Altered endocannabinoid metabolism compromises the brain-CSF barrier and exacerbates chronic deficits after traumatic brain injury in mice.

Endocannabinoids [2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (AEA)], endogenously produced arachidonate-based lipids, are anti-inflammatory physiological ligands for two known cannabinoid receptors, CB1 and CB2, yet the molecular and cellular mechanisms underlying their effects after brain injury are poorly defined. In the present study, we hypothesize that traumatic brain injury (TBI)-induced loss of endocannabinoids exaggerates neurovascular injury, compromises brain-cerebrospinal fluid (CSF) barriers (BCB) and causes behavioral dysfunction. Preliminary analysis in human CSF and plasma indicates changes in endocannabinoid levels. This encouraged us to investigate the levels of endocannabinoid-metabolizing enzymes in a mouse model of controlled cortical impact (CCI). Reductions in endocannabinoid (2-AG and AEA) levels in plasma were supported by higher expression of their respective metabolizing enzymes, monoacylglycerol lipase (MAGL), fatty acid amide hydrolase (FAAH), and cyclooxygenase 2 (Cox-2) in the post-TBI mouse brain. Following increased metabolism of endocannabinoids post-TBI, we observed increased expression of CB2, non-cannabinoid receptor Transient receptor potential vanilloid-1 (TRPV1), aquaporin 4 (AQP4), ionized calcium binding adaptor molecule 1 (IBA1), glial fibrillary acidic protein (GFAP), and acute reduction in cerebral blood flow (CBF). The BCB and pericontusional cortex showed altered endocannabinoid expressions and reduction in ventricular volume. Finally, loss of motor functions and induced anxiety behaviors were observed in these TBI mice. Taken together, our findings suggest endocannabinoids and their metabolizing enzymes play an important role in the brain and BCB integrity and highlight the need for more extensive studies on these mechanisms.

Pilot Study of Remote Ischemic Conditioning in Acute Spontaneous Intracerebral Hemorrhage.

Spontaneous Intracerebral hemorrhage (ICH) is a devastating injury that accounts for 10-15% of all strokes. The rupture of cerebral blood vessels damaged by hypertension or cerebral amyloid angiopathy creates a space-occupying hematoma that contributes toward neurological deterioration and high patient morbidity and mortality. Numerous protocols have explored a role for surgical decompression of ICH via craniotomy, stereotactic guided endoscopy, and minimally invasive catheter/tube evacuation. Studies including, but not limited to, STICH, STICH-II, MISTIE, MISTIE-II, MISTIE-III, ENRICH, and ICES have all shown that, in certain limited patient populations, evacuation can be done safely and mortality can be decreased, but functional outcomes remain statistically no different compared to medical management alone. Only 10-15% of patients with ICH are surgical candidates based on clot location, medical comorbidities, and limitations regarding early surgical intervention. To date, no clearly effective treatment options are available to improve ICH outcomes, leaving medical and supportive management as the standard of care. We recently identified that remote ischemic conditioning (RIC), the non-invasive, repetitive inflation-deflation of a blood pressure cuff on a limb, non-invasively enhanced hematoma resolution and improved neurological outcomes via anti-inflammatory macrophage polarization in pre-clinical ICH models. Herein, we propose a pilot, placebo-controlled, open-label, randomized trial to test the hypothesis that RIC accelerates hematoma resorption and improves outcomes in ICH patients. Twenty ICH patients will be randomized to receive either mock conditioning or unilateral arm RIC (4 cycles × 5 min inflation/5 min deflation per cycle) beginning within 48 h of stroke onset and continuing twice daily for one week. All patients will receive standard medical care according to latest guidelines. The primary outcome will be the safety evaluation of unilateral RIC in ICH patients. Secondary outcomes will include hematoma volume/clot resorption rate and functional outcomes, as assessed by the modified Rankin Scale (mRS) at 1- and 3-months post-ICH. Additionally, blood will be collected for exploratory genomic analysis. This study will establish the feasibility and safety of RIC in acute ICH patients, providing a foundation for a larger, multi-center clinical trial.

Rescuing mitochondria in traumatic brain injury and intracerebral hemorrhages - A potential therapeutic approach.

Mitochondria are dynamic organelles responsible for cellular energy production. Besides, regulating energy homeostasis, mitochondria are responsible for calcium homeostasis, signal transmission, and the fate of cellular survival in case of injury and pathologies. Accumulating reports have suggested multiple roles of mitochondria in neuropathologies, neurodegeneration, and immune activation under physiological and pathological conditions. Mitochondrial dysfunction, which occurs at the initial phase of brain injury, involves oxidative stress, inflammation, deficits in mitochondrial bioenergetics, biogenesis, transport, and autophagy. Thus, development of targeted therapeutics to protect mitochondria may improve functional outcomes following traumatic brain injury (TBI) and intracerebral hemorrhages (ICH). In this review, we summarize mitochondrial dysfunction related to TBI and ICH, including the mechanisms involved, and discuss therapeutic approaches with special emphasis on past and current clinical trials.

AMPK induces regulatory innate lymphoid cells after traumatic brain injury.

The CNS is regarded as an immunoprivileged organ, evading routine immune surveillance; however, the coordinated development of immune responses profoundly influences outcomes after brain injury. Innate lymphoid cells (ILCs) are cytokine-producing cells that are critical for the initiation, modulation, and resolution of inflammation, but the functional relevance and mechanistic regulation of ILCs are unexplored after acute brain injury. We demonstrate increased proliferation of all ILC subtypes within the meninges for up to 1 year after experimental traumatic brain injury (TBI) while ILCs were present within resected dura and elevated within cerebrospinal fluid (CSF) of moderate-to-severe TBI patients. In line with energetic derangements after TBI, inhibition of the metabolic regulator, AMPK, increased meningeal ILC expansion, whereas AMPK activation suppressed proinflammatory ILC1/ILC3 and increased the frequency of IL-10-expressing ILC2 after TBI. Moreover, intracisternal administration of IL-33 activated AMPK, expanded ILC2, and suppressed ILC1 and ILC3 within the meninges of WT and Rag1-/- mice, but not Rag1-/- IL2rg-/- mice. Taken together, we identify AMPK as a brake on the expansion of proinflammatory, CNS-resident ILCs after brain injury. These findings establish a mechanistic framework whereby immunometabolic modulation of ILCs may direct the specificity, timing, and magnitude of cerebral immunity.

Revisiting Traumatic Brain Injury: From Molecular Mechanisms to Therapeutic Interventions.

Studying the complex molecular mechanisms involved in traumatic brain injury (TBI) is crucial for developing new therapies for TBI. Current treatments for TBI are primarily focused on patient stabilization and symptom mitigation. However, the field lacks defined therapies to prevent cell death, oxidative stress, and inflammatory cascades which lead to chronic pathology. Little can be done to treat the mechanical damage that occurs during the primary insult of a TBI; however, secondary injury mechanisms, such as inflammation, blood-brain barrier (BBB) breakdown, edema formation, excitotoxicity, oxidative stress, and cell death, can be targeted by therapeutic interventions. Elucidating the many mechanisms underlying secondary injury and studying targets of neuroprotective therapeutic agents is critical for developing new treatments. Therefore, we present a review on the molecular events following TBI from inflammation to programmed cell death and discuss current research and the latest therapeutic strategies to help understand TBI-mediated secondary injury.

Neutrophil extracellular traps exacerbate neurological deficits after traumatic brain injury.

Traumatic brain injury (TBI) is a major cause of mortality and morbidity. Preventative measures reduce injury incidence and/or severity, yet one-third of hospitalized patients with TBI die from secondary pathological processes that develop during supervised care. Neutrophils, which orchestrate innate immune responses, worsen TBI outcomes via undefined mechanisms. We hypothesized that formation of neutrophil extracellular traps (NETs), a purported mechanism of microbial trapping, exacerbates acute neurological injury after TBI. NET formation coincided with cerebral hypoperfusion and tissue hypoxia after experimental TBI, while elevated circulating NETs correlated with reduced serum deoxyribonuclease-1 (DNase-I) activity in patients with TBI. Functionally, Toll-like receptor 4 (TLR4) and the downstream kinase peptidylarginine deiminase 4 (PAD4) mediated NET formation and cerebrovascular dysfunction after TBI. Last, recombinant human DNase-I degraded NETs and improved neurological function. Thus, therapeutically targeting NETs may provide a mechanistically innovative approach to improve TBI outcomes without the associated risks of global neutrophil depletion.

Atypical Intracranial Meningioma with Metastasis to C7 Vertebral Body: A Case Report.

BACKGROUND: Extracranial metastasis, mainly a feature of World Health Organization (WHO) grade III meningiomas, is only rarely reported in grade II meningiomas. CASE DESCRIPTION: We report a case of a 48-year-old man who was initially diagnosed in 2010 with an occipital convexity meningioma based on computed tomography scan/magnetic resonance imaging (MRI) and treated with surgical therapy and gamma knife. The first operation achieved a macroscopically complete resection. The tumor was histologically classified as an atypical meningioma. The patient had a recurrence in 2014 on the left tentorial leaflet as noted on postcontrast MRI. The patient was asymptomatic, without focal neurologic deficits. In 2016, the patient reported new-onset pain in the neck and left upper extremity. MRI indicated complete replacement of the C7 vertebral marrow, with a soft tissue component extending posteriorly into the epidural space that appeared to be flattening the thecal sac but without evidence of abnormal cord signal. Histopathology of resection confirmed atypical meningioma. CONCLUSIONS: This case represents a rare instance of intraosseous spine as the first site of metastasis of WHO grade II atypical meningioma and is the first reported case of extracranial metastasis of a meningioma to the C7 vertebral body.

A Retrospective Cohort Analysis of Hemorrhagic Arteriovenous Malformations Treated with Combined Endovascular Embolization and Gamma Knife Stereotactic Radiosurgery.

BACKGROUND: The management of brain arteriovenous malformations (AVMs) remains a controversial topic. Given the relatively low incidence, high heterogeneity, and high morbidity and mortality of these lesions, consensus on treatment strategies is an issue of concern to organized neurosurgery. The present retrospective analysis examined and quantified the outcomes of patients with an initial presentation of intracranial hemorrhage from a Spetzler-Martin grade III or IV AVM, later ruled out as surgical candidates. METHODS: A total of 16 patients (5 females; 11 males) had presented with symptomatic hemorrhage confirmed by non-contrast-enhanced computed tomography and were deemed to not be surgical candidates owing to AVM location and/or architecture. The patients underwent combined endovascular embolization and gamma knife stereotactic radiosurgery (SRS). The modified Rankin scale was used to measure the clinical outcomes, comparing the scores at presentation, gamma knife treatment, and the last known follow-up examination. A radiographic evaluation was used to determine the level of AVM nidus involution after the procedure. RESULTS: The present study identified 16 patients with ruptured high-grade AVMs of high surgical risk. All the patients had undergone immediate embolization with delayed SRS for treatment of the hemorrhage and nidus of the AVM. A statistically significant proportion of patients showed marked improvement in the modified Rankin scale scores. No subsequent repeat hemorrhage or any associated complications after embolization occurred in any patient. CONCLUSION: These findings warrant consideration of endovascular embolization with adjuvant SRS as a powerful treatment option for cases with high surgical morbidity due to AVM characteristics.

Remote ischemic post-conditioning promotes hematoma resolution via AMPK-dependent immune regulation.

Spontaneous intracerebral hemorrhage (ICH) produces the highest acute mortality and worst outcomes of all stroke subtypes. Hematoma volume is an independent determinant of ICH patient outcomes, making clot resolution a primary goal of clinical management. Herein, remote-limb ischemic post-conditioning (RIC), the repetitive inflation-deflation of a blood pressure cuff on a limb, accelerated hematoma resolution and improved neurological outcomes after ICH in mice. Parabiosis studies revealed RIC accelerated clot resolution via a humoral-mediated mechanism. Whereas RIC increased anti-inflammatory macrophage activation, myeloid cell depletion eliminated the beneficial effects of RIC after ICH. Myeloid-specific inactivation of the metabolic regulator, AMPKα1, attenuated RIC-induced anti-inflammatory macrophage polarization and delayed hematoma resolution, providing a molecular link between RIC and immune activation. Finally, chimera studies implicated myeloid CD36 expression in RIC-mediated neurological recovery after ICH. Thus, RIC, a clinically well-tolerated therapy, noninvasively modulates innate immune responses to improve ICH outcomes. Moreover, immunometabolic changes may provide pharmacodynamic blood biomarkers to clinically monitor the therapeutic efficacy of RIC.

White matter damage after traumatic brain injury: A role for damage associated molecular patterns.

Traumatic brain injury (TBI) is a leading cause of mortality and long-term morbidity worldwide. Despite decades of pre-clinical investigation, therapeutic strategies focused on acute neuroprotection failed to improve TBI outcomes. This lack of translational success has necessitated a reassessment of the optimal targets for intervention, including a heightened focus on secondary injury mechanisms. Chronic immune activation correlates with progressive neurodegeneration for decades after TBI; however, significant challenges remain in functionally and mechanistically defining immune activation after TBI. In this review, we explore the burgeoning evidence implicating the acute release of damage associated molecular patterns (DAMPs), such as adenosine 5'-triphosphate (ATP), high mobility group box protein 1 (HMGB1), S100 proteins, and hyaluronic acid in the initiation of progressive neurological injury, including white matter loss after TBI. The role that pattern recognition receptors, including toll-like receptor and purinergic receptors, play in progressive neurological injury after TBI is detailed. Finally, we provide support for the notion that resident and infiltrating macrophages are critical cellular targets linking acute DAMP release with adaptive immune responses and chronic injury after TBI. The therapeutic potential of targeting DAMPs and barriers to clinical translational, in the context of TBI patient management, are discussed.

Activation of Myeloid TLR4 Mediates T Lymphocyte Polarization after Traumatic Brain Injury.

Traumatic brain injury (TBI) is a major public health issue, producing significant patient mortality and poor long-term outcomes. Increasing evidence suggests an important, yet poorly defined, role for the immune system in the development of secondary neurologic injury over the days and weeks following a TBI. In this study, we tested the hypothesis that peripheral macrophage infiltration initiates long-lasting adaptive immune responses after TBI. Using a murine controlled cortical impact model, we used adoptive transfer, transgenic, and bone marrow chimera approaches to show increased infiltration and proinflammatory (classically activated [M1]) polarization of macrophages for up to 3 wk post-TBI. Monocytes purified from the injured brain stimulated the proliferation of naive T lymphocytes, enhanced the polarization of T effector cells (TH1/TH17), and decreased the production of regulatory T cells in an MLR. Similarly, elevated T effector cell polarization within blood and brain tissue was attenuated by myeloid cell depletion after TBI. Functionally, C3H/HeJ (TLR4 mutant) mice reversed M1 macrophage and TH1/TH17 polarization after TBI compared with C3H/OuJ (wild-type) mice. Moreover, brain monocytes isolated from C3H/HeJ mice were less potent stimulators of T lymphocyte proliferation and TH1/TH17 polarization compared with C3H/OuJ monocytes. Taken together, our data implicate TLR4-dependent, M1 macrophage trafficking/polarization into the CNS as a key mechanistic link between acute TBI and long-term, adaptive immune responses.

Overexpression of Nrf2 attenuates Carmustine-induced cytotoxicity in U87MG human glioma cells.

BACKGROUND: Malignant glioma is one of the most devastating tumors in adults with poor patient prognosis. Notably, glioma often exhibits resistance to conventional chemotherapeutic approaches, complicating patient treatments. However, the molecular mediators involved in tumor chemoresistance remain poorly defined, creating a barrier to the successful management of glioma. In the present study, we hypothesized that the antioxidant transcription factor, Nrf2 (nuclear factor erythroid-derived 2 like 2), attenuates glioma cytotoxicity to Carmustine (BCNU), a widely used chemotherapeutic agent known to modulate cellular oxidative balance. METHODS: To test the hypothesis, we employed human malignant glioma cell line, U87MG and overexpression of Nrf2 in glioma cells was achieved using both pharmacological and genetic approaches. RESULTS: Notably, induction of Nrf2 was associated with increased expression of heme oxygenase-1 (HO-1), a stress inducible enzyme involved in anti-oxidant defense. In addition, over expression of Nrf2 in U87MG cells significantly attenuated the cytotoxicity of Carmustine as evidenced by both cellular viability assay and flow cytometry analysis. Consistent with this, antioxidants such as glutathione and N-acetyl cysteine significantly reduced Carmustine mediated glioma cytotoxicity. CONCLUSIONS: Taken together, these data strongly implicate an unexplored role of Nrf2 in glioma resistance to Carmustine and raise the possible use of Nrf2 inhibitors as adjunct to Carmustine for the treatment of malignant glioma.

High mobility group box protein-1 promotes cerebral edema after traumatic brain injury via activation of toll-like receptor 4.

Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide. Cerebral edema, a life-threatening medical complication, contributes to elevated intracranial pressure (ICP) and a poor clinical prognosis after TBI. Unfortunately, treatment options to reduce post-traumatic edema remain suboptimal, due in part, to a dearth of viable therapeutic targets. Herein, we tested the hypothesis that cerebral innate immune responses contribute to edema development after TBI. Our results demonstrate that high-mobility group box protein 1 (HMGB1) was released from necrotic neurons via a NR2B-mediated mechanism. HMGB1 was clinically associated with elevated ICP in patients and functionally promoted cerebral edema after TBI in mice. The detrimental effects of HMGB1 were mediated, at least in part, via activation of microglial toll-like receptor 4 (TLR4) and the subsequent expression of the astrocytic water channel, aquaporin-4 (AQP4). Genetic or pharmacological (VGX-1027) TLR4 inhibition attenuated the neuroinflammatory response and limited post-traumatic edema with a delayed, clinically implementable therapeutic window. Human and rodent tissue culture studies further defined the cellular mechanisms demonstrating neuronal HMGB1 initiates the microglial release of interleukin-6 (IL-6) in a TLR4 dependent mechanism. In turn, microglial IL-6 increased the astrocytic expression of AQP4. Taken together, these data implicate microglia as key mediators of post-traumatic brain edema and suggest HMGB1-TLR4 signaling promotes neurovascular dysfunction after TBI.

Evaluation of salvage techniques for infected baclofen pumps in pediatric patients with cerebral palsy.

OBJECT: Intrathecal baclofen therapy has been used successfully for intractable spasticity in children with cerebral palsy. Infections are rare, but they are potentially life threatening if complicated by bacteremia or meningitis. Treatment without removal of the system is desirable if it can be done safely and effectively. METHODS: The Authors reviewed the records of 207 patients ranging from 3 to 18 years of age with cerebral palsy who underwent placement or revision of a baclofen pump. They identified 38 patients with suspected or documented infectious complications. Initial attempts were made to eradicate infection with the devices in situ in all patients. Methods and effectiveness of pump salvage were evaluated. RESULTS: Of the 38 patients identified, 13 (34.2%) had documented infections; 11 had deep wound/pocket empyemas and 2 had meningitis. Eight patients with deep wound infections received intravenous antibiotics alone. All required pump explantation. The remaining 3 patients underwent a washout procedure as well; the infection was cured in 1 patient. Both patients with meningitis received intravenous and intrathecal antibiotics, and both required device explantation. In addition, 25 patients (65.8%) had excessive or increasing wound erythema. No objective criteria to document a superficial infection were present. The wounds were considered suspicious and were managed with serial examinations and oral antibiotics. The erythema resolved in 24 of the 25 patients. CONCLUSIONS: In general, observation, wound care, and oral antibiotics are sufficient for wounds that are suspicious for superficial infection. For deep-seated infection, antibiotic therapy alone is generally insufficient and explantation is required. Washout procedures can be considered, but failures are common.

Activation of P2X7 promotes cerebral edema and neurological injury after traumatic brain injury in mice.

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Cerebral edema, the abnormal accumulation of fluid within the brain parenchyma, contributes to elevated intracranial pressure (ICP) and is a common life-threatening neurological complication following TBI. Unfortunately, neurosurgical approaches to alleviate increased ICP remain controversial and medical therapies are lacking due in part to the absence of viable drug targets. In the present study, genetic inhibition (P2X7-/- mice) of the purinergic P2x7 receptor attenuated the expression of the pro-inflammatory cytokine, interleukin-1ß (IL-1ß) and reduced cerebral edema following controlled cortical impact, as compared to wild-type mice. Similarly, brilliant blue G (BBG), a clinically non-toxic P2X7 inhibitor, inhibited IL-1ß expression, limited edemic development, and improved neurobehavioral outcomes after TBI. The beneficial effects of BBG followed either prophylactic administration via the drinking water for one week prior to injury or via an intravenous bolus administration up to four hours after TBI, suggesting a clinically-implementable therapeutic window. Notably, P2X7 localized within astrocytic end feet and administration of BBG decreased the expression of glial fibrillary acidic protein (GFAP), a reactive astrocyte marker, and attenuated the expression of aquaporin-4 (AQP4), an astrocytic water channel that promotes cellular edema. Together, these data implicate P2X7 as a novel therapeutic target to prevent secondary neurological injury after TBI, a finding that warrants further investigation.

Expanded endoscopic endonasal approaches to skull base meningiomas.

Anterior cranial base meningiomas have traditionally been addressed via frontal or frontolateral approaches. However, with the advances in endoscopic endonasal treatment of pituitary lesions, the transphenoidal approach is being expanded to address lesions of the petrous ridge, anterior clinoid, clivus, sella, parasellar region, tuberculum, planum, olfactory groove, and crista galli regions. The expanded endoscopic endonasal approach (EEEA) has the advantage of limiting brain retraction and resultant brain edema, as well as minimizing manipulation of neural structures. Herein, we describe the techniques of transclival, transphenoidal, transplanum, and transcribiform resections of anterior skull base meningiomas. Selected cases are presented.

Traumatic cerebrospinal fluid leaks.

This article discusses the epidemiology, diagnosis, and management of traumatic cerebrospinal fluid (CSF) leaks. An overview of traumatic CSF leaks is presented, and both conservative and operative therapies are reviewed. Management decisions are discussed based on the current literature. Controversial clinical topics are addressed, including the use of prophylactic antibiotics and the timing of surgical repair.

Dural-based metastatic carcinomas mimicking primary CNS neoplasia: report of 7 cases emphasizing the role of timely surgery and accurate pathologic evaluation.

Clinical presentation with dural-based metastasis mimicking meningiomas is rare. We aimed to evaluate the role of frozen section in guiding surgery and histopathologic diagnosis in determining primary sites of dural-based metastatic carcinomas. Following the receipt of HAC approval, we retrospectively reviewed 7cases presenting with dural-based masses clinically suspected to be primary brain tumors (6 meningiomas and 1 superficial glioblastoma), but diagnosed to be metastatic carcinomas on subsequent resection. Pertinent clinical records and follow-up data were reviewed. Patient's age ranged from 59 to 80 years. Imaging showed extra-axial dural-based masses with contiguous but not primary brain involvement. On intra-operative frozen section (not performed in case 7), differential diagnoses included metastatic carcinoma in all cases, and surgery modified accordingly. Nesting, cribriform, and "picket-fence" like glands were among useful histologic diagnostic patterns. Immunoprofile supported histologic diagnosis in all cases. Subsequent clinical and radiologic evaluation confirmed coexistent sites of origin in all cases. The metastases were solitary in all cases; except multiple dural-based tumors in case 1, in which interestingly no systemic metastasis were identified. Dural-based metastatic carcinomas mimicking meningiomas may be solitary, of unknown primary, or without concomitant systemic spread on imaging. Frozen section evaluation is helpful in modifying surgery. Although high-grade, these are typically differentiated enough to allow accurate histopathologic diagnosis, and reasonable determination of primary tumor site, especially with a judicious panel of cytokeratins, transcription factors, hormone receptors and relatively organ-specific markers. Clinicians and pathologists need to be aware of the occurrence, spectrum, need for timely intervention, and accurate diagnosis of dural-based metastatic carcinomas.

Dietary phytochemicals induce p53- and caspase-independent cell death in human neuroblastoma cells.

Neuroblastoma (NB) is the most prevalent pediatric solid tumor and a leading cause of cancer-related death in children. In the present study, a novel cytotoxic role for the dietary compounds, curcumin, andrographolide, wedelolactone, dibenzoylmethane, and tanshinone IIA was identified in human S-type NB cells, SK-N-AS and SK-N-BE(2). Mechanistically, cell death appeared apoptotic by flow cytometry; however, these effects proceeded independently from both caspase-3 and p53 activation, as assessed by both genetic (shRNA) and pharmacological approaches. Notably, cell death induced by both curcumin and andrographolide was associated with decreased NFκB activity and a reduction in Bcl-2 and Bcl-xL expression. Finally, curcumin and andrographolide increased cytotoxicity following co-treatment with either cisplatin or doxorubicin, two chemotherapeutic agents widely used in the clinical management of NB. Coupled with the documented safety in humans, dietary compounds may represent a potential adjunct therapy for NB.

mTOR inhibition reduces cellular proliferation and sensitizes pituitary adenoma cells to ionizing radiation.

BACKGROUND: Pituitary adenomas are the most frequent brain tumor in adults. Although histologically benign, pituitary tumors cause significant morbidity and mortality. Neurosurgery and medical therapeutics may lessen the morbidity and mortality associated with pituitary tumors; however, these treatments are associated with significant adverse side effects. Thus, an improved understanding of pituitary adenomas at the molecular and cellular level is needed to design novel therapeutic compounds. METHODS: To assess the effect of mammalian target of rapamycin (mTOR) inhibition on pituitary adenoma cells, rat GH3 or MMQ cells were treated with the clinically useful mTOR inhibitors, rapamycin or RAD001. Cellular proliferation and growth following exposure to mTOR inhibitors or radiation were assessed using biochemical methods. RESULTS: In the present study, we observed basal activation of mTOR, downstream of constitutive Akt signaling, in rat GH3 adenoma cells. Functionally, the mTOR inhibitors, rapamycin and RAD001 (500 pM-5 nM), induced G1 growth arrest within 24 hours, an effect associated with reduced cellular proliferation. Both rapamycin and RAD001 decreased the phosphorylation of mTOR at the serine 2448, a key determinant of mTOR activity. Inhibition of mTOR also radiosensitized GH3 cells such that 2.5 Gy in combination with 500 pM rapamycin or RAD001 reduced cellular viability more effectively than 2.5 or 10 Gy alone. CONCLUSIONS: These data may support a possible therapeutic role for mTOR inhibitors in limiting the cellular proliferation and radioresistance of pituitary adenoma cells.