Yoshie Yasui

PDGFRA gene rearrangements are frequent genetic events in PDGFRA-amplified glioblastomas

Gene rearrangement in the form of an intragenic deletion is the primary mechanism of oncogenic mutation of the epidermal growth factor receptor (EGFR) gene in gliomas. However, the incidence of platelet-derived growth factor receptor-α (PDGFRA) gene rearrangement in these tumors is unknown. We investigated the PDGFRA locus in PDGFRA-amplified gliomas and identified two rearrangements, including the first case of a gene fusion between kinase insert domain receptor (KDR) (VEGFRII) and the PDGFRA gene, and six cases of PDGFRA(Δ8, 9), an intragenic deletion rearrangement. The PDGFRA(Δ8, 9) mutant was common, being present in 40% of the glioblastoma multiformes (GBMs) with PDGFRA amplification. Tumors with these two types of PDGFRA rearrangement displayed histologic features of oligodendroglioma, and the gene products of both rearrangements showed constitutively elevated tyrosine kinase activity and transforming potential that was reversed by PDGFR blockade. These results suggest the possibility that these PDGFRA mutants behave as oncogenes in this subset of gliomas, and that the prevalence of such rearrangements may have been considerably underestimated.

Analysis of muscle proteins in acute quadriplegic myopathy

We investigated the changes of muscle proteins in acute quadriplegic myopathy (AQM) using immunohistochemistry and stoichiometry. Cases of AQM were observed in which it was difficult to type muscle fibers with adenosine triphosphatase staining in biopsied muscle. Well‐defined typing of these cases was possible by performing immunofluorescent staining using slow and fast skeletal troponin I (TnI) antibodies. By this means, small angular fibers were shown to be fast skeletal muscle, and myosin was absent from these muscle fibers. Actin and tropomyosin were maintained. Muscle protein ratios were determined by stoichiometry following sodium dodecyl sulfate–polyacrylamide gel electrophoresis of AQM myofibril specimens from four subjects. The myosin heavy chain/actin ratio was significantly decreased compared with a normal control group and other neuromuscular diseases. These pathologic findings returned to normal during recovery from AQM. Thus, myosin selectively decreases, whereas actin and regulatory proteins located above it are maintained during AQM.

Hypoxia-mediated cancer stem cells in pseudopalisades with activation of hypoxia-inducible factor-1α/Akt axis in glioblastoma☆☆☆

Pseudopalisades (Ps) around necrotic foci are severely hypoxic and overexpress hypoxia-inducible factor (HIF) in glioblastoma (GBM). Hypoxic regions have been proposed as one of several distinct niches for cancer stem cells (CSCs) in GBM, but little is known about the association between Ps features and CSC properties. Herein, we focused on the biological role of Ps lesions. In clinical cases of GBM, expression of hypoxia-related molecules including HIF-1α, Glut-1, p27(Kip1), and pAkt was significantly increased in perinecrotic Ps lesions compared with nonnecrotic areas and perinecrotic lesions lacking Ps features. Significantly higher expression levels of several CSC-related markers, including CD133, Sox2, CD44s, and aldehyde dehydrogenase (ALDH) 1, were also observed in Ps lesions, which were positively correlated with expression of hypoxia-related molecules and pAkt. Ps lesions also showed increased number of apoptotic cells and decreased bcl-2 and survivin expression compared with the surrounding tissue. Short-term exposure of astrocytoma cell lines to cobalt chloride, which is known to mimic the effect of hypoxia, caused an increase in expression of both hypoxia- and CSC-related markers, in line with increases in the ALDH(high) cell population and number of spheroids. Inhibition of endogenous Akt by LY294002 resulted in decreased expression of Sox2, ALDH1, and CD133, leading to enhancement of cobalt chloride-mediated apoptotic events due to altered ratio of bcl-2 to bax expression. These findings suggest that Ps lesions within GBM may serve as a specialized hypoxic niche, in which the HIF-1α/pAkt axis is activated, in response to severe hypoxia.

Immunohistochemical Differentiation of Fiber Types in Human Skeletal Muscle Using Monoclonal Antibodies to Slow and Fast Isoforms of Troponin I Subunit

The cDNA sequence of troponin I (TnI), one of the subunits of the skeletal muscle regulatory protein, differs between slow-twitch muscle and fast-twitch muscle. We prepared monoclonal antibodies to the slow and fast isoforms of human TnI for the purpose of differentiating muscle fiber types in human neuromuscular disorders. Slow TnI antibody was labeled with tetramethylrhodamine isothiocyanate while fast TnI antibody was labeled with fluorescein isothiocyanate; then these two antibodies were mixed. This mixture was then used to stain biopsied muscle from patients with neuromuscular disorders. It was possible to differentiate muscle fibers into slow, fast and intermediate fibers having various contents of slow and fast TnI. In tissue composed of small muscle fibers, this method facilitated differentiation of types of muscle fibers by allowing staining of only a single section. The usefulness of our technique using slow and fast TnI antibodies is discussed in comparison with ATPase staining. Because our staining method can distinguish slow and fast fiber components, it is useful for clinical application.

Primary central nervous system lymphoma in acquired immune deficiency syndrome mimicking toxoplasmosis

A 37-year-old man, a hepatitis B virus carrier due to mother-to-child transmission, had a medical examination in September 2008 in nearby hospitals due to anorexia and weight loss. He was transported to our hospital because computed tomography (CT) detected intracranial lesions, and he had a positive human immunodeficiency virus (HIV) antibody test. Head computed tomography (CT) revealed multiple hemorrhagic lesions and enhancement effect, suggesting a thin wall. Also, an enhancement effect was present in the ventricle walls and the subarachnoid space. No accumulation was found in the thallium-201 scintigraphy. The enhancement effect of the ventricle walls and the subarachnoid space disappeared after oral administration of pyrimethamine, sulfadiazine, and calcium folinate, contributing to the diagnosis of an abscess and meningitis due to toxoplasma. However, mass lesions did not reduce. A biopsy was performed on 30 October, and the pathological diagnosis was malignant lymphoma. He died from respiratory function deterioration on 8 November. Lymphoma cells were found in ventricle wall tissue and the subarachnoid space at the autopsy. Toxoplasmosis will typically occur as a brain lesion most commonly in acquired immune deficiency syndrome (AIDS), whereas malignant lymphoma commonly manifests as a brain neoplastic lesion. However, differentiating between images of these lesions is difficult, so diagnosis by early biopsy is recommended.

Subependymal giant cell astrocytoma with oncocytic change

A 49-year-old woman presented with a history of periodic episodes of nausea and vomiting starting in 2006. In June 2009, the patient lost consciousness and was transported to our hospital. Head computed tomography (CT) revealed hydrocephalus caused by an enhancing mass lesion with calcification located in the right lateral ventricle around the foramen of Monro. Total tumor removal was performed. Histologic findings revealed fibrillated spindle tumor cells and giant tumor cells with abundant cytoplasm. The spindle tumor cells were immunoreactive for GFAP and S-100 protein, but none of the giant tumor cells were immunoreactive for GFAP or S-100 protein. Electron microscopic examination revealed abundant mitochondria in the tumor cell cytoplasm. According to these findings, this tumor was diagnosed as subependymal giant cell astrocytoma (SEGA) with oncocytic change, which is extremely rare.

Primary central nervous system large B-cell lymphoma with prolific, mixed T-cell and macrophage infiltrates, mimicking multiple sclerosis

Although tissue confirmation is essential for a diagnosis of primary central nervous system large B-cell lymphoma (PCNSBL), accurate assessment may still be difficult, even when tissue is obtained. We report a 59-year-old man, first diagnosed as multiple sclerosis by open biopsy at another institution, who was then correctly diagnosed as PCNSBL after stereotactic biopsy at our hospital. The initial biopsy showed heavy lymphoid and macrophage influx with visible demyelination. On rebiopsy, a diffuse infiltrate of small to medium-sized lymphocytes was prominent and largely stained as T cells (CD3) by immunohistochemistry. There was also an admixture of macrophages, but this time, relatively low numbers of large malignant cells were also identified. The latter stained as B cells (CD20), enabling a diagnosis of B-cell lymphoma, and the condition responded fully to high-dose methotrexate. It is thus possible for PCNSBL to be histologically misinterpreted as a result of ancillary inflammation, characterized here as a profusion of T cells and macrophages.

Pilocytic astrocytoma with abundant oligodendroglioma-like component

An 18-year-old girl presented with a history of visual disturbance without headache, nausea, or vomiting in May 2010. In July 2010, the patient visited our hospital because of visual disturbance. Head magnetic resonance images revealed hydrocephalus caused by a ring-enhancing mass lesion located in the vermis. Total tumor removal was performed. Histological findings revealed that honeycomb cells resembling oligodendrocytes accounted for most parts of the tumor. Rosenthal fibers and hyaline droplets were seen in a small portion. The tumor cells were immunoreactive for GFAP and Olig2, but none of the tumor cells were immunoreactive for Symaptophysin, EMA, or IDH 1. according to these findings, the tumor was diagnosed as pilocytic astrocytoma with an abundant oligodendroglioma-like component. Pilocytic astrocytoma is known to be associated with an oligodendroglioma-like component; however, the differential diagnosis for oligodendroglioma may be difficult when an oligodendroglioma-like component occupies most of the tumor.

A De Novo Mouse Model of C11orf95-RELA Fusion-Driven Ependymoma Identifies Driver Functions in Addition to NF-κB

SUMMARY The majority of supratentorial ependymomas (ST-ependymomas) have few mutations but frequently display chromothripsis of chromosome 11q that generates a fusion between C11orf95 and RELA (RELAFUS). Neural stem cells transduced with RELAFUS ex vivo form ependymomas when implanted in the brain. These tumors display enhanced NF-κB signaling, suggesting that this aberrant signal is the principal mechanism of oncogenesis. However, it is not known whether RELAFUS is sufficient to drive de novo ependymoma tumorigenesis in the brain and, if so, whether these tumors also arise from neural stem cells. We show that RELAFUS drives ST-ependymoma formation from periventricular neural stem cells in mice and that RELAFUS-induced tumorigenesis is likely dependent on a series of cell signaling pathways in addition to NF-κB.

Pathophysiological evaluation of cerecyte coil embolization for experimental broad neck aneurysms.

Cerecyte second-generation coils feature inner surfaces coated with an absorbable polyglycolic acid (PGA) polymer. Their use is expected to accelerate aneurysm organization, but time course data are limited. The present experimental study was therefore conducted to clarify the processes by pathological examination. Methods. Two types of experimental aneurysms were initially generated in adult mongrel dogs, one bifurcation and another of lateral wall type. Long-term persistence of each was defined by follow-up angiography for more than 1 year. Embolization of the aneurysms was then performed using only cerecyte coils, and follow-up angiography was conducted after 2 and 4 weeks followed by pathological examination. Results. Organization of both types of broad neck aneurysm was apparent 4 weeks after embolization, which is earlier as compared with already reported data for bare coils.