Ferroptosis and PPAR-gamma in the limelight of brain tumors and edema

Human malignant brain tumors such as gliomas are devastating due to the induction of cerebral edema and neurodegeneration. A major contributor to glioma-induced neurodegeneration has been identified as glutamate. Glutamate promotes cell growth and proliferation in variety of tumor types. Intriguently, glutamate is also an excitatory neurotransmitter and evokes neuronal cell death at high concentrations. Even though glutamate signaling at the receptor and its downstream effectors has been extensively investigated at the molecular level, there has been little insight into how glutamate enters the tumor microenvironment and impacts on metabolic equilibration until recently. Surprisingly, the 12 transmembrane spanning tranporter xCT (SLC7A11) appeared to be a major player in this process, mediating glutamate secretion and ferroptosis. Also, PPARγ is associated with ferroptosis in neurodegeneration, thereby destroying neurons and causing brain swelling. Although these data are intriguing, tumor-associated edema has so far been quoted as of vasogenic origin. Hence, glutamate and PPARγ biology in the process of glioma-induced brain swelling is conceptually challenging. By inhibiting xCT transporter or AMPA receptors in vivo, brain swelling and peritumoral alterations can be mitigated. This review sheds light on the role of glutamate in brain tumors presenting the conceptual challenge that xCT disruption causes ferroptosis activation in malignant brain tumors. Thus, interfering with glutamate takes center stage in forming the basis of a metabolic equilibration approach.

Glial Glutamate Transporter-Mediated Plasticity: System xc-/xCT/SLC7A11 and EAAT1/2 in Brain Diseases

Glial cells play an essential role in the complex function of the nervous system. In particular, astrocytes provide nutritive support for neuronal cells and are involved in regulating synaptic transmission. Oligodendrocytes ensheath axons and support information transfer over long distances. Microglial cells constitute part of the innate immune system in the brain. Glial cells are equipped with the glutamate-cystine-exchanger xCT (SLC7A11), the catalytic subunit of system xc-, and the excitatory amino acid transporter 1 (EAAT1, GLAST) and EAAT2 (GLT-1). Thereby, glial cells maintain balanced extracellular glutamate levels that enable synaptic transmission and prevent excitotoxic states. Expression levels of these transporters, however, are not fixed. Instead, expression of glial glutamate transporters are highly regulated in reaction to the external situations. Interestingly, such regulation and homeostasis is lost in diseases such as glioma, (tumor-associated) epilepsy, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis or multiple sclerosis. Upregulation of system xc- (xCT or SLC7A11) increases glutamate export from the cell, while a downregulation of EAATs decreases intracellular glutamate import. Occurring simultaneously, these reactions entail excitotoxicity and thus harm neuronal function. The release of glutamate via the antiporter system xc- is accompanied by the import of cystine-an amino acid essential in the antioxidant glutathione. This homeostasis between excitotoxicity and intracellular antioxidant response is plastic and off-balance in central nervous system (CNS) diseases. System xc- is highly expressed on glioma cells and sensitizes them to ferroptotic cell death. Hence, system xc- is a potential target for chemotherapeutic add-on therapy. Recent research reveals a pivotal role of system xc- and EAAT1/2 in tumor-associated and other types of epilepsy. Numerous studies show that in Alzheimer's disease, amyotrophic lateral sclerosis and Parkinson's disease, these glutamate transporters are dysregulated-and disease mechanisms could be interposed by targeting system xc- and EAAT1/2. Interestingly, in neuroinflammatory diseases such as multiple sclerosis, there is growing evidence for glutamate transporter involvement. Here, we propose that the current knowledge strongly suggest a benefit from rebalancing glial transporters during treatment.

Genetic Profiles of Ferroptosis in Malignant Brain Tumors and Off-Target Effects of Ferroptosis Induction

Glioblastoma represents the most devastating form of human brain cancer, associated with a very poor survival rate of patients. Unfortunately, treatment options are currently limited and the gold standard pharmacological treatment with the chemotherapeutic drug temozolomide only slightly increases the survival rate. Experimental studies have shown that the efficiency of temozolomide can be improved by inducing ferroptosis – a recently discovered form of cell death, which is different from apoptosis, necrosis, or necroptosis and, which is characterized by lipid peroxidation and reactive oxygen species accumulation. Ferroptosis can also be activated to improve treatment of malignant stages of neuroblastoma, meningioma, and glioma. Due to their role in cancer treatment, ferroptosis-gene signatures have recently been evaluated for their ability to predict survival of patients. Despite positive effects during chemotherapy, the drugs used to induce ferroptosis – such as erastin and sorafenib – as well as genetic manipulation of key players in ferroptosis – such as the cystine-glutamate exchanger xCT and the glutathione peroxidase GPx4 – also impact neuronal function and cognitive capabilities. In this review, we give an update on ferroptosis in different brain tumors and summarize the impact of ferroptosis on healthy tissues.

Therapeutic Potential of Selenium in Glioblastoma

Little progress has been made in the long-term management of malignant brain tumors, leaving patients with glioblastoma, unfortunately, with a fatal prognosis. Glioblastoma remains the most aggressive primary brain cancer in adults. Similar to other cancers, glioblastoma undergoes a cellular metabolic reprogramming to form an oxidative tumor microenvironment, thereby fostering proliferation, angiogenesis and tumor cell survival. Latest investigations revealed that micronutrients, such as selenium, may have positive effects in glioblastoma treatment, providing promising chances regarding the current limitations in surgical treatment and radiochemotherapy outcomes. Selenium is an essential micronutrient with anti-oxidative and anti-cancer properties. There is additional evidence of Se deficiency in patients suffering from brain malignancies, which increases its importance as a therapeutic option for glioblastoma therapy. It is well known that selenium, through selenoproteins, modulates metabolic pathways and regulates redox homeostasis. Therefore, selenium impacts on the interaction in the tumor microenvironment between tumor cells, tumor-associated cells and immune cells. In this review we take a closer look at the current knowledge about the potential of selenium on glioblastoma, by focusing on brain edema, glioma-related angiogenesis, and cells in tumor microenvironment such as glioma-associated microglia/macrophages.

Medulloblastoma in adults - reviewing the literature from a surgeon's point of view

Medulloblastoma is a common primary brain tumor in children but it is a rare cancer in adult patients. We reviewed the literature, searching PubMed for articles on this rare tumor entity, with a focus on tumor biology, advanced neurosurgical opportunities for safe tumor resection, and multimodal treatment options. Adult medulloblastoma occurs at a rate of 0.6 per one million people per year. There is a slight disparity between male and female patients, and patients with a fair skin tone are more likely to have a medulloblastoma. Patients present with cerebellar signs and signs of elevated intracranial pressure. Diagnostic efforts should consist of cerebral MRI and MRI of the spinal axis. Cerebrospinal fluid should be investigated to look for tumor dissemination. Medulloblastoma tumors can be classified as classic, desmoplastic, anaplastic, and large cell, according to the WHO tumor classification. Molecular subgroups include WNT, SHH, group 3, and group 4 tumors. Further molecular analyses suggest that there are several subgroups within the four existing subgroups, with significant differences in patient age, frequency of metastatic spread, and patient survival. As molecular markers have started to play an increasing role in determining treatment strategies and prognosis, their importance has increased rapidly. Treatment options include microsurgical tumor resection and radiotherapy and, in addition, chemotherapy that respects the tumor biology of individual patients offers targeted therapeutic approaches. For neurosurgeons, intraoperative imaging and tumor fluorescence may improve resection rates. Disseminated disease, residual tumor after surgery, lower radiation dose, and low Karnofsky performance status are all suggestive of a poor outcome. Extraneural spread occurs only in very few cases. The reported 5-year-survival rates range between 60% and 80% for all adult medulloblastoma patients.

Delivery of hepatocyte growth factor mRNA from nanofibrillar scaffolds in a pig model of peripheral arterial disease

Background: Chemical modification of mRNA (mmRNA) substantially improves their stability and translational efficiency within cells. Nanofibrillar collagen scaffolds were previously shown to enable the spatially localized delivery and temporally controlled release of mmRNA encoding HGF both in vitro and in vivo. Materials & methods: Herein we developed an improved slow-releasing HGF mmRNA scaffold and tested its therapeutic efficacy in a porcine model of peripheral arterial disease. Results & conclusion: The HGF mmRNA was released from scaffolds in a temporally controlled fashion in vitro with preserved transfection activity. The mmRNA scaffolds improved vascular regeneration when sutured to the ligated porcine femoral artery. These studies validate the therapeutic potential of HGF mmRNA delivery from nanofibrillar scaffolds for treatment of peripheral arterial disease.

Dynamics of outcome after aneurysmal subarachnoid hemorrhage

In this observational study, we analyzed and described the dynamics of the outcome after aneurysmal subarachnoid hemorrhage (SAH) in a collective of 203 cases. We detected a significant improvement of the mean aggregate modified Rankin Score (mRS) in every time interval from discharge to 6 months and up to 1 year. Every forth to fifth patient with potential of recovery (mRS 1-5) at discharge improved by 1 mRS point in the time interval from 6 month to 1 year (22.6%). Patients with mRS 3 at discharge had a remarkable late recovery rate (73.3%, p = 0.000085). Multivariate analysis revealed age ≤ 65 years (odds ratio 4.93; p = 0.0045) and "World Federation of Neurological Surgeons" (WFNS) grades I and II (odds ratio 4.77; p = 0.0077) as significant predictors of early improvement (discharge to 6 months). Absence of a shunting procedure (odds ratio 8.32; p = 0.0049) was a significant predictor of late improvement (6 months to 1 year), but not age ≤ 65 years (p = 0.54) and WFNS grades I and II (p = 0.92). Thus, late recovery (6 month to 1 year) is significant and independent from age and WFNS grade.

Impact of Comorbidities and Smoking on the Outcome in Aneurysmal Subarachnoid Hemorrhage

The intention of this observational study is to show the significant impact of comorbidities and smoking on the outcome in aneurysmal subarachnoid hemorrhage (SAH). During this observational study 203 cases of treatment of ruptured intracranial aneurysms were analyzed. We examined and classified prospectively the 12 month outcome according to the modified Rankin Scale (mRS) considering retrospectively a history of smoking and investigated prospectively the occurrence of early and delayed cerebral ischemia between 2012 and 2017. Using logistic regression methods, we revealed smoking (odds ratio 0.21; p = 0.0031) and hypertension (odds ratio 0.18; p = 0.0019) to be predictors for a good clinical outcome (mRS 0-2). Age (odds ratio 1.05; p = 0.0092), WFNS Grade (odds ratio 6.28; p < 0.0001), early cerebral ischemia (ECI) (odds ratio 10.06; p < 0.00032) and delayed cerebral ischemia (DCI) (odds ratio 4.03; p = 0.017) were detected as predictors for a poor clinical outcome. Significant associations of occurrence of death with hypertension (odds ratio 0.12; p < 0.0001), smoking (odds ratio 0.31; p = 0.048), WFNS grade (odds ratio 3.23; p < 0.0001) and age (odds ratio 1.09; p < 0.0001), but not with ECI (p = 0.29) and DCI (p = 0.62) were found. Smoking and hypertension seem to be predictors for a good clinical outcome after aneurysmal SAH.

Aligned Nanofibrillar Scaffolds for Controlled Delivery of Modified mRNA

RNA-based vector delivery is a promising gene therapy approach. Recent advances in chemical modification of mRNA structure to form modified mRNA (mmRNA or cmRNA or modRNA) have substantially improved their stability and translational efficiency within cells. However, mmRNA conventionally delivered in solution can be taken up nonspecifically or become cleared away prematurely, which markedly limits the potential benefit of mmRNA therapy. To address this limitation, we developed mmRNA-incorporated nanofibrillar scaffolds that could target spatially localized delivery and temporally controlled release of the mmRNA both in vitro and in vivo. To establish the efficacy of mmRNA therapy, mmRNA encoding reporter proteins such as green fluorescence protein or firefly luciferase (Fluc) was loaded into aligned nanofibrillar collagen scaffolds. The mmRNA was released from mmRNA-loaded scaffolds in a transient and temporally controlled manner and induced transfection of human fibroblasts in a dose-dependent manner. In vitro transfection was further verified using mmRNA encoding the angiogenic growth factor, hepatocyte growth factor (HGF). Finally, scaffold-based delivery of HGF mmRNA to the site of surgically induced muscle injury in mice resulted in significantly higher vascular regeneration after 14 days, compared to implantation of Fluc mmRNA-releasing scaffolds. After transfection with Fluc mmRNA-releasing scaffold in vivo, Fluc activity was detectable and localized to the muscle region, based on noninvasive bioluminescence imaging. Scaffold-based local mmRNA delivery as an off-the-shelf form of gene therapy has broad translatability for treating a wide range of diseases or injuries.

PRG3 induces Ras-dependent oncogenic cooperation in gliomas

Malignant gliomas are one of the most devastating cancers in humans. One characteristic hallmark of malignant gliomas is their cellular heterogeneity with frequent genetic lesions and disturbed gene expression levels conferring selective growth advantage. Here, we report on the neuronal-associated growth promoting gene PRG3 executing oncogenic cooperation in gliomas. We have identified perturbed PRG3 levels in human malignant brain tumors displaying either elevated or down-regulated PRG3 levels compared to non-transformed specimens. Further, imbalanced PRG3 levels in gliomas foster Ras-driven oncogenic amplification with increased proliferation and cell migration although angiogenesis was unaffected. Hence, PRG3 interacts with RasGEF1 (RasGRF1/CDC25), undergoes Ras-induced challenges, whereas deletion of the C-terminal domain of PRG3 (PRG3^ΔCT) inhibits Ras. Moreover PRG3 silencing makes gliomas resistant to Ras inhibition. In vivo disequilibrated PRG3 gliomas show aggravated proliferation, invasion, and deteriorate clinical outcome. Thus, our data show that the interference with PRG3 homeostasis amplifies oncogenic properties and foster the malignancy potential in gliomas.

Chemotherapeutic xCT inhibitors sorafenib and erastin unraveled with the synaptic optogenetic function analysis tool

In the search for new potential chemotherapeutics, the compounds’ toxicity to healthy cells is an important factor. The brain with its functional units, the neurons, is especially endangered during the radio- and chemotherapeutic treatment of brain tumors. The effect of the potential compounds not only on neuronal survival but also neuronal function needs to be taken into account. Therefore, in this study we aimed to comprehend the biological effects of chemotherapeutic xCT inhibition on healthy neuronal cells with our synaptic optogenetic function analysis tool (SOFA). We combined common approaches, such as investigation of morphological markers, neuronal function and cell metabolism. The glutamate-cystine exchanger xCT (SLC7A11, system X_c⁻) is the main glutamate exporter in malignant brain tumors and as such a relevant drug target for treating deadly glioblastomas (WHO grades III and IV). Recently, two small molecules termed sorafenib (Nexavar) and erastin have been found to efficiently block xCT function. We investigated neuronal morphology, metabolic secretome profiles, synaptic function and cell metabolism of primary hippocampal cultures (containing neurons and glial cells) treated with sorafenib and erastin in clinically relevant concentrations. We found that sorafenib severely damaged neurons already after 24 h of treatment. Noteworthy, also at a lower concentration, where no morphological damage or metabolic disturbance was monitored, sorafenib still interfered with synaptic and metabolic homeostasis. In contrast, erastin-treated neurons displayed mostly inconspicuous morphology and metabolic rates. Key parameters of proper neuronal function, such as synaptic vesicle pool sizes, were however disrupted following erastin application. In conclusion, our data revealed that while sorafenib and erastin effectively inhibited xCT function they also interfered with essential neuronal (synaptic) function. These findings highlight the particular importance of investigating the effects of potential neurooncological and general cancer chemotherapeutics also on healthy neuronal cells and their function as revealed by the SOFA tool.

Abstract 320: Delivery of Hepatocyte Growth Factor mRNA From Nanofibrillar Scaffolds for Treatment of Peripheral Arterial Disease

Biological approaches to augment angiogenesis are promising for treatment of peripheral arterial disease (PAD). We propose the use of scaffold-based modified mRNA (mmRNA) delivery as a favorable approach for transient, localized gene delivery. We hypothesized that hepatocyte growth factor (HGF) mmRNA-seeded nanofibrillar scaffolds will enable localized and temporally controlled delivery of mmRNA, leading to augmentation of angiogenesis in a murine model of PAD. To establish the efficacy of mmRNA therapy, mmRNA encoding green fluorescence protein (GFP) was used as a fluorescent reporter for quantification of transfection efficiency. Aligned nanofibrillar collagen scaffolds were loaded with mmRNA and lipofectamine transfection agent. The temporal kinetics of mmRNA release into media was measured by ribogreen assay. To determine the transfection efficiency, human fibroblasts were cultured on the aligned nanofibrillar scaffolds, or on tissue culture plastic, and the efficiency of transfection was measured for up to 7 days and assayed for GFP expression. Based on ribogreen assay, the cumulative release of GFP mmRNA over the course of 14 days was 235 ng/cm scaffold. In vitro transfection efficiency on aligned scaffolds (75%) was markedly higher than on tissue culture plastic (45%) after 24h. The persistence of cellular transfection as quantified by western blotting showed GFP expression >5 days post-transfection. Next, to demonstrate therapeutic efficacy for treatment of PAD, scaffolds releasing HGF or GFP mmRNA were transplanted to the site of the murine ischemic hindlimb. At the end of the 14 day experiment, laser Doppler spectroscopy showed that HGF mmRNA scaffold group had a higher mean perfusion ratio (0.32 ±0.10) than the GFP mmRNA scaffold group (0.23±0.14), suggesting that HGF-scaffolds improved blood perfusion. In summary, these data suggest that HGF mmRNA-releasing scaffolds marked improved blood perfusion in a murine model of PAD.

Vascular Aging: Implications for Cardiovascular Disease and Therapy

The incidence and prevalence of cardiovascular disease is highest among the elderly, in part, due to deleterious effects of advancing age on the heart and blood vessels. Aging, a known cardiovascular risk factor, is progressively associated with structural and functional changes to the vasculature including hemodynamic disturbance due to increased oxidative stress, premature cellular senescence and impairments in synthesis and/or secretion of endothelium-derived vasoactive molecules. These molecular and physiological changes lead to vessel wall stiffening and thickening, as well as other vascular complications that culminate to loss of vascular tone regulation and endothelial function. Intriguingly, the vessel wall, a biochemically active structure composed of collagen, connective tissue, smooth muscle and endothelial cells, is adversely affected by processes involved in premature or normal aging. Notably, the inner most layer of the vessel wall, the endothelium, becomes senescent and dysfunctional with advancing age. As a result, its ability to release vasoactive molecules such as acetylcholine (ACh), prostacyclin (PGI2), endothelium-derived hyperpolarizing factor (EDHF), and nitric oxide (NO) is reduced and the cellular response to these molecules is also impaired. By contrast, the vascular endothelium increases its generation and release of reactive oxygen (ROS) and nitrogen (RNS) species, vasoconstrictors such as endothelin (ET) and angiotensin (AT), and endogenous inhibitors of NO synthases (NOSs) to block NO. This skews the balance of the endothelium in favor of the release of highly tissue reactive and harmful molecules that promote DNA damage, telomere erosion, senescence, as well as stiffened and hardened vessel wall that is prone to the development of hypertension, diabetes, atherosclerosis and other cardiovascular risk factors. This Review discusses the impact of advancing age on cardiovascular health, and highlights the cellular and molecular mechanisms that underlie age-associated vascular changes. In addition, the role of pharmacological interventions in preventing or delaying age-related cardiovascular disease is discussed.

Efficacy and Safety of Treatment of Ruptured Intracranial Aneurysms

OBJECTIVE

To compare the treatment results of ruptured aneurysms treated endovascularly with aneurysms treated with microsurgical clipping.

METHODS

This prospective multicenter study recorded and analyzed 661 cases of ruptured intracranial aneurysms with consecutive subarachnoid hemorrhage treated between 1997 and 2014 at 2 large medical centers. Endovascular treatment was performed in 271 cases, and microsurgical treatment was performed in 390 cases. The treatment modality was chosen by neuroradiologists and vascular neurosurgeons and was classified by predetermined decision criteria.

RESULTS

Symptomatic ischemic stroke occurred in 46 patients (17.0%) in the endovascular group versus 26 patients (6.7%) in the microsurgery group (odds ratio [OR] = 2.86; 95% confidence interval [CI], 1.72-4.76; P < 0.0001). There was a significantly better occlusion rate (OR = 11.48; 95% CI, 5.10-25.83; P < 0.0001) in the microsurgery group compared with the endovascular group. The rebleeding rate was significantly lower in the microsurgery group (OR = 14.90; 95% CI, 1.90-117.13; P = 0.00085). No patient required retreatment in the microsurgery group, whereas 23 patients required retreatment in the endovascular group (P < 0.0001). There was no significant difference regarding the low direct mortality rate of coil embolization versus microsurgical clipping (P = 0.21).

CONCLUSIONS

Microsurgical clipping shows a lower rate of treatment-associated complications and a higher occlusion rate of ruptured intracranial aneurysms than coil embolization. The individual evaluation and decision process for choice of treatment modality in this study is very effective.

Hidden association of Cowden syndrome, PTEN mutation and meningioma frequency

Cowden syndrome (CS) is clinically presented by multiple hamartomas, often with mucocutaneous lesions, goiter, breast cancer and gastrointestinal polyps. CS is a genetic disorder of autosomal dominant inheritance and is one distinct syndrome of the phosphatase and tensin homolog on chromosome 10 (PTEN) hamartoma tumor spectrum. Noteworthy, PTEN germline mutations are related to a wide range of brain tumors. We performed a systematic analysis and review of the medical literature for Cowden syndrome and meningioma and additionally present the case of a 29-year- old CS patient diagnosed with multiple meningiomas. We found strong evidence for high incidence of brain tumors in CS patients. In particular meningiomas and gangliocytomas/Lhermitte-Duclos disease were often associated with 8% and 9% respectively in CS patients. Since aberrations in chromosome 10q are associated with meningiomas, it is likely that the underlying mutations in CS drive to a certain extent neoplastic meningioma growth. We propose to include meningiomas and brain tumors in the major criteria spectrum of CS-related disorders. This could warrant early diagnosis of brain lesions and close therapy, as well as better monitoring of patients with CS.

MIF-CD74 signaling impedes microglial M1 polarization and facilitates brain tumorigenesis

Microglial cells in the brain tumor microenvironment are associated with enhanced glioma malignancy. They persist in an immunosuppressive M2 state at the peritumoral site and promote the growth of gliomas. Here, we investigated the underlying factors contributing to the abolished immune surveillance. We show that brain tumors escape pro-inflammatory M1 conversion of microglia via CD74 activation through the secretion of the cytokine macrophage migration inhibitory factor (MIF), which results in a M2 shift of microglial cells. Interruption of this glioma-microglial interaction through an antibody-neutralizing approach or small interfering RNA (siRNA)-mediated inhibition prolongs survival time in glioma-implanted mice by reinstating the microglial pro-inflammatory M1 function. We show that MIF-CD74 signaling inhibits interferon (IFN)-γ secretion in microglia through phosphorylation of microglial ERK1/2 (extracellular signal-regulated protein kinases 1 and 2). The inhibition of MIF signaling or its receptor CD74 promotes IFN-γ release and amplifies tumor death either through pharmacological inhibition or through siRNA-mediated knockdown. The reinstated IFN-γ secretion leads both to direct inhibition of glioma growth as well as inducing a M2 to M1 shift in glioma-associated microglia. Our data reveal that interference with the MIF signaling pathway represents a viable therapeutic option for the restoration of IFN-γ-driven immune surveillance.

Glioblastoma cells induce differential glutamatergic gene expressions in human tumor-associated microglia/macrophages and monocyte-derived macrophages

Glioblastoma cells produce and release high amounts of glutamate into the extracellular milieu and subsequently can trigger seizure in patients. Tumor-associated microglia/macrophages (TAMs), consisting of both parenchymal microglia and monocytes-derived macrophages (MDMs) recruited from the blood, are known to populate up to 1/3 of the glioblastoma tumor environment and exhibit an alternative, tumor-promoting and supporting phenotype. However, it is unknown how TAMs respond to the excess extracellular glutamate in the glioblastoma microenvironment. We investigated the expressions of genes related to glutamate transport and metabolism in human TAMs freshly isolated from glioblastoma resections. Quantitative real-time PCR analysis showed (i) significant increases in the expressions of GRIA2 (GluA2 or AMPA receptor 2), SLC1A2 (EAAT2), SLC1A3 (EAAT1), (ii) a near-significant decrease in the expression of SLC7A11 (cystine-glutamate antiporter xCT) and (iii) a remarkable increase in GLUL expression (glutamine synthetase) in these cells compared to adult primary human microglia. TAMs co-cultured with glioblastoma cells also exhibited a similar glutamatergic profile as freshly isolated TAMs except for a slight increase in SLC7A11 expression. We next analyzed these genes expressions in cultured human MDMs derived from peripheral blood monocytes for comparison. In contrast, MDMs co-cultured with glioblastoma cells compared to MDMs co-cultured with normal astrocytes exhibited decreased expressions in the tested genes except for GLUL. This is the first study to demonstrate transcriptional changes in glutamatergic signaling of TAMs in a glioblastoma microenvironment, and the findings here suggest that TAMs and MDMs might potentially elicit different cellular responses in the presence of excess extracellular glutamate.

Transient delivery of modified mRNA encoding TERT rapidly extends telomeres in human cells

Telomere extension has been proposed as a means to improve cell culture and tissue engineering and to treat disease. However, telomere extension by nonviral, nonintegrating methods remains inefficient. Here we report that delivery of modified mRNA encoding TERT to human fibroblasts and myoblasts increases telomerase activity transiently (24-48 h) and rapidly extends telomeres, after which telomeres resume shortening. Three successive transfections over a 4 d period extended telomeres up to 0.9 kb in a cell type-specific manner in fibroblasts and myoblasts and conferred an additional 28 ± 1.5 and 3.4 ± 0.4 population doublings (PDs), respectively. Proliferative capacity increased in a dose-dependent manner. The second and third transfections had less effect on proliferative capacity than the first, revealing a refractory period. However, the refractory period was transient as a later fourth transfection increased fibroblast proliferative capacity by an additional 15.2 ± 1.1 PDs, similar to the first transfection. Overall, these treatments led to an increase in absolute cell number of more than 10(12)-fold. Notably, unlike immortalized cells, all treated cell populations eventually stopped increasing in number and expressed senescence markers to the same extent as untreated cells. This rapid method of extending telomeres and increasing cell proliferative capacity without risk of insertional mutagenesis should have broad utility in disease modeling, drug screening, and regenerative medicine.

Selenium action in neuro-oncology

The trace element selenium and selenocysteine-carrying selenoproteins play a pivotal role in the brain. Beside the essential function during development and maintenance of brain action, selenium has also been associated with several neurological and neuro-oncological conditions. Reliable supply of selenium is important since selenium compounds can affect tumor microenvironment and neoangiogenesis in malignant gliomas (WHO grade III and IV [glioblastoma, GBM]) via induction of apoptosis and alteration of matrix metalloproteinases expression. Here, we summarize recent findings focusing on the anti-toxicity and cancer-preventive properties of selenium and their implication in current multimodal therapies including temozolomide (Temodal), cyclophosphamide (Endoxan), and cisplatin (DDP, Platiblastin, and Platinol). We shed light on unintended side effects in chemotherapy and the developments of novel combinatorial chemotherapeutics with selenium compounds. We found that selenium and selenium compounds have dual action profiles with direct anti-cancer and chemotherapy-intensifier effects as well as neuroprotective and cytoprotective agents. Current selenium trials and selenium supplementation with focus on neuro-oncology will be discussed with regard to low-adequate-to-high/toxic selenium status.

Activation of innate immunity is required for efficient nuclear reprogramming

Retroviral overexpression of reprogramming factors (Oct4, Sox2, Klf4, c-Myc) generates induced pluripotent stem cells (iPSCs). However, the integration of foreign DNA could induce genomic dysregulation. Cell-permeant proteins (CPPs) could overcome this limitation. To date, this approach has proved exceedingly inefficient. We discovered a striking difference in the pattern of gene expression induced by viral versus CPP-based delivery of the reprogramming factors, suggesting that a signaling pathway required for efficient nuclear reprogramming was activated by the retroviral, but not CPP approach. In gain- and loss-of-function studies, we find that the toll-like receptor 3 (TLR3) pathway enables efficient induction of pluripotency by viral or mmRNA approaches. Stimulation of TLR3 causes rapid and global changes in the expression of epigenetic modifiers to enhance chromatin remodeling and nuclear reprogramming. Activation of inflammatory pathways are required for efficient nuclear reprogramming in the induction of pluripotency.

Zinc supplementation augments in vivo antitumor effect of chemotherapy by restoring p53 function

Activated p53 is necessary for tumor suppression. Homeodomain-interacting protein kinase-2 (HIPK2) is a positive regulator of functional p53. HIPK2 modulates wild-type p53 activity toward proapoptotic transcription and tumor suppression by the phosphorylation of serine 46. Knock-down of HIPK2 interferes with tumor suppression and sensitivity to chemotherapy. Combined administration of adriamycin and zinc restores activity of misfolded p53 and enables the induction of its proapoptotic and tumor suppressor functions in vitro and in vivo. We therefore looked for a cancer model where HIPK2 expression is low. MMTV-neu transgenic mice overexpressing HER2/neu, develop mammary tumors at puberty with a long latency, showing very low expression of HIPK2. Here we show that whereas these tumors are resistant to adriamycin treatment, a combination of adriamycin and zinc suppresses tumor growth in vivo in these mice, an effect evidenced by the histological features of the mammary tumors. The combined treatment of adriamycin and zinc also restores wild-type p53 conformation and induces proapoptotic transcription activity. These findings may open up new possibilities for the treatment of human cancers via the combination of zinc with chemotherapeutic agents, for a selected group of patients expressing low levels of HIPK2, with an intact p53. In addition, HIPK2 may serve as a new biomarker for tumor aggressiveness.

Reprogramming of human fibroblasts to pluripotent stem cells using mRNA of four transcription factors

Reprogramming of differentiated cells into induced pluripotent cells (iPS) was accomplished in 2006 by expressing four, or less, embryonic stem cell (ESC)-specific transcription factors. Due to the possible danger of DNA damage and the potential tumorigenicity associated with such DNA damage, attempts were made to minimize DNA integration by the vectors involved in this process without complete success. Here we present a method of using RNA transfection as a tool for reprogramming human fibroblasts to iPS. We used RNA synthesized in vitro from cDNA of the same reprogramming four transcription factors. After transfection of the RNA, we show intracellular expression and nuclear localization of the respective proteins in at least 70% of the cells. We used five consecutive transfections to support continuous protein expression resulting in the formation of iPS colonies that express alkaline phosphatase and several ESC markers and that can be expanded. This method completely avoids DNA integration and may be developed to replace the use of DNA vectors in the formation of iPS.

Overexpression of dopamine receptor genes and their products in the postnatal rat brain following maternal n-3 fatty acid dietary deficiency

A combination of PCR-Select cDNA subtraction and gene array hybridization was used to identify differentially expressed genomic markers in brains of rats fed for 3 weeks in utero and 2 weeks after birth on an n-3 polyunsaturated fatty acid (PUFA)-deficient diet supplied to dams. Total RNA was isolated, switch mechanism at 5'-end of the RNA transcripts (SMART) applied and used for PCR-Select subtraction of PUFA-deficient and adequately-fed control preparations. Subtracted and amplified ds-cDNA end-products were fragmented, terminally labeled with biotin-ddUTP and hybridized with a RN-U34A gene array. A 10-fold increase in potential genes with log2(Tester/Driver) = 1.4 was found compared with traditional gene array technology when the same chip was tested using non-subtracted targets. Reverse transcription-real-time relative PCR confirmed 30% of the transcripts. Among the validated transcripts, D1 and D2 receptors for dopamine (DA), were most prominent among a number of over-expressed neurotransmitter receptors and retinoic acid receptor (RXR alpha-2 and alpha-1). Immunohistochemical staining of brain sections from 2-week-old pups revealed a substantial enrichment of the D2 receptor in discrete regions of the mesolimbic and mesocortical pathways as well as in a large number of brain areas from the n-3 PUFA-deficient pups. Punches of the same areas run on western blots showed similar results. The overwhelming expression of D1 and D2 receptors may be attributed to a behavioral hypersensitivity caused by the possible impairment of DA production during brain development, which may have implications in certain disorders of the nervous system.

Improved representation of gene markers on microarray by PCR-Select subtracted cDNA targets

Despite the success and popularity of microarrays as a high-throughput technology for gene-expression studies, its sensitivity is as yet fairly limited. We have successfully combined the use of PCR-Select cDNA subtraction and Affymetrix GeneChips (AGC) to identify differentially expressed gene markers. Total RNA (totRNA) from combined hippocampus and cerebellum tissues of 2-week-old rat pups maintained for 5 weeks on an n-3 fatty acid (FA) deficient diet supplied to dams was isolated, SMART-amplified, and used for PCR-Select subtraction versus an adequately fed control litter preparation. Subtracted and amplified ds-cDNA end products were fragmented, terminally labeled with biotin-ddUTP and hybridized with RN-U34A AGC. At least 10-fold more potential gene markers with log2(T/D) > or = 1.4 were found versus the traditional AGC technology when the same chip was tested using nonsubtracted targets. Of this set of markers, 30% were robustly validated by real-time relative RT-PCR (rtrRT-PCR) and grouped as "confirmed" markers while the remaining were ascribed as "latent" markers. An improved and universal protocol to provide a rapid assessment for gene profiling in biological specimens is indicated.

Overexpression of genes in the CA1 hippocampus region of adult rat following episodes of global ischemia

Ischemic stress is associated with marked changes in gene expression in the hippocampus--albeit little information exists on the activation of nonabundant genes. We have examined the expression of several known genes and identified novel ones in the adult rat hippocampus after a mild, transient, hypovolemic and hypotensive, global ischemic stress. An initial differential screening using a prototype array to assess gene expression after stress followed by a suppression subtractive hybridization protocol and cDNA microarray revealed 124 nonoverlapped transcripts predominantly expressed in the CA1 rat hippocampus region in response to ischemic stress. About 78% of these genes were not detected with nonsubtracted probes. Reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization on these 124 transcripts confirmed the differential expression of at least 83. Most robustly expressed were gene sequences NFI-B, ATP1B1, RHOGAP, PLA2G4A, BAX, CASP3, P53, MAO-A, FRA1, HSP70.2, and NR4A1 (NUR77), as well as sequence tags of unknown function. New stress-related genes of similar functional motifs were identified, reemphasizing the importance of functional grouping in the analysis of multiple gene expression profiles. These data indicate that ischemia elicits expression of an array of functional gene clusters that may be used as an index for stress severity and a template for target therapy design.