Chromosome 11p15 deletions in human malignant astrocytomas and primitive neuroectodermal tumors.

Chromosome 11p15 deletions occur frequently in several types of human cancer, both sporadic and familial, suggesting that a tumor suppressor gene is present within the deleted chromosome region. We carried out a restriction fragment length polymorphism analysis of chromosome 11p in two types of human brain tumors: malignant astrocytoma, the most common glial tumor in adults; and primitive neuroectodermal tumor (PNET), a malignant embryonic tumor that afflicts children. Loss of heterozygosity was found in 11/43 malignant astrocytomas (26%) and in 3/11 PNETs (27%). Deletion mapping revealed a region of loss on chromosome 11p (p15.4-pter) that was common to both tumor types. To determine whether the c-H-ras gene, located on chromosome 11p in the common region of deletion, was a candidate gene, we analyzed polymerase chain reaction products corresponding to all four c-H-ras coding exons for single-strand conformation polymorphisms. The absence of electrophoretic mobility shifts in tumor DNA compared to leukocyte DNA indicated that c-H-ras gene mutations were most likely not present. These results suggested that loss of a gene on chromosome 11p15 distinct from c-H-ras is an important step in tumorigenesis within the central nervous system in both children and adults.     

Fine needle aspiration cytology of primitive neuroectodermal tumors. A report of these cases.

Primitive neuroectodermal tumor (PNET) is a small round cell malignancy arising in soft tissue and bone, predominantly in older children and adolescents. We report the cytomorphologic features and findings of ancillary studies of eight fine needle aspiration (FNA) biopsies from three patients (7-year-old male, 12-year-old female, 9-year-old female). Two of the biopsies suggested the initial diagnosis of PNET of the chest wall, while the remaining six documented recurrent or metastatic disease. In one of these cases the primary diagnosis made by FNA biopsy enabled the pediatric oncologists to give specific therapy for the unresectable tumor and achieve remission. Local recurrences included the chest wall (two cases), pleura (one case) and pericardium (one case), while metastatic disease involved the supraclavicular lymph node and breast. All the cases consisted of small malignant cells with a high nuclear/cytoplasmic ratio and hyperchromatic nuclei without prominent nucleoli. Homer Wright rosettes were seen in only two of the aspirates, and neuropil and ganglion cells were not present. Ancillary studies, including electron microscopy (two cases), immunocytochemistry (four aspirates from two cases) and cytogenetics (11/22 translocation, one case) performed on the aspirated material were aids in making a specific diagnosis and excluded other small round cell tumors of childhood, such as malignant lymphoma, rhabdomyosarcoma and Ewing's sarcoma. The differential diagnosis between PNET and neuroblastoma can be difficult on the basis of an FNA biopsy alone, although light microscopic morphologic differences exist. Clinical features (e.g., age, primary site, metastatic patterns), catecholamine levels, electron microscopy and cytogenetics are necessary in establishing the correct diagnosis.     

Centrosome amplification as a possible mechanism for numerical chromosome aberrations in cerebral primitive neuroectodermal tumors with TP53 mutations

Although alterations in chromosome number have frequently been detected in human tumor cells and associated with tumor initiation and progression, the causal mechanisms are still not understood. One protein known to be involved in maintaining genetic stability is tumor suppressor p53. In mice, p53 has been implicated in the maintenance of diploidy (Cross et al., 1995) and the regulation of centrosome duplication (Fukasawa et al., 1996). Here we report on cerebral primitive neuroectodermal tumors that lacked the wild-type p53 gene (TP53) and showed multiple numerical chromosome aberrations, as detected by comparative genomic hybridization. In these tumors, the centrosome number was significantly higher than in a control tumor without a detected TP53 mutation and with few chromosomal imbalances. These findings indicate that abnormal centrosome amplification can occur in human tumors lacking wild-type TP53 and may be a mechanism by which numerical chromosome aberrations are generated.     

Episome-generated N-myc antisense RNA restricts the differentiation potential of primitive neuroectodermal cell lines.

Neuroectodermal tumors of childhood provide a unique opportunity to examine the role of genes potentially regulating neuronal growth and differentiation because many cell lines derived from these tumors are composed of at least two distinct morphologic cell types. These types display variant phenotypic characteristics and spontaneously interconvert, or transdifferentiate, in vitro. The factors that regulate transdifferentiation are unknown. Application of antisense approaches to the transdifferentiation process has allowed us to explore the precise role that N-myc may play in regulating developing systems. We now report construction of an episomally replicating expression vector designed to generate RNA antisense to part of the human N-myc gene. Such a vector is able to specifically inhibit N-myc expression in cell lines carrying both normal and amplified N-myc alleles. Inhibition of N-myc expression blocks transdifferentiation in these lines, with accumulation of cells of an intermediate phenotype. A concomitant decrease in growth rate but not loss of tumorigenicity was observed in the N-myc nonamplified cell line CHP-100. Vector-generated antisense RNA should allow identification of genes specifically regulated by the proto-oncogene N-myc.     

Functional Heterogeneity within the Developing Zebrafish Epicardium

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Retroperitoneal primitive neuroectodermal tumour (PNET). A case report and review of the literature

PurposeWe report a clinical case and present a brief review of the literature of peripheral primitive neuroectodermal tumour (PNET) as a rare disease. We discuss the difficult clinical and pathological diagnosis and the multidisciplinary approach to treatment of PNET. We debate radiosensitivity of extracranial recurrent retroperitoneal PNET.Methods and materialsExternal beam radiation therapy was applied for a non-resectable local recurrence of retroperitoneal PNET in a 74-year-old woman. There were no distant metastases and our patient has refused chemotherapy.ResultsLocal tumour control (LTC) was achieved after administration of a total dose of 60 Gy in 30 fractions by external beam 60 Cobalt radiotherapy.ConclusionsPNET is an aggressive malignant tumour infiltrating lymphatics and metastasizing haematogenously. It requires a multimodality treatment. Late local recurrence of extracranial retroperitoneal PNET has shown high radiosensitivity, so local tumour irradiation could be a radical treatment even in non-resectable cases.     

Peripheral primitive neuroectodermal tumor of the vulva: report of a case with imprint cytology.

BACKGROUND: Peripheral primitive neuroectodermal tumor (PNET) of the vulva is an extremely rare disease, and, to our knowledge, only two cases have been previously reported. CASE: A 45-year-old woman presented with a mass in the right labium major. Three years after removal of the tumor, she noticed a new lesion in the same place and underwent a partial vulvectomy. The imprint cytology of the recurrent tumor showed a monomorphic appearance, composed of small round cells with scant cytoplasm against a hemorrhagic background. These tumor cells were loosely connective, but rosettelike structures were observed focally. On pathologic examination, the neoplasm was composed of small round tumor cells showing sinusoidal, diffuse or micropapillary growth. Immunohistochemically, the neoplastic cells stained positively for neuron-specific enolase, vimentin and HBA 71 and negatively for cytokeratin, HBA 45 and muscle-specific actin. The morphologic characteristics of the disease were well expressed in the imprint cytology, and this influenced the selection of immunohistochemical studies. CONCLUSION: Cytologic examination for vulvar tumors, even imprint cytology, can be a useful tool in obtaining an accurate pathologic diagnosis of a rare disease, such as peripheral PNET.     

Establishment and characterization of a cell line of congenital primitive neuroectodermal tumor of soft tissue

A new human cell line, termedMuraoka, has been established from the recurrent tumor of a case of congenital primitive neuroectodermal tumor (PNET) arising at the temporofacial region of a male infant. The microscopic findings of this cell line were epithelioid, and the xenografted tumor in a nude mouse consisted of the malignant epithelioid cells. Immunohistochemically, the cells were positive for neuron-specific enolase, S-100 protein, carcinoembryonic antigen, cytokeratin, epithelial membrane antigen, and glial fibrillary acidic protein. These findings were quite smiliar to those of the epithelioid cells in the original tumor and of the xenografted tumor cells. Neither chromosomal abnormalities nor N-myc amplification were observed. Morphological differentiation after treatment with N⁶-2′-Odibutyryladenosine 3′:5′-cyclic monophosphate (Bt₂cAMP), all-trans-retinoic acid (RA), prostaglandin E₁ (PGE₁, and 5-bromo-2′-deoxyuridine (BrdU) showed two different results. Bt₂-cAMP and PGE₁ induced neuronal differentiation with the extension of neurites, whereas RA and BrdU predominantly induced Schwannian differentiation (flat cells). In these respects, the cell lineMuraoka seems to be useful for studying characteristics of PNET as well as for developing the new treatments against such tumors.     

Establishment and characterization of a cell line of congenital primitive neuroectodermal tumor of soft tissue.

A new human cell line, termed Muraoka, has been established from the recurrent tumor of a case of congenital primitive neuroectodermal tumor (PNET) arising at the temporofacial region of a male infant. The microscopic findings of this cell line were epithelioid, and the xenografted tumor in a nude mouse consisted of the malignant epithelioid cells. Immunohistochemically, the cells were positive for neuron-specific enolase, S-100 protein, carcinoembryonic antigen, cytokeratin, epithelial membrane antigen, and glial fibrillary acidic protein. These findings were quite similar to those of the epithelioid cells in the original tumor and of the xenografted tumor cells. Neither chromosomal abnormalities nor N-myc amplification were observed. Morphological differentiation after treatment with N6-2'-O-dibutyryladenosine 3':5'-cyclic monophosphate (Bt2-cAMP), all-trans-retinoic acid (RA), prostaglandin E1 (PGE1), and 5-bromo-2'-deoxyuridine (BrdU) showed two different results. Bt2-cAMP and PGE1 induced neuronal differentiation with the extension of neurites, whereas RA and BrdU predominantly induced Schwannian differentiation (flat cells). In these respects, the cell line Muraoka seems to be useful for studying characteristics of PNET as well as for developing the new treatments against such tumors.     

Heterogeneity of N-acetylglucosamine 1-phosphotransferase within mucolipidosis III

The primary defect responsible for mucolipidosis III is a deficiency of UDP-N-acetylglucosamine:lysosomal enzyme N-acetylglucosamine 1-phosphotransferase activity (GlcNAc phosphotransferase). Genetic complementation analysis of cultured fibroblasts derived from 12 patients with mucolipidosis III identified complementation groups A, B, and C (Honey, N. K., Mueller, O. T., Little, L. E., Miller, A. L., and Shows, T. B. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 7420-7424). The GlcNAc phosphotransferase activity present in the cell lines comprising the complementation groups was characterized with respect to endogenous substrates and two exogenous acceptors, alpha-methyl-D-mannoside and high mannose glycopeptides. All group C cell lines and one group A cell line were found to have normal GlcNAc phosphotransferase activity levels at 37 degrees C when screened with these exogenous acceptors. The enzyme activity in group A cell lines was within normal range when assayed at 23 degrees C. Inhibition of the phosphorylation of alpha-methyl-D-mannoside in the presence of increasing amounts of endogenous substrate N-acetyl-beta-D-hexosaminidase B was demonstrated in normal cell lines at 23 and 37 degrees C and in group A cells at 23 degrees C. However, group C cell lines did not show any inhibition at either temperature. This suggests that the alteration of the GlcNAc phosphotransferase from individuals in group C affects the recognition site for the protein portion of lysosomal enzymes, whereas group A individuals have mutations which result in a temperature-sensitive enzyme.     

Analysis of the neurofibromatosis type 2 gene in different human tumors of neuroectodermal origin

The autosomal dominant syndrome neurofibromatosis type 2 (NF2) is characterized by the development of bilateral vestibular schwannomas, meningiomas, ependymomas and gliomas. The NF2 gene, recently isolated from chromosome 22, is mutated in both sporadic and NF2 tumors such as schwannomas, meningiomas and ependymomas. Mutations of the gene have been described not only in the neoplasms usually associated with NF2, but also in 30% of the melanomas and 41% of the mesotheliomas analyzed. In particular, the finding of mutations in melanomas supports the hypothesis that the NF2 gene is involved in the genesis of several tumor types that arise from the embryonic neural crest. In this study we examined, by single-strand conformation polymorphism (SSCP) analysis, 41 tumors of the central nervous system (11 schwannomas and 30 gliomas), 19 melanomas and 15 Merkel cell carcinoma specimens for mutations in the coding sequence of the NF2 gene. We found three inactivating mutations of the NF2 gene in schwannomas. No alterations of the gene were detected by SSCP analysis of the other tumors. These results confirm the role of NF2 in pathogenesis of schwannomas, but do not define its significance in the genesis of the other neuroectodermal tumors studied. Received: 27 July 1995 / Revised: 11 September 1995     

Establishment and characterization of a primitive neuroectodermal tumor of bone continuous cell line (LAP-35)

A continuous tumor cell line (LAP-35) was established from a primitive neuroectodermal tumor of bone from the right tibia of a 12-year-old female. The neural character of the cell line was documented by the spontaneous growth of neurites and by the presence of several neural markers, including neuron-specific enolase (NSE), S-100 protein, neurofilaments, chromogranin A, synaptophysin and positivity to monoclonal antibodies UJ127.11, UJ13A, UJ181.4. Cell-sorter analysis showed a high expression of nerve growth factor receptor (NGFr) and major histocompatibility complex class I-related molecules. A unique cytogenetic profile was observed, including a reciprocal chromosomal translocation (rct) 11:22 (q24;q12), typically associated with Ewing's sarcoma and neuroepithelioma, and deletion of the short arm of chromosome 1 (lp-), otherwise a feature of neuroblastoma. N-myc proto-oncogene was neither amplified nor expressed, whereas the expression of c-myc was documented by northern blot analysis. These features distinguish this new cell line from previously reported neuroectodermal cell lines, identifying LAP-35 as a unique model of a group of neural bone tumors that share characteristics of neuroblastoma as well as neuroepithelioma.     

The enigmatic primitive streak: prevailing notions and challenges concerning the body axis of mammals

The primitive streak establishes the antero‐posterior body axis in all amniote species. It is thought to be the conduit through which mesoderm and endoderm progenitors ingress and migrate to their ultimate destinations. Despite its importance, the streak remains poorly defined and one of the most enigmatic structures of the animal kingdom. In particular, the posterior end of the primitive streak has not been satisfactorily identified in any species. Unexpectedly, and contrary to prevailing notions, recent evidence suggests that the murine posterior primitive streak extends beyond the embryo proper. In its extraembryonic site, the streak creates a node‐like cell reservoir from which the allantois, a universal caudal appendage of all amniotes and the future umbilical cord of placental mammals, emerges. This new insight into the fetal/umbilical relationship may explain the etiology of a large number of umbilical‐associated birth defects, many of which are correlated with abnormalities of the embryonic midline.