Human Glial Tumors Research Articles

Visualization of Brain Tumors with Infrared-Labeled Aptamers for Fluorescence-Guided Surgery.

Gliomas remain challenging brain tumors to treat due to their infiltrative nature. Accurately identifying tumor boundaries during surgery is crucial for successful resection. This study introduces an innovative intraoperative visualization method utilizing surgical fluorescence microscopy to precisely locate tumor cell dissemination. Here, the focus is on the development of a novel contrasting agent (IR-Glint) for intraoperative visualization of human glial tumors comprising infrared-labeled Glint aptamers. The specificity of IR-Glint is assessed using flow cytometry and microscopy on primary cell cultures. In vivo effectiveness is studied on mouse and rabbit models, employing orthotopic xenotransplantation of human brain gliomas with various imaging techniques, including PET/CT, in vivo fluorescence visualization, confocal laser scanning, and surgical microscopy. The experiments validate the potential of IR-Glint for the intraoperative visualization of gliomas using infrared imaging. IR-Glint penetrates the blood-brain barrier and can be used for both intravenous and surface applications, allowing clear visualization of the tumor. The surface application directly to the brain reduces the dosage required and mitigates potential toxic effects on the patient. The research shows the potential of infrared dye-labeled aptamers for accurately visualizing glial tumors during brain surgery. This novel aptamer-assisted fluorescence-guided surgery (AptaFGS) may pave the way for future advancements in the field of neurosurgery.

Aptamers for the diagnosis and treatment of human glial tumors

Purpose of the study: to evaluate the feasibility of using functional analogues of protein antibodies – dNa/ RNa aptamers in diagnostics, treatment and prognosis of human brain glial tumors.Material and Methods. The relevant literature sources were searched in scopus, Web of science, pubmed, elibrary with inclusion of publications from 2000 to 2023. sixty articles are presented in the review.Results. The analysis of the literature devoted to classification, diagnostics and therapy of brain glioblastomas was carried out and the feasibility of using for in vivo diagnostics and therapy of this disease aptamers, which are molecular recognition elements based on DNA/RNA oligonucleotides, capable of binding to the given molecular targets and distinguishing even separate functional groups in them, was studied. A list of aptamers to human glial brain tumors and their molecular targets that can be used for diagnostics and therapy of glioblastoma, including tumor imaging by pet/ct, mRi, plasmon resonance, fluorescence and confocal microscopy, etc., is presented. literature data suggest that DNA/RNA aptamers can be used to search for circulating tumor cells in the blood of glioblastoma patients, to target therapeutic drugs to the tumor and to inhibit tumor growth.Conclusion. Brain glioblastoma is a heterogeneous tumor consisting of cells at different stages of malignancy and, accordingly, with a different set of oncogenes. For this reason, a multitarget strategy that includes combined suppression of angiogenesis, invasion, metastasis, proliferation and survival of tumor cells should be proposed for the therapy of this disease. DNA/RNA aptamers tailored to key proteins involved in oncogenic transformation may be suitable candidates for the implementation of multitarget therapy for brain glioblastoma.

Development of DNA aptamers for visualization of glial brain tumors and detection of circulating tumor cells

Here, we present DNA aptamers capable of specific binding to glial tumor cells invitro, exvivo, and invivo for visualization diagnostics of central nervous system tumors. We selected the aptamers binding specifically to the postoperative human glial primary tumors and not to the healthy brain cells and meningioma, using a modified process of systematic evolution of ligands by exponential enrichment to cells; sequenced and analyzed ssDNA pools using bioinformatic tools and identified the best aptamers by their binding abilities; determined three-dimensional structures of lead aptamers (Gli-55 and Gli-233) with small-angle X-ray scattering and molecular modeling; isolated and identified molecular target proteins of the aptamers by mass spectrometry; the potential binding sites of Gli-233 to the target protein and the role of post-translational modifications were verified by molecular dynamics simulations. The anti-glioma aptamers Gli-233 and Gli-55 were used to detect circulating tumor cells in liquid biopsies. These aptamers were used for in situ, exvivo tissue staining, histopathological analyses, and fluorescence-guided tumor and PET/CT tumor visualization in mice with xenotransplanted human astrocytoma. The aptamers did not show invivo toxicity in the preclinical animal study. This study demonstrates the potential applications of aptamers for precise diagnostics and fluorescence-guided surgery of brain tumors.

Incorporation of a Disposable ESI Emitter into Inline Cartridge Extraction Mass Spectrometry Improves Throughput and Spectra Stability.

Rapid and reliable methods for detecting tumor margins are crucial for neuro-oncology. Several mass spectrometry-based methods have been recently proposed to address this problem. Inline Cartridge Extraction (ICE) demonstrates the potential for clinical application, based on ex-vivo analysis of dissected tissues, but requires time-consuming steps to avoid cross-contamination. In this work, a method of incorporating a disposable electrospray emitter into the ICE cartridge by PEEK sleeves melting is developed. It reduces total analysis time and improves throughput. The proposed setup also improves the robustness of the ICE molecular profiling as demonstrated with human glial tumor samples in that stability and reproducibility of the spectra were increased.

"Smart" nanoscalpel for microsurgery of glial tumors of the human brain

We studied the effectiveness of magnetomechanical therapy in the treatment of brain glial tumors using magnetic nanodiscs functionalized with DNA aptamers to human brain tumor glial cells. • Materials and methods. The formation of a model of human glioblastoma was carried out by intracranial injection of tumor cells of glioblastoma obtained from a patient with glioblastoma. Antitumor therapy was carried out using nanodiscs modified with the Gli233 aptamer. The growth of the glial tumor was monitored using NMR tomography. • Results and discussion. Therapy of a glial tumor during 4 sessions of magnetomechanical therapy using a "smart" nanoscalpel in MF (10Hz, 100Oe) led to a significant reduction in its size, while glial tumors in mice that were treated with nanodiscs modified with nonspecific aptamers continued to increase in size. • Conclusion. Microsurgery using three-layer magnetic nanodisks with a quasi-dipole structure (Au/Ni/Au) modified with the specific for glial cells Gli233 aptamer (“smart” nanoscalpel) is effective for the treatment of human glial tumors in the brain.

A Novel Highly Selective Cannabinoid CB2 Agonist Reduces in vitro Growth and TGF-beta Release of Human Glial Cell Tumors

Cannabinoid receptors have been detected in human gliomas and cannabinoids have been proposed as novel drug candidates in the treatment of brain tumors. To test the in vitro antitumor activity of COR167, a novel cannabinoid CB2-selective agonist displaying a high binding affinity for human CB2 receptors, on tumor cells isolated from human glioblastoma multiforme and anaplastic astrocytoma. Glioma cell cultures were established from two glioblastoma multiforme and two anaplastic astrocytomas. Proliferation was measured in the presence or absence of COR167 with a bromodeoxyuridine (BrdU) cell proliferation ELISA assay. CB2 receptor expression was detected by western blotting. Apoptosis was assessed with phycoerythrin (PE) annexin V flow cytometry kit. TGF-beta 1 and 2 levels were analyzed in culture supernatants with commercial ELISAs. COR167 was found to significantly reduce the proliferation of both glioblastoma and anaplastic astrocytoma in a dose-dependent manner at lower doses than other known, less specific CB2 agonists. This activity is independent of apoptosis and is associated with a significant reduction of TGF-beta 1 and 2 levels in supernatants of glioma cell cultures. These findings add to the role of cannabinoid CB2 receptor as a possible pharmacological target to counteract glial tumor growth and encourage further work to explore any other pharmacological effect of this novel CB2 agonist useful in the treatment of human gliomas.

P04.49 The evaluation of anti cancer activity of isothiourea derivatives and CK2 inhibitors on cell lines of human glial tumor in vitro

P04.49 The evaluation of anti cancer activity of isothiourea derivatives and CK2 inhibitors on cell lines of human glial tumor in vitro

Towards an advanced cell-based in vitro glioma model system.

The modulation of tumor growth and development in vitro has always been one of the key factors in the research of the malignant transformation, including gliomas, prevalent and most deadly cancers of the brain. Indeed, cellular and molecular biology research employing in vitro model cell-based systems have great potential to advance both the mechanistic understanding and the treatment of human glial tumors, as it facilitates not only the understanding of glioma biology and its regulatory mechanisms Additionally they promise to afford the screening of the putative anti-tumor agents and alternative treatment approaches in a personalized manner, i.e. by virtue of using the patient-derived tumor material for such tests. However, in order to become reliable and representative, glioma model systems need to move towards including most inherent cancer features such as local hypoxia, specific genetic aberrations, native tumor microenvironment, and the three-dimensional extracellular matrix.This review starts with a brief introduction on the general epidemiological and molecular characteristics of gliomas followed by an overview of the cell-based in vitro models currently used in glioma research. As a conclusion, we suggest approaches to move to innovative cell-based in vitro glioma models. We consider that main criteria for selecting these approaches should include the adequate resemblance to the key in vivo characteristics, robustness, cost-effectiveness and ease to use, as well as the amenability to high throughput handling to allow the standardized drug screening.

From epidemiology and neurodevelopment to antineoplasticity. Medroxyprogesterone reduces human glial tumor growth in vitro and C6 glioma in rat brain in vivo

ObjectiveGlial tumor growth may accelerate during gestation, but epidemiological studies consistently demonstrated that parousity reduces life long risk of glial tumors. Pregnancy may also accelerate growth of medulloblastoma and meningioma, but parousity does not confer protection against these tumors. We were the first to show that medroxyprogesterone acetate (MPA) reduces rat C6 glioma growth in vitro. Now we aimed to determine the effects of MPA on human brain cancers (particularly glioblastoma) in vitro and C6 glioma in vivo. Patients and MethodsWe evaluated the effects of MPA on: i) monolayer growth of human U87 and U251 glioblastoma, ii) 3D-spheroid growth and invasion of C6 rat glioma and human U251 glioma, iii) interactions with PI3-Kinase inhibitors and coxsackie-adenovirus receptor (CAR) in modifying 3D-spheroid invasion of glioma. ResultsMPA at low doses (3.25–13 μM) insignificantly stimulated and at high doses (above 52 μM) strongly suppressed the growth of human U87 and U251 cells in vitro. MPA also binds to glucocorticoid receptors similar to dexamethasone (Dex) and unexpectedly, PI3-Kinase inhibitors at low doses suppressed anti-invasive efficacies of MPA and Dex. MPA exerted higher invasion-inhibitory effects on CAR-expressing human glioma cells. Lastly, MPA suppressed growth of C6 glioma implanted into rat brain. ConclusionProgesterone analogues deserve to be studied in future experimental models of high grade glial brain tumors.

Quantitative assessment of changes in diffusion tensor imaging (DTI) metrics along the courses of the cortico-ponto-cerebellar tracts secondary to supratentorial human brain glial tumors.

The cortico-ponto-cerebellar tract (CPCT) is the largest projection pathway, which synapses at the pons. Remote effects of supratentorial brain tumors have not been evaluated along the infratentorial course of the CPCT. The purpose of this study is to evaluate the possible lateralization of the diffusion tensor metrics of the affected CPCT in patients with supratentorial brain tumor. We included 39 patients with 29 left-sided tumors (LST) and 10 right-sided tumors, retrospectively. We measured the magnitude of changes of the fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the CPCT prior to the brain surgery at the level of crus cerebri and middle cerebellar peduncle. Regions of interest (ROIs) were placed on the lateral side of crus cerebri, and ROI-1 (anterior 1/3), ROI-2 (middle 1/3), ROI-3 (posterior 1/3), and ROI-4 were placed at the level of middle cerebellar peduncle. We hypothesized that there would be decreased FA and increased ADC values of the ipsilesional CPCT compared with contralesional CPCT. Ipsilesional FA values were decreased with simultaneous increased ADC value along the CPCT compared with contralesional CPCT in following ROIs, ROI-1 (LST FA: P=.005, ADC: P=.037) and ROI-3 (LST FA: P=.049, ADC: P=.049), respectively. Affected ROI-4 in LST cases also showed lower FA values, although not statistically significant. We observed a statistically significant FA value decrease and ADC increase along the left ROI-1 and ROI-3 as well as the nonstatistically significant FA decrease of the left ROI-4 at the second neuron level when there was a related supratentorial tumor. These findings are suggestive of presynaptic and postsynaptic microstructural changes of these tracts following the presynaptic involvement by a primary supratentorial brain tumor.

Abstract 3182: A human neural stem cell glial brain tumor model identifies the relative contribution of different oncogenic elements to malignant transformation

Abstract Diffuse intrinsic pontine glioma (DIPG) is an invasive malignancy of the brainstem that accounts for greater than 80% of pediatric brainstem gliomas. In the past 40 years, there have been no significant advances in DIPG treatments and survival, so it remains a leading cause of death from pediatric brain tumors. Nearly 80% of DIPG harbor a point mutation in H3F3A or HIST1H3B, and the presence of this H3.3K27M mutation is inversely correlated with reduced OS, suggesting that epigenetic dysregulation is a key driver to cause the pathogenesis of DIPG. However, it is unclear how the H3.3K27M mutation and the other common alterations in DIPG contribute to tumorigenicity in human neural stem cells. To address the relative contributions of different oncogenic elements to DIPG, we sought to add common DIPG elements in a stepwise fashion to human neural stem cells derived from the developing hindbrain. We chose oncogenic elements that are known to present in DIPG, including the stem cell factor BMI1, mutant (R248W) p53, H3.3K27M, constitutively active AKT (representing the activation of mTOR detected in the vast majority of DIPG) and hTERT. We found that the combination of the stem cell factor BMI1 along with mutant (R248W) p53 and hTERT could immortalize neural stem cells, but was insufficient to form orthotopic xenograft tumors when placed in the pons of immunodeficient mice. Addition of activated AKT led to aggressive tumor formation, with a glial phenotype as evidenced by robust GFAP expression and absence of synaptophysin expression. All mice bearing these four genetic alterations succumbed to their tumors within 100 days of implantation. We found that introduction of H3.3K27M mutation reduces the level of tri-methylation of H3.3KK27 to that seen in patient-derived DIPG cell lines. Furthermore, we found that H3.3KK27 mutation introduction increases expression of LIN28B, a stem cell factor, which is also found in patient-derived DIPGs. Our previous study showing that LIN28A, another family member of LIN28 proteins, regulates invasion and tumorigenicity in adult high-grade gliomas suggests that H3.3K27M mutation might facilitate invasiveness of DIPG through LIN28B and its downstream effectors HMGA2, SNAI1, and SLUG. In summary, we have developed a human hindbrain neural stem cell DIPG model that has both accurate cell of origin and genetic defects including H3.3K27M mutation. Our models allow for assessment of the relative contribution to transformation of each genetic element in a stepwise fashion in the likely cell of origin of this deadly tumor. Citation Format: Youngran Park, Ping An, Dacheng Ding, Charles G. Eberhart, Eric H. Raabe. A human neural stem cell glial brain tumor model identifies the relative contribution of different oncogenic elements to malignant transformation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3182.

The role of surgery in low-grade gliomas: do timing and extent of resection matter?

Hugues Duffau is a Professor and Chairman of the Neurosurgery Department in the Montpellier University Medical Center and Head of the INSERM 1051 Team "plasticity of the central nervous system, human stem cells and glial tumors" at the Institute for Neurosciences of Montpellier (France). He is an expert in the awake cognitive neurosurgery of slow-growing brain tumors, such as low-grade gliomas, a routine which he has developed since 20 years. His fundamental approach is centered on the concepts of the brain connectomics and neuroplasticity, breaking with the traditional localizationist view of cerebral processing. For his innovative work in neurosurgery and neurosciences, he was awarded Doctor Honoris Causa several times, and he was the youngest recipient of the prestigious Herbert Olivecrona Award from the Karolinska Institute in Stockholm. He has written four textbooks and over 335 publications in international journals ranging from neurosurgery to fundamental neurosciences, including cognitive sciences and brain plasticity for a total of more than 20,800 citations and with an h-index of 77. He is a member of editorial boards of many journals (as brain and language, neurosurgery or neuro-oncology) and ad hoc reviewer for around 100 journals (over 900 reviews) including: New England Journal of Medicine, Lancet Oncology, Nature Medicine, Nature Reviews Neuroscience, Nature Reviews Neurology; Annals of Neurology, Brain, Cerebral Cortex, Trends in Cognitive Science, Current Biology, among others. He is a member of many societies: member of the French Academy of Medicine, member of the French Academy of Surgery, member of the World Academy of Neurological Surgery, member of the Young Neurosurgeons Award Committee of the World Federation of Neurosurgical Societies, member of the Scientific Committee of the European Association for Neuro-oncology, etc.

P08.49 Sensitivity of glioma cell lines and normal human cultured astrocytes to modified isothiourea derivative (ZKK-13) and Caseine Kinase II inhibitors

Abstract Introduction: Glioblastoma multiforme (WHO grade IV) is the most aggressive primary brain tumour that is characterized by intratumoral heterogeneity, invasive growth and poor prognosis. The therapy of astroglial tumours remains still challenging. Promising group of compounds are derivatives of pentabromobenzylisothiouronium salt, which affect proliferation of some human cancer cells. Isothioureas are a class of amphiphilic compounds carrying a highly basic isothiourea group of pKa » 10. They exist in the protonated (cation) form, what is very important for molecular recognition of specific receptors. Second interesting class of compounds with a potential for cancer treatment are Caseine Kinase II (CK2) inhibitors. CK2 is an oncogenic protein kinase present in both the nucleus and cytoplasm of cells. The serine/threonine protein kinase CK2 modulates multiple signaling pathways involved in cell survival and function, and is therefore a promising drug target. The aim of this study was to evaluate the cytostatic effect of novel CK2 inhibitors and S-pentabromobenzylisothiourea derivative (ZKK-13) on cell lines of human glial tumours, as compared to normal human cultured astrocytes. Materials and Methods: We examined the cytostatic effect of selected modified isothiourea derivatives - pentabromobenzylisothioureas (ZKKs) including ZKK-13 and CK2 inhibitors against adult human glioblastoma cell line (T98G) and normal human cultured astrocytes. We analyzed cell viability (MTT metabolism assay), and conducted cell proliferation assay (Multisizer3; Beckman Coulter cell counter) after 24, 48 and 72 hours of incubation with investigated compounds. Results: In all experimental groups there was a marked decrease of a total cells number, especially after 48 and 72 hours of treatment. T98G cells treated with ZKK-13 showed a statistically significant decrease of proliferation rate at 10µM in comparison to the control cells. Inhibitor of kinase CK2 - 2- aminoethylamino-4,5,6,7- tetrabromo-1H- benzimidazole, appeared to be the most effective compound that exhibits a strong anti-proliferative effect on neoplastic astroglial cells in gliomas in vitro. Conclusions: The results show that CK2 inhibitors and S-pentabromobenzylisothiourea derivative have a potent antiproliferative efficacy against malignant glioma cells. It may offer a promising anti-tumour therapy, including treatment of glial cells-derived primary brain tumours.ACKNOWLEDGEMENT: The research was supported by the Foundation for the Development of Diagnostic and Therapy, Warsaw.

Glioblastoma spheroids produce infiltrative gliomas in the rat brainstem.

Diffuse intrinsic pontine glioma (DIPG) is universally fatal without proven therapy other than radiation therapy for palliation. Representative animal models will play an essential role in the preclinical stage of future therapy development. To address the shortage of representative models, we created a novel infiltrative brainstem glioma model in rats based on glioblastoma spheroids. Cells dissociated from glioblastoma spheroids grown from surgical specimens were implanted into the brainstem of NIH nude rats. Animals were serially assessed clinically and radiographically with magnetic resonance imaging (MRI). Tumors were further characterized using histology, immunohistochemistry, and cytogenetics. Tumor generation was successful in all animals receiving glioblastoma spheroid cells. The rats survived 17-25weeks before severe symptoms developed. The tumors showed as diffuse hyperintense lesions on T2-weighted images. Histologically, they demonstrated cellular heterogeneity, and infiltrative and invasive features, with cells engorging vascular structures. The tumors were shown to comprise immature human origin glial tumor cells, with human epidermal growth factor receptor (EGFR) gene amplification and gain. This study showed that cells from glioblastoma spheroids produced infiltrative gliomas in rat brainstem. The rat brainstem gliomas are radiographically and histologically accurate compared to DIPG. These tumors develop over several months that would allow sequential clinical and radiographic assessments of therapeutic interventions. This study demonstrated in principle the feasibility of developing patient-specific animal models based on putative cancer stem cells from biopsy or resection samples.

Connexin 43 expression in human brain glial tumors

Тo conduct an immunohistochemical (IHC) study of the expression of connexin 43 in the samples of glial tumors of various grades: gemistocytic astrocytomas (Grade 2), oligodendrogliomas (Grade 2) and glioblastomas (Grade 4). The material investigated was fragments of human brain glial tumors (grade 2 gemistocytic astrocytomas (n=2), grade 2 oligodendrogliomas (n=2), and grade 4 glioblastomas (n=14) and those of tumor-surrounding tissue (n=4). The material was fixed in 10% buffered formalin, dehydrated, and embedded in paraffin according to the standard technique. IHC studies of the slices applied primary rabbit polyclonal antibodies against connexin 43 ('Spring Bioscience', USA) and the Dako EnVision + Peroxidase (DAB) visualization system ('Dako', Denmark). After the immunohistochemical reaction, the cell nuclei were stained with Mayer's hematoxylin. Immunohistochemistry showed the changing pattern of connexin 43 expression as compared with intact tissue in the glial tumors. Instead of the fine-granular expression in the thin cellular processes in the neuropil, the tumors mainly displayed a coarse-grained cytoplasmic and even nuclear reaction. The morphology and localization of positive structures depended on the variant of an examined tumor. In addition, the most malignant brain gliomas generally exhibited a reduction in the expression of connexin 43, i.e. its quantity is inversely proportional to the degree of malignancy of the tumor. The low connexin 43 expression levels may reflect both a reduction in astroglial functional gap junctions and semicanals and a decrease in the amount of the protein itself that has independently antioncogenic properties. The observed cytoplasmic and nuclear expression of connexin 43 is most likely to be associated with the aberrant activity of a number of kinases, such as proto-oncogene tyrosine-kinase Src or protein kinase C (PKC).

Ultrastructural characteristics of gap junctions in human glial brain tumors

to conduct an electron microscopic study of intercellular communication in the samples of gemistocytic astrocytoma, oligodendroglioma, and glioblastoma. Surgically resected tumor tissue fragments were fixed in 2.5% glutaraldehyde solution, afterfixed in 1% OsO4 solution, dehydrated, and embedded in epoxy resin. Ultrathin sections were examined using a Jem 1011 electron microscope (Jeol, Japan). Solitary and closely spaced gap junctions (GJs) formed by the thin processes that have the ultrastructure of an astroglial processes were identified in the astrocytoma samples. In this case, chemical synapses were noted to be completely absent in gemistocytic astrocytoma and glioblastoma. The identified GJs had a small length and deformed nexuses. The oligodendroglioma samples exhibited intact astroglial processes around the chemical synapses; however, interglial GJs were not found. The investigation showed the presence of intercellular GJs with some ultrastructural differences in the samples of low- and high-grade astroglial tumors. According to current data, astrocytomic GJs are able to create a stable self-sustaining network that promotes tumor progression and provides resistance to a therapeutic intervention. At the same time, the noticeable reduction in the number of GJs, which is most pronounced in the oligodendroglioma sample, can accelerate tumor cell migration into the surrounding parenchyma. The investigation of GJs should be, of course, continued using a group of a larger number of glial tumors to confirm the intercellular communication features revealed in this study.

MiRNA regulation of Sirtuin-1 expression in human astrocytoma.

Sirtuins are a family of 7 histone deacetylases largely involved in the regulation of cell proliferation, survival and death. The role of sirtuins in tumorigenesis and cancer progression has been previously studied in certain cancer types. Few studies have investigated sirtuin expression in gliomas, with controversial results. The aim of the present study was to investigate the expression of sirtuin-1 (Sirt-1) in diffuse astrocytoma [low grade astrocytoma (LGA)], anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM) and in primary glioma cell lines: PLGAC (primary LGA cells); PAAC (primary AA cells); and PGBMC (primary GBM cells). Tumor samples were obtained from patients who underwent craniotomy for microsurgical tumor resection at the Neurosurgery Unit of the University of Messina between 2011 and 2014. Sirt-1 expression was qualitatively analyzed in 30 human glial tumor samples and 5 non-neoplastic brain tissue (NBT) specimens using immunohistochemistry and western blotting techniques. Sirt-1 expression was quantitatively analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, Sirt-1 expression in primary cell lines was investigated by immunoblotting and RT-qPCR. Sirt-1 expression was downregulated in gliomas compared to NBTs. Sirt-1 levels also varied among different tumor grades, with more evident downregulation in high-grade (P<0.001) than low-grade tumors (P<0.01). These data were confirmed in cell lines, with the exception of upregulation of protein level in the highest malignancy grade cell lines. The present results suggest a role for miRNA-34a, miRNA-132 and miRNA-217 in the epigenetic control of Sirt-1 during gliomagenesis and progression, and demonstrate the different implications of Sirt-1 in human tissues and cell lines. Furthermore, the present results reveal that Sirt-1 may be an intrinsic regulator of tumor progression and the regulation of Sirt-1 involves complex molecular pathways. However, the biological functions of Sirt-1 in gliomagenesis require additional investigation.

Mapping of global R1 and R2* values versus lipids R1 values as potential markers of hypoxia in human glial tumors: A feasibility study

Availability of an innocuous and repeatable technique for monitoring tumor oxygenation throughout therapeutic course should be a key factor for adaptative therapeutic strategies. We previously qualified lipids R1 as a marker of oxygen level on experimental tumor models. The objectives of the present study were to assess the applicability of measuring lipids R1 in primary central nervous system malignancies in a clinical setting as well as to compare lipids R1 with global (water+lipids) R1 and R2* which are also sensitive to the oxygen environment. 25 patients with brain neuroepithelial tumors were examined on a clinical 3T MR system. Values obtained within regions of interest contouring contrast-enhanced tumor (C+), unenhanced tumor (C−), peritumoral edema, and normal appearing white matter (NAWM) were compared to those obtained for the normal brain parenchyma of 17 healthy volunteers. Global R1 and lipids R1 values were significantly lower in tumors than in NAWM of patients or healthy brain of normal volunteers. In contrast, R2* values were not significantly different in tumors compared to NAWM or healthy brains. None of them showed significant difference between C+ and C− tumors. Global R1 values within NAWM were significantly different from that of both tumor and peritumoral edema, but lacked sensitivity to differentiate between tumor and peritumoral edema. In turn, lipids R1 measurements enabled discrimination between tumor areas and peritumoral edema. In conclusion, global R1 and lipids R1 deserve further attention as potential markers of tumor hypoxia in primary brain tumors.

Effect of cold plasma on glial cell morphology studied by atomic force microscopy.

The atomic force microscope (AFM) is broadly used to study the morphology of cells. The morphological characteristics and differences of the cell membrane between normal human astrocytes and glial tumor cells are not well explored. Following treatment with cold atmospheric plasma, evaluation of the selective effect of plasma on cell viability of tumor cells is poorly understood and requires further evaluation. Using AFM we imaged morphology of glial cells before and after cold atmospheric plasma treatment. To look more closely at the effect of plasma on cell membrane, high resolution imaging was used. We report the differences between normal human astrocytes and human glioblastoma cells by considering the membrane surface details. Our data, obtained for the first time on these cells using atomic force microscopy, argue for an architectural feature on the cell membrane, i.e. brush layers, different in normal human astrocytes as compared to glioblastoma cells. The brush layer disappears from the cell membrane surface of normal E6/E7 cells and is maintained in the glioblastoma U87 cells after plasma treatment.

The combination of artificial neural networks and synchrotron radiation-based infrared micro-spectroscopy for a study on the protein composition of human glial tumors.

Protein-related changes associated with the development of human brain gliomas are of increasing interest in modern neuro-oncology. It is due to the fact that they might make some of these tumors highly aggressive and difficult to treat. This paper presents a methodology for protein-based analysis of human brain gliomas using synchrotron radiation based Fourier transform infrared spectroscopy (SRFTIR) coupled with artificial neural networks (ANNs). The main goal of this study was to optimize a set of ANNs to predict the secondary structure of proteins (alpha-helices, beta-sheets, beta-turns, bends, random coils) in brain gliomas, based on the amide I-II spectral range. All networks were tested and optimized to reach the standard error of prediction (SEP) lower than 5%. The results indicate that protein-related changes are associated with a tumor's malignancy grade. Particularly, the content of alpha helices increases with increasing malignancy grade, while the content of beta sheets decreases. We also found that proteomic information could be a useful marker to distinguish either between low and high grade tumors or between oligodendroglial- and astrocyte-derived ones. This demonstrates the applicability of FTIR coupled with ANNs to provide clinically relevant information.