Stephen Skirboll

An RNAi Screen Identifies TRRAP as a Regulator of Brain Tumor-Initiating Cell Differentiation

Glioblastoma multiforme (GBM) is a highly aggressive form of brain cancer associated with a very poor prognosis. Recently, the initiation and growth of GBM has been linked to brain tumor-initiating cells (BTICs), which are poorly differentiated and share features with neural stem cells (NSCs). Here we describe a kinome-wide RNA interference screen to identify factors that control the tumorigenicity of BTICs. We identified several genes whose silencing induces differentiation of BTICs derived from multiple GBM patients. In particular, knockdown of the adaptor protein TRRAP significantly increased differentiation of cultured BTICs, sensitized the cells to apoptotic stimuli, and negatively affected cell cycle progression. TRRAP knockdown also significantly suppressed tumor formation upon intracranial BTIC implantation into mice. Together, these findings support a critical role for TRRAP in maintaining a tumorigenic, stem cell-like state.

NGF treatment promotes development of basal forebrain tissue grafts in the anterior chamber of the eye

SummaryThe effects of nerve growth factor (NGF) on developing central cholinergic neurons were studied using intraocular grafts of rat fetal (E17) basal forebrain tissue. Prior to grafting, grafts were incubated in NGF or saline. Transplants were allowed to mature for six weeks, receiving weekly intraocular injections of NGF or saline. Measurements of NGF levels in oculo after one single injection showed that NGF slowly decreases in the anterior chamber fluid, and after one week, low but significant levels were still present in the eye. Following pretreatment with diisopropylfluorophosphate (DFP), the cholinergic neurons in the grafts were analyzed using three morphological markers: antibodies to cholineacetyltransferase (ChAT), antibodies to acetylcholinesterase (AChE Ab) and acetylcholinesterase histochemistry (AChE). The transplants grew well and became vascularized within the first week. The growth of the NGF-treated basal forebrain grafts was significantly enhanced as compared to the growth of the saline-treated grafts evaluated with repeated stereomicroscopical observations directly through the cornea of the etheranaesthetized hosts. The NGF-treated grafts contained almost twice as many cholinergic neurons seen with all the cholinergic markers used, as the salinetreated grafts. However, there was no difference in cholinergic cell density between the two groups. The morphology and size of an individual cholinergic neuron was similar in the two groups. The fiber density as evaluated with AChE-immunohistochemistry did not change after NGF-treatment. The DFP-treatment did not seem to affect the AChE-immunoreactivity since an extensive fiber network was found, whereas almost no fibers were seen using conventional AChE histochemistry. We have demonstrated that in oculo transplantation of basal forebrain is a useful model for examining in vivo effects of NGF on central cholinergic function. The marked volume increase of NGF-treated grafts and the unchanged density of cholinergic cells and terminals suggests, that NGF increases the survival of not only developing cholinergic neurons, but possibly other non-cholinergic neurons and non-neuronal cells as well. These results support the notion that NGF acts as a neurotrophic factor on cholinergic and possibly non-cholinergic cells in the central nervous system

“Paradoxical” transtentorial herniation due to CSF drainage in the presence of a hemicraniectomy

Decompressive hemicraniectomy can be a life-saving treatment for uncontrolled elevations in intracranial pressure (ICP) due to trauma or space-occupying ischemic or hemorrhagic stroke.1 Herniation in the direction opposite the site of the craniectomy—paradoxical herniation—is an underrecognized and potentially fatal complication of this procedure. It can occur spontaneously or may be precipitated by a lumbar puncture (LP) or a CSF shunt. It is critical to recognize this treatable entity because standard interventions aimed at lowering ICP are harmful. A 24-year-old man with a right-sided subdural hemorrhage (SDH) and temporal contusion from head trauma underwent SDH evacuation, anterior temporal lobectomy, and a right-sided hemicraniectomy. Subsequently, a medium pressure ventriculoperitoneal shunt (VPS) was placed for hydrocephalus. Two months later, he followed simple commands and had a left-sided hemianopsia and hemiparesis. At this time, his scalp was slightly sunken over the skull defect. He was transferred to our hospital for rehabilitation, where he developed fevers and decreased responsiveness. An LP revealed an opening pressure of 11 cm H2O. …

Neurotrophin-3 modulates noradrenergic neuron function and opiate withdrawal

Somatic symptoms and aversion of opiate withdrawal, regulated by noradrenergic signaling, were attenuated in mice with a CNS-wide conditional ablation of neurotrophin-3. This occurred in conjunction with altered cAMP-mediated excitation and reduced upregulation of tyrosine hydroxylase in A6 (locus coeruleus) without loss of neurons. Transgene-derived NT-3 expressed by noradrenergic neurons of conditional mutants restored opiate withdrawal symptoms. Endogenous NT-3 expression, strikingly absent in noradrenergic neurons of postnatal and adult brain, is present in afferent sources of the dorsal medulla and is upregulated after chronic morphine exposure in noradrenergic projection areas of the ventral forebrain. NT-3 expressed by non-catecholaminergic neurons may modulate opiate withdrawal and noradrenergic signalling.

Nerve growth factor can influence growth of cortex cerebri and hippocampus: Evidence from intraocular grafts

The effects of nerve growth factor and antiserum against nerve growth factor on cortical cholinergic projection areas in the central nervous system and cerebellum were evaluated using intraocular grafts of cortex cerebri, hippocampus and cerebellum in rat hosts receiving injections into the anterior chamber of the eye of nerve growth factor (at transplantation, 5 and 10 days after transplantation) or antiserum to nerve growth factor (every 5 days). The controls received cytochrome c or preimmune serum. Growth of grafts was followed by repeated observations directly through the cornea of the host using a stereomicroscope. Nerve growth factor-treated grafts of cortex cerebri and hippocampus grew significantly smaller as compared to the corresponding control grafts. In one experiment, growth of cytochrome c and saline-treated cortex cerebri was compared and no difference in growth was found. Growth of nerve growth factor-treated cerebellar grafts did not differ significantly from growth of cytochrome c-treated grafts. Morphological analysis using Nissl-staining, antibodies to glial acidic fibrillary protein to evaluate the degree of gliosis and antiserum to neurofilament as a neuronal marker did not reveal any marked differences between nerve growth factor- and cytochrome c-treated grafts. Cortical grafts receiving anti-nerve growth factor antiserum by injection or by immunizing host rats against nerve growth factor showed similar growth to the controls. Similarly, grafts of fetal hippocampus to rats immunized with nerve growth factor were not significantly different from grafts to host rats immunized with cytochrome c. We conclude that exogenous nerve growth factor affects the development of grafted cortex cerebri and hippocampus. The fact that these cortical areas stop growing earlier in the presence of nerve growth factor without the grafts showing evidence of disturbed glial or neuronal populations compared to control grafts indicates that nerve growth factor acts to induce overall/premature differentiation and maturation. The mechanism for this whether or not it is receptor-mediated and which cells are primarily affected by nerve growth factor is not yet known.

Pituitary Adenomas Can Appear as Hypermetabolic Lesions in 18F-FDG PET Imaging

The 2‐deoxy‐2‐[18F] fluoro‐D‐glucose positron emission tomography (FDG‐PET) scan is commonly used in detection and staging of many malignant neoplasms. However, several benign or non‐neoplastic conditions avidly accumulate 18F‐FDG, causing ambiguity in interpretation of results. It is unknown whether pituitary adenomas uptake 18F‐FDG and appear positive in PET imaging. Here, we present 2 cases of benign pituitary adenoma with elevated metabolic activity in 18F‐FDG PET scan.

The effect of postoperative infection on survival in patients with glioblastoma

OBJECTIVE Glioblastoma is a primary glial neoplasm with a median survival of approximately 1 year. There are anecdotal reports that postoperative infection may confer a survival advantage in patients with glioblastoma. However, only a few case reports in the literature, along with 2 retrospective cohort studies, show some potential link between infection and prolonged survival in patients with glioblastoma. The objective of this study was to evaluate the effect of postoperative infection in patients with glioblastoma using a large national database. METHODS The linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database was searched to identify patients 66 years of age and older with glioblastoma, with and without infection, from 1997 to 2010. The primary outcome was survival after diagnosis. The statistical analysis was performed with a graphical representation using Kaplan-Meier curves, univariate analysis with the log-rank test, and multivariate analysis with proportional hazards modeling. RESULTS A total of 3784 patients with glioblastoma were identified from the database, and from these, 369 (9.8%) had postoperative infection within 1 month of surgery. In patients with glioblastoma who had an infection within 1 month of surgery, there was no significant difference in survival (median 5 months) compared with patients with no infection (median 6 months; p = 0.17). The study also showed that older age, increased Gagne comorbidity score, and having diabetes may be negatively associated with survival. CONCLUSIONS Infection after craniotomy within 1 month was not associated with a survival benefit in patients with glioblastoma.

Reversal of preoperative catatonic state by surgical resection of an adult-onset craniopharyngioma: case report and review of the literature.

ObjectiveTo describe a case of a rare adult-onset craniopharyngioma presenting as rapidly progressive catatonia that was reversed after surgical resection of the tumor. BackgroundProfoundly depressed states of awareness classified as either catatonia or akinetic mutism have been reported in patients with hypothalamic neoplasms, but reports of improvement in consciousness level after surgical resection are rare and limited to very large tumors. MethodMedical, neurologic, and psychiatric histories, physical examination findings, laboratory workup results, pathologic and imaging studies, and response to surgical treatment were documented. ResultThe patient showed progressive improvement in mental status and overall neurologic function after surgical treatment. ConclusionsThe search for an etiology of a profound catatonic state should include the probability of a suprasellar/hypothalamic lesion, which in this case was owing to the rare finding of an imaging-documented adult-onset craniopharyngioma.

Patterns of Care and Outcomes of Adjuvant Radiotherapy for Meningiomas: A Surveillance, Epidemiology, and End Results and Medicare Linked Analysis

Background: The role of adjuvant stereotactic radiosurgery (SRS) and fractionated radiotherapy (XRT) are unknown in patients with resected meningiomas. Objective: To identify patterns of care and outcomes of adjuvant radiotherapy for meningiomas in the Linked Surveillance, Epidemiology, and End Results (SEER) Medicare data. Methods: A total of 1,964 patients older than 66 years included in the SEER-Medicare data, who were diagnosed with meningioma, and underwent craniotomy were included for analysis. Results: Patients were less likely to receive adjuvant therapy if they were older than 75 (OR 0.730, 95% CI 0.548-0.973), female sex (OR 0.731, 95% CI 0.547-0.978), or unmarried (OR 0.692, 95% CI 0.515-0.929). Patients were more likely to receive adjuvant treatment for Grade II/III tumors (OR 5.586, 95% CI 2.135-13.589), tumors over 5 cm (OR 1.850, 95% CI 1.332-2.567), or partial resection (OR 3.230, 95% CI 2.327-4.484). Yearly between 2000 and 2009, 10.65 – 19.77% of patients received adjuvant therapy. Although no survival benefit was seen with the addition of adjuvant therapy (p = 0.1236), the subgroup of patients receiving SRS had a decreased risk of death compared to those receiving surgery alone (aHR 0.544, 95% CI 0.318 – 0.929). Conclusion: Utilization of adjuvant XRT and SRS remained stable between 2000 and 2010. Male sex, young age, marriage, partial resection, Grade II/III tumors, and large tumors predicted the use of adjuvant therapy. For all patients, SRS decreased the risk of death compared to craniotomy alone.

Abstract 3733: Defining and targeting a Glioblastoma cancer stem cell population with EGF Receptor Variant III.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC The relationship between mutated proteins and the relatively rare cancer stem cell population is unclear since driver mutations are present throughout a tumor. Glioblastoma (GBM) tumors frequently express EGFRvIII, an EGFR variant that arises via gene rearrangement and amplification. The expression of EGFRvIII is restricted despite the prevalence of the alteration. Here we show that EGFRvIII is expressed in a population of human GBM cancer stem cells. EGFRvIII positive cancer stem cells demonstrate greater self-renewal and tumor initiation than the more abundant EGFRvIII negative cells. EGFRvIII positive cells are associated with stem/progenitor markers while markers of differentiation are found in EGFRvIII negative cells. EGFRvIII is highly co-expressed with CD133, and the EGFRvIII positive/CD133 positive sub-population defines the highest self-renewal and tumor initiating population. Surprisingly, wildtype EGFR was infrequently co-expressed with EGFRvIII but present in the majority of cells, both in primary GBM and cultured GBM neurospheres. Elimination of the EGFRvIII positive or the EGFRvIII/CD133 dual positive population with an engineered anti-EGFRvIII/CD133 bi-specific antibody reduced tumorigenicity of implanted tumor cells. This work demonstrates that a mutated oncogene can have CSC specific expression and be used to specifically target this population. Citation Format: David R. Emlet, Catherine Del Vecchio, Puja Gupta, Siddhartha Mitra, Shuang-Yin Han, Marina Holgado-Madruga, Gordon Li, Kristen Jensen, Hannes Vogel, Stephen Skirboll, Albert J. Wong. Defining and targeting a Glioblastoma cancer stem cell population with EGF Receptor Variant III. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3733. doi:10.1158/1538-7445.AM2013-3733