Troglitazone Reduces Glyoxalase I Protein Expression in Glioma and Potentiates the Effects of Chemotherapeutic Agents

Despite resistance of most gliomas to chemotherapy, approximately 2/3 of oligodendrogliomas show sensitivity to such agents. This sensitivity has been associated with deletions on chromosome 1p alone or in combination with 19q. Higher expression of the enzyme glyoxalase I has been found in oligodendrogliomas with chromosome 1p intact compared to those with a deletion. Higher expression of this enzyme is also associated with tumor chemoresistance in other cancers. The present study tested whether the drug troglitazone would make a glioma cell line more sensitive to chemotherapeutic agents. This drug was chosen because it has been shown to decrease glyoxalase I enzyme activity in cells. Treatment with troglitazone decreased expression of glyoxalase I, and potentiated cell death when used in combination with chemotherapeutic agents. This decrease in glyoxalase I protein may be one mechanism by which this potentiation occurs, and troglitazone may be a candidate for use in glioma therapy

Advancing gene therapies, methods, and technologies for Parkinson’s Disease and other neurological disorders

Introduction. Vector-based intracerebral gene therapies are being used to treat specific neurodegenerative conditions such as Parkinson’s Disease (PD). This review presents a basis for central nervous system (CNS) gene therapy treatments of neurodegenerative diseases such as PD, as well as the need for novel skill sets and health delivery strategies within the clinical neurosciences (neurology and neurosurgery) to meet future demand for such therapies.State of the art. Preclinical vector-based gene therapy approaches have been translated into clinical trials for PD and other neurodegenerative conditions. Unfortunately, such trials, and parallel efforts using other therapeutics, have yet to provide a breakthrough. Image-guided convection enhanced delivery (CED) optimises the parenchymal distribution of gene therapies applied within the CNS, and may ultimately provide such a breakthrough.Clinical implications. Currently, image-guided CED and gene therapy are not part of training programmes for most neurosurgeons and neurologists. As a result, few medical centres and hospitals have sufficiently experienced teams to participate in gene transfer clinical trials for PD or other neurological conditions. If CNS gene therapies prove to be efficacious for PD and/or other conditions, the demand for such treatments will overwhelm the available number of experienced clinical neuroscience teams and treatment centres.Future directions. Expanded indications and demand for CNS gene therapies will require a worldwide educational effort to supplement the training of clinical neuroscience practitioners. Initially, a limited number of Centres of Excellence will need to establish relevant educational training requirements and best practice for such therapeutic approaches. Advanced technologies, including robotics and artificial intelligence, are especially germane in this regard, and will expand the treatment team’s capabilities while assisting in the safe and timely care of those afflicted

Pharmacologic Modulation of Serine/Threonine Phosphorylation Highly Sensitizes PHEO in a MPC Cell and Mouse Model to Conventional Chemotherapy

The failure of cytotoxic cancer regimens to cure the most drug-resistant, well-differentiated solid tumors has been attributed to the heterogeneity of cell types that differ in their capacities for growth, differentiation, and metastases. We investigated the effect of LB1, a small molecule inhibitor of serine/threonine protein phosphatase 2A (PP2A), on its ability to inhibit a low growth fraction and highly drug-resistant solid neuroendocrine tumor, such as metastatic pheochromocytoma (PHEO). Subsequently, we evaluated the increased efficacy of chemotherapy combined with LB1.The effect of LB1 and temozolomide (TMZ), a standard chemotherapeutic agent that alone only transiently suppressed the growth and regression of metastatic PHEO, was evaluated in vitro on a single PHEO cell line and in vivo on mouse model of metastatic PHEO. In the present study, we show that metastatic PHEO, for which there is currently no cure, can be eliminated by combining LB1, thereby inhibiting PP2A, with TMZ. This new treatment approach resulted in long term, disease-free survival of up to 40% of animals bearing multiple intrahepatic metastases, a disease state that the majority of patients die from. Inhibition of PP2A was associated with prevention of G1/S phase arrest by p53 and of mitotic arrest mediated by polo-like kinase 1 (Plk-1).The elimination of DNA damage-induced defense mechanisms, through transient pharmacologic inhibition of PP2A, is proposed as a new approach for enhancing the efficacy of non-specific cancer chemotherapy regimens against a broad spectrum of low growth fraction tumors very commonly resistant to cytotoxic drugs

Earlier post-operative hypocortisolemia may predict durable remission from Cushings disease.

CONTEXT: Achievement of hypocortisolemia following transsphenoidal surgery (TSS) for Cushings disease (CD) is associated with successful adenoma resection. However, up to one-third of these patients recur. OBJECTIVE: We assessed whether delay in reaching post-operative cortisol nadir may delineate patients at risk of recurrence for CD following TSS. METHODS: A retrospective review of 257 patients who received 291 TSS procedures for CD at NIH, between 2003 and 2016. Early biochemical remission (serum cortisol nadir <5 μg/dL) was confirmed with endocrinological and clinical follow-up. Recurrence was detected by laboratory testing, clinical stigmata or medication dependence during a median follow-up of 11 months. RESULTS: Of the 268 unique admissions, remission was recorded in 241 instances. Recurrence was observed in 9% of these cases with cortisol nadir ≤5 μg/dL and 6% of cases with cortisol nadir ≤2 μg/dL. The timing of hypocortisolemia was critical in detecting late recurrences. Morning POD-1 cortisol <3.3 μg/dL was 100% sensitive in predicting durable remission and morning POD-3 cortisol ≥18.5 μg/dL was 98.6% specific in predicting remote recurrence. AUROC analysis revealed that hypocortisolemia ≤5 µg/dL before 15 h (post-operative) had 95% sensitivity and an NPV of 0.98 for durable remission. Serum cortisol level ≤2 µg/dL, when achieved before 21 h, improved sensitivity to 100%. CONCLUSIONS: In our cohort, early, profound hypocortisolemia could be used as a clinical prediction tool for durable remission. Achievement of hypocortisolemia ≤2 µg/dL before 21 post-operative hours appeared to accurately predict durable remission in the intermediate term

Developmentally arrested structures preceding cerebellar tumors in von Hippel-Lindau disease.

There is increasing evidence that suggests that knockout of tumor-suppressor gene function causes developmental arrest and protraction of cellular differentiation. In the peripheral nervous system of patients with the tumor-suppressor gene disorder, von Hippel-Lindau disease, we have demonstrated developmentally arrested structural elements composed of hemangioblast progenitor cells. Some developmentally arrested structural elements progress to a frank tumor, hemangioblastoma. However, in von Hippel-Lindau disease, hemangioblastomas are frequently observed in the cerebellum, suggesting an origin in the central nervous system. We performed a structural and topographic analysis of cerebellar tissues obtained from von Hippel-Lindau disease patients to identify and characterize developmentally arrested structural elements in the central nervous system. We examined the entire cerebella of five tumor-free von Hippel-Lindau disease patients and of three non-von Hippel-Lindau disease controls. In all, 9 cerebellar developmentally arrested structural elements were detected and topographically mapped in 385 blocks of von Hippel-Lindau disease cerebella. No developmentally arrested structural elements were seen in 214 blocks from control cerebella. Developmentally arrested structural elements are composed of poorly differentiated cells that express hypoxia-inducible factor (HIF)2α, but not HIF1α or brachyury, and preferentially involve the molecular layer of the dorsum cerebelli. For the first time, we identify and characterize developmentally arrested structural elements in the central nervous system of von Hippel-Lindau patients. We provide evidence that developmentally arrested structural elements in the cerebellum are composed of developmentally arrested hemangioblast progenitor cells in the molecular layer of the dorsum cerebelli

von Hippel-Lindau Disease-Associated Hemangioblastomas Are Derived from Embryologic Multipotent Cells

BACKGROUND: To determine the origin of the neoplastic cell in central nervous system (CNS) hemangioblastomas in von Hippel-Lindau disease (VHL) and its role in tumor formation and distribution, we characterized and differentiated neoplastic cells from hemangioblastomas removed from VHL patients. METHODS AND FINDINGS: A total of 31 CNS hemangioblastomas from 25 VHL patients were resected and analyzed. Tumor cells from the hemangioblastomas were characterized, grown, and differentiated into multiple lineages. Resected hemangioblastomas were located in the cerebellum (11 tumors), brainstem (five tumors), and spinal cord (15 tumors). Consistent with an embryologically derived hemangioblast, the neoplastic cells demonstrated coexpression of the mesodermal markers brachyury, Flk-1 (vascular endothelial growth factor-2), and stem cell leukemia (Scl). The neoplastic cells also expressed hematopoietic stem cell antigens and receptors including CD133, CD34, c-kit, Scl, erythropoietin, and erythropoietin receptor. Under specific microenvironments, neoplastic cells (hemangioblasts) were expanded and differentiated into erythrocytic, granulocytic, and endothelial progenitors. Deletion of the wild-type VHL allele in the hematopoietic and endothelial progeny confirmed their neoplastic origin. CONCLUSIONS: The neoplastic cell of origin for CNS hemangioblastomas in VHL patients is the mesoderm-derived, embryologically arrested hemangioblast. The hematopoietic and endothelial differentiation potential of these cells can be reactivated under suitable conditions. These findings may also explain the unique tissue distribution of tumor involvement

Angiogenic Factors Stimulate Growth of Adult Neural Stem Cells

The ability to grow a uniform cell type from the adult central nervous system (CNS) is valuable for developing cell therapies and new strategies for drug discovery. The adult mammalian brain is a source of neural stem cells (NSC) found in both neurogenic and non-neurogenic zones but difficulties in culturing these hinders their use as research tools.Here we show that NSCs can be efficiently grown in adherent cell cultures when angiogenic signals are included in the medium. These signals include both anti-angiogenic factors (the soluble form of the Notch receptor ligand, Dll4) and pro-angiogenic factors (the Tie-2 receptor ligand, Angiopoietin 2). These treatments support the self renewal state of cultured NSCs and expression of the transcription factor Hes3, which also identifies the cancer stem cell population in human tumors. In an organotypic slice model, angiogenic factors maintain vascular structure and increase the density of dopamine neuron processes.We demonstrate new properties of adult NSCs and a method to generate efficient adult NSC cultures from various central nervous system areas. These findings will help establish cellular models relevant to cancer and regeneration

Cholera Toxin Regulates a Signaling Pathway Critical for the Expansion of Neural Stem Cell Cultures from the Fetal and Adult Rodent Brains

Background: New mechanisms that regulate neural stem cell (NSC) expansion will contribute to improved assay systems and the emerging regenerative approach that targets endogenous stem cells. Expanding knowledge on the control of stem cell self renewal will also lead to new approaches for targeting the stem cell population of cancers. Methodology/Principal Findings: Here we show that Cholera toxin regulates two recently characterized NSC markers, the Tie2 receptor and the transcription factor Hes3, and promotes the expansion of NSCs in culture. Cholera toxin increases immunoreactivity for the Tie2 receptor and rapidly induces the nuclear localization of Hes3. This is followed by powerful cultured NSC expansion and induction of proliferation both in the presence and absence of mitogen. Conclusions/Significance: Our data suggest a new cell biological mechanism that regulates the self renewal and differentiation properties of stem cells, providing a new logic to manipulate NSCs in the context of regenerative disease and cancer

Safety and Feasibility of Long-term Intravenous Sodium Nitrite Infusion in Healthy Volunteers

BACKGROUND: Infusion of sodium nitrite could provide sustained therapeutic concentrations of nitric oxide (NO) for the treatment of a variety of vascular disorders. The study was developed to determine the safety and feasibility of prolonged sodium nitrite infusion. METHODOLOGY: Healthy volunteers, aged 21 to 60 years old, were candidates for the study performed at the National Institutes of Health (NIH; protocol 05-N-0075) between July 2007 and August 2008. All subjects provided written consent to participate. Twelve subjects (5 males, 7 females; mean age, 38.8±9.2 years (range, 21-56 years)) were intravenously infused with increasing doses of sodium nitrite for 48 hours (starting dose at 4.2 µg/kg/hr; maximal dose of 533.8 µg/kg/hr). Clinical, physiologic and laboratory data before, during and after infusion were analyzed. FINDINGS: The maximal tolerated dose for intravenous infusion of sodium nitrite was 267 µg/kg/hr. Dose limiting toxicity occurred at 446 µg/kg/hr. Toxicity included a transient asymptomatic decrease of mean arterial blood pressure (more than 15 mmHg) and/or an asymptomatic increase of methemoglobin level above 5%. Nitrite, nitrate, S-nitrosothiols concentrations in plasma and whole blood increased in all subjects and returned to preinfusion baseline values within 12 hours after cessation of the infusion. The mean half-life of nitrite estimated at maximal tolerated dose was 45.3 minutes for plasma and 51.4 minutes for whole blood. CONCLUSION: Sodium nitrite can be safely infused intravenously at defined concentrations for prolonged intervals. These results should be valuable for developing studies to investigate new NO treatment paradigms for a variety of clinical disorders, including cerebral vasospasm after subarachnoid hemorrhage, and ischemia of the heart, liver, kidney and brain, as well as organ transplants, blood-brain barrier modulation and pulmonary hypertension. CLINICAL TRIAL REGISTRATION INFORMATION: http://www.clinicaltrials.gov; NCT00103025