title: Immunohistochemical and ultrastructural characterization of brain tumors in S100beta-v-erbB transgenic rats.
abstract: Transgenic rats expressing v-erbB (viral form of the EGF receptor) under transcriptional regulation by the S100beta promoter develop brain tumors (Ohgaki et al. J Neuropathol Experimental Neurol 65: 1111-1117, 2006). In the present study, we carried out detailed immunohistochemical and ultrastructural characterization of the brain tumors that developed in these rats. Of 49 homozygous transgenic rats between 16 and 94 weeks of age (mean, 59 weeks), 31 rats were autopsied because they showed severe neurological symptoms and/or became moribund. Among these, 30 rats had brain tumors, which were classified histologically as malignant glioma, anaplastic oligodendroglioma, and low-grade oligodendroglioma. Six transgenic rats developed two different histologic types of brain tumor, which were considered to be of multiclonal origin, because of the lack of histological transitions. All brain tumors contained neoplastic cells immunoreactive for S100 and GFAP. Diffuse immunoreactivity for Olig2 and Nkx2.2 was observed in neoplastic cells in all seven anaplastic oligodendrogliomas and in all three low-grade oligodendrogliomas analyzed, but in none of 26 malignant gliomas. Electron microscopy, carried out on four malignant gliomas and four anaplastic oligodendrogliomas, revealed the presence of intermediate filament bundles devoid of side arms, indicating glial differentiation. There was no evidence of cilia, microvilli, neurosecretory granules, synaptic structures or neurofilaments, excluding the possibility of ependymal or neuronal tumors. The present study thus provides additional evidence that the brain tumors developing in S100beta-v-erbB transgenic rats are of glial origin, with or without oligodendroglial differentiation. Reproducible development of three distinct histologic types of brain tumor in unique localizations may be explained by activation of the v-erbB transgene driven by the S100beta promoter in specific precursor cells during development of the brain. Thus, S100beta-v-erbB transgenic rats may be useful to study the histogenesis and molecular mechanisms of development of glial tumors due to disruption of the EGFR pathway.
authors.affiliation: Department of Human Pathology, Gunma University Graduate School of Medicine, Maebashi, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yokoo
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Sumihito
authors.initials: S
authors.lastname: Nobusawa
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Nakazato
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ohgaki
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000032:analysis; D001932:Brain Neoplasms / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure*; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D005910:Glioma / Q000737:chemistry / Q000648:ultrastructure; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins / Q000032:analysis; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D009414:Nerve Growth Factors / Q000235:genetics*; D009419:Nerve Tissue Proteins / Q000032:analysis; D009457:Neuroglia / Q000473:pathology; D009687:Nuclear Proteins; D000076104:Oligodendrocyte Transcription Factor 2; D009837:Oligodendroglioma / Q000737:chemistry / Q000648:ultrastructure; D018739:Oncogene Proteins v-erbB / Q000235:genetics*; D051381:Rats; D055647:Rats, Transgenic; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000032:analysis; D029961:Zebrafish Proteins
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D005904:Glial Fibrillary Acidic Protein; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D000076104:Oligodendrocyte Transcription Factor 2; D018739:Oncogene Proteins v-erbB; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D014157:Transcription Factors; D029961:Zebrafish Proteins; C000715631:NKX2-2 protein, human; C000715628:Nkx2-2 protein, rat; C522729:Olig2 protein, rat; C000715630:nkx2.2b protein, zebrafish