell R. Lonser
Nuclear receptor corepressor (N-CoR) forms a complex that maintains neural stem cells in an undifferentiated state through transcriptional repression. Recently, it has been shown that N-CoR is overexpressed in glioblastoma multiforme (GBM) tumor stem cells and has a putative role in maintaining these cells in an undifferentiated immortal state. To determine the effects of disruption of N-CoR complex function by serine/threonine protein phosphatase 2A (PP2A) inhibition on GBM tumor cell differentiation and proliferation, the authors developed and investigated a competitive small molecule inhibitor (LB1) of PP2A in GBM.
The authors investigated the effects of LB1 on GBM proliferation and molecular differentiation pathways using in vitro and in vivo studies.
The LB1 inhibited PP2A, leading to increased levels of phosphorylated Akt kinase and decreased NCoR expression, as well as dose-dependent antiproliferative activity in cultured U87 and U251 malignant glioma cells (dose range 1–10 μM). Systemic LB1 treatment (1.5 mg/kg/day for 21 days) had significant tumor antiproliferative effects in mice harboring U87 glioma xenografts (73% mean reduction in tumor volume compared with controls; p < 0.001). Moreover, a reduction in PP2A expression and activity after LB1 treatment in vivo correlated with increased Akt phosphorylation, reduced nuclear N-CoR expression and N-CoR cytoplasmic translocation, and increased accumulation of acetylated core histones, which coincided with the appearance of glial fibrillary acidic protein–expressing tumor cells.
These findings indicate that PP2A inhibition effectively disrupts N-CoR complex function/expression and leads to cytoplasmic translocation of N-CoR with subsequent tumor cell differentiation and/or death. Therapeutic paradigms that target N-CoR function in the cancer stem cell component of malignant gliomas may have treatment utility.