Inhibition of SUR1 decreases the vascular permeability of cerebral metastases

Ion Channel Dysregulation Following Intracerebral Hemorrhage

Injury to the brain after intracerebral hemorrhage (ICH) results from numerous complex cellular mechanisms. At present, effective therapy for ICH is limited and a better understanding of the mechanisms of brain injury is necessary to improve prognosis. There is increasing evidence that ion channel dysregulation occurs at multiple stages in primary and secondary brain injury following ICH. Ion channels such as TWIK-related K+ channel 1, sulfonylurea 1 transient receptor potential melastatin 4 and glutamate-gated channels affect ion homeostasis in ICH. They in turn participate in the formation of brain edema, disruption of the blood-brain barrier, and the generation of neurotoxicity. In this review, we summarize the interaction between ions and ion channels, the effects of ion channel dysregulation, and we discuss some therapeutics based on ion-channel modulation following ICH.

Crosstalk between small-cell lung cancer cells and astrocytes mimics brain development to promote brain metastasis

Brain metastases represent an important clinical problem for patients with small-cell lung cancer (SCLC). However, the mechanisms underlying SCLC growth in the brain remain poorly understood. Here, using intracranial injections in mice and assembloids between SCLC aggregates and human cortical organoids in culture, we found that SCLC cells recruit reactive astrocytes to the tumour microenvironment. This crosstalk between SCLC cells and astrocytes drives the induction of gene expression programmes that are similar to those found during early brain development in neurons and astrocytes. Mechanistically, the brain development factor Reelin, secreted by SCLC cells, recruits astrocytes to brain metastases. These astrocytes in turn promote SCLC growth by secreting neuronal pro-survival factors such as SERPINE1. Thus, SCLC brain metastases grow by co-opting mechanisms involved in reciprocal neuron-astrocyte interactions during brain development. Targeting such developmental programmes activated in this cancer ecosystem may help prevent and treat brain metastases.

Research progress on pleiotropic neuroprotective drugs for traumatic brain injury

Traumatic brain injury (TBI) has become one of the most important causes of death and disability worldwide. A series of neuroinflammatory responses induced after TBI are key factors for persistent neuronal damage, but at the same time, such inflammatory responses can also promote debris removal and tissue repair after TBI. The concept of pleiotropic neuroprotection delves beyond the single-target treatment approach, considering the multifaceted impacts following TBI. This notion embarks deeper into the research-oriented treatment paradigm, focusing on multi-target interventions that inhibit post-TBI neuroinflammation with enhanced therapeutic efficacy. With an enriched comprehension of TBI's physiological mechanisms, this review dissects the advancements in developing pleiotropic neuroprotective pharmaceuticals to mitigate TBI. The aim is to provide insights that may contribute to the early clinical management of the condition.

CD155 is a putative therapeutic target in medulloblastoma

BACKGROUND

Medulloblastoma is the most common pediatric malignant brain tumor, consisting of four molecular subgroups (WNT, SHH, Group 3, Group 4) and 12 subtypes. Expression of the cell surface poliovirus receptor (PVR), CD155, is necessary for entry of the viral immunotherapeutic agent, PVSRIPO, a polio:rhinovirus chimera. CD155, physiologically expressed in the mononuclear phagocytic system, is widely expressed ectopically in solid tumors. The objective of this study is to elucidate CD155 expression as both a receptor for PVSRIPO and a therapeutic target in medulloblastoma.

METHODS

PVR mRNA expression was determined in several patient cohorts and human medulloblastoma cell lines. Patient samples were also analyzed for CD155 expression using immunohistochemistry and cell lines were analyzed using Western Blots. CD155 was blocked using a monoclonal antibody and cell viability, invasion, and migration were assessed.

RESULTS AND DISCUSSION

PVR mRNA expression was highest in the WNT subgroup and lowest in Group 4. PVR expression in the subgroups of medulloblastoma were similar to other pediatric brain and non-brain tumors. PVR expression was largely not associated with subgroup or subtype. Neither PVR protein expression intensity nor frequency were associated with overall survival. PVR expression was elevated in Group 3 patients with metastases but there was no difference in paired primary and metastatic medulloblastoma. Blocking PVR resulted in dose-dependent cell death, decreased invasion in vitro, and modestly inhibited cell migration.

CONCLUSIONS

CD155 is expressed across medulloblastoma subgroups and subtypes. Blocking CD155 results in cell death and decreased cellular invasion. This study provides rationale for CD155-targeting agents including PVSRIPO and antibody-mediated blockade of CD155.

Do animal models of brain tumors replicate human peritumoral edema? a systematic literature search

INTRODUCTION

Brain tumors cause morbidity and mortality in part through peritumoral brain edema. The current main treatment for peritumoral brain edema are corticosteroids. Due to the increased recognition of their side-effect profile, there is growing interest in finding alternatives to steroids but there is little formal study of animal models of peritumoral brain edema. This study aims to summarize the available literature.

METHODS

A systematic search was undertaken of 5 literature databases (Medline, Embase, CINAHL, PubMed and the Cochrane Library). The generic strategy was to search for various terms associated with "brain tumors", "brain edema" and "animal models".

RESULTS

We identified 603 reports, of which 112 were identified as relevant for full text analysis that studied 114 peritumoral brain edema animal models. We found significant heterogeneity in the species and strain of tumor-bearing animals, tumor implantation method and edema assessment. Most models did not produce appreciable brain edema and did not test for observable manifestations thereof.

CONCLUSION

No animal model currently exists that enable the investigation of novel candidates for the treatment of peritumoral brain edema. With current interest in alternative treatments for peritumoral brain edema, there is an unmet need for clinically relevant animal models.

Dual Functionalized Liposomes for Selective Delivery of Poorly Soluble Drugs to Inflamed Brain Regions

Dual functionalized liposomes were developed to cross the blood−brain barrier (BBB) and to release their cargo in a pathological matrix metalloproteinase (MMP)-rich microenvironment. Liposomes were surface-functionalized with a modified peptide deriving from the receptor-binding domain of apolipoprotein E (mApoE), known to promote cargo delivery to the brain across the BBB in vitro and in vivo; and with an MMP-sensitive moiety for an MMP-triggered drug release. Different MMP-sensitive peptides were functionalized at both ends with hydrophobic stearate tails to yield MMP-sensitive lipopeptides (MSLPs), which were assembled into mApoE liposomes. The resulting bi-functional liposomes (i) displayed a < 180 nm diameter with a negative ζ-potential; (ii) were able to cross an in vitro BBB model with an endothelial permeability of 3 ± 1 × 10−5 cm/min; (iii) when exposed to functional MMP2 or 9, efficiently released an encapsulated fluorescein dye; (iv) showed high biocompatibility when tested in neuronal cultures; and (v) when loaded with glibenclamide, a drug candidate with poor aqueous solubility, reduced the release of proinflammatory cytokines from activated microglial cells.

Blood-Brain Barrier Alterations and Edema Formation in Different Brain Mass Lesions

Differential diagnosis of brain lesion pathologies is complex, but it is nevertheless crucial for appropriate clinical management. Advanced imaging methods, including diffusion-weighted imaging and apparent diffusion coefficient, can help discriminate between brain mass lesions such as glioblastoma, brain metastasis, brain abscesses as well as brain lymphomas. These pathologies are characterized by blood-brain barrier alterations and have been extensively studied. However, the changes in the blood-brain barrier that are observed around brain pathologies and that contribute to the development of vasogenic brain edema are not well described. Some infiltrative brain pathologies such as glioblastoma are characterized by glioma cell infiltration in the brain tissue around the tumor mass and thus affect the nature of the vasogenic edema. Interestingly, a common feature of primary and secondary brain tumors or tumor-like brain lesions characterized by vasogenic brain edema is the formation of various molecules that lead to alterations of tight junctions and result in blood-brain barrier damage. The resulting vasogenic edema, especially blood-brain barrier disruption, can be visualized using advanced magnetic resonance imaging techniques, such as diffusion-weighted imaging and apparent diffusion coefficient. This review presents a comprehensive overview of blood-brain barrier changes contributing to the development of vasogenic brain edema around glioblastoma, brain metastases, lymphomas, and abscesses.

Glibenclamide in aneurysmal subarachnoid hemorrhage: a randomized controlled clinical trial

OBJECTIVE

Glibenclamide has been shown to improve outcomes in cerebral ischemia, traumatic brain injury, and subarachnoid hemorrhage (SAH). The authors sought to evaluate glibenclamide's impact on mortality and functional outcomes of patients with aneurysmal SAH (aSAH).

METHODS

Patients with radiologically confirmed aSAH, aged 18 to 70 years, who presented to the hospital within 96 hours of ictus were randomly allocated to receive 5 mg of oral glibenclamide for 21 days or placebo, in a modified intention-to-treat analysis. Outcomes were mortality and functional status at discharge and 6 months, evaluated using the modified Rankin Scale (mRS).

RESULTS

A total of 78 patients were randomized and allocated to glibenclamide (n = 38) or placebo (n = 40). Baseline characteristics were similar between groups. The mean patient age was 53.1 years, and the majority of patients were female (75.6%). The median Hunt and Hess, World Federation of Neurosurgical Societies (WFNS), and modified Fisher scale (mFS) scores were 3 (IQR 2-4), 3 (IQR 3-4), and 3 (IQR 1-4), respectively. Glibenclamide did not improve the functional outcome (mRS) after 6 months (ordinal analysis, unadjusted common OR 0.66 [95% CI 0.29-1.48], adjusted common OR 1.25 [95% CI 0.46-3.37]). Similar results were found for analyses considering the dichotomized 6-month mRS score (favorable score 0-2), as well as for the secondary outcomes of discharge mRS score (either ordinal or dichotomized), mortality, and delayed cerebral ischemia. Hypoglycemia was more frequently observed in the glibenclamide group (5.3%).

CONCLUSIONS

In this study, glibenclamide was not associated with better functional outcomes after aSAH. Mortality and delayed cerebral ischemia rates were also similar compared with placebo.

Sulfonylurea Receptor 1 in Central Nervous System Injury: An Updated Review

Sulfonylurea receptor 1 (SUR1) is a member of the adenosine triphosphate (ATP)-binding cassette (ABC) protein superfamily, encoded by Abcc8, and is recognized as a key mediator of central nervous system (CNS) cellular swelling via the transient receptor potential melastatin 4 (TRPM4) channel. Discovered approximately 20 years ago, this channel is normally absent in the CNS but is transcriptionally upregulated after CNS injury. A comprehensive review on the pathophysiology and role of SUR1 in the CNS was published in 2012. Since then, the breadth and depth of understanding of the involvement of this channel in secondary injury has undergone exponential growth: SUR1-TRPM4 inhibition has been shown to decrease cerebral edema and hemorrhage progression in multiple preclinical models as well as in early clinical studies across a range of CNS diseases including ischemic stroke, traumatic brain injury, cardiac arrest, subarachnoid hemorrhage, spinal cord injury, intracerebral hemorrhage, multiple sclerosis, encephalitis, neuromalignancies, pain, liver failure, status epilepticus, retinopathies and HIV-associated neurocognitive disorder. Given these substantial developments, combined with the timeliness of ongoing clinical trials of SUR1 inhibition, now, another decade later, we review advances pertaining to SUR1-TRPM4 pathobiology in this spectrum of CNS disease—providing an overview of the journey from patch-clamp experiments to phase III trials.

Emerging therapeutic targets for cerebral edema

INTRODUCTION

Cerebral edema is a key contributor to death and disability in several forms of brain injury. Current treatment options are limited, reactive, and associated with significant morbidity. Targeted therapies are emerging based on a growing understanding of the molecular underpinnings of cerebral edema.

AREAS COVERED

We review the pathophysiology and relationships between different cerebral edema subtypes to provide a foundation for emerging therapies. Mechanisms for promising molecular targets are discussed, with an emphasis on those advancing in clinical trials, including ion and water channels (AQP4, SUR1-TRPM4) and other proteins/lipids involved in edema signaling pathways (AVP, COX2, VEGF, and S1P). Research on novel treatment modalities for cerebral edema [including recombinant proteins and gene therapies] is presented and finally, insights on reducing secondary injury and improving clinical outcome are offered.

EXPERT OPINION

Targeted molecular strategies to minimize or prevent cerebral edema are promising. Inhibition of SUR1-TRPM4 (glyburide/glibenclamide) and VEGF (bevacizumab) are currently closest to translation based on advances in clinical trials. However, the latter, tested in glioblastoma multiforme, has not demonstrated survival benefit. Research on recombinant proteins and gene therapies for cerebral edema is in its infancy, but early results are encouraging. These newer modalities may facilitate our understanding of the pathobiology underlying cerebral edema.

Glibenclamide Attenuates Neuroinflammation and Promotes Neurological Recovery After Intracerebral Hemorrhage in Aged Rats

Intracerebral hemorrhage (ICH) is a common disease in the elderly population. Inflammation following ICH plays a detrimental role in secondary brain injury, which is associated with a poor prognosis of patients with ICH, and no efficient pharmacological preventions are available. Here, we investigated the effects of glibenclamide (GLC) on neuroinflammation in an autoblood-induced aged rat (18 months old) model of ICH. Rats were randomized into the sham, vehicle, and GLC groups. First, we investigated the expression level of sulfonylurea receptor 1 (Sur1) surrounding the hematoma after ICH. Then, neurological scores were calculated, and water maze tests, brain water content analysis, western blotting, and immunofluorescence assays were implemented to detect the neuroprotective effect of GLC. The expression of the Sur1-Trpm4 channel was significantly increased in the perihematomal tissue following ICH in aged rats. The GLC administration effectively reduced brain edema and improved neurofunction deficits following ICH. In addition, GLC increased the expression of brain-derived neurotrophic factors and decreased the expression of proinflammatory factors [tumor necrosis factor (TNF)-α,interleukin (IL)-1, and IL-6]. Moreover, GLC markedly reduced Ikappa-B (IκB) kinase (IKK) expression in microglia and nuclear factor (NF)-κB-P65 levels in perihematomal tissue. GLC ameliorated ICH-induced neuroinflammation and improved neurological outcomes in aged rats. In part, GLC may exert these effects by regulating the NF-κB signaling pathway through the Sur1-Trpm4 channel.

Emerging Pharmacological Treatments for Cerebral Edema: Evidence from Clinical Studies

Cerebral edema, a common and often fatal companion to most forms of acute central nervous system disease, has been recognized since the time of ancient Egypt. Unfortunately, our therapeutic armamentarium remains limited, in part due to historic limitations in our understanding of cerebral edema pathophysiology. Recent advancements have led to a number of clinical trials for novel therapeutics that could fundamentally alter the treatment of cerebral edema. In this review, we discuss these agents, their targets, and the data supporting their use, with a focus on agents that have progressed to clinical trials.

ABCC8 mRNA expression is an independent prognostic factor for glioma and can predict chemosensitivity

Glioma is the most common primary intracranial tumor and is associated with very low survival rates. The development of reliable biomarkers can help to elucidate the molecular mechanisms involved in glioma development. Here the expression of ABCC8 mRNA, clinical characteristics, and survival information based on 1893 glioma samples from four independent databases were analyzed. The expression patterns of ABCC8 mRNA were compared by a Chi square test. The overall survival rate of gliomas was evaluated according to the expression level of ABCC8 mRNA. The prognostic value of this marker in gliomas was tested using Cox single factor and multi factor regression analyses. We found patients with low WHO grade, oligodendrocytoma, low molecular grade, IDH mutation, and 1p19q combined deletion had high ABCC8 mRNA expression. The patients with high expression of ABCC8 mRNA had longer survival. ABCC8 mRNA expression was a new independent prognostic index for glioma. Temozolomide chemotherapy was an independent index to prolong overall survival in high ABCC8 mRNA expression glioma patients, whereas in patients with low expression, there was no significant difference. So ABCC8 mRNA expression could be an independent prognostic indicator for glioma patients and could predict the sensitivity of glioma to temozolomide.

ABC Transporter Inhibition Plus Dexamethasone Enhances the Efficacy of Convection Enhanced Delivery in H3.3K27M Mutant Diffuse Intrinsic Pontine Glioma

BACKGROUND

An impermeable blood-brain barrier and drug efflux via ATP-binding cassette (ABC) transporters such as p-glycoprotein may contribute to underwhelming efficacy of peripherally delivered agents to treat diffuse intrinsic pontine glioma (DIPG).

OBJECTIVE

To explore the pharmacological augmentation of convection-enhanced delivery (CED) infusate for DIPG.

METHODS

The efficacy of CED dasatinib, a tyrosine kinase inhibitor, in a transgenic H3.3K27M mutant murine model was assessed. mRNA expression of ABCB1 (p-glycoprotein) was analyzed in 14 tumor types in 274 children. In Vitro viability studies of dasatinib, the p-glycoprotein inhibitor, tariquidar, and dexamethasone were performed in 2 H3.3K27M mutant cell lines. Magnetic resonance imaging (MRI) was used to evaluate CED infusate (gadolinium/dasatinib) distribution in animals pretreated with tariquidar and dexamethasone. Histological assessment of apoptosis was performed.

RESULTS

Continuous delivery CED dasatinib improved median overall survival (OS) of animals harboring DIPG in comparison to vehicle (39.5 and 28.5 d, respectively; P = .0139). Mean ABCB1 expression was highest in K27M gliomas. In Vitro, the addition of tariquidar and dexamethasone further enhanced the efficacy of dasatinib (P < .001). In Vivo, MRI demonstrated no difference in infusion dispersion between animals pretreated with dexamethasone plus tariquidar prior to CED dasatinib compared to the CED dasatinib. However, tumor apoptosis was the highest in the pretreatment group (P < .001). Correspondingly, median OS was longer in the pretreatment group (49 d) than the dasatinib alone group (39 d) and no treatment controls (31.5 d, P = .0305).

CONCLUSION

ABC transporter inhibition plus dexamethasone enhances the efficacy of CED dasatinib, resulting in enhanced tumor cellular apoptosis and improved survival in H3.3K27M mutant DIPG.

Role of Sulfonylurea Receptor 1 and Glibenclamide in Traumatic Brain Injury: A Review of the Evidence

Cerebral edema and contusion expansion are major determinants of morbidity and mortality after TBI. Current treatment options are reactive, suboptimal and associated with significant side effects. First discovered in models of focal cerebral ischemia, there is increasing evidence that the sulfonylurea receptor 1 (SUR1)-Transient receptor potential melastatin 4 (TRPM4) channel plays a key role in these critical secondary injury processes after TBI. Targeted SUR1-TRPM4 channel inhibition with glibenclamide has been shown to reduce edema and progression of hemorrhage, particularly in preclinical models of contusional TBI. Results from small clinical trials evaluating glibenclamide in TBI have been encouraging. A Phase-2 study evaluating the safety and efficacy of intravenous glibenclamide (BIIB093) in brain contusion is actively enrolling subjects. In this comprehensive narrative review, we summarize the molecular basis of SUR1-TRPM4 related pathology and discuss TBI-specific expression patterns, biomarker potential, genetic variation, preclinical experiments, and clinical studies evaluating the utility of treatment with glibenclamide in this disease.

BIIB093 (IV glibenclamide): an investigational compound for the prevention and treatment of severe cerebral edema

Introduction: Brain swelling due to edema formation is a major cause of neurological deterioration and death in patients with large hemispheric infarction (LHI) and severe traumatic brain injury (TBI), especially contusion-TBI. Preclinical studies have shown that SUR1-TRPM4 channels play a critical role in edema formation and brain swelling in LHI and TBI. Glibenclamide, a sulfonylurea drug and potent inhibitor of SUR1-TRPM4, was reformulated for intravenous injection, known as BIIB093.Areas covered: We discuss the findings from Phase 2 clinical trials of BIIB093 in patients with LHI (GAMES-Pilot and GAMES-RP) and from a small Phase 2 clinical trial in patients with TBI. For the GAMES trials, we review data on objective biological variables, adjudicated edema-related endpoints, functional outcomes, and mortality which, despite missing the primary endpoint, supported the initiation of a Phase 3 trial in LHI (CHARM). For the TBI trial, we review data on MRI measures of edema and the initiation of a Phase 2 trial in contusion-TBI (ASTRAL).Expert opinion: Emerging clinical data show that BIIB093 has the potential to transform our management of patients with LHI, contusion-TBI and other conditions in which swelling leads to neurological deterioration and death.

Emerging roles for multifunctional ion channel auxiliary subunits in cancer

Several superfamilies of plasma membrane channels which regulate transmembrane ion flux have also been shown to regulate a multitude of cellular processes, including proliferation and migration. Ion channels are typically multimeric complexes consisting of conducting subunits and auxiliary, non-conducting subunits. Auxiliary subunits modulate the function of conducting subunits and have putative non-conducting roles, further expanding the repertoire of cellular processes governed by ion channel complexes to processes such as transcellular adhesion and gene transcription. Given this expansive influence of ion channels on cellular behaviour it is perhaps no surprise that aberrant ion channel expression is a common occurrence in cancer. This review will focus on the conducting and non-conducting roles of the auxiliary subunits of various Ca2+, K+, Na+ and Cl- channels and the burgeoning evidence linking such auxiliary subunits to cancer. Several subunits are upregulated (e.g. Cavβ, Cavγ) and downregulated (e.g. Kvβ) in cancer, while other subunits have been functionally implicated as oncogenes (e.g. Navβ1, Cavα2δ1) and tumour suppressor genes (e.g. CLCA2, KCNE2, BKγ1) based on in vivo studies. The strengthening link between ion channel auxiliary subunits and cancer has exposed these subunits as potential biomarkers and therapeutic targets. However further mechanistic understanding is required into how these subunits contribute to tumour progression before their therapeutic potential can be fully realised.

Glucocorticoid-mediated effects on angiogenesis in solid tumors

Angiogenesis is essential in tumor development to maintain the oxygen and nutrient supply. Glucocorticoids have shown both direct and indirect angiostatic properties in various types of solid cancers. In most of the reported cases glucocorticoid-mediated actions involved suppression of multiple pro-angiogenic factors expression by cancer cells. The anti-angiogenic properties of glucocorticoids correlated with diminished tumor vasculature and reduced tumor growth in multiple in vivo studies. However, when glucocorticoid treatment is considered, possible adverse events should be taken into account. Additional research is needed to further test the use of these steroidal drugs in cancer therapy.

Different sulfonylureas induce the apoptosis of proximal tubular epithelial cell differently via closing KATP channel

BACKGROUND

Sulfonylureas (SUs) are widely prescribed for the treatment of type 2 diabetes (T2DM). Sulfonylurea receptors (SURs) are their main functional receptors. These receptors are also found in kidney, especially the tubular cells. However, the effects of SUs on renal proximal tubular epithelial cells (PTECs) were unclear.

METHODS

Three commonly used SUs were included in this study to investigate if different SUs have different effects on the apoptosis of PTECs. HK-2 cells were exposed to SUs for 24 h prior to exposure to 30 mM glucose, the apoptosis rate was evaluated by Annexin/PI flow cytometry. Bcl-2, Bax and the ratio of LC3II to LC3I were also studied by western blot in vitro. Diazoxide was used to evaluate the role of KATP channel in SUs-induced apoptosis of PTECs. A Student's t-test was used to assess significance for data within two groups.

RESULTS

Treatment with glibenclamide aggravated the apoptosis of HK-2 cells in high-glucose, as indicated by a significant decrease in the expression of Bcl-2 and increase in Bax. Additionally, the decreased LC3II/LC3I reflects that the autophagy was inhibited by glibenclamide. Similar but less pronounced change was found in glimepiride group, however, nearly opposite effects were found in gliclazide group. Further, the effects of glibenclamide on apoptosis promotion and the decreased LC3II/LC3I were ameliorated obviously by treatment with 100uM diazoxide. The potential protection effect of gliclazide was also inhibited after opening the KATP channel.

CONCLUSION

Our results suggest that, the effects of glibenclamide and glimepiride on PTECs apoptosis, especially the former, were achieved in part by closing the KATP channel. In contrast to glibenclamide and glimepiride, therapeutic concentrations of gliclazide showed an inhibitory effect on apoptosis of PTECs, which may have a benefit in the preservation of functional PTECs mass.

Multi-parameter MRI to investigate vasculature modulation and photo-thermal ablation combination therapy against cancer

Nanotransducer-mediated photothermal therapy (PTT) has emerged as an attractive therapy modality against cancer, but its efficacy is often limited by the amount of nanoparticles delivered to tumors. Previous studies showed a vasculature modulation treatment, which dilates or prunes tumor blood vessels, may enhance tumor uptake of nanoparticles. However, exploiting these approaches for improved PTT has seldom been studied. In this study, we investigated the impact of mild hyperthermia or anti-angiogenesis therapy on PTT. Briefly, we gave tumor-bearing balb/c mice low doses of sunitinib or submerged tumors in a 42 °C water bath. Next, we injected PEGylated reduced graphene oxide (RGO-PEG) and irradiated the tumors to induce PTT. We then followed up the treatment with multi-parameter MRI. Contrary to expectation, both vessel modulation strategies led to diminished PTT efficacy. Our results show that vessel modulation does not warrant improved PTT, and should be carefully gauged when used in combination with PTT.

The role of angiogenesis in Group 3 medulloblastoma pathogenesis and survival

Background

Of the 4 medulloblastoma subgroups, Group 3 is the most aggressive but the importance of angiogenesis is unknown. This study sought to determine the role of angiogenesis and identify clinically relevant biomarkers of tumor vascularity and survival in Group 3 medulloblastoma.

Methods

VEGFA mRNA expression and survival from several patient cohorts were analyzed. Group 3 xenografts were implanted intracranially in nude rats. Dynamic susceptibility weighted (DSC) MRI and susceptibility weighted imaging (SWI) were obtained. DSC MRI was used to calculate relative cerebral blood volume (rCBV) and flow (rCBF). Tumor vessel density and rat vascular endothelial growth factor alpha (VEGFA) expression were determined.

Results

Patient VEGFA mRNA levels were significantly elevated in Group 3 compared with the other subgroups (P < 0.001) and associated with survival. Xenografts D283, D341, and D425 were identified as Group 3 by RNA hierarchical clustering and MYC amplification. The D283 group had the lowest rCBV and rCBF, followed by D341 and D425 (P < 0.05). These values corresponded to histological vessel density (P < 0.05), rat VEGFA expression (P < 0.05), and survival (P = 0.002). Gene set enrichment analysis identified 5 putative genes with expression profiles corresponding with these findings: RNH1, SCG2, VEGFA, AGGF1, and PROK2. SWI identified 3 xenograft-independent categories of intratumoral vascular architecture with distinct survival (P = 0.004): organized, diffuse microvascular, and heterogeneous.

Conclusions

Angiogenesis plays an important role in Group 3 medulloblastoma pathogenesis and survival. DSC MRI and SWI are clinically relevant biomarkers for tumor vascularity and overall survival and can be used to direct the use of antivascular therapies for patients with Group 3 medulloblastoma.

State-of-the-art considerations in small cell lung cancer brain metastases

BACKGROUND

Small cell lung cancer (SCLC) frequently leads to development of brain metastases. These unfortunately continue to be associated with short survival. Substantial advances have been made in our understanding of the underlying biology of disease. This understanding on the background of previously evaluated and currently utilized therapeutic treatments can help guide the next steps in investigations into this disease with the potential to influence future treatments.

DESIGN

A comprehensive review of the literature covering epidemiology, pathophysiology, imaging characteristics, prognosis, and therapeutic management of SCLC brain metastases was performed.

RESULTS

SCLC brain metastases continue to have a poor prognosis. Both unique aspects of SCLC brain metastases as well as features seen more universally across other solid tumor brain metastases are discussed. Systemic therapeutic studies and radiotherapeutic approaches are reviewed.

CONCLUSIONS

A clearer understanding of SCLC brain metastases will help lay the framework for studies which will hopefully translate into meaningful therapeutic options for these patients.

Increasing of Blood-Brain Tumor Barrier Permeability through Transcellular and Paracellular Pathways by Microbubble-Enhanced Diagnostic Ultrasound in a C6 Glioma Model

Most of the anticancer agents cannot be efficiently delivered into the brain tumor because of the existence of blood-brain tumor barrier (BTB). The objective of this study was to explore the effect of microbubble-enhanced diagnostic ultrasound (MEUS) on the BTB permeability and the possible mechanism. Glioma-bearing rats were randomized into three groups as follows: the microbubble-enhanced continued diagnostic ultrasound (MECUS) group; the microbubble-enhanced intermittent diagnostic ultrasound (MEIUS) group and the control group. The gliomas were insonicated through the skull with a diagnostic ultrasound and injected with microbubbles through the tail veins. Evans Blue (EB) and dynamic contrast-enhanced-MRI were used to test changes in the BTB permeability. Confocal laser scanning microscopy was used to observe the deposition of the EB in the tumor tissues. The distribution and expression of junctional adhesion molecule-A (JAM-A) and calcium-activated potassium channels (K_Ca channels) were detected by a Western blot, qRT-PCR, and immunohistochemical staining. In the MEUS groups, the EB extravasation (11.0 ± 2.2 μg/g in MECUS group and 17.9 ± 2.3 μg/g in MEIUS group) exhibited a significant increase compared with the control group (5.3 ± 0.9 μg/g). The MEIUS group had more EB extravasation than the MECUS group. The K_trans value of the dynamic contrast-enhanced-MRI in the MEUS groups was higher than that of the control group and correlated strongly with the EB extravasation in the tumor (R² = 0.97). This showed that the K_trans value might be a non-invasive method to evaluate the BTB permeability in rat glioma after microbubble-enhanced ultrasound treatment.Western blot, qRT-PCR and immunohistochemical staining revealed that MEUS increased the K_Ca channels expression and reduced JAM-A expression in glioma. This change was more obvious in the MEIUS group than in the MECUS group. The results demonstrated that MEUS effectively increased the BTB permeability in glioma. The mechanisms might involve the up-regulation of K_Ca channels expression and affecting the formation of tight junctions in the BTB by a reduction of JAM-A expression. These findings might provide some new guidance for glioma drug therapy.

Simulating vasogenic brain edema using chronic VEGF infusion

OBJECTIVE To study peritumoral brain edema (PTBE), it is necessary to create a model that accurately simulates vasogenic brain edema (VBE) without introducing a complicated tumor environment. PTBE associated with brain tumors is predominantly a result of vascular endothelial growth factor (VEGF) secreted by brain tumors, and VEGF infusion alone can lead to histological blood-brain barrier (BBB) breakdown in the absence of tumor. VBE is intimately linked to BBB breakdown. The authors sought to establish a model for VBE with chronic infusion of VEGF that can be validated by serial in-vivo MRI and histological findings. METHODS Male Fischer rats (n = 182) underwent stereotactic striatal implantation of MRI-safe brain cannulas for chronic infusion of VEGF (2-20 µg/ml). Following a preinfusion phase (4-6 days), the rats were exposed to VEGF or control rat serum albumin (1.5 µl/hr) for as long as 144 hours. Serial MRI was performed during infusion on a high-field (9.4-T) machine at 12-24, 24-36, 48-72, and 120-144 hours. Rat brains were then collected and histological analysis was performed. RESULTS Control animals and animals infused with 2 µg/ml of VEGF experienced no neurological deficits, seizure activity, or abnormal behavior. Animals treated with VEGF demonstrated a significantly larger volume (42.90 ± 3.842 mm³) of T2 hyper-attenuation at 144 hours when compared with the volume (8.585 ± 1.664 mm³) in control animals (mean difference 34.31 ± 4.187 mm³, p < 0.0001, 95% CI 25.74-42.89 mm³). Postcontrast T1 enhancement in the juxtacanalicular region indicating BBB breakdown was observed in rats undergoing infusion with VEGF. At the later time periods (120-144 hrs) the volume of T1 enhancement (34.97 ± 8.99 mm³) was significantly less compared with the region of edema (p < 0.0001). Histologically, no evidence of necrosis or inflammation was observed with VEGF or control infusion. Immunohistochemical analysis demonstrated astrocyte activation, vascular remodeling, and increased claudin-5 expression in juxtacanalicular regions. Aquaporin-4 expression was increased in both control and VEGF animals in the juxtacanalicular regions. CONCLUSIONS The results of this study show that chronic brain infusion of VEGF creates a reliable model of VBE. This model lacks necrosis and inflammation that are characteristic of previous models of VBE. The model allows for a precise investigation into the mechanism of VBE formation. The authors also anticipate that this model will allow for investigation into the mechanism of glucocorticoid action in abrogating VBE, and to test novel therapeutic strategies targeting PTBE.

Glibenclamide–sulfonylurea receptor 1 antagonist alleviates LPS-induced BV2 cell activation through the p38/MAPK pathway

We investigated the anti-neuroinflammatory activity and mechanism of glibenclamide, sulfonylurea receptor 1 (Sur1) antagonist, against LPS-induced microglial activationin vitro.

Role of Glibenclamide in Brain Injury After Intracerebral Hemorrhage

Brain edema following intracerebral hemorrhage (ICH) causes severe secondary brain injury, and no efficient pharmacological preventions are available. The present study was designed to demonstrate the neuroprotective effects of glibenclamide on brain edema and key factors of the blood-brain barrier (BBB). The study was divided into two parts. First, we utilized an autoblood-induced rat model to investigate the expression of sulfonylurea receptor 1 (Sur1). Second, rats were randomized into sham, vehicle, and glibenclamide groups. Neurological scores, brain water content, Evans blue extravasation, Morris water maze test, western blots, and immunofluorescence were used to study the effects of glibenclamide. The expression of the Sur1-Trpm4 channel but not the Sur1-KATP channel was increased in the perihematomal tissue following ICH. Glibenclamide administration significantly decreased the brain water content, restored the BBB, and reduced the expression of MMPs. In addition, glibenclamide improved long-term cognitive deficits following ICH. Glibenclamide protected BBB integrity and improved neurological outcomes after ICH by inhibiting the Sur1-Trpm4 channel, which reduces the expression of MMPs and thereby increases BBB tight-junction protein levels. Glibenclamide may have potential to protect the BBB after ICH.

Whole exome sequencing analysis of ABCC8 and ABCD2 genes associating with clinical course of breast carcinoma

The aim of the present study was to introduce methods for exome sequencing of two ATP-binding cassette (ABC) transporters ABCC8 and ABCD2 recently suggested to play a putative role in breast cancer progression and prognosis of patients. We performed next generation sequencing targeted at analysis of all exons in ABCC8 and ABCD2 genes and surrounding noncoding sequences in blood DNA samples from 24 patients with breast cancer. The revealed alterations were characterized by in silico tools. We then compared the most frequent functionally relevant polymorphism rs757110 in ABCC8 with clinical data of patients. In total, the study identified 113 genetic alterations (>70 % novel ones) in both genes. Of these alterations, 83 were noncoding, 13 synonymous, 10 frameshifts and 7 were missense alterations. Four in silico programs predicted pathogenicity of two polymorphisms and four newly identified alterations. Rs757110 polymorphism in ABCC8 did not significantly associate with clinical data of the patients. In conclusion, exome sequencing identified several functionally relevant alterations in ABCC8 and ABCD2 genes that may further be used for a larger follow-up study aiming to assess their clinical significance.

Glibenclamide Attenuates Blood-Brain Barrier Disruption in Adult Mice after Traumatic Brain Injury

Glibenclamide is a hypoglycemic drug that is widely used for the treatment of diabetes mellitus type 2 (DM II), but it also plays a protective role following injury to the central nervous system (CNS). However, the precise mechanisms underlying its neuroprotective actions remain to be elucidated. Therefore, the present study evaluated the effects of glibenclamide on the blood-brain barrier (BBB) in a mouse model of traumatic brain injury (TBI). In the present study, 86 adult male C57BL/6 mice were exposed to a controlled cortical impact (CCI) injury and then received glibenclamide (10 μg) for 3 days. Tight junction (TJ) protein levels, BBB permeability, and tissue hemoglobin levels were evaluated following the CCI injury. Additionally, a biaxial stretch injury was applied to cell cultures of bEnd.3 cells using the Cell Injury Controller II system to explore the mechanisms by which glibenclamide inhibits apoptosis-signaling pathways. Compared with the control group, glibenclamide-treated mice exhibited decreases in brain water content (p < 0.05), tissue hemoglobin levels (p < 0.05), and Evans Blue extravasation (p < 0.01) after the CCI injury. Glibenclamide primarily attenuated apoptosis via the JNK/c-jun signaling pathway and resulted in an elevation of stretch injury-induced ZO-1 expression in bEnd.3 cells (p < 0.01).Glibenclamide downregulated the activity of the JNK/c-jun apoptosis-signaling pathway which, in turn, decreased apoptosis in endothelial cells (ECs). This may have prevented the disruption of the BBB in a mouse model of TBI.

Glibenclamide enhances the effects of delayed hypothermia after experimental stroke in rats

In order to evaluate whether glibenclamide can extend the therapeutic window during which induced hypothermia can protect against stroke, we subjected adult male Sprague-Dawley rats to middle cerebral artery occlusion (MCAO). We first verified the protective effects of hypothermia induced at 0, 2, 4 or 6h after MCAO onset, and then we assessed the effects of the combination of glibenclamide and hypothermia at 6, 8 or 10h after MCAO onset. At 24h after MCAO, we assessed brain edema, infarct volume, modified neurological severity score, Evans Blue leakage and expression of Sulfonylurea receptor 1 (SUR1) protein and pro-inflammatory factors. No protective effects were observed when hypothermia was induced too long after MCAO. At 6h after MCAO onset, hypothermia alone failed to decrease cerebral edema and infarct volume, but the combination of glibenclamide and hypothermia decreased both. The combination also improved neurological outcome, ameliorated blood-brain barrier damage and decreased levels of COX-2, TNF-α and IL-1β. These results suggest that glibenclamide enhances and extends the therapeutic effects of delayed hypothermia against ischemia stroke, potentially by ameliorating blood-brain barrier damage and declining levels of pro-inflammatory factors.

The role of ABC transporters in ovarian cancer progression and chemoresistance

Over 80% of ovarian cancer patients develop chemoresistance which results in a lethal course of the disease. A well-established cause of chemoresistance involves the family of ATP-binding cassette transporters, or ABC transporters that transport a wide range of substrates including metabolic products, nutrients, lipids, and drugs across extra- and intra-cellular membranes. Expressions of various ABC transporters, shown to reduce the intracellular accumulation of chemotherapy drugs, are increased following chemotherapy and impact on ovarian cancer survival. Although clinical trials to date using ABC transporter inhibitors have been disappointing, ABC transporter inhibition remains an attractive potential adjuvant to chemotherapy. A greater understanding of their physiological functions and role in ovarian cancer chemoresistance will be important for the development of more effective targeted therapies. This article will review the role of the ABC transporter family in ovarian cancer progression and chemoresistance as well as the clinical attempts used to date to reverse chemoresistance.

The role of tight junctions in cancer metastasis

Over the last decade, it has become apparent that the tight junction (TJ) is a key component in tumour progression and metastasis. In addition to its role in the control of paracellular diffusion of ions and certain molecules, the TJ has a vital role in maintaining cell to cell adhesion and tissue integrity. Changes in the expression and/or distribution of TJ proteins can result in loss in cohesion of the TJ structure, which in turn results in the ability of cancer cells to become invasive and then ultimately lead to the metastasis of cancer cells. This review will discuss recent insights into how TJ are involved in the process of tumour metastasis.

Cancer subclonal genetic architecture as a key to personalized medicine

The future of personalized oncological therapy will likely rely on evidence-based medicine to integrate all of the available evidence to delineate the most efficacious treatment option for the patient. To undertake evidence-based medicine through use of targeted therapy regimens, identification of the specific underlying causative mutation(s) driving growth and progression of a patient's tumor is imperative. Although molecular subtyping is important for planning and treatment, intraclonal genetic diversity has been recently highlighted as having significant implications for biopsy-based prognosis. Overall, delineation of the clonal architecture of a patient's cancer and how this will impact on the selection of the most efficacious therapy remain a topic of intense interest.

Delivery of chemotherapeutics across the blood-brain barrier: challenges and advances

The blood-brain barrier (BBB) limits drug delivery to brain tumors. We utilize intraarterial infusion of hyperosmotic mannitol to reversibly open the BBB by shrinking endothelial cells and opening tight junctions between the cells. This approach transiently increases the delivery of chemotherapy, antibodies, and nanoparticles to brain. Our preclinical studies have optimized the BBB disruption (BBBD) technique and clinical studies have shown its safety and efficacy. The delivery of methotrexate-based chemotherapy in conjunction with BBBD provides excellent outcomes in primary central nervous system lymphoma (PCNSL) including stable or improved cognitive function in survivors a median of 12 years (range 2-26 years) after diagnosis. The addition of rituximab to chemotherapy with BBBD for PCNSL can be safely accomplished with excellent overall survival. Our translational studies of thiol agents to protect against platinum-induced toxicities led to the development of a two-compartment model in brain tumor patients. We showed that delayed high-dose sodium thiosulfate protects against carboplatin-induced hearing loss, providing the framework for large cooperative group trials of hearing chemoprotection. Neuroimaging studies have identified that ferumoxytol, an iron oxide nanoparticle blood pool agent, appears to be a superior contrast agent to accurately assess therapy-induced changes in brain tumor vasculature, in brain tumor response to therapy, and in differentiating central nervous system lesions with inflammatory components. This chapter reviews the breakthroughs, challenges, and future directions for BBBD.

Connexin hemichannel induced vascular leak suggests a new paradigm for cancer therapy

It is 40 years since cancer growth was correlated with neovascularisation. Anti-angiogenic drugs remain at the forefront of cancer investigations but progress has been disappointing and unexpected toxicities are emerging. Gap junction channels are implicated in lesion spread following injury, with channel blockers shown to improve healing; in particular preventing vascular disruption and/or restoring vascular integrity. Here we briefly review connexin roles in vascular leak and endothelial cell death that occurs following acute wounds and during chronic disease, and how connexin channel regulation has been used to ameliorate vascular disruption. We then review chronic inflammatory disorders and trauma in the eye, concluding that vascular disruption under these conditions mimics that seen in tumours, and can be prevented with connexin hemichannel modulation. We apply this knowledge to tumour vessel biology, proposing that contrary to current opinion, these data suggest a need to protect, maintain and/or restore cancer vasculature. This may lead to reduced tumour hypoxia, promote the survival of normal cells, and enable improved therapeutic delivery or more effective radiation therapy.

A comparison of individual and population-derived vascular input functions for quantitative DCE-MRI in rats

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) can quantitatively and qualitatively assess physiological characteristics of tissue. Quantitative DCE-MRI requires an estimate of the time rate of change of the concentration of the contrast agent in the blood plasma, the vascular input function (VIF). Measuring the VIF in small animals is notoriously difficult as it requires high temporal resolution images limiting the achievable number of slices, field-of-view, spatial resolution, and signal-to-noise. Alternatively, a population-averaged VIF could be used to mitigate the acquisition demands in studies aimed to investigate, for example, tumor vascular characteristics. Thus, the overall goal of this manuscript is to determine how the kinetic parameters estimated by a population based VIF differ from those estimated by an individual VIF. Eight rats bearing gliomas were imaged before, during, and after an injection of Gd-DTPA. K(trans), ve, and vp were extracted from signal-time curves of tumor tissue using both individual and population-averaged VIFs. Extended model voxel estimates of K(trans) and ve in all animals had concordance correlation coefficients (CCC) ranging from 0.69 to 0.98 and Pearson correlation coefficients (PCC) ranging from 0.70 to 0.99. Additionally, standard model estimates resulted in CCCs ranging from 0.81 to 0.99 and PCCs ranging from 0.98 to 1.00, supporting the use of a population based VIF if an individual VIF is not available.

Tumor-associated edema in brain cancer patients: pathogenesis and management

The long-term treatment of peritumoral edema remains a major challenge in clinical neuro-oncology. Steroids have been and will remain the backbone of any anti-edematous therapy because of their striking activity, convenient oral administration and also because of their cost-effectiveness. Their side effects, however, can compromise quality of life, particularly upon continuous administration. Therapeutic alternatives which may replace or - at least - help to reduce the steroid dose are limited. However, with the development of new agents such as corticorelin acetate, there is a hope that steroid-induced side effects can be delayed and reduced. The administration of anti-angiogenic agents with steroid-sparing effects, for example, bevacizumab, is limited due to their costs. Increased knowledge on boswellic acids and cyclooxygenase-2 inhibitors which are available for clinical application may help to exploit their anti-edema activity more efficiently in the future.

Glibenclamide for the treatment of acute CNS injury

First introduced into clinical practice in 1969, glibenclamide (US adopted name, glyburide) is known best for its use in the treatment of diabetes mellitus type 2, where it is used to promote the release of insulin by blocking pancreatic K_ATP [sulfonylurea receptor 1 (Sur1)-Kir6.2] channels. During the last decade, glibenclamide has received renewed attention due to its pleiotropic protective effects in acute CNS injury. Acting via inhibition of the recently characterized Sur1-Trpm4 channel (formerly, the Sur1-regulated NC_Ca-ATP channel) and, in some cases, via brain K_ATP channels, glibenclamide has been shown to be beneficial in several clinically relevant rodent models of ischemic and hemorrhagic stroke, traumatic brain injury, spinal cord injury, neonatal encephalopathy of prematurity, and metastatic brain tumor. Glibenclamide acts on microvessels to reduce edema formation and secondary hemorrhage, it inhibits necrotic cell death, it exerts potent anti-inflammatory effects and it promotes neurogenesis—all via inhibition of Sur1. Two clinical trials, one in TBI and one in stroke, currently are underway. These recent findings, which implicate Sur1 in a number of acute pathological conditions involving the CNS, present new opportunities to use glibenclamide, a well-known, safe pharmaceutical agent, for medical conditions that heretofore had few or no treatment options.