To identify mediators of glioblastoma anti-angiogenic therapy resistance and target these mediators in xenografts.
We performed microarray analysis comparing bevacizumab-resistant glioblastomas (BRGs) to pre-treatment tumors from the same patients. We established novel xenograft models of anti-angiogenic therapy resistance to target candidate resistance mediator(s).
BRG microarray analysis revealed upregulation versus pre-treatment of receptor tyrosine kinase c-Met, which underwent further investigation because of its prior biologic plausibility as a bevacizumab resistance mediator. BRGs exhibited increased hypoxia versus pre-treatment in a manner correlating with their c-Met upregulation, increased c-Met phosphorylation, and increased phosphorylation of c-Met-activated focal adhesion kinase (FAK) and STAT3. We developed two novel xenograft models of anti-angiogenic therapy resistance. In the first model, serial bevacizumab treatment of an initially responsive xenograft generated a xenograft with acquired bevacizumab resistance, which exhibited upregulated c-Met expression versus pre-treatment. In the second model, a BRG-derived xenograft maintained refractoriness to the MRI tumor vasculature alterations and survival-promoting effects of bevacizumab. Growth of this BRG-derived xenograft was inhibited by a c-Met inhibitor. Transducing these xenograft cells with c-Met shRNA inhibited their invasion and survival in hypoxia, disrupted their mesenchymal morphology, and converted them from bevacizumab-resistant to bevacizumab-responsive. Engineering bevacizumab-responsive cells to express constitutively active c-Met caused these cells to form bevacizumab-resistant xenografts.
These findings support the role of c-Met in survival in hypoxia and invasion, features associated with anti-angiogenic therapy resistance; and growth and therapeutic resistance of xenografts resistant to anti-angiogenic therapy. Therapeutically targeting c-Met could prevent or overcome anti-angiogenic therapy resistance.
bevacizumab; resistance; glioblastoma; invasion; c-Met
Medulloblastoma is diagnosed histologically; treatment depends on staging and age of onset. Whereas clinical factors identify a standard- and a high-risk population, these findings cannot differentiate which standard-risk patients will relapse and die. Outcome is thought to be influenced by tumor subtype and molecular alterations. Poor prognosis has been associated with isochromosome (i)17q in some but not all studies. In most instances, molecular investigations document that i17q is not a true isochromosome but rather an isodicentric chromosome, idic(17)(p11.2), with rearrangement breakpoints mapping within the REPA/REPB region on 17p11.2. This study explores the clinical utility of testing for idic(17)(p11.2) rearrangements using an assay based on fluorescent in situ hybridization (FISH). This test was applied to 58 consecutive standard- and high-risk medulloblastomas with a 5-year minimum of clinical follow-up. The presence of i17q (ie, including cases not involving the common breakpoint), idic(17)(p11.2), and histologic subtype was correlated with clinical outcome. Overall survival (OS) and disease-free survival (DFS) were consistent with literature reports. Fourteen patients (25%) had i17q, with 10 (18%) involving the common isodicentric rearrangement. The presence of i17q was associated with a poor prognosis. OS and DFS were poor in all cases with anaplasia (4), unresectable disease (7), and metastases at presentation (10); however, patients with standard-risk tumors fared better. Of these 44 cases, tumors with idic(17)(p11.2) were associated with significantly worse patient outcomes and shorter mean DFS. FISH detection of idic(17)(p11.2) may be useful for risk stratification in standard-risk patients. The presence of this abnormal chromosome is associated with early recurrence of medulloblastoma.
FISH; idic(17)(p11.2); i17q; medulloblastoma; pediatric oncology
Recent work has identified novel point mutations in isocitrate dehydrogenase 1 (IDH1) in the majority of the World Health Organization grades II and III infiltrative gliomas and secondary grade IV glioblastomas. Gangliogliomas consist of neoplastic ganglion and glial cells and, in contrast to infiltrative gliomas, are generally indolent. Yet distinguishing between a ganglioglioma and an infiltrative glioma with admixed gray matter can be difficult, perhaps accounting for some “gangliogliomas” that ultimately show aggressive behavior. In this multi-institutional study, 98 cases originally diagnosed as ganglioglioma were analyzed for IDH1 mutations, 86 of which had follow-up data available. Eight cases (8.2%) were positive for R132H IDH1 mutations; six had silent IDH2 mutations and two had nonsense IDH2 mutations. The presence of mutant IDH1 in gangliogliomas correlated with a greater risk of recurrence (P = 0.0007) and malignant transformation and/or death (P < 0.0001) compared with tumors that were IDH1 wild type. Furthermore, the age of patients with IDH1-mutant gangliogliomas was higher than those without mutations (25.5 vs. 46.1 years, P = 0.0033). IDH1/2 testing of tumors suspected of being gangliogliomas may therefore be advisable, particularly in the adult population.
ganglioglioma; glioneuronal; isocitrate dehydrogenase
The proto-oncogene MYCN is mis-expressed in various types of human brain tumors. To clarify how developmental and regional differences influence transformation, we transduced wild-type or mutationally-stabilized murine N-mycT58A into neural stem cells (NSCs) from perinatal murine cerebellum, brain stem and forebrain. Transplantation of N-mycWT NSCs was insufficient for tumor formation. N-mycT58A cerebellar and brain stem NSCs generated medulloblastoma/primitive neuroectodermal tumors, whereas forebrain NSCs developed diffuse glioma. Expression analyses distinguished tumors generated from these different regions, with tumors from embryonic versus postnatal cerebellar NSCs demonstrating SHH-dependence and SHH-independence, respectively. These differences were regulated in-part by the transcription factor SOX9, activated in the SHH subclass of human medulloblastoma. Our results demonstrate context-dependent transformation of NSCs in response to a common oncogenic signal.
N-MYC; GFAP; SOX9; medulloblastoma; neural stem cells; glioma
Metastatic tumors are the most common neoplasms encountered in the central nervous system (CNS), and continue to be major cause for mortality and morbidity. Macroscopic features and corresponding radiological findings can be diagnostic in majority of the cases, however, microscopic evaluation would be necessary when the differential diagnosis includes a primary CNS tumor, unknown primary tumor site, and when the resection of the tumor is either considered therapeutic or palliative. The first step in the diagnosis of a metastatic brain lesion is to exclude a primary CNS tumor, followed by verification or identification of the primary tumor and the site. Although general approach to a metastatic lesion from an unknown primary tumor is the same everywhere else, there are slight variations for the metastatic lesions in the CNS versus other regions. When morphological features are not enough to establish a definitive diagnosis, additional studies including immunohistochemical stains are applied. With the expending immunohistochemical armamentarium for pathologists, more accurate assessments are possible even in cases of unknown primary tumor. This review summarizes the diagnostic approach to CNS metastases, immunohistochemical assessment of neoplasm of unknown primary, and primary CNS lesions entering in the differential diagnosis of metastases.
Brain metastases; central nervous system metastases; metastasis
Peripheral nerve sheath tumors are common neoplasms, with classic identifiable features, but on occasion, they are diagnostically challenging. Although well defined subtypes of peripheral nerve sheath tumors were described early in the history of surgical pathology, controversies regarding the classification and grading of these tumors persist. Advances in molecular biology have provided new insights into the nature of the various peripheral nerve sheath tumors, and have begun to suggest novel targeted therapeutic approaches. In this review we discuss current concepts and problematic areas in the pathology of peripheral nerve sheath tumors. Diagnostic criteria and differential diagnosis for the major categories of nerve sheath tumors are proposed, including neurofibroma, schwannoma, and perineurioma. Diagnostically challenging variants, including plexiform, cellular and melanotic schwannomas are highlighted. A subset of these affects the childhood population, and has historically been interpreted as malignant, although current evidence and outcome data suggests they represent benign entities. The growing current literature and the authors experience with difficult to classify borderline or “hybrid tumors” are discussed and illustrated. Some of these classification gray zones occur with frequency in the gastrointestinal tract, an anatomical compartment that must always be entertained when examining these neoplasms. Other growing recent areas of interest include the heterogeneous group of pseudoneoplastic lesions involving peripheral nerve composed of mature adipose tissue and/or skeletal muscle, such as the enigmatic neuromuscular choristoma. Malignant peripheral nerve sheath tumors (MPNST) represent a diagnostically controversial group; difficulties in grading and guidelines to separate “atypical neurofibroma” from MPNST are provided. There is an increasing literature of MPNST mimics which neuropathologists must be aware of, including synovial sarcoma and ossifying fibromyxoid tumor. Finally, we discuss entities that are lacking from the section on cranial and paraspinal nerves in the current WHO classification, and that may warrant inclusion in future classifications. In summary, although the diagnosis and classification of most conventional peripheral nerve sheath tumors are relatively straightforward for the experienced observer, borderline and difficult to classify neoplasms continue to be problematic. In the current review, we attempt to provide some useful guidelines for the surgical neuropathologist to help navigate these persistent, challenging problems.
peripheral nerve; neurofibroma; schwannoma; perineurioma; MPNST
A recent study of CDK4/6-inhibitors in glioblastoma (GBM) xenografts identified retinoblastoma tumor suppressor protein RB1 status as a determinant of tumor therapeutic efficacy. Because of the need for clinically applicable RB1 testing, we assessed the utility of 2 complementary methods for determining RB1 status in GBM. Using fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), we analyzed 34 GBMs that had also undergone molecular characterization as part of The Cancer Genome Atlas (TCGA). By IHC, 4 tumors (11.8%) had complete loss of RB protein expression, including 2 with homozygous deletion of RB1 by FISH and 1 with hemizygous deletion of RB1 by FISH combined with a novel nonsense mutation in RB1. Consistent with these results, in an independent set of 51 GBMs tested by IHC we demonstrated loss of RB1 protein in 5 (9.8%). In GBM molecular subtype analysis of TCGA data, complete loss of RB1 transcript expression was seen in 18 of 170 tumors (10.6%) and these were highly enriched for, but not exclusive to, the proneural subtype (p < 0.01). These data support the use of IHC for determining RB1 status in clinical GBM specimens and suggest that RB1 alterations may be more common in certain GBM subgroups.
Fluorescence in situ hybridization; Glioblastoma; Immunohistochemistry; Patient stratification; RB1; The Cancer Genome Atlas (TCGA)
Medulloblastoma is heterogeneous, being characterized by molecular subgroups that demonstrate distinct gene expression profiles. Activation of the WNT or SHH signaling pathway characterizes two of these molecular subgroups, the former associated with low-risk disease and the latter potentially targeted by novel SHH pathway inhibitors. This manuscript reports the validation of a novel diagnostic immunohistochemical method to distinguish SHH, WNT, and non-SHH/WNT tumors and details their associations with clinical, pathological and cytogenetic variables. A cohort (n = 235) of medulloblastomas from patients aged 0.4–52 years was studied for expression of four immunohistochemical markers: GAB1, β-catenin, filamin A, and YAP1. Immunoreactivity (IR) for GAB1 characterizes only SHH tumors and nuclear IR for β-catenin only WNT tumors. IRs for filamin A and YAP1 identify SHH and WNT tumors. SHH, WNT, and non-SHH/WNT tumors contributed 31, 14, and 55% to the series. All desmoplastic/nodular (D/N) medulloblastomas were SHH tumors, while most WNT tumors (94%) had a classic phenotype. Monosomy 6 was strongly associated with WNT tumors, while PTCH1 loss occurred almost exclusively among SHH tumors. MYC or MYCN amplification and chromosome 17 imbalance occurred predominantly among non-SHH/WNT tumors. Among patients aged 3–16 years and entered onto the SIOP PNET3 trial, outcome was significantly better for children with WNT tumors, when compared to SHH or non-SHH/WNT tumors, which showed similar survival curves. However, high-risk factors (M+ disease, LC/A pathology, MYC amplification) significantly influenced survival in both SHH and non-SHH/WNT groups. We describe a robust method for detecting SHH, WNT, and non-SHH/WNT molecular subgroups in formalin-fixed medulloblastoma samples. In corroborating other studies that indicate the value of combining clinical, pathological, and molecular variables in therapeutic stratification schemes for medulloblastoma, we also provide the first outcome data based on a clinical trial cohort and novel data on how molecular subgroups are distributed across the range of disease.
Embryonal tumor with multilayered rosettes (ETMR, previously known as ETANTR) is a highly aggressive embryonal CNS tumor, which almost exclusively affects infants and is associated with a dismal prognosis. Accurate diagnosis is of critical clinical importance because of its poor response to current treatment protocols and its distinct biology. Amplification of the miRNA cluster at 19q13.42 has been identified previously as a genetic hallmark for ETMR, but an immunohistochemistry-based assay for clinical routine diagnostics [such as INI-1 for atypical teratoid rhabdoid tumor (AT/RT)] is still lacking. In this study, we screened for an ETMR-specific marker using a gene-expression profiling dataset of more than 1,400 brain tumors and identified LIN28A as a highly specific marker for ETMR. The encoded protein binds small RNA and has been implicated in stem cell pluripotency, metabolism and tumorigenesis. Using an LIN28A specific antibody, we carried out immunohistochemical analysis of LIN28A in more than 800 childhood brain-tumor samples and confirmed its high specificity for ETMR. Strong LIN28A immunoexpression was found in all 37 ETMR samples tested, whereas focal reactivity was only present in a small (6/50) proportion of AT/RT samples. All other pediatric brain tumors were completely LIN28A-negative. In summary, we established LIN28A immunohistochemistry as a highly sensitive and specific, rapid, inexpensive diagnostic tool for routine pathological verification of ETMR.
ETMR; Pediatric brain tumor; LIN28A; Diagnostic marker
To describe the development of progressive multifocal leukoencephalopathy (PML) in patients with rheumatoid arthritis (RA) treated with rituximab.
Clinical care for patients with rheumatologic diseases. Most were referred to academic centers for care after diagnosis (Washington University, St Louis, Missouri; Karolinska Insitute, Stockholm, Sweden; and Royal Melbourne Hospital, Melbourne, Australia) while one was cared for in a neurology practice in Dallas, Texas, with consultation by an academic neurovirologist from the University of Colorado in Denver.
Four patients developing PML in the setting of rituximab therapy for RA.
Main Outcome Measures
Clinical and pathological observations.
Four patients from an estimated population of 129 000 exposed to rituximab therapy for RA are reported in whom PML developed after administration of this drug. All were women older than 50 years, commonly with Sjögren syndrome and a history of treatment for joint disease ranging from 3 to 14 years. One case had no prior biologic and minimal immunosuppressive therapy. Progressive multifocal leukoencephalopathy presented as a progressive neurological disorder, with diagnosis confirmed by detection of JC virus DNA in the cerebrospinal fluid or brain biopsy specimen. Two patients died in less than 1 year from PML diagnosis, while 2 remain alive after treatment withdrawal. Magnetic resonance scans and tissue evaluation confirmed the frequent development of inflammatory PML during the course of the disease.
These cases suggest an increased risk, about 1 case per 25 000 individuals, of PML in patients with RA being treated with rituximab. Inflammatory PML may occur in this setting even while CD20 counts remain low.
There are few pathologic studies of gliomas in patients with neurofibromatosis type 1. We analyzed clinical and pathologic features of gliomas from 100 neurofibromatosis type 1 patients (57 men; 43 women). The median age at tumor diagnosis was 13 years (range, 4 months to 68 years). Most tumors were typical pilocytic astrocytoma (PA) (49%) or diffusely infiltrating astrocytoma (DA) (27%) that included World Health Organization Grades II (5%), III (15%), and IV (7%); others were designated as low-grade astrocytoma, subtype indeterminate (LGSI; 17%). Two pilomyxoid astrocytomas, 1 desmoplastic infantile ganglioglioma and 1 conventional ganglioglioma, were also identified. The tumors in 24 cases arose in the optic pathways and included PA (n = 14), LGSI (n = 4), DA (n = 4), pilomyxoid astrocytoma (n = 1), and ganglioglioma (n = 1). The prognoses of the PA and LGSI gliomas overall were generally favorable; there were no survival differences between PA and LGSI groups based on site, tumor size, mitotic activity, or MIB-1 labeling index. In the combined PA and LGSI group, age younger than 10 years and gross total resection were associated with an increased overall survival rate (p = 0.047 and 0.002, respectively). Compared with the combined group (PA + LGSI), patients with DA at all sites had decreased overall and recurrence-free survival times (p < 0.001 and p = 0.003, respectively). This study emphasizes the wide histologic spectrum of gliomas that occur in patients with neurofibromatosis type 1. Classic PA and LGSI are the most common, and most have favorable prognoses. By contrast, DAs are more aggressive, similar to those that arise sporadically.
Astrocytoma; Brain tumor; Central nervous system; Glioma; Neurofibromatosis; Pilocytic astrocytoma
Pilocytic Astrocytomas (PAs) are common low-grade central nervous system malignancies for which few recurrent and specific genetic alterations have been identified. In an effort to better understand the molecular biology underlying the pathogenesis of these pediatric brain tumors, we performed higher-order transcriptional network analysis of a large gene expression dataset to identify gene regulatory pathways that are specific to this tumor type, relative to other, more aggressive glial or histologically distinct brain tumours.
RNA derived from frozen human PA tumours was subjected to microarray-based gene expression profiling, using Affymetrix U133Plus2 GeneChip microarrays. This data set was compared to similar data sets previously generated from non-malignant human brain tissue and other brain tumour types, after appropriate normalization.
In this study, we examined gene expression in 66 PA tumors compared to 15 non-malignant cortical brain tissues, and identified 792 genes that demonstrated consistent differential expression between independent sets of PA and non-malignant specimens. From this entire 792 gene set, we used the previously described PAP tool to assemble a core transcriptional regulatory network composed of 6 transcription factor genes (TFs) and 24 target genes, for a total of 55 interactions. A similar analysis of oligodendroglioma and glioblastoma multiforme (GBM) gene expression data sets identified distinct, but overlapping, networks. Most importantly, comparison of each of the brain tumor type-specific networks revealed a network unique to PA that included repressed expression of ONECUT2, a gene frequently methylated in other tumor types, and 13 other uniquely predicted TF-gene interactions.
These results suggest specific transcriptional pathways that may operate to create the unique molecular phenotype of PA and thus opportunities for corresponding targeted therapeutic intervention. Moreover, this study also demonstrates how integration of gene expression data with TF-gene and TF-TF interaction data is a powerful approach to generating testable hypotheses to better understand cell-type specific genetic programs relevant to cancer.
This study explores whether meningioma expresses epidermal growth factor receptor (EGFR) and determines if there is a correlation between the WHO grade of this tumor and the degree of EGFR expression.
Following institutional review board approval, 113 meningioma specimens from 89 patients were chosen. Of these, 85 were used for final analysis. After a blinded review, immunohistochemical stains for EGFR were performed. Staining intensity (SI) was scored on a scale 0-3 (from no staining to strong staining). Staining percentage of immunoreactive cells (SP) was scored 1-5 (from the least to the maximum percent of the specimen staining). Immunohistochemical score (IHS) was calculated as the product of SI and SP.
Eighty-five samples of meningioma were classified in accordance with World Health Organization (WHO) criteria: benign 57/85 (67%), atypical 23/85 (27%), and malignant 5/85 (6%). The majority of samples demonstrated a moderate SI for EGFR. IHS for EGFR demonstrated a significant association between SI and histopathologic subtype. Also, there was a correlation between the SP and histopathologic subtype (p = 0.029). A significant association was determined when the benign and the atypical samples were compared to the malignant with respect to the SP (p = 0.009). While there was a range of the IHS for the benign and the atypical histologic subtypes, malignant tumors exhibited the lowest score and were statistically different from the benign and the atypical specimens (p < 0.001).
To our knowledge, this represents the largest series of meningioma samples analyzed for EGFR expression reported in the literature. EGFR expression is greatest in benign meningiomas and may serve a potential target for therapeutic intervention with selective EGFR inhibitors.
Although oligodendroglial neoplasms are traditionally considered purely glial, increasing evidence suggests that they are capable of neuronal or neurocytic differentiation. Nevertheless, ganglioglioma-like foci (GGLF) have not been previously described. Herein, we report seven examples where the primary differential diagnosis was a ganglioglioma with an oligodendroglial component. These five male and two female patients ranged in age from 29 to 63 (median 44) years at initial presentation and neuroimaging features were those of diffuse gliomas in general. At presentation, the glial component was oligodendroglioma in six and oligoastrocytoma in one; one was low-grade and six were anaplastic. A sharp demarcation from adjacent GGLF was common, although some intermingling was always present. The GGLF included enlarged dysmorphic and occasionally binucleate ganglion cells, Nissl substance, expression of neuronal antigens, GFAP-positive astrocytic elements, and low Ki-67 labeling indices. In contrast to classic ganglioglioma, however, cases lacked eosinophilic granular bodies and CD34-positive tumor cells. Scattered bizarre astrocytes were also common and one case had focal neurocytic differentiation. By FISH analysis, five cases showed 1p/19q codeletion. In the four cases with deletions and ample dysmorphic ganglion cells for analysis, the deletions were found in both components. At last follow-up, two patients suffered recurrences, one developed radiation necrosis mimicking recurrence, and one died of disease 7.5 years after initial surgery. We conclude that GGLF represents yet another form of neuronal differentiation in oligodendroglial neoplasms. Recognition of this pattern will prevent a misdiagnosis of ganglioglioma with its potential for under-treatment.
Anaplasia; FISH; Ganglioglioma; Immunohistochemistry; Oligodendroglioma; Neuronal
To determine the temporal relationships of clinical, cognitive, Pittsburgh Compound-B (PiB) amyloid imaging, and cerebrospinal fluid (CSF) markers of Alzheimer’s disease (AD).
A case report of a longitudinally assessed participant in a memory and aging study who had serial clinical and psychometric assessments over 6 years, in addition to PiB imaging and CSF biomarker assays, prior to coming to autopsy.
Alzheimer’s Disease Research Center
An 85-year old individual was cognitively normal at his initial and next 3 annual assessments. Decline in measures of episodic memory and, to a lesser degree, working memory began at about age 88 years. PiB-PET amyloid imaging was negative at age 88.5 years, but at age 89.5 years there was reduced amyloid-beta 42 (Aβ42) and elevated levels of tau in the CSF. At his 6th assessment, when he was 90 years old, he was diagnosed with very mild dementia of the Alzheimer type. After death at age 91 years, the autopsy revealed foci of frequent neocortical diffuse Aβ plaques, sufficient to fulfill Khachaturian neuropathologic criteria for AD, but neuritic plaques and neurofibrillary tangles were sparse. Postmortem biochemical analysis of the cerebral tissue confirmed that PiB-PET-binding was below the level needed for in vivo detection.
Clinical, cognitive, and CSF markers consistent with AD may precede detection of cerebral Aβ with amyloid imaging agents such as PiB, which primarily label fibrillar Aβ plaques.
Pilocytic astrocytomas (PAs) are WHO grade I gliomas; they most often affect children and young adults and occur in patients with neurofibromatosis type 1 (NF-1). To identify genes that are differentially expressed in sporadic (S-PA) versus NF-1-associated PAs (NF1-PAs) and those that might reflect differences in clinical behavior, we performed gene expression profiling using Affymetrix U133 Plus2.0 GeneChip arrays in 36 S-PAs and 11 NF1-PAs. Thirteen genes were over-expressed and another 13 genes were under-expressed in NF1-associated PAs relative to S-PAs. Immunohistochemical studies performed on 103 tumors, representing 2 independently generated tissue microarrays, confirmed the differential expression of CUGBP2 (p = 0.0014), RANBP9 (p = 0.0075), ITGAV1 (p = 0.0001), and INFGR1 (p = 0.024) proteins. One of the underexpressed genes, aldehyde dehydrogenase 1 family, member L1 (ALDH1L1), was also reduced in clinically aggressive compared to typical PAs (p = 0.01) and in PAs with increased cellularity and necrosis. Furthermore, in an additional independent set of tumors, weak to absent ALDH1L1 expression was found in 13/18 (72%) clinically aggressive PAs, in 8/9 (89%) PAs with pilomyxoid features, in 7/10 (70%) PAs with anaplastic transformation and in 16/21 (76%) diffusely infiltrating astrocytomas of various grades. In summary, we have identified a molecular signature that distinguishes NF1-PA from S-PA, and found that ALDH1L1 underexpression is associated with aggressive histology and/or biological behavior.
Brain tumor; Glioma; Microarray; Molecular signature; Neurofibromatosis; Pilocytic astrocytoma
Statement of Clinical Relevance
Therapies that can overcome the resistance of malignant brain tumors would be a major clinical advance. Here, we investigate the role of cAMP Phosphodiesterase-4 in stimulating brain tumor growth and the therapeutic utility of cAMP Phosphodiesterase-4 inhibition in the treatment of malignant brain tumors. Cyclic AMP Phosphodiesterase-4 was widely expressed in human brain tumors of glial and neuronal lineage, and forced expression of PDE4A1 accelerated intracranial glioblastoma and medulloblastoma xenograft growth. Moreover, targeted inhibition of PDE4, in combination with standard radiation and chemotherapy, induced a unique regression of established intracranial glioblastoma xenografts. These findings identify PDE4 as a novel molecular target for brain tumor therapy and indicate that PDE4 inhibition should be evaluated in clinical trials for malignant brain tumors.
As favorable outcomes from malignant brain tumors remain limited by poor survival and treatment-related toxicity, novel approaches to cure are essential. Previously, we identified the cyclic AMP phosphodiesterase-4 (PDE4) inhibitor Rolipram as a potent anti-tumor agent. Here, we investigate the role of PDE4 in brain tumors and examine the utility of PDE4 as a therapeutic target.
Immunohistochemistry was used to evaluate the expression pattern of a subfamily of PDE4, PDE4A, in multiple brain tumor types. To evaluate the effect of PDE4A on growth, a brain-specific isoform, PDE4A1 was overexpressed in xenografts of Daoy medulloblastoma and U87 glioblastoma cells. To determine therapeutic potential of PDE4 inhibition, Rolipram, temozolomide, and radiation were tested alone and in combination on mice bearing intracranial U87 xenografts.
We found that PDE4A is expressed in medulloblastoma, glioblastoma, oligodendroglioma, ependymoma and meningioma. Moreover, when PDE4A1 was overexpressed in Daoy medulloblastoma and U87 glioblastoma cells, in vivo doubling times were significantly shorter for PDE4A1 overexpressing xenografts compared to controls. In long-term survival and bioluminescence studies, Rolipram in combination with first-line therapy for malignant gliomas (temozolomide and conformal radiation therapy) enhanced the survival of mice bearing intracranial xenografts of U87 glioblastoma cells. Bioluminescence imaging indicated that while temozolomide and radiation therapy arrested intracranial tumor growth, the addition of Rolipram to this regimen resulted in tumor regression.
This study shows that PDE4 is widely expressed in brain tumors and promotes their growth, and that inhibition with Rolipram overcomes tumor resistance and mediates tumor regression.
Brain Tumor; Cyclic AMP; Phosphodiesterase; Rolipram; Bioluminescence; PDE4A
The INI1/SMARCB1 protein product (INI1), a component of a transcription complex, was recently implicated in the pathogenesis of schwannomas in two members of a single family with familial schwannomatosis1. Tumors were found to have both constitutional and somatic mutations of the SMARCB1 gene and showed a mosaic pattern of loss of INI1 expression by immunohistochemistry, suggesting a tumor composition of mixed null and haploinsufficient cells. To determine if this finding could be extended to all tumors arising in familial schwannomatosis, and how it compares to other multiple schwannoma syndromes (sporadic schwannomatosis and neurofibromatosis 2) as well as to sporadic, solitary schwannomas, we performed an immunohistochemistry analysis on 45 schwannomas from patients with multiple schwannoma syndromes and on 38 solitary, sporadic schwannomas from non-syndromic patients. A mosaic pattern of INI1 expression was seen in 93% of tumors from familial schwannomatosis patients, 55% of tumors from sporadic schwannomatosis, 83% of NF2-associated tumors and only 5% of solitary, sporadic schwannomas. These results confirm a role for INI1/SMARCB1 in multiple schwannoma syndromes and suggest that a different pathway of tumorigenesis occurs in solitary, sporadic tumors.
Infantile or capillary hemangioma is the most common vascular tumor of childhood. The tumors most frequently affect the head and neck area, but rare cases of intracranial lesions have been reported. Their natural history is marked by initial rapid growth velocity followed by a plateau and, in most cases, subsequent involution. Although the lesions are considered benign, 10% of affected children develop life-threatening complications (mortality rate 20–80% in this subgroup). When surgical intervention or other methods of local control are not possible, therapeutic options are limited. Corticosteroids have been the mainstay of therapy but therapeutic response is not predictable and the infectious risk is not negligible. Interferon α-2a may also be effective but has significant toxicities.
Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) have been implicated in the pathogenesis of hemangiomas, and antiangiogenesis agents are being evaluated in the treatment of these tumors. Thalidomide may be an ideal therapy for life-threatening hemangiomas because it inhibits new blood vessel formation by antagonizing both the bFGF and VEGF pathways and has a more acceptable toxicity profile than other agents. The authors present the case of an infant born with a life-threatening, unresectable intracranial hemangioma in which treatment with thalidomide resulted in a good clinical outcome.
intracranial hemangioma; thalidomide; vascular endothelial growth factor
Diagnosis and classification of aggressive mature B-cell lymphoma with atypical morphology remains a challenge. To identify factors that may contribute to the atypical morphology, we selected eight such cases and evaluated their morphologic, immunophenotypic and cytogenetic features and clinical outcomes. The neoplastic cells showed a diffuse monotonous infiltrating pattern with a spectrum of morphology including: 1) L1 lymphoblastic; 2) centroblastic; 3) immunoblastic; and 4) mixed centroblastic and immunoblastic. The lymphoma cells in most cases were positive for CD10 and/or BCL6, and showed BCL2 expression. 6 of 8 cases showed C-MYC rearrangements, and interestingly, all 6 cases demonstrated a proliferation index of ≤90%. 3 of the 6 cases also demonstrated t(14;18). Clinical follow-up indicated that aggressive mature B-cell lymphoma may benefit from more intensified chemotherapeutic regimens used for BL. Our study suggests that aggressive mature B-cell lymphoma with atypical morphology may be another “grey zone lymphoma” lying in the spectrum between Burkitt lymphoma and diffuse large B-cell lymphoma.
Aggressive mature B-cell lymphoma; Burkitt lymphoma; diffuse large B-cell lymphoma; grey zone lymphoma; C-MYC rearrangement
Donor-acquired solid organ malignancy is a rare complication of organ transplantation. We report a case of a patient who received bilateral lung transplants for pulmonary fibrosis from a donor with known glioblastoma multiforme (GBM). The lungs, heart, liver, and kidneys were harvested after a lethal intracranial bleed and accepted for transplantation by four centers. An enlarged hilar lymph node sampled at the time of transplant was found to contain GBM. Four months later, the patient developed diffuse interstitial pulmonary infiltrates with mediastinal lymphadenopathy. Lung biopsy confirmed metastatic GBM. The patient died 2 weeks after the diagnosis was established. The patient receiving the donor liver also developed GBM. We present a case study, review of the literature, and suggested interventions to minimize the risk of transmission.
Survival periods vary considerably for patients with high-grade astrocytomas, and reliable prognostic markers are not currently available. We therefore investigated whether genetic losses from chromosomes 1p, 19q, 9p, or 10q were associated with survival in 89 high-grade astrocytomas using tissue microarrays (TMAs) derived from Radiation Therapy Oncology Group clinical trials. Cases included 15 anaplastic astrocytomas (AAs) and 74 glioblastomas (GBMs) selected on the basis of survival times significantly shorter or longer than the expected median. Genetic analysis was performed by TMA-fluorescence in situ hybridization (FISH) on array sections using 8 DNA probes, including those directed at 1p32, 19q13.4, 9p21 (p16/CDKN2A), and 10q (PTEN and DMBT1). Genetic status for each locus was correlated with patient survival group, and data were analyzed by using Fisher’s exact test of association (adjusted P = 0.025). Losses of chromosome 1p, either alone or in combination with 19q, were encountered in only 2 cases, both AAs. This contrasts with oligodendrogliomas, in which combined 1p and 19q losses are frequent and predictive of prolonged survival. Solitary 19q loss was noted in 3/15 AAs and in 7/70 GBMs and was more frequent in the long-term survival group (P = 0.041, AA and GBM combined). Chromosome 9p loss was seen in 5/8 AAs and 39/57 GBMs, whereas chromosome 10q loss was detected in 4/15 AAs and 48/68 GBMs. The 9p and 10q deletions were slightly more frequent in short-term survivors, though none of the comparisons achieved statistical significance. Long-term and short-term survival groups of high-grade astrocytomas appear to have dissimilar frequencies of 19q, 9p, and 10q deletions. TMA-FISH is a rapid and efficient way of evaluating genetic alterations in such tumors.
Although the term low-grade glioma (LGG) is useful for its connotation of a slow-growing, better prognosis CNS primary neoplasm typically occurring in a young patient, it also serves as a potential diagnostic wastebasket, occasionally leading to conceptual errors, therapeutic uncertainty, or misinterpretation of clinical data. For example, the LGG designation is occasionally invoked as a justification for lumping together biologically unrelated entities such as pilocytic astrocytoma and diffuse astrocytoma. Whereas the former represents a benign and potentially surgically curable neoplasm that virtually never undergoes malignant transformation, the latter is a surgically incurable low-grade malignancy, prone to further malignant progression and eventual fatality. Therefore, although rare cases lacking a clear distinction may be encountered, the term LGG should be abandoned for a more specific diagnosis whenever possible. The primary goals of this paper are to review practical surgical pathology issues related to the diagnosis of diffuse LGGs and to update the reader on emerging clinicopathologic and molecular genetic concepts. Also discussed are current controversies of classification/grading and the role of ancillary testing via immunohistochemical and genetic techniques.