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Xinghua Ding, Chao Zhang, Jason M. Frerich, Anand Germanwala, Chunzhang Yang, Russell R. Lonser, Ying Mao, Zhengping Zhuang, and Mingguang Zhang

Von Hippel-Lindau (VHL) disease is an autosomal dominant multiorgan tumor syndrome caused by a germline mutation in the VHL gene. Characteristic tumors include CNS hemangioblastomas (HBs), endolymphatic sac tumors, renal cell carcinomas, pheochromocytomas, and pancreatic neuroendocrine tumors. Sporadic VHL disease with a de novo germline mutation is rare. The authors describe a case of multiple CNS HBs in a patient with a heterozygous de novo germline mutation at c.239G>T [p.S80I] of VHL. This is the first known case of a sporadic de novo germline mutation of VHL at c.239G>T. Clinicians should continue to consider VHL disease in patients presenting with sporadic CNS HBs, including those without a family history, to confirm or exclude additional VHL-associated visceral lesions.

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Edjah K. Nduom, Chunzhang Yang, Marsha J. Merrill, Zhengping Zhuang, and Russell R. Lonser

Object

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.

Methods

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.

Results

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.

Conclusions

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.

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Jie Lu, Alexander Ksendzovsky, Chunzhang Yang, Gautam U. Mehta, Raymund L. Yong, Robert J. Weil, Deric M. Park, Harry M. Mushlin, Xueping Fang, Brian M. Balgley, Dae-Hee Lee, Cheng S. Lee, Russell R. Lonser, and Zhengping Zhuang

Object

Tumor-initiating cells are uniquely resilient to current treatment modalities and play an important role in tumor resistance and recurrence. The lack of specific tumor-initiating cell markers to identify and target these cells presents a major obstacle to effective directed therapy.

Methods

To identify tumor-initiating cell markers in primary brain tumors, the authors compared the proteomes of glioma tumor-initiating cells to their differentiated progeny using a novel, nongel/shotgun-based, multidimensional liquid-chromatography protein separation technique. An in vivo xenograft model was used to demonstrate the tumorigenic and stem cell properties of these cells. Western blot and immunofluorescence analyses were used to confirm findings of upregulated ciliary neurotrophic factor receptor subunit–α (CNTFRα) in undifferentiated tumor-initiating cells and gliomas of increasing tumor grade. Sequencing of the CNTFRα coding regions was performed for mutation analysis. Finally, antibody-dependent cell-mediated cytotoxicity was used to establish the role of CNTFRα as a potential immunotherapeutic target.

Results

Ciliary neurotrophic factor receptor subunit–α expression was increased in tumor-initiating cells and was decreased in the cells' differentiated progeny, and expression levels increased with glioma grade. Mutations of CNTFRα are not common in gliomas. Functional studies using CNTF treatment in glioma tumor-initiating cells showed induction of differentiation through the CNTFRα pathway. Treatment with anti-CNTFRα antibody resulted in increased antibody-dependent cell-mediated cytotoxicity in CNTFRα expressing DAOY cells but not in cell lines that lack CNTFRα.

Conclusions

These data indicate that CNTFRα plays a role in the formation or maintenance of tumor-initiating cells in gliomas, is a marker that correlates with histological grade, may underlie treatment resistance in some cases, and is a potential therapeutic target.

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Zhengping Zhuang, Meng Qi, Jie Li, Hiroaki Okamoto, David S. Xu, Rajiv R. Iyer, Jie Lu, Chunzhang Yang, Robert J. Weil, Alexander Vortmeyer, and Russell R. Lonser

Object

Astrocytomas and oligodendrogliomas are primary CNS tumors that remain a challenge to differentiate histologically because of their morphological variability and because there is a lack of reliable differential diagnostic markers. To identify proteins that are differentially expressed between astrocytomas and oligodendrogliomas, the authors analyzed the proteomic expression patterns and identified uniquely expressed proteins in these neoplasms.

Methods

Proteomes of astrocytomas and oligodendrogliomas were analyzed using 2D gel electrophoresis and subsequent computerized gel analysis to detect differentially expressed proteins. The proteins were identified using high-performance liquid chromatography accompanied by tandem mass spectrometry. To determine the role of the differentially expressed proteins in astrocytes, undifferentiated glial cell cultures were treated with dibutyryl–cyclic adenosine monophosphate (cAMP).

Results

Two-dimensional gel electrophoresis revealed that glutamine synthetase was differentially expressed in astrocytomas and oligodendrogliomas. Western blot and immunohistochemical analyses confirmed the increased expression of glutamine synthetase in astrocytomas compared with oligodendrogliomas. Whereas glutamine synthetase expression was demonstrated across all grades of astrocytomas (Grade II–IV [15 tumors]) and oligoastrocytomas (4 tumors), it was expressed in only 1 oligodendroglioma (6% [16 tumors]). Treatment of undifferentiated glial cell cultures with dibutyryl-cAMP resulted in astrocyte differentiation that was associated with increased levels of glial fibrillary acidic protein and glutamine synthetase.

Conclusions

These data indicate that glutamine synthetase expression can be used to distinguish astrocytic from oligodendroglial tumors and may play a role in the pathogenesis of astrocytomas.