Faculty Bibliography

The goal of this study was to describe the demographic, histologic, and prognostic features of children with low-grade neuroepithelial tumors (LGN) of the CNS presenting with leptomeningeal metastases (LM) at diagnosis. We identified 528 newly diagnosed LGN children, 13 (3%) of whom had LM at diagnosis. LM was defined by neuroimaging, clinical evidence, and/or biopsy. The charts were reviewed and patients contacted to validate the demographic data, treatment, and clinical status. The distribution of LM patients by primary tumor site was diencephalon, 5; cerebrum, 2; spinal cord, 3; brainstem, 2; and cerebellum, 1. Six of 8 patients with LM had durable objective responses to chemotherapy. The 5-year progression-free survival of patients with LM at diagnosis was 17%, compared to 85% (95% CI, 80%-91%) for those with localized LGN who had a gross total resection and 51% (95% CI, 44%-52%) for those with localized LGN who had less aggressive surgery ( P < 0.0001). Only 1 of these 13 LM patients died. The 5-year overall survival of the localized LGN group with a gross total resection was 97% (95% CI, 92%-99.9%), and that of the localized LGN group with less aggressive surgery was 88% (95% CI, 84%-95%) ( P = 0.004). The 3% frequency of LM at diagnosis is likely an underestimate since patients with newly diagnosed LGN were not routinely staged. We suggest that staging be considered in the following circumstances: diencephalic primary site, unexplained hydrocephalus, clinical features suggestive of LM, and before adjuvant therapy is initiated. The prognosis for children with LM at diagnosis is favorable, and its identification alters therapeutic strategies

Glioblastoma (GBM) remains one of the most challenging solid cancers to treat due to its highly proliferative, angiogenic and invasive nature. The small molecule CDK inhibitor, flavopiridol, has demonstrated antitumor activity in human xenograft models and is currently in clinical trials showing efficacy in patients with advanced disease. We have developed an experimental animal model using the murine glioma GL261 cells as a novel in vivo system to screen potential therapeutic agents for GBM. Results of in vitro testing demonstrate that flavopiridol has several relevant clinical characteristics such as its ability to: 1. inhibit cell growth; 2. inhibit cell migration; 3. decrease expression of cyclin D1, CDK4 and p21; 4. induce apoptosis in cells with high levels of p27 expression; and 5. decrease the expression of the anti-apoptotic protein Bcl-2. The mechanism by which flavopiridol induces apoptosis is mitochondrial-mediated. We demonstrate by electron microscopy and immunohistochemistry that drug treatment induces mitochondrial damage that was accompanied by the release of cytochrome c into the cytosol together with the translocation of apoptosis inducing factor (AIF) into the nucleus. This finding in murine glioma cells differs from the mechanism of flavopiridolinduced cell death reported by us for human glioma cells (Alonso et al., Mol Cancer Ther 2003; 2:139) where drug treatment induced a caspase- and cytochrome c-independent pathway in the absence of detectable damage to mitochondria. In apoptotic human glioma cells only translocation of AIF into the nucleus occurred. Thus, the same drug kills different types of glioma cells by different mitochondrial-dependent pathways

The aim of this study was to develop an MRI protocol to evaluate the growth and vascularity of implanted GL261 mouse gliomas on a 7T microimaging system. Both conventional T(1)- and T(2)-weighted imaging and dynamic, contrast-enhanced T(2)*-weighted imaging were performed on 34 mice at different stages of tumor development. MRI measurements of relative cerebral blood volume (rCBV) were compared to histological assessments of microvascular density (MVD). Enhancement on postcontrast T(1)-weighted images was compared to histological assessments of Evan's blue extravasation. Conventional T(2)-weighted and postcontrast T(1)-weighted images demonstrated tumor growth characteristics consistent with previous descriptions of GL261 glioma. Furthermore, measurements of rCBV from MRI data were in good agreement with histological measurements of MVD from the same tumors. Postcontrast enhancement on T(1)-weighted images was observed at all stages of GL261 glioma progression, even before evidence of angiogenesis, indicating that the mechanism of conventional contrast enhancement in MRI does not require neovascularization. These results provide quantitative support for MRI approaches currently used to assess human brain tumors, and form the basis for future studies of angiogenesis in genetically engineered mouse brain tumor models. Magn Reson Med 49:848-855, 2003

We recently identified a mutation in the I-kappa B kinase associated protein (IKBKAP) gene as the major cause of familial dysautonomia (FD), a recessive sensory and autonomic neuropathy. This alteration, located at base pair 6 of the intron 20 donor splice site, is present on >99.5% of FD chromosomes and results in tissue-specific skipping of exon 20. A second FD mutation, a missense change in exon 19 (R696P), was seen in only four patients heterozygous for the major mutation. Here, we have further characterized the consequences of the major mutation by examining the ratio of wild-type to mutant (WT:MU) IKBKAP transcript in EBV-transformed lymphoblast lines, primary fibroblasts, freshly collected blood samples, and postmortem tissues from patients with FD. We consistently found that WT IKBKAP transcripts were present, albeit to varying extents, in all cell lines, blood, and postmortem FD tissues. Further, a corresponding decrease in the level of WT protein is seen in FD cell lines and tissues. The WT:MU ratio in cultured lymphoblasts varied with growth phase but not with serum concentration or inclusion of antibiotics. Using both densitometry and real-time quantitative polymerase chain reaction, we found that relative WT:MU IKBKAP RNA levels were highest in cultured patient lymphoblasts and lowest in postmortem central and peripheral nervous tissues. These observations suggest that the relative inefficiency of WT IKBKAP mRNA production from the mutant alleles in the nervous system underlies the selective degeneration of sensory and autonomic neurons in FD.Therefore, exploration of methods to increase the WT:MU IKBKAP transcript ratio in the nervous system offers a promising approach for developing an effective therapy for patients with FD

Intracranial chondrosarcomas have a predilection for the skull base, for which CT and MR imaging findings have been described. We present a rare case of primary chondrosarcoma arising from the falx in a young woman with no history of radiation. The CT, conventional MR imaging, perfusion MR imaging, and digital subtraction angiography findings are described

Numerous studies examining the prognostic significance of p27KIP1 expression in human cancer have shown that decreased expression often is an independent prognostic factor associated with worse survival. However, the prognostic value of p27KIP1 expression in gliomas is less well established. To further address this issue, we evaluated the relationship between p27KIP1 protein expression in a series of 50 astrocytomas with clinicopathologic parameters including age, tumor grade, MIB-1 proliferation index, and patient survival using both Western blot analysis and immunohistochemistry. The level of p27KIP1 protein expression in 9 nonneoplastic brain tissue specimens served as a control. Sixteen high-grade astrocytomas were analyzed by Western blot, and 26 high-grade astrocytomas were analyzed by immunohistochemistry for levels of p27KIP1 protein expression. Regardless of the technique used to measure p27KIP1, approximately 50% of the high-grade tumors were low expressors and the other 50% were high expressors. Thus, expression of p27KIP1 was independent of tumor grade. Loss of p27KIP1 expression is often associated with an increase in proliferative activity. We measured the rate of tumor cell proliferation using MIB-1 immunostaining in 16 high-grade astrocytomas to determine whether there was an inverse correlation between p27KIP1 expression and proliferation. No correlation between p27KIP1 expression and MIB-1 labeling index or patient survival was found. Using immunohistochemistry, we noted that the staining pattern of p27KIP1 in glioblastomas was mainly in the pseudopalisading cells that outline areas of necrosis. Because p27KIP1 can be up-regulated by hypoxia, this staining pattern would be consistent with our observation that hypoxia-inducible factor 1alpha is expressed primarily in pseudopalisading tumor cells around necrotic zones. It has been shown that a high level of p27KIP1 prevents apoptosis in hypoxic cells. Thus, maintenance of high levels of p27KIP1 in gliomas could result from the hypoxic microenvironment present within the tumor. No correlation was found between p27KIP1 expression and any of the clinicopathologic parameters tested, including patient age and tumor grade, the 2 strongest predictors of survival among glioma patients

In vivo animal models of primary brain tumors are necessary to advance knowledge related to the complex interactions between glioma cells and the adjacent brain. A cardinal feature of glioma growth, and a major reason why neurosurgical and adjunctive therapies ultimately fail in most patients is their invasive properties. We have adapted a previously described animal model developed by one of us to give better histological detail while preserving the identification of single infiltrating glioma cells. GL261 glioma cells were first transfected with the plasmid encoding green fluorescent protein (GFP) and then implanted into the brains of syngeneic C57BL/6 mice. Identification of GFP-positive tumor cells in paraffin sections of the brains of tumor-bearing animals utilized an antibody for conventional immunoperoxidase immunohistochemistry. This method is a more powerful technique compared with the prior use of frozen sections and fluorescence microscopy to identify GFP-tagged tumor cells. We find that this new method provides improved morphology and proves to be a sensitive and reliable system for detection of invading glioma cells. Using this methodology with other advanced technologies (eg, laser capture microdissection) holds out the promise of helping to elucidate the molecular mechanisms of glioma cell infiltration and invasion into the surrounding brain