Iren Horkayne-Szakaly

BRAF duplications and MAPK pathway activation are frequent in gliomas of the optic nerve proper

Abstract Optic pathway gliomas represent a specific subtype of astrocytoma with unique clinicopathologic and biologic properties, but studies of tumors in the optic nerve proper have been hampered by limited tissue availability. We analyzed optic nerve gliomas of 59 patients (median age, 9 years; range, 3 months–66 years; 33 female, 26 male) using formalin-fixed paraffin-embedded material in tissue microarrays. Seven patients had the clinical diagnosis of neurofibromatosis type 1 (NF1). Fluorescence in situ hybridization studies were performed for BRAF, PTEN, CDKN2A (p16), and NF1. Immunohistochemistry was performed for glial fibrillary acidic protein, phospho-ERK, and mutant IDH1R132H protein. The BRAF duplication was present in 11 (73%) of 15 evaluable tumors, including 1 NF1 patient (1 of 4 tested; 25%). The single tumor lacking BRAF duplication or NF1 association had histologic features of a ganglioglioma. Conversely, heterozygous PTEN deletions were present in 2 (8%) of 25 evaluable cases, one of which was BRAF duplicated and the other was NF1 associated. CDKN2A and NF1 deletions were absent in all tumors tested. Phospho-ERK immunoreactivity was present in 55 (96%) of 57 tumors and was mostly strong and diffuse (80%). Only 1 case of 53 expressed IDH1R132H. Thus, optic nerve gliomas demonstrated molecular alterations typical of pilocytic astrocytomas, including the universal presence of either BRAF duplication or NF1 association and common mitogen-activated protein kinase pathway activation but very rare mutant IDH1 expression.

Activation of mTORC1/mTORC2 signaling in pediatric low-grade glioma and pilocytic astrocytoma reveals mTOR as a therapeutic target

BACKGROUND Previous studies support a role for mitogen-activated protein kinase pathway signaling, and more recently Akt/mammalian target of rapamycin (mTOR), in pediatric low-grade glioma (PLGG), including pilocytic astrocytoma (PA). Here we further evaluate the role of the mTORC1/mTORC2 pathway in order to better direct pharmacologic blockade in these common childhood tumors. METHODS We studied 177 PLGGs and PAs using immunohistochemistry and tested the effect of mTOR blockade on 2 PLGG cell lines (Res186 and Res259) in vitro. RESULTS Moderate (2+) to strong (3+) immunostaining was observed for pS6 in 107/177 (59%) PAs and other PLGGs, while p4EBP1 was observed in 35/115 (30%), pElF4G in 66/112 (59%), mTOR (total) in 53/113 (47%), RAPTOR (mTORC1 component) in 64/102 (63%), RICTOR (mTORC2 component) in 48/101 (48%), and pAkt (S473) in 63/103 (61%). Complete phosphatase and tensin homolog protein loss was identified in only 7/101 (7%) of cases. In PA of the optic pathways, compared with other anatomic sites, there was increased immunoreactivity for pS6, pElF4G, mTOR (total), RICTOR, and pAkt (P < .05). We also observed increased pS6 (P = .01), p4EBP1 (P = .029), and RICTOR (P = .05) in neurofibromatosis type 1 compared with sporadic tumors. Treatment of the PLGG cell lines Res186 (PA derived) and Res259 (diffuse astrocytoma derived) with the rapalog MK8669 (ridaforolimus) led to decreased mTOR pathway activation and growth. CONCLUSIONS These findings suggest that the mTOR pathway is active in PLGG but varies by clinicopathologic subtype. Additionally, our data suggest that mTORC2 is differentially active in optic pathway and neurofibromatosis type 1-associated gliomas. MTOR represents a potential therapeutic target in PLGG that merits further investigation.

High-grade astrocytomas show increased Nestin and Wilms's tumor gene (WT1) protein expression.

Wilms’s tumor gene (WT1) is overexpressed in a variety of hematologic malignancies and solid tumors. Recently, WT1 protein has been considered as a molecular target of cancer immunotherapy for several solid tumors and as a tool for monitoring minimal residual disease in leukemia patients. There are only few investigations on WT1 expression in central nervous system neoplasms, which suggest that the WT1 gene may play an important role in tumorigenesis of primary astrocytic tumors and that high-grade tumors express high levels of WT1 proteins. We examined 50 low-grade and high-grade gliomas using tissue microarray and immunohistochemical methods to identify WT1 protein, P53, Ki-67, GFAP, NFP, EGFR, nestin, and Neu-N expression. WT1 and nestin shared overlapping expression in all gliomas and were increased in high-grade examples, highlighting their potential use as diagnostic and prognostic tumor markers. Our results support the combined role of WT1 and nestin in glial tumorigenesis and progression.

Trimyelia with divergent cord pathways and three foramina magni

ObjectWe report the rare finding of trimyelia with divergent cord pathways in a 33 5/7-week-old fetus who died shortly after spontaneous vaginal delivery.MethodsThe main autopsy findings were three separate and distinct spinal cords, arising from the medulla and exiting through three separate foramina magni. The two lateral cords coursed toward each upper extremity and the medulla split into two halves that rejoined to form a central cervical cord. Further evaluation of this anomaly revealed agenesis of the cerebellar vermis and cystic dilation of the fourth ventricle. Microscopic cross-sections of the two lateral cords demonstrated well-formed central canals, white matter, and central gray with motor neurons. Sections of the abnormal mid-cervical cord demonstrated abnormally structured cord parenchyma without central canals.ConclusionsSome features were consistent with iniencephaly; however, defects of the occipital bone, anterior spina bifida, and shortening of the spinal cord were absent. Although agenesis of the cerebellar vermis and cystic dilation of the fourth ventricle indicate Dandy–Walker syndrome, other features such as hydrocephalus, agenesis of the corpus callosum, infundibular hamartomas, and malformations of the inferior olives or an occipital encephalocele were absent. The possible pathogenesis of this intriguing pathological entity is briefly discussed.

Engraftment of donor mesenchymal stem cells in chimeric BXSB includes vascular endothelial cells and hepatocytes

Somatic tissue engraftment was studied in BXSB mice treated with mesenchymal stem cell transplantation. Hosts were conditioned with nonlethal radiation prior to introducing donor cells from major histocompatibility complex-matched green fluorescent protein transgenic mice. Transplant protocols differed for route of injection, ie, intravenous (i.v.) versus intraperitoneal (i.p.), and source of mesenchymal stem cells, ie, unfractionated bone marrow cells, ex vivo expanded mesenchymal stem cells, or bone chips. Tissue chimerism was determined after short (10–12 weeks) or long (62 weeks) posttransplant follow-up by immunohistochemistry for green fluorescent protein. Engraftment of endothelial cells was seen in several organs including liver sinusoidal cells in i.v. treated mice with ex vivo expanded mesenchymal stem cells or with unfractionated bone marrow cells. Periportal engraftment of liver hepatocytes, but not engraftment of endothelial cells, was found in mice injected i.p. with bone chips. Engraftment of adipocytes was a common denominator in both i.v. and i.p. routes and occurred during early phases post-transplant. Disease control was more robust in mice that received both i.v. bone marrow and i.p. bone chips compared to mice that received i.v. bone marrow alone. Thus, the data support potential use of mesenchymal stem cell transplant for treatment of severe lupus. Future studies are needed to optimize transplant conditions and tailor protocols that may in part be guided by fat and endothelial biomarkers. Furthermore, the role of liver chimerism in disease control and the nature of cellular communication among donor hematopoietic and mesenchymal stem cells in a chimeric host merit further investigation.

Nonfrozen Transport Medium Preserves and Restores Skeletal Muscle Enzymatic Activity and Morphology

Abstract Muscle biopsy plays an integral role in the evaluation of patients with neuromuscular disease. Optimal interpretation requires adequate preservation of both morphology and enzymatic activity of the tissue. Ideally, fresh tissue should be transported immediately to a specialized neuromuscular laboratory, where a portion of the biopsy is frozen for the evaluation of labile sarcoplasmic enzymes. This is not always possible, and problems associated with on-site freezing and transport of frozen tissue may arise. When performed improperly, freezing muscle introduces ice crystal artifacts that distort the aqueous sarcoplasm, which potentially limits recognition of underlying pathology. The authors describe a new method to transport muscle biopsies in Aedesta™-cell/tissue preservation (ACTP) media. Our results indicate that skeletal muscle transported in ACTP is better preserved and exhibits fewer artifacts than muscle transported via conventional methods. In addition, the immersion in ACTP of previously frozen muscle with extensive artifacts significantly reduces ice crystal artifacts and restores original sarcoplasmic morphology and enzymatic activity. (The J Histotechnol 32(2):49–53, 2009) Submitted January 7, 2009; accepted with revisions February 24, 2009