[Show abstract][Hide abstract] ABSTRACT: We present a unique case of an anterior cranial base von Hippel-Lindau disease (VHL)-associated microcystic neoplasm. To determine the lesion's relationship with VHL and its appropriate management, we discuss its salient clinical, pathological, and molecular features.
A 36-year-old woman with VHL presented with a 3-month history of phantosmia. Serial magnetic resonance imaging studies revealed a lesion within the ethmoid and frontal sinus region that was first evident 18 months before symptom development and demonstrated progressive growth over the interval period. The lesion was resected via a transbasal approach. Histopathological and immunohistochemical analysis revealed a microcystic lesion composed of bland clear cells and underlying endothelial cells consistent with a VHL-associated microcystic neoplasm that are not known to metastasize. Molecular testing demonstrated loss of heterozygosity of the VHL locus, verifying the tumor as a VHL-related neoplasm.
Because primary VHL-associated microcystic tumors in the anterior cranial base have not been described previously, the natural history of these tumors remains unclear. Based on the benign features of these lesions, they can be managed conservatively with close observation and surgical intervention reserved for those that produce symptoms.
[Show abstract][Hide abstract] ABSTRACT: Despite resistance of most gliomas to chemotherapy, approximately 2/3 of oligodendrogliomas show sensitivity to such agents. This sensitivity has been associated with deletions on chromosome 1p alone or in combination with 19q. Higher expression of the enzyme glyoxalase I has been found in oligodendrogliomas with chromosome 1p intact compared to those with a deletion. Higher expression of this enzyme is also associated with tumor chemoresistance in other cancers. The present study tested whether the drug troglitazone would make a glioma cell line more sensitive to chemotherapeutic agents. This drug was chosen because it has been shown to decrease glyoxalase I enzyme activity in cells. Treatment with troglitazone decreased expression of glyoxalase I, and potentiated cell death when used in combination with chemotherapeutic agents. This decrease in glyoxalase I protein may be one mechanism by which this potentiation occurs, and troglitazone may be a candidate for use in glioma therapy.
[Show abstract][Hide abstract] ABSTRACT: Pheochromocytomas and paragangliomas are rare catecholamine-secreting neuroendocrine tumors arising from the adrenal medulla and sympathetic tissues. When complete surgical resection is not an option, the treatment of pheochromocytoma is limited.
The objective of the study was to identify and characterize overexpression of IL-13 receptor-alpha2 (IL-13Ralpha2) gene expression in human and murine tumors and verify xenograft mouse pheochromocytoma cell (MPC)-derived tumor's response to a selective cytotoxin.
Expression of IL-13Ralpha2 was evaluated in a panel of 25 human pheochromocytoma clinical samples by RT-PCR and eight MPC tumors by indirect immunofluorescence assay and RT-PCR. Intervention: The function of IL-13Ralpha2 in these tumor cells was examined by evaluating tumor sensitivity to a recombinant IL-13-Pseudomonas exotoxin (IL-13PE). Subcutaneous small and large MPC tumors in athymic nude mice (n = 10) were treated intratumorally with IL-13PE (100 m icrog/kg).
IC(50) and tumor size were measured.
IL-13PE immunotoxin was highly cytotoxic to IL-13Ralpha2-overexpressing MPC cells (IC(50) <2.5 ng/ml) in vitro. Furthermore, IL-13PE was highly cytotoxic to sc tumors. Our results showed a statistically significant decrease in tumor size as early as 3 d after initial treatment and further suppressed growth of MPC tumors. All tumors displayed a histological evidence of necrosis in response to IL-13 immunotoxin without any adverse effects in host at this dose.
Human and murine neuroendocrine pheochromocytoma overexpress the IL-13Ralpha2 chain, and an IL-13PE-based receptor-directed anticancer approach may prove useful in treatment for metastatic pheochromocytoma patients.
The Journal of Clinical Endocrinology and Metabolism 06/2009; 94(8):2952-7. · 6.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pheochromocytomas are chromaffin cell-derived neuroendocrine tumors. There is presently no cure for metastatic pheochromocytoma and no reliable way to distinguish malignant from benign tumors before the development of metastases. In order to successfully manage pheochromocytoma, it is necessary to better understand the biological determinants of tumor behavior. For this purpose, we have recently established a mouse model of metastatic pheochromocytoma using tail vein injection of mouse pheochromocytoma (MPC) cells. We optimized this model modifying the number of cells injected, length of trypsin pre-treatment, and incubation temperature and duration for the MPC cells before injection, and by serial passage and re-selection of tumors exhibiting the metastatic phenotype. We evaluated the effect of these modifications on tumor growth using serial in vivo Magnetic Resonance Imaging studies. These results show that number of cells injected, the pre-injection incubation temperature, and duration of trypsin treatment are important factors to produce faster growing, more aggressive tumors that yielded secondary metastatic lesions. Serial harvest, culture and re-selection of metastatic liver lesions produced even more aggressive pheochromocytoma cells that retained their biochemical phenotype. Microarray gene expression comparison and quantitative real-time PCR of these more aggressive cells to the MPC-parental cell line identified genes that may be important for the metastatic process.
Clinical and Experimental Metastasis 02/2009; 26(3):239-50. · 3.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The von Hippel-Lindau (VHL) syndrome is a pleomorphic familial disease characterized by the development of highly vascularized tumors, such as hemangioblastomas of the central nervous system, pheochromocytomas, renal cell carcinomas, cysts and neuroendocrine tumors of the pancreas. Up to 75% of VHL patients are affected by VHL-associated pancreatic lesions; however, very few reports in the published literature have described the cellular origins and biological roles of VHL in the pancreas. Since homozygous loss of Vhl in mice resulted in embryonic lethality, this study aimed to characterize the functional significance of VHL in the pancreas by conditionally inactivating Vhl utilizing the Cre/LoxP system. Specifically, Vhl was inactivated in different pancreatic cell populations distinguished by their roles during embryonic organ development and their endocrine lineage commitment. With Cre recombinase expression directed by a glucagon promoter in alpha-cells or an insulin promoter in beta-cells, we showed that deletion of Vhl is dispensable for normal functions of the endocrine pancreas. In addition, deficiency of VHL protein (pVHL) in terminally differentiated alpha-cells or beta-cells is insufficient to induce pancreatic neuroendocrine tumorigenesis. Most significantly, we presented the first mouse model of VHL-associated pancreatic disease in mice lacking pVHL utilizing Pdx1-Cre transgenic mice to inactivate Vhl in pancreatic progenitor cells. The highly vascularized microcystic adenomas and hyperplastic islets that developed in Pdx1-Cre;Vhl f/f homozygous mice exhibited clinical features similar to VHL patients. Establishment of three different, cell-specific Vhl knockouts in the pancreas have allowed us to provide evidence suggesting that VHL is functionally important for postnatal ductal and exocrine pancreas, and that VHL-associated pancreatic lesions are likely to originate from progenitor cells, not mature endocrine cells. The novel model systems reported here will provide the basis for further functional and genetic studies to define molecular mechanisms involved in VHL-associated pancreatic diseases.
PLoS ONE 02/2009; 4(4):e4897. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pheochromocytoma (PCC) is a rare catecholamine-producing tumor that arises from the adrenal medulla and is often familial. The genetic basis for familial PCC involves mutations of RET, VHL, SHDx or NF-1 in more than 20% of cases. Additional genes may be important in pathogenesis of both familial and sporadic PCC. ErbB-2/Her2/Neu is a growth factor receptor tyrosine kinase that is frequently overexpressed in tumors and there is clinical evidence suggesting that enhanced ErbB-2 growth factor receptor signaling may play a role in PCC. In the present study, ectopic expression of an activated ErbB-2 transgene resulted in bilateral adrenal PCC. Analyses of tumor samples and normal adrenal tissue revealed that levels of the Pten tumor suppressor protein were greatly reduced in PCCs, while levels of the cell cycle regulatory protein cyclin D1 were usually increased. In addition, levels of phospo-AKT were increased in PCCs versus normal adrenal tissue. Biochemical analyses established that PCC's were functionally active, producing abundant levels of the catecholamines, epinephrine and norepinephrine. These data establish that increased ErbB-2 growth factor receptor signaling in the adrenal medulla can lead to PCC through combined influences on Pten, AKT andcyclin D1.
[Show abstract][Hide abstract] ABSTRACT: von Hippel-Lindau disease is an autosomal dominant inherited disorder characterized by a predisposition to multiple neoplasms. Renal cell carcinoma and hemangioblastomas of the retina and cerebellum are the most common of these, but other neoplasms and cysts also occur throughout the body. We report a distinctive, yet never described lung lesion in a 43-year-old woman with von Hippel-Lindau disease. Molecular genetic studies confirmed the presence of a VHL gene mutation in the cells of this lesion. We discuss the salient features of this novel lesion, and hypothesize on its origin and nature.
American Journal of Surgical Pathology 09/2007; 31(8):1292-6. · 4.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pheochromocytomas are catecholamine-producing tumors that can occur in the context of von Hippel-Lindau syndrome (VHL) and multiple endocrine neoplasia type 2 (MEN2). Pheochromocytomas in these two syndromes differ in histopathological features, catecholamine metabolism, and clinical phenotype. To further investigate the nature of these differences, we compared the global protein expressions of 8 MEN2A-associated pheochromocytomas with 11 VHL-associated pheochromocytomas by two-dimensional gel electrophoresis proteomic profiling followed by sequencing and identification of differentially expressed proteins. Although both types of pheochromocytoma shared similarities in their protein expression patterns, the expression of several proteins was distinctly different between VHL- and MEN2A-associated pheochromocytomas. We identified several of these differentially expressed proteins. One of the proteins with higher expression in MEN2-associated tumors was chromogranin B, of which the differential expression was confirmed by western blot analysis. Our results expand the evidence for proteomic differences between these two tumor entities, and suggest that VHL-associated pheochromocytomas may be deficient in fundamental machinery for catecholamine storage. In light of these new findings, as well as existing evidence for differences between both types of pheochromocytomas, we propose that these tumors may have different developmental origins.
Endocrine Related Cancer 07/2007; 14(2):463-71. · 4.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Chemoresistance is a widespread therapeutic challenge in glial tumors. The molecular basis of chemoresistance is poorly understood, precluding advances in glioma treatment and leaving gliomas among the most lethal tumors. Oligodendrogliomas provide a unique model to study the molecular basis of chemoresistance, as there are two distinct genetic subtypes with significant differences in chemosensitivity. Despite a high morphological similarity, tumors with allelic loss on the short arm of chromosome 1 (1pLOH) are more chemosensitive than those without 1pLOH.
In order to identify candidate proteins potentially responsible for glioma chemosensitivity, we compared the proteome of four oligodendrogliomas with and five without 1pLOH using comparative proteomic profiling. Proteomic analysis was performed by two-dimensional protein gel electrophoresis and subsequent computerized gel analysis for detection of distinguishing patterns of protein expression. Differentially expressed proteins were identified using Liquid Chromatography/Mass Spectrometry. Differential expression of select proteins was confirmed by Western blotting.
We identified seven candidate proteins that are overexpressed in oligodendrogliomas without 1pLOH. Two of these proteins (glyoxalase I and Rho GDP dissociation inhibitor) have previously been shown to enhance chemoresistance in other tumors. In turn, we identified twelve overexpressed proteins in tumors with 1pLOH that have previously been reported to induce chemosensitivity in other forms of human neoplasia.
These identified proteins are potential targets for pharmacological therapy and may also be useful as biomarkers for differentiation of chemoresistant and chemosensitive oligodendroglioma.
Cancer biology & therapy 04/2007; 6(3):391-6. · 3.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nuclear receptor corepressor (N-CoR) is a critical regulator of neural stem cell differentiation. Nuclear localization of N-CoR is a feature of undifferentiated neural stem cells and cytoplasmic translocation of N-CoR leads to astrocytic differentiation. Comparative proteomic analysis of microdissected glioblastoma multiforme (GBM) specimens and matched normal glial tissue reveals increased expression of N-CoR in GBM. In GBM primary cell cultures, tumor cells with nuclear localization of N-CoR demonstrate an undifferentiated phenotype, but are subject to astroglial differentiation upon exposure to agents promoting phosphorylation of N-CoR and its subsequent translocation to the cytoplasm. Treatment of glioma cell lines with a combination of retinoic acid and low-dose okadaic acid decreases the corepressor effect of N-CoR and has a striking synergistic effect on growth inhibition. The identification of N-CoR in GBM provides insights into the tumorigenesis process and supports the development of differentiation-based therapeutic strategies.
[Show abstract][Hide abstract] ABSTRACT: To determine the origin of the neoplastic cell in central nervous system (CNS) hemangioblastomas in von Hippel-Lindau disease (VHL) and its role in tumor formation and distribution, we characterized and differentiated neoplastic cells from hemangioblastomas removed from VHL patients.
A total of 31 CNS hemangioblastomas from 25 VHL patients were resected and analyzed. Tumor cells from the hemangioblastomas were characterized, grown, and differentiated into multiple lineages. Resected hemangioblastomas were located in the cerebellum (11 tumors), brainstem (five tumors), and spinal cord (15 tumors). Consistent with an embryologically derived hemangioblast, the neoplastic cells demonstrated coexpression of the mesodermal markers brachyury, Flk-1 (vascular endothelial growth factor-2), and stem cell leukemia (Scl). The neoplastic cells also expressed hematopoietic stem cell antigens and receptors including CD133, CD34, c-kit, Scl, erythropoietin, and erythropoietin receptor. Under specific microenvironments, neoplastic cells (hemangioblasts) were expanded and differentiated into erythrocytic, granulocytic, and endothelial progenitors. Deletion of the wild-type VHL allele in the hematopoietic and endothelial progeny confirmed their neoplastic origin.
The neoplastic cell of origin for CNS hemangioblastomas in VHL patients is the mesoderm-derived, embryologically arrested hemangioblast. The hematopoietic and endothelial differentiation potential of these cells can be reactivated under suitable conditions. These findings may also explain the unique tissue distribution of tumor involvement.
PLoS Medicine 03/2007; 4(2):e60. · 14.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gastrointestinal and pancreatic neuroendocrine tumors originate from the cells of the diffuse endocrine system. Their molecular genetic mechanism of development and progression is complex and remains largely unknown, and they are different in genetic composition from the gastrointestinal epithelial tumors. The current literature suggests that multiple genes are involved in their tumorigenesis with significant differences for tumors of different embryological derivatives: foregut, midgut and hindgut. The MEN1 gene is involved in initiation of 33% of foregut gastrointestinal neuroendocrine tumors. 18q defects are present almost exclusively in mid/hindgut neuroendocrine tumors. X-chromosome markers are associated with malignant behavior in foregut tumors only. Analysis of poorly differentiated neuroendocrine carcinomas of any site demonstrates high chromosomal instability and frequent p53 alterations similar to other poorly differentiated carcinomas. Several factors played a limiting role in the molecular studies published to date: the tumors are rare and heterogeneous, it is difficult to predict their behavior and prognosis, and several different tumor classifications are used by the investigators in the studies. Future studies need to evaluate molecular genetic composition of large series of gastrointestinal and pancreatic neuroendocrine tumors of each specific tumor type. Understanding of specific genetic alterations characteristic for gastrointestinal and pancreatic neuroendocrine tumors might lead to their improved diagnosis, morphologic and molecular characterization and treatment.
[Show abstract][Hide abstract] ABSTRACT: Hemangioblastomas are benign CNS tumors that occur sporadically or in patients with von Hippel-Lindau (VHL) disease. These tumors are characteristically associated with formation of intra- or peritumoral cysts. Hemangioblastoma cyst formation is a major cause of morbidity and mortality with these tumors. While peritumoral cysts have been suggested to result from vascular leakage, the mechanism of intratumoral cyst formation is not understood.
To elucidate the origin of intratumoral hemangioblastoma cyst fluid, we characterized its biochemical composition by two-dimensional (2D) proteomic profiling followed by sequencing of several proteins. The proteomic pattern of intratumoral cyst fluid was furthermore compared to the proteomic pattern of serum, hemangioblastoma tumor tissue, and hemangioblastoma peritumoral cyst fluid.
We show that proteomic patterns of intra- and peritumoral cyst fluid are identical Both are highly similar to serum and not to tumor.
Intratumoral hemangioblastoma cyst fluid originates from serum. Cyst formation associated with hemangioblastoma, whether peri- or intratumoral, is a consequence of vascular leakage. Anti-VEGF therapy may effectively control hemangioblastoma cyst formation.
Cancer biology & therapy 06/2006; 5(5):549-53. · 3.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The pathogenesis of de novo glioblastoma multiforme (GBM) is poorly understood and precursor cells are not known. To gain insight into the pathogenesis of GBM we analyzed brains from primates that developed de novo tumors ten years after whole brain radiation. Four animals had clinical and radiological evidence of GBM, and two animals had no evidence of GBM at the time of euthanization. Tumor precursor cells were identified diffusely scattered in the grossly normal white matter of all animals including two monkeys without evidence of GBM by MR-imaging or on autopsy examination. Tumor precursors demonstrated cellular atypia and mitoses, and were negative for tumor-associated markers GFAP, EGFR and p53. The cells were positive for Ki67 and N-CoR, the nuclear corepressor of astroglial differentiation. These results suggest that radiation-induced nuclear damage to neural stem cells or early astrocytic precursor cells can prevent normal differentiation and lead to tumor development. The findings provide insight into the tumorigenesis of de novo GBMs and suggest a new strategy for treatment of these lethal tumors by targeting both inactivation of N-CoR and inhibition of EGFR.
[Show abstract][Hide abstract] ABSTRACT: Correlation of disease phenotype with protein profile (proteotype) is a significant challenge for biomedical research. The main obstacles have been the need to insure sufficient quantities of pure protein sample, the reproducibility of protein display, and rapid and accurate protein identification. We present a modified approach that combines enhanced detection sensitivity with tissue microdissection from frozen primary renal cancer tissues of different histological subtypes, followed by 2D gel analysis and protein identification with MALDI mass spectrometry. We obtained reliable and highly consistent results in phenotypically similar tumors of each individual subtype by performing strict morphological control of the analyzed tumor cells without physical or chemical alteration of the frozen tissue samples. By application of non-oxidizing silver staining, proteins were resolved and identified with high levels of specificity and sensitivity. This new combination of techniques allows not only for sensitive identification of specific protein patterns that correspond to a histological tumor phenotype, but also for identification of specific disease-associated protein targets.
International Journal of Oncology 02/2006; 28(1):103-10. · 2.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Neurons, once committed, exit the cell cycle and undergo maturation that promote specialized activity and are believed to operate upon a stable genome. We used fluorescence in situ hybridization, selective cell microdissection, and loss of heterozygosity analysis to assess degree of aneuploidy in patients with a neurodegenerative disease and in normal controls. We found that aneuploidy occurs in approximately 40% of mature, adult human neurons in health or disease and may be a physiological mechanism that maintains neuronal fate and function; it does not appear to be an unstable state. The fact that neuronal stem cells can be identified in adult humans and that somatic mosaicism may be found in neuronal precursor cells deserves further investigation before using adult neural stem cells to treat human disease.
[Show abstract][Hide abstract] ABSTRACT: By virtue of meiotic cell division, primordial germ cells with heterozygous alleles develop into postmeiotic germ cells with homozygous alleles. Female and male germ cells may develop tumors--so-called teratomas--with a unique coexistence of a variety of histological elements from all three embryonic germ layers. In particular, mature teratomas consist exclusively of developmentally mature tissues whereas immature teratomas contain variable amounts of mature and immature tissues. In this study, we report genetic analysis of individual tissue components from mature and immature teratomas. The majority of mature teratomas showed consistent and concordant homozygous alleles in all selectively procured tissue components. In a small subset of mature teratomas, we observed discordant homozygous alleles. In contrast, immature teratomatous tissue revealed a heterozygous genotype. Remarkably, mature tissue components within immature teratoma revealed homozygosity. The findings suggest that immature teratomas and at least a subset of mature teratomas may originate from premeiotic cells, and implicate that meiosis may be required for differentiation into mature tissues.
[Show abstract][Hide abstract] ABSTRACT: Von Hippel-Lindau (VHL) disease is characterized by multiple tumors in specific organs. The cell of origin and the reason for the particular organ distribution of the tumors remains unknown. Endolymphatic sac tumor (ELST) is one of the lesions associated with VHL disease. Data from previous studies of VHL disease-associated hemangioblastomas (HBs) and renal cell carcinomas (RCCs) have indicated that VHL gene deficiency causes coexpression of erythropoietin (Epo) and its receptor (Epo-R), which facilitates tumor growth.
The authors studied ELSTs from five patients with VHL germline mutations. Analysis of the five ELST samples revealed loss of the wild-type allele, consistent with Knudson's two-hit hypothesis for tumorigenesis. All five ELST specimens were characterized microscopically and by immunohistochemical analysis. Coexpression of Epo and Epo-R was found in all five tumors on immunohistochemical studies and confirmed through reverse transcription-polymerase chain reaction and Western blot analysis.
Expression of Epo appears to be a result of VHL gene deficiency, whereas the simultaneous coexpression of Epo-R may reflect a developmental mechanism of tumorigenesis. Coexpression of Epo and Epo-R in ELSTs together with the morphological and genetic similarities of these lesions with other VHL disease-associated tumors indicates that VHL disease-associated tumors in different organs share common pathogenetic pathways.
Journal of Neurosurgery 09/2005; 103(2):284-8. · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pheochromocytoma is a neuroendocrine tumor associated with a variety of genetic disorders, which include von Hippel-Lindau disease (VHL), multiple endocrine neoplasia type 2 (MEN 2), neurofibromatosis type 1, hereditary paraganglioma, and succinate dehydrogenase gene-related tumors. Previous studies of VHL-associated and MEN 2-associated pheochromocytomas suggest morphological, biochemical, and clinical differences exist among the tumors, but the process by which they develop remains unclear. Studies in other VHL-associated tumors suggest that VHL gene deficiency causes coexpression of erythropoietin (Epo) and its receptor (Epo-R), which facilitates tumor growth. The objective of this study was to understand the different process of tumorigenesis for VHL and MEN 2-associated pheochromocytomas. Ten pheochromocytomas (VHL patients n = 5, MEN 2 patients n = 5) were examined for the presence or absence of Epo and Epo-R using Western blot, immunohistochemistry, and RT-PCR analyses. Coexpression of Epo and Epo-R was found in all five VHL-associated pheochromocytomas; in contrast, expression of Epo-R, but not Epo, was documented in all five MEN 2-associated pheochromocytomas. Expression of Epo appears to be a result of VHL gene deficiency, possibly through activation of the hypoxia inducible factor-1 pathway, whereas Epo-R is an embryonal marker whose sustained expression in both VHL- and MEN 2-associated pheochromocytomas reflects an arrest or defect in development. These findings suggest an alternative process of tumorigenesis in VHL- and MEN 2-associated pheochromocytomas and implicate Epo as a clinical biomarker to differentiate these tumors.
[Show abstract][Hide abstract] ABSTRACT: Von Hippel-Lindau (VHL) disease is characterized by multiple tumors in specific target organs. The tumors at different sites share distinct morphologic and genetic characteristics but their cell of origin is unknown. We show that VHL disease-associated renal clear cell carcinomas (RCC) consistently coexpress erythropoietin (Epo) and Epo receptor (EpoR). In addition, coexpression of Epo and EpoR is detected in many renal cysts, providing further evidence that renal cysts are potential precursors for RCC. In conjunction with VHL gene deficiency, coexpression of Epo and EpoR in renal cysts and tumors may reflect a developmental arrest in immature mesenchymal cells. Such arrest may lead to autocrine stimulation, cell proliferation, and renal tumor development, similar to tumorigenesis of VHL disease-associated hemangioblastomas.
Clinical Cancer Research 03/2005; 11(3):1059-64. · 8.19 Impact Factor