Synaptophysin: a reliable marker for medulloblastomas

Low number of neurosecretory vesicles in neuroblastoma impairs massive catecholamine release and prevents hypertension

INTRODUCTION

Neuroblastoma (NB) is a pediatric cancer of the developing sympathetic nervous system. It produces and releases metanephrines, which are used as biomarkers for diagnosis in plasma and urine. However, plasma catecholamine concentrations remain generally normal in children with NB. Thus, unlike pheochromocytoma and paraganglioma (PHEO/PGL), two other non-epithelial neuroendocrine tumors, hypertension is not part of the usual clinical picture of patients with NB. This suggests that the mode of production and secretion of catecholamines and metanephrines in NB is different from that in PHEO/PGL, but little is known about these discrepancies. Here we aim to provide a detailed comparison of the biosynthesis, metabolism and storage of catecholamines and metanephrines between patients with NB and PHEO.

METHOD

Catecholamines and metanephrines were quantified in NB and PHEO/PGL patients from plasma and tumor tissues by ultra-high pressure liquid chromatography tandem mass spectrometry. Electron microscopy was used to quantify neurosecretory vesicles within cells derived from PHEO tumor biopsies, NB-PDX and NB cell lines. Chromaffin markers were detected by qPCR, IHC and/or immunoblotting.

RESULTS

Plasma levels of metanephrines were comparable between NB and PHEO patients, while catecholamines were 3.5-fold lower in NB vs PHEO affected individuals. However, we observed that intratumoral concentrations of metanephrines and catecholamines measured in NB were several orders of magnitude lower than in PHEO. Cellular and molecular analyses revealed that NB cell lines, primary cells dissociated from human tumor biopsies as well as cells from patient-derived xenograft tumors (NB-PDX) stored a very low amount of intracellular catecholamines, and contained only rare neurosecretory vesicles relative to PHEO cells. In addition, primary NB expressed reduced levels of numerous chromaffin markers, as compared to PHEO/PGL, except catechol O-methyltransferase and monoamine oxidase A. Furthermore, functional assays through induction of chromaffin differentiation of the IMR32 NB cell line with Bt2cAMP led to an increase of neurosecretory vesicles able to secrete catecholamines after KCl or nicotine stimulation.

CONCLUSION

The low amount of neurosecretory vesicles in NB cytoplasm prevents catecholamine storage and lead to their rapid transformation by catechol O-methyltransferase into metanephrines that diffuse in blood. Hence, in contrast to PHEO/PGL, catecholamines are not secreted massively in the blood, which explains why systemic hypertension is not observed in most patients with NB.

Molecular Targets for Combined Therapeutic Strategies to Limit Glioblastoma Cell Migration and Invasion

The highly invasive nature of glioblastoma imposes poor prospects for patient survival. Molecular evidence indicates glioblastoma cells undergo an intriguing expansion of phenotypic properties to include neuron-like signaling using excitable membrane ion channels and synaptic proteins, augmenting survival and motility. Neurotransmitter receptors, membrane signaling, excitatory receptors, and Ca2+ responses are important candidates for the design of customized treatments for cancers within the heterogeneous central nervous system. Relatively few published studies of glioblastoma multiforme (GBM) have evaluated pharmacological agents targeted to signaling pathways in limiting cancer cell motility. Transcriptomic analyses here identified classes of ion channels, ionotropic receptors, and synaptic proteins that are enriched in human glioblastoma biopsy samples. The pattern of GBM-enriched gene expression points to a major role for glutamate signaling. However, the predominant role of AMPA receptors in fast excitatory signaling throughout the central nervous system raises a challenge on how to target inhibitors selectively to cancer cells while maintaining tolerability. This review critically evaluates a panel of ligand- and voltage-gated ion channels and synaptic proteins upregulated in GBM, and the evidence for their potential roles in the pathological disease progress. Evidence suggests combinations of therapies could be more effective than single agents alone. Natural plant products used in traditional medicines for the treatment of glioblastoma contain flavonoids, terpenoids, polyphenols, epigallocatechin gallate, quinones, and saponins, which might serendipitously include agents that modulate some classes of signaling compounds highlighted in this review. New therapeutic strategies are likely to exploit evidence-based combinations of selected agents, each at a low dose, to create new cancer cell-specific therapeutics.

Differential expression of neurogenes among breast cancer subtypes identifies high risk patients

The nervous system is now recognized to be a relevant component of the tumor microenvironment. Receptors for neuropeptides and neurotransmitters have been identified in breast cancer. However, very little is known about the role of neurogenes in regulating breast cancer progression. Our purpose was to identify neurogenes associated with breast cancer tumorigenesis with a potential to be used as biomarker and/or targets for treatment. We used three databases of human genes: GeneGo, GeneCards and Eugenes to generate a list of 1266 relevant neurogenes. Then we used bioinformatics tools to interrogate two published breast cancer databases SAGE and MicMa (n=96) and generated a list of 7 neurogenes that are differentially express among breast cancer subtypes. The clinical potential was further investigated using the GOBO database (n=1881). We identified 6 neurogenes that are differentially expressed among breast cancer subtypes and whose expression correlates with prognosis. Histamine receptor1 (HRH1), neuropilin2 (NRP2), ephrin-B1 (EFNB1), neural growth factor receptor (NGFR) and amyloid precursor protein (APP) were differentially overexpressed in basal and HER2-enriched tumor samples and syntaxin 1A (STX1A) was overexpressed in HER2-enriched and luminal B tumors. Analysis of HRH1, NRP2, and STX1A expression using the GOBO database showed that their expression significantly correlated with a shorter overall survival (p < 0.0001) and distant metastasis-free survival (p < 0.0001). In contrast, elevated co-expression of NGFR, EFNB1 and APP was associated with longer overall (p < 0.0001) and metastasis-free survival (p < 0.0001). We propose that HRH1, NRP2, and STX1A can be used as prognostic biomarkers and therapeutic targets for basal and HER2-enriched breast cancer subtypes.

MB3W1 is an orthotopic xenograft model for anaplastic medulloblastoma displaying cancer stem cell- and Group 3-properties

Background

Medulloblastoma is the most common malignant brain tumor in children and can be divided in different molecular subgroups. Patients whose tumor is classified as a Group 3 tumor have a dismal prognosis. However only very few tumor models are available for this subgroup.

Methods

We established a robust orthotopic xenograft model with a cell line derived from the malignant pleural effusions of a child suffering from a Group 3 medulloblastoma.

Results

Besides classical characteristics of this tumor subgroup, the cells display cancer stem cell characteristics including neurosphere formation, multilineage differentiation, CD133/CD15 expression, high ALDH-activity and high tumorigenicity in immunocompromised mice with xenografts exactly recapitulating the original tumor architecture.

Conclusions

This model using unmanipulated, human medulloblastoma cells will enable translational research, specifically focused on Group 3 medulloblastoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2170-z) contains supplementary material, which is available to authorized users.

Morphologic characterization of spontaneous nervous system tumors in mice and rats

Spontaneous rodent nervous system tumors, in comparison to those of man, are less well differentiated. Among the central nervous system (CNS) tumors, the "embryonic" forms (medulloblastoma, pineoblastoma) occur both in rodents and humans, whereas the human "adult" forms (gliomas, ependymomas, meningiomas) have fewer counterparts in rodents. In general, the incidence of spontaneous CNS tumors is higher in rats (>1%) than in mice (>0.001%). A characteristic rat CNS tumor is the granular cell tumor. Usually it is associated with the meninges, and most meningeal tumors in rats seem to be totally or at least partly composed of granular cells, which have eosinophilic granular cytoplasm, are periodic acid-Schiff reaction (PAS)-positive, and contain lysosomes. Such tumors are frequently found on the cerebellar surface or at the brain basis. Rat astrocytomas are diffuse, frequently multifocal, and they invade perivascular spaces and meninges. The neoplastic cells with round to oval nuclei and indistinct cytoplasm grow around preexisting neurons, producing satellitosis. In large tumors, there are necrotic areas surrounded by palisading cells. Extensive damage of brain tissue is associated with the presence of scavenger cells that react positively with histiocytic/macrophage markers. The neoplastic astrocytes do not stain positively for glial fibrillary acidic protein; they probably represent an immature phenotype. In contrast to neoplastic oligodendroglia, they bind the lectin RCA-1. Astrocytomas are frequently located in the brain stem, especially the basal ganglia. Rat oligodendroglial tumors are well circumscribed and frequently grow in the walls of brain ventricles. Their cells have water-clear cytoplasm and round, dark-staining nuclei. Atypical vascular endothelial proliferation occurs, especially at the tumor periphery. Occasionally in the oligodendrogliomas, primitive glial elements with large nuclei occur in the form of cell groups that form rows and circles. Primitive neuroectodermal tumors of rats, such as pineal tumors or medulloblastomas, appear to have features similar to those found in man. In mice, the meningeal tumors are mostly devoid of granular cells and the astrocytomas are similar to those occurring in rats, whereas spontaneous oligodendrogliomas are observed extremely rarely. Tumorlike lesions, such as lipomatous hamartomas or epidermoid cysts, are occasionally encountered in the mouse CNS. It is suggested that we classify rodent CNS lesions as "low grade" and "high grade" rather than as "benign" and "malignant." The size of CNS tumors is generally related to their malignancy. Tumors of the peripheral nervous system are schwannomas and neurofibromas or neurofibrosarcomas consisting of Schwann cells, fibroblasts, and perineural cells. Well-differentiated schwannomas are characterized by S-100 positivity and the presence of basement membrane. They show either Antoni A pattern with fusiform palisading cells or Antoni B pattern, which is sparsely cellular and has a clear matrix. The rat develops specific forms of schwannomas in the areas of the submandibular salivary gland, the external ear, the orbit, and the endocardium. Spontaneous ganglioneuromas occur in the rat adrenal medulla or thyroid gland. Compared to experimentally induced neoplasms, the spontaneous tumors of the rodent nervous system are poor and impractical models of human disease, although they may serve as general indicators of the carcinogenic potential of tested chemicals.

Diagnostic markers in paediatric medulloblastoma: a Paediatric Oncology Group Study

AIMS

We have reviewed immunohistochemically 17 paediatric medulloblastomas in order to determine if correlations exist that might be useful in subclassifying these tumours.

METHODS AND RESULTS

The patient group included 11 children who had died (mean survival 13 months) and six still alive (followed for up to 10 years). Ten tumours were diffuse and six were nodular (one biopsy had only perivascular tumour). Of the 10 diffuse tumours, three were desmoplastic: of the six nodular tumours, all six were desmoplastic. All 17 tumours were synaptophysin-reactive: three nodular tumours were glial fibrillary acidic protein (GFAP)-reactive in the nodules (two of three S 100-reactive tumours were also GFAP-reactive). MIB-1 labelling indices (LI) ranged from 5 to 80%. Six tumours exhibited at least 1% LI against Tp53 (Mab D07 and/or Mab 1801). Eight cases were 100% bcl2-reactive with nine cases having an LI <80% ('low labelling'). All nine 'low labelling' bcl2 cases were TP53 non-reactive; all six Tp53-reactive cases were bcl2 100% reactive. Six of 10 patients with diffuse medulloblastomas survived 18 months or less while four of 10 are alive up to 10 years. In contrast, five of six patients with nodular neoplasms died within 48 months of diagnosis with one patient followed up for less than 1 year.

CONCLUSIONS

Immunohistochemistry is a useful adjunct in characterizing subsets of paediatric medulloblastomas and confirms that larger co-operative studies may be fruitful in identifying a prognostic utility of a combined histochemical/immunohistochemical analysis on these tumours.

Neuropathology of pediatric brain tumors

Pediatric central nervous system neoplasms include a spectrum of both glial and nonglial tumors that differ significantly in location and biological behavior from those of adults. Brain tumors in infants and children most often arise from central neuroepithelial tissue, whereas a significant number of adult tumors arise from central nervous system coverings (e.g., meningioma), adjacent tissue (e.g., pituitary adenoma), or metastases. Most adult brain tumors are supratentorial malignant gliomas, whereas the most common malignant pediatric brain tumor is the cerebellar primitive neuroectodermal tumor (medulloblastoma). This article reviews neuropathological characteristics of the more common pediatric brain tumors. Entities, such as the brainstem glioma, and less common neoplasms like the desmoplastic infantile ganglioglioma and the central nervous system atypical teratoid/rhabdoid tumor are reviewed because they occur almost exclusively in children. Known cytogenetic and molecular characteristics of childhood brain tumors are also reviewed.

Lipomatous medulloblastoma in adults. A distinct clinicopathological entity

We report on three patients who presented with a cerebellar medulloblastoma at age 48, 53, and 59 years. Histopathology showed typical features of medulloblastoma, in one case with marked neuronal differentiation. In addition, all neoplasms contained focal accumulations of mature fat cells. Immunoreactivity of adipocytes for S-100 protein, neuron-specific enolase, synaptophysin, microtubule-associated protein-2, and glial fibrillary acidic protein and the lack of immunoreactivity to type IV collagen suggest lipomatous differentiation of neoplastic primitive neuroectodermal cells rather than an admixture of mesenchymal elements. Mitotic activity was low and the growth faction, as determined by the MIB-1 labeling index, was less than 5%. All patients are alive with a recurrence-free interval ranging from 3.5 to 12 years. These three patients and five similar previously reported cases all fit into the concept of the lipomatous medulloblastoma as a new clinicopathological entity characterized by (a) typical features of a cerebellar medulloblastoma with advanced neuronal differentiation, (b) areas of lipomatous differentiation, (c) low proliferative potential, (d) manifestation in adults (mean age, 50 years), and (e) apparent favorable clinical prognosis.

EGFR gene amplification--rearrangement in human glioblastomas

Immunostaining using an affinity-purified rabbit polyclonal antibody against the extracellular domain of the epidermal-growth-factor receptor (EGFR) showed over-expression occurring in a fraction of tumor cells in 17 out of 18 human glioblastomas and in a majority of cells in 7 of the 18. Southern-blotting technique using a full-length EGFR cDNA probe showed a variable degree of amplification in 10 of the 17 glioblastomas, which was associated with EGFR over-expression in each case. In 2 of the glioblastomas with EGFR gene amplification, a rearrangement of the gene affecting the extracellular domain of the receptor was identified and DNA sequence analyses revealed an identical deletion-rearrangement of 801 base pairs between exons 2 to 7, resulting in an in-frame fusion of exons 1 and 8.

Deregulated expression of PAX5 in medulloblastoma

Medulloblatoma is a pediatric brain tumor originating in the human cerebellum. A collection of 23 medulloblastomas was analyzed for expression of the developmental control genes of the PAX and EN gene families by RNase protection and in situ hybridization. Of all nine PAX genes investigated, only PAX5 and PAX6 were consistently expressed in most medulloblastomas (70 and 78% of all cases, respectively), as were the genes EN1 (57%) and EN2 (78%). EN1, EN2, and PAX6 genes were also expressed in normal cerebellar tissue, and their expression in medulloblastoma is consistent with the hypothesis that this tumor originates in the external granular layer of the developing cerebellum. PAX5 transcripts were, however, not detected in the neonatal cerebellum, indicating that this gene is deregulated in medulloblastoma. In the desmoplastic variant of medulloblastoma, PAX5 expression was restricted to the reticulin-producing proliferating tumor areas containing undifferentiated cells; PAX5 was not expressed in the reticulin-free nonproliferating islands undergoing neuronal differentiation. These data suggest that deregulated expression of PAX5 correlates positively with cell proliferation and inversely with neuronal differentiation in desmoplastic medulloblastoma.

Primitive neuroectodermal tumors: ultrastructural and immunohistochemical studies

We report here ultrastructural and immunohistochemical studies of neuroblastic differentiation in the retrospective (n = 17) and prospective (n = 26) series of primitive neuroectodermal tumors (PNETs). By electron microscopy, neuritelike structures containing parallel-oriented microtubules, adhesive plaque junctions, and pleomorphic dense-core vesicles were found in the majority of tumor specimens while synaptic specializations were very rare. By immunohistochemistry, synaptophysin appeared to be the most reliable marker for neuroblastic differentiation present in the most reliable marker for neuroblastic differentiation present in the majority of tumors, while 200 kDa neurofilament protein was immunovisualized in a lower proportion of tumors. Glial fibrillary acidic protein (GFAP) was expressed in both reactive astrocytes and in a small proportion of otherwise typical neoplastic cells. We conclude that the majority of PNETs revealed diverse differentiation and that electron microscopy is still the most reliable tool for its detection followed by immunohistochemistry for synaptophysin.

Adenoid formation in medulloblastoma: a case report

A medulloblastoma in a 3-year-old girl was described that showed epithelial features in the form of adenoid or acinar structure. Ultrastructurally, these adenoid formations exhibited glandular features and immunohistochemically stained for cytokeratin. Such structures were interpreted to be a distinct and hitherto unreported form of epithelial differentiation in medulloblastoma, similar to other epithelial features described in rare cases of high grade astrocytomas.

Experimental induction of primitive neuro-ectodermal tumours in rats: a re-appraisement of the ENU-model of neurocarcinogenesis

A series of 122 experimental brain tumours, induced in the Wistar rat by means of prenatal exposition to ethyl-nitrosourea, were studied with histological, immunohistochemical and ultrastructural techniques. Although with conventional histological techniques, most of the induced tumours showed morphological features suggesting their classification as malignant schwannomas or oligodendroglioma-like neoplasms, their study by means of immunohistochemistry and electron microscopy suggested that they are, in fact, primitive neuroectodermal tumours, with a tendency toward neuronal differentiation. This finding obliges us to re-appraise the ethyl-nitrosourea model of neurocarcinogenesis and to consider its possible usefulness for the experimental study of therapeutic approaches with potential applications in human neuro-ectodermal neoplasms.

The new WHO classification of brain tumours

The new edition of the World Health Organization (WHO) book on 'Histological Typing of Tumours of the Central Nervous System' reflects the progress in brain tumour classification which has been achieved since publication of the first edition in 1979. Several new tumour entities have been added, including the pleomorphic xanthoastrocytoma, central neurocytoma, the infantile desmoplastic astrocytoma/ganglioglioma, and the dysembryoplastic neuroepithelial tumour. The list of histological variants has also been expanded. In line with recent morphological and molecular data on glioma progression, the glioblastoma is now grouped together with astrocytic tumours. The classification of childhood tumours has been largely retained, the diagnosis primitive neuroectodermal tumour (PNET) only being recommended as a generic term for cerebellar medulloblastomas and neoplasms that are histologically indistinguishable from medulloblastoma but located in the CNS at sites other than the cerebellum. The WHO grading scheme was revised and adapted to new entities but its use, as before, remains optional.

Mutation and expression of the p53 gene in malignant melanoma cell lines

Three monoclonal antibodies (MAbs) against p53 protein (PAb 24o, DO-I and PAb1801) were used to define the immunophenotype of 13 melanoma cell lines. Immunoreactions could be detected in 12 out of 13 cell lines by using the indirect immunofluorescence technique. In 7 of these the majority of cells displayed cytoplasmic staining whereas positive nuclei were detected in only a few cells. Two cell lines had predominantly nuclear reactivity, while the remaining 3 cell lines showed signals in both locations. Despite identical nuclear staining patterns, the 3 MAbs produced qualitatively distinct cytoplasmic immunoreactions. PAb240 and DO-1, which showed similar staining frequencies, appeared more sensitive in the detection of p53 protein than did PAb1801. Immunoprecipitations of lysates from each of the cell lines, with MAbs DO-1 and 1801 (which bind to both wild-type and mutant p53 species) detected 53-kDa proteins, whereas PAb240 (which recognizes the mutant conformation of the protein in this type of assay) detected 53-kDa proteins in only 4 cell lines. Nucleotide sequencing of exons 5 to 9 of TP53 in these latter cell lines showed that each has homozygous point mutations in the locus, whereas in the others no TP53 alterations were found. Three of the 4 mutations were C-to-T transversions, alterations possibly caused by damage from UV-light. Our findings indicate that immunostaining with p53 antibodies, although common in malignant melanoma, results from the presence of mutant p53 protein in about 30% of the cases tested. Neither immunostaining with PAb240 nor the patterns of intracellular distributions of the signals are sufficient to detect TP53 mutations.

Age-related immunoreactivity pattern in medulloblastoma

Thirty-five paraffin-embedded medulloblastomas (19 from children and 16 from adults; 24 classic medulloblastomas, 10 desmoplastic medulloblastomas, 1 tumor with neuronal differentiation) were examined for reactions with antibodies against glial fibrillary acidic protein (GFAP), cytokeratins KL1 and MNF116, desmin, and vimentin. Only the tumor from the youngest patient, a 152-day-old boy, showed a positive immunoreaction for cytokeratins. Because of this age-related expression of cytokeratins in medulloblastomas primarily in very young children, cytokeratin positivity was interpreted as a sign of tumor immaturity. Five medulloblastomas showed scattered GFAP-positive reactive astrocytes and/or other positive, probably neoplastic, cells. Only two tumors showed GFAP immunoreactivity in unequivocally neoplastic cells. Of six tumors that reacted with vimentin, three showed strong reactivity throughout, one being the tumor from the 152-day-old boy. The remaining three demonstrated nests of vimentin-positive cells with weak or intense somatic immunoreactivity for vimentin. None of the 35 cases showed positivity for desmin; indicating that mesenchymal differentiation is restricted to the rare so-called medullomyoblastomas.

Desmoplastic supratentorial neuroepithelial tumours of infancy

The clinicopathological features of two infants with desmoplastic supratentorial neuroepithelial tumours are described. The cases were similar to the 26 cases reported previously as desmoplastic infantile ganglioglioma and superficial cerebral astrocytoma attached to dura. Neuronal differentiation was absent on routine stains, but was immunohistochemically established. We review the literature and suggest classifying this clinicopathological entity by using a general designation such as desmoplastic supratentorial neuroepithelial tumours of infancy, a term which indicates the variability in the amount and lines of differentiation.

Primitive neuroectodermal tumors after prophylactic central nervous system irradiation in children. Association with an activated K-ras gene

Three patients had supratentorial malignant brain tumors 7 to 9 years after prophylactic central nervous system (CNS) treatment for acute lymphocytic leukemia or malignant T-cell lymphoma. Therapy was administered at the age of 3 to 8 years and included cranial irradiation (total dose, 1800 to 2400 cGy) and intrathecal methotrexate. The brain tumors had histologic and immunohistochemical features of primitive neuroectodermal tumors (PNET), including neuroblastic rosettes, rhythmic arrangement of tumor cells, and immunohistochemical expression of glial, and in one patient neuronal, marker proteins. Using polymerase chain reaction-mediated DNA amplification from paraffin-embedded tissues and subsequent DNA sequence analysis, an activating point mutation was detected in the K-ras protooncogene in one tumor. This mutation was a G to A transition in position 2 of codon 12, substituting aspartate (GAT) for glycine (GGT). This type of mutation has not been observed before in human brain tumors, but it is frequent in radiation-induced murine lymphomas. These observations suggest that PNET can be induced after completion of the embryonal and fetal development of the human CNS. Oncogene-activating point mutations may represent a pathogenetic mechanism involved in the genesis of radiation-induced brain tumors.

A clinicopathologic and immunomorphologic study of 13 cases of ganglioglioma

The authors present the clinical, histopathologic, and immunomorphologic data of 13 intracranial gangliogliomas. Preoperative computed tomography scans showed a commonly cystic tumor of variable density. Six tumors were completely excised and seven were subtotally resected. After a mean follow-up of 4.5 +/- 2.6 years, 11 patients are asymptomatic or only slightly incapacitated. All tumors were examined with a panel of neuronal and neuroendocrine markers. Immunoreactivity (IR) to anti-neurofilament polypeptide (clone 2F11) was observed in neuronal processes in ten cases and in neuronal perikarya in five. With anti-synaptophysin (clone SY38), IR was present along the lining of ganglion cell perikarya and processes in 11 tumors whereas staining of the perinuclear cytoplasm was prominent in two. IR to anti-chromogranin A (clone LK2H10) was observed within the neuronal perikarya in eight cases. Only one ganglioglioma of the brain stem showed IR for tyrosine-hydroxylase (clone 2/40/15) and dopamine-beta-hydroxylase in some neoplastic ganglion cells. In this study, synaptophysin was the most reliable neuronal marker. For immunocytochemical identification of neoplastic neurons in ganglioglioma as well as other tumors with neuronal differentiation the authors propose a panel of well-characterized monoclonal antibodies against neurofilament polypeptides, synaptophysin, and chromogranin A to support the histomorphologic diagnoses.

Immunohistochemical characterization of primitive neuroectodermal tumors and their possible relationship to the stepwise ontogenetic development of the central nervous system. 2. Tumor studies

Thirty-five selected intracranial tumors qualifying as primitive neuroectodermal tumors (PNETs) were investigated; these included medulloblastomas, cerebral neuroblastomas, pinealoblastomas, retinoblastomas, polar spongioblastomas, ependymoblastomas. For control purposes 11 tumors, including glioblastomas (small cell, spongioblastic variants), one anaplastic astrocytoma (astroblastic component), anaplastic oligo-astrocytomas, gangliogliomas, one primary melanoblastoma, and one pineal germinoma, were also studied. Six neuronal markers, i.e., synaptophysin, chromogranin A, neuron-specific enolase (NSE), neurofilament protein (NFP) (160 kDa, 200 kDa, 70 and 200 kDa), and six other markers (glial fibrillary acidic protein, S-100 protein, vimentin, myoglobin, desmin, cytokeratin) were investigated immunohistochemically. A certain recapitulation of the ontogenetic development of neuronal differentiation in PNETs is given by the fact that chromogranin A immunoreactivity can regularly be seen already in poorly differentiated neurons and synaptophysin in well-differentiated ones. Immunostaining for NFPs showed different results depending on the subunit investigated. NSE reaction gave different results even within the single tumor groups. This study is, to the best of our knowledge, the first attempt to evaluate and compare, by combined morphological and immunohistochemical methods, PNETs without and with different stages of cellular differentiation with the stepwise differentiation of the human embryonic neuroectoderm.

Immunohistochemistry in childhood brain tumors: what are the facts?

In the past, contradictory results have been reported concerning the specificity of neuronal or glial cell markers. However, we have investigated this aspect in a large group of more than 550 brain tumors (among them 60 medulloblastomas). These contradictions can easily be explained by considering two basic facts. First, every neoplastic cell population, especially in embryonic tumors, diffusely infiltrates the brain tissue: non-neoplastic cells, intermingled with tumor cells, can therefore give rise to immunohistochemical and histogenetic misinterpretations. Second, different cell markers can be expressed by one and the same cell (e.g., GFAP, NSE, vimentin), making nosological interpretation of the tumor difficult, impossible, or at best rather subjective. Clear-cut marker positivity is mostly found in the differentiated tumors for which the nosological classification is already clear by the usual histological methods. Only synaptophysin seems to be a reliable marker for neurogenic cells. In embryonic brain tumors (so-called PNET), no correlations between the presence of a given cell marker and the biological behavior of the tumor have so far been detected.

Protein gene product (PGP) 9.5 as a reliable marker in primitive neuroectodermal tumours--an immunohistochemical study of 21 childhood cases

A number of antibodies to neural proteins have been used to demonstrate neuronal differentiation in primitive neuroectodermal tumours. One of them is protein gene product (PGP) 9.5, a neuronal protein isolated from brain, whose function is unknown at present. We have studied differentiation in 21 cases of primitive neuroectodermal tumours of the CNS in children. Immunocytochemical staining was performed for such neuronal markers as: PGP 9.5, neuron specific enolase and synaptophysin, a glycosylated protein associated with synaptic vesicles. Positive staining for PGP 9.5 was present in 16 cases (strong staining in 12), for neuron-specific enolase in 16 cases (strong staining in 10) and for synaptophysin in 10 cases (strong staining in six). Both PGP 9.5 and synaptophysin showed a clear staining pattern with less non-specific background than with neuron-specific enolase. Our findings demonstrate the value of using more than one antibody marker in assessing neuronal differentiation in tumours. The high incidence of positive staining with antibody to PGP 9.5 suggests that this is an essential marker in the panel of antibodies used for the identification of primitive neuroectodermal tumours.

Patterns of differentiation in central neurocytoma. An immunohistochemical study of eleven biopsies

Central neurocytoma has been characterised by its intraventricular localisation, predominant occurrence in young adults, oligodendroglioma-like histology, benign course and ultrastructural evidence for neuronal differentiation. Eleven intraventricular central neurocytomas were studied histopathologically, employing cell type-specific immunocytochemical markers and electron microscopic analysis. In the past, these lesions have caused diagnostic problems since central neurocytomas share basic histopathological features with other periventricular neoplasms. Accordingly, several tumours of this series had previously been classified as ependymomas of the foramen of Monro or oligodendrogliomas. Although generally regarded as benign lesions, two central neurocytomas of this series showed histopathological evidence of anaplasia, with focal necrosis, mitotic activity and vascular proliferation. All central neurocytomas exhibited immunoreactivity for neuron-specific enolase and synaptophysin, indicating consistent neuronal differentiation. Three tumours were studied by electron microscopy and contained synaptic vesicles, neuritic processes and neurosecretory granules. In addition, one tumour contained ganglioid cells and this was associated with focal immunoreactivity for neurofilament protein, suggesting that some central neurocytomas may, at least focally, continue to differentiate towards the formation of mature neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Histogenesis and cell lineage analysis of medulloblastomas

Although the histopathology, ultrastructural features, and cellular immunoreactivity for neuron-specific enolase and synaptophysin suggest that medulloblastomas are neuronal in character, the histogenesis of these tumors has not been firmly established due to conflicting observations surrounding the expression of intermediate filament proteins. In the present study the question of cell lineage in medulloblastomas was re-explored by examining tumors for the presence of neurofilament protein using a highly sensitive assay which employs a cocktail of monoclonal antibodies, as well as A2B5 antigen, and glial fibrillary acidic protein. With this assay, 12 of 14 tumors tested (86%) expressed high levels of both neurofilament protein and A2B5 antigen, whereas glial fibrillary acidic protein was either absent or expressed in very low percentages of the cells. The distributions of neurofilament and A2B5 antigens closely paralleled one another. These observations suggest that medulloblastomas have a common histogenesis from A2B5+ progenitor cells, and consistently manifest a trend toward neuronal rather than glial differentiation.

Synaptophysin and chromogranins/secretogranins--widespread constituents of distinct types of neuroendocrine vesicles and new tools in tumor diagnosis

Normal and neoplastic neuroendocrine (NE) cells have been identified for many years by morphological criteria only. With the advent of immunocytochemistry, antibodies against NE-specific polypeptides have been used to identify NE cells that had been missed by conventional techniques, thus improving the diagnosis of NE cells. In this review article we discuss (i) the biochemical, cell biological and molecular biological data obtained so far for two major types of NE markers, synaptophysin, which is characteristic of the small "transparent-looking" neurosecretory vesicles, and the chromogranins/secretogranins, which are widespread constituents of the larger "dense-cored" secretory granules; (ii) the immunohistochemical data obtained for these marker proteins in normal and neoplastic human NE cells and tissues; and (iii) future possible developments involving these as well as other proteins that are associated with these two distinct secretory organelles of NE cells and may serve as potential markers in NE cell diagnosis.

Differentiation in medulloblastomas and other primitive neuroectodermal tumours

Fifty-four cases of primitive neuroectodermal tumour (PNET) including 47 medulloblastomas, were examined for evidence of neuronal and glial differentiation, using antibodies to neuron-specific enolase (NSE), neurofilament protein (NF), and glial fibrillary acidic protein (GFAP). In 30 of the cases, antibodies to vimentin, alphafetoprotein, cytokeratin, epithelial membrane antigen and lymphoid markers were also used. Most of the 47 medulloblastomas in the group were NSE positive but NF negative; about half were GFAP positive and three of them were positive for both neuronal markers and for GFAP. Vimentin was demonstrated in four cases and was not always co-expressed with GFAP. Medulloblastomas were negative for all the other markers. Supratentorial PNETs were sometimes positive with neuronal markers but were GFAP negative. The cell specificity of these markers and the interpretation of immunocytochemical findings are discussed in relation to differentiation potential in primitive neuroectodermal tumours.

Diagnostic markers in human neurooncology. A progress report

In this progress report, some of the most commonly used antibodies are discussed in regard to their immunohistochemical application to human neurooncology. The importance of determining the spectrum of antibody immunoreactivity in a wide panel of normal, reactive, and neoplastic tissues is stressed. in atypical and aberrant cases, immunopositivity needs to be interpreted with caution and in the context of all other available data. The demonstration of a well-characterized, cell type-specific marker in a tumor reflects not so much its cytogenesis as its differentiation potential and its capacity for metaplasia. The relation of an abnormal or aberrant expression of antigenic determinants to the process of neoplasia raises a number of intriguing questions to which research in the next few years will likely provide answers.