Taurine Administration Counteracts Aging-Associated Impingement of Skeletal Muscle Regeneration by Reducing Inflammation and Oxidative Stress.

Sarcopenia, which occurs during aging, is characterized by the gradual loss of skeletal muscle mass and function, resulting in a functional decline in physical abilities. Several factors contribute to the onset of sarcopenia, including reduced regenerative capacity, chronic low-grade inflammation, mitochondrial dysfunction, and increased oxidative stress, leading to the activation of catabolic pathways. Physical activity and adequate protein intake are considered effective strategies able to reduce the incidence and severity of sarcopenia by exerting beneficial effects in improving the muscular anabolic response during aging. Taurine is a non-essential amino acid that is highly expressed in mammalian tissues and, particularly, in skeletal muscle where it is involved in the regulation of biological processes and where it acts as an antioxidant and anti-inflammatory factor. Here, we evaluated whether taurine administration in old mice counteracts the physiopathological effects of aging in skeletal muscle. We showed that, in injured muscle, taurine enhances the regenerative process by downregulating the inflammatory response and preserving muscle fiber integrity. Moreover, taurine attenuates ROS production in aged muscles by maintaining a proper cellular redox balance, acting as an antioxidant molecule. Although further studies are needed to better elucidate the molecular mechanisms responsible for the beneficial effect of taurine on skeletal muscle homeostasis, these data demonstrate that taurine administration ameliorates the microenvironment allowing an efficient regenerative process and attenuation of the catabolic pathways related to the onset of sarcopenia.

Evidence of Reelin Signaling in GBM and Its Derived Cancer Stem Cells.

Glioblastoma (GBM) is the most aggressive and malignant form of primary brain cancer, characterized by an overall survival time ranging from 12 to 18 months. Despite the progress in the clinical treatment and the growing number of experimental data aimed at investigating the molecular bases of GBM development, the disease remains characterized by a poor prognosis. Recent studies have proposed the existence of a population of GBM cancer stem cells (CSCs) endowed with self-renewal capability and a high tumorigenic potential that are believed to be responsible for the resistance against common chemotherapy and radiotherapy treatments. Reelin is a large secreted extracellular matrix glycoprotein, which contributes to positioning, migration, and laminar organization of several central nervous system structures during brain development. Mutations of the reelin gene have been linked to disorganization of brain structures during development and behavioral anomalies. In this study, we explored the expression of reelin in GBM and its related peritumoral tissue and performed the same analysis in CSCs isolated from both GBM (GCSCs) and peritumoral tissue (PCSCs) of human patients. Our findings reveal (i) the higher expression of reelin in GBM compared to the peritumoral tissue by immunohistochemical analysis, (ii) the mRNA expression of both reelin and its adaptor molecule Dab1 in either CSC subtypes, although at a different extent; and (iii) the contribution of CSCs-derived reelin in the migration of human primary GBM cell line U87MG. Taken together, our data indicate that the expression of reelin in GBM may represent a potential contribution to the regulation of GBM cancer stem cells behavior, further stimulating the interest on the reelin pathway as a potential target for GBM treatment.

Age-Related Alterations at Neuromuscular Junction: Role of Oxidative Stress and Epigenetic Modifications.

With advancing aging, a decline in physical abilities occurs, leading to reduced mobility and loss of independence. Although many factors contribute to the physio-pathological effects of aging, an important event seems to be related to the compromised integrity of the neuromuscular system, which connects the brain and skeletal muscles via motoneurons and the neuromuscular junctions (NMJs). NMJs undergo severe functional, morphological, and molecular alterations during aging and ultimately degenerate. The effect of this decline is an inexorable decrease in skeletal muscle mass and strength, a condition generally known as sarcopenia. Moreover, several studies have highlighted how the age-related alteration of reactive oxygen species (ROS) homeostasis can contribute to changes in the neuromuscular junction morphology and stability, leading to the reduction in fiber number and innervation. Increasing evidence supports the involvement of epigenetic modifications in age-dependent alterations of the NMJ. In particular, DNA methylation, histone modifications, and miRNA-dependent gene expression represent the major epigenetic mechanisms that play a crucial role in NMJ remodeling. It is established that environmental and lifestyle factors, such as physical exercise and nutrition that are susceptible to change during aging, can modulate epigenetic phenomena and attenuate the age-related NMJs changes. This review aims to highlight the recent epigenetic findings related to the NMJ dysregulation during aging and the role of physical activity and nutrition as possible interventions to attenuate or delay the age-related decline in the neuromuscular system.

Immunohistochemical Analysis of DNA Repair- and Drug-Efflux-Associated Molecules in Tumor and Peritumor Areas of Glioblastoma.

Glioblastoma (GBM), the most commonly occurring primary tumor arising within the central nervous system, is characterized by high invasiveness and poor prognosis. In spite of the improvement in surgical techniques, along with the administration of chemo- and radiation therapy and the incessant investigation in search of prospective therapeutic targets, the local recurrence that frequently occurs within the peritumoral brain tissue makes GBM the most malignant and terminal type of astrocytoma. In the current study, we investigated both GBM and peritumoral tissues obtained from 55 hospitalized patients and the expression of three molecules involved in the onset of resistance/unresponsiveness to chemotherapy: O6-methylguanine methyltransferase (MGMT), breast cancer resistance protein (BCRP1), and A2B5. We propose that the expression of these molecules in the peritumoral tissue might be crucial to promoting the development of early tumorigenic events in the tissue surrounding GBM as well as responsible for the recurrence originating in this apparently normal area and, accordingly, for the resistance to treatment with the standard chemotherapeutic regimen. Notably, the inverse correlation found between MGMT expression in peritumoral tissue and patients' survival suggests a prognostic role for this protein.

Taurine Attenuates Catabolic Processes Related to the Onset of Sarcopenia.

Sarcopenia that occurs with advancing age is characterized by a gradual loss of muscle protein component due to the activation of catabolic pathways, increased level of inflammation, and mitochondrial dysfunction. Experimental evidence demonstrates that several physio-pathological processes involved in the onset of sarcopenia may be counteracted by the intake of specific amino acids or antioxidant molecules, suggesting that diet may represent an effective strategy for improving the anabolic response of muscle during aging. The non-essential amino acid taurine is highly expressed in several mammalian tissues, including skeletal muscle where it is involved in the ion channel regulation, in the modulation of intracellular calcium concentration, and where it plays an important role as an antioxidant and anti-inflammatory factor. Here, with the purpose to reproduce the chronic low-grade inflammation characteristics of senescent muscle in an in vitro system, we exploited the role of Tumor Necrosis Factor α (TNF) and we analyzed the effect of taurine in the modulation of different signaling pathways known to be dysregulated in sarcopenia. We demonstrated that the administration of high levels of taurine in myogenic L6 cells stimulates the differentiation process by downregulating the expression of molecules involved in inflammatory pathways and modulating processes such as autophagy and apoptosis. Although further studies are currently ongoing in our laboratory to better elucidate the molecular mechanisms responsible for the positive effect of taurine on myogenic differentiation, this study suggests that taurine supplementation may represent a strategy to delay the loss of mass and functionality characteristic of senescent muscles.

Nutrition and microRNAs: Novel Insights to Fight Sarcopenia.

Sarcopenia is a progressive age-related loss of skeletal muscle mass and strength, which may result in increased physical frailty and a higher risk of adverse events. Low-grade systemic inflammation, loss of muscle protein homeostasis, mitochondrial dysfunction, and reduced number and function of satellite cells seem to be the key points for the induction of muscle wasting, contributing to the pathophysiological mechanisms of sarcopenia. While a range of genetic, hormonal, and environmental factors has been reported to contribute to the onset of sarcopenia, dietary interventions targeting protein or antioxidant intake may have a positive effect in increasing muscle mass and strength, regulating protein homeostasis, oxidative reaction, and cell autophagy, thus providing a cellular lifespan extension. MicroRNAs (miRNAs) are endogenous small non-coding RNAs, which control gene expression in different tissues. In skeletal muscle, a range of miRNAs, named myomiRNAs, are involved in many physiological processes, such as growth, development, and maintenance of muscle mass and function. This review aims to present and to discuss some of the most relevant molecular mechanisms related to the pathophysiological effect of sarcopenia. Besides, we explored the role of nutrition as a possible way to counteract the loss of muscle mass and function associated with ageing, with special attention paid to nutrient-dependent miRNAs regulation. This review will provide important information to better understand sarcopenia and, thus, to facilitate research and therapeutic strategies to counteract the pathophysiological effect of ageing.

Inhibition of Phosphoinositide 3-Kinase/Protein Kinase B Signaling Hampers the Vasopressin-dependent Stimulation of Myogenic Differentiation.

Arginine-vasopressin (AVP) promotes muscle differentiation, hypertrophy, and regeneration through the combined activation of the calcineurin and Calcium/Calmodulin-dependent Protein Kinase (CaMK) pathways. The AVP system is impaired in several neuromuscular diseases, suggesting that AVP may act as a physiological factor in skeletal muscle. Since the Phosphoinositide 3-kinases/Protein Kinase B/mammalian Target Of Rapamycin (PI3K/Akt/mTOR) signaling plays a significant role in regulating muscle mass, we evaluated its role in the AVP myogenic effect. In L6 cells AKT1 expression was knocked down, and the AVP-dependent expression of mTOR and Forkhead box O3 (FoxO) was analyzed by Western blotting. The effect of the PI3K inhibitor LY294002 was evaluated by cellular and molecular techniques. Akt knockdown hampered the AVP-dependent mTOR expression while increased the levels of FoxO transcription factor. LY294002 treatment inhibited the AVP-dependent expression of Myocyte Enhancer Factor-2 (MEF2) and myogenin and prevented the nuclear translocation of MEF2. LY294002 also repressed the AVP-dependent nuclear export of histone deacetylase 4 (HDAC4) interfering with the formation of multifactorial complexes on the myogenin promoter. We demonstrate that the PI3K/Akt pathway is essential for the full myogenic effect of AVP and that, by targeting this pathway, one may highlight novel strategies to counteract muscle wasting in aging or neuromuscular disorders.

Multifaceted Functional Role of Semaphorins in Glioblastoma.

Glioblastoma (GBM) is the most malignant tumor type affecting the adult central nervous system. Despite advances in therapy, the prognosis for patients with GBM remains poor, with a median survival of about 15 months. To date, few treatment options are available and recent trials based on the molecular targeting of some of the GBM hallmark pathways (e.g., angiogenesis) have not produced any significant improvement in overall survival. The urgent need to develop more efficacious targeted therapies has led to a better molecular characterization of GBM, revealing an emerging role of semaphorins in GBM progression. Semphorins are a wide group of membrane-bound and secreted proteins, originally identified as axon guidance cues, signaling through their receptors, neuropilins, and plexins. A number of semaphorin signals involved in the control of axonal growth and navigation during development have been found to furthermore participate in crosstalk with different dysfunctional GBM pathways, controlling tumor cell proliferation, migration, and invasion, as well as tumor angiogenesis or immune response. In this review, we summarize the regulatory activities mediated by semaphorins and their receptors on the oncogenic pathways implicated in GBM growth and invasive/metastatic progression.

Pathological and Molecular Features of Glioblastoma and Its Peritumoral Tissue.

Glioblastoma (GBM) is one of the most aggressive and lethal human brain tumors. At present, GBMs are divided in primary and secondary on the basis of the mutational status of the isocitrate dehydrogenase (IDH) genes. In addition, IDH1 and IDH2 mutations are considered crucial to better define the prognosis. Although primary and secondary GBMs are histologically indistinguishable, they retain distinct genetic alterations that account for different evolution of the tumor. The high invasiveness, the propensity to disperse throughout the brain parenchyma, and the elevated vascularity make these tumors extremely recidivist, resulting in a short patient median survival even after surgical resection and chemoradiotherapy. Furthermore, GBM is considered an immunologically cold tumor. Several studies highlight a highly immunosuppressive tumor microenvironment that promotes recurrence and poor prognosis. Deeper insight into the tumor immune microenvironment, together with the recent discovery of a conventional lymphatic system in the central nervous system (CNS), led to new immunotherapeutic strategies. In the last two decades, experimental evidence from different groups proved the existence of cancer stem cells (CSCs), also known as tumor-initiating cells, that may play an active role in tumor development and progression. Recent findings also indicated the presence of highly infiltrative CSCs in the peritumoral region of GBM. This region appears to play a key role in tumor growing and recurrence. However, until recently, few studies investigated the biomolecular characteristics of the peritumoral tissue. The aim of this review is to recapitulate the pathological features of GBM and of the peritumoral region associated with progression and recurrence.

Levetiracetam enhances the temozolomide effect on glioblastoma stem cell proliferation and apoptosis.

BACKGROUND: Glioblastoma multiforme (GBM) is a highly aggressive brain tumor in which cancer cells with stem cell-like features, called cancer stem cells (CSCs), were identified. Two CSC populations have been previously identified in GBM, one derived from the GBM area called enhanced lesion (GCSCs) and the other one from the brain area adjacent to the tumor margin (PCSCs) that greatly differ in their growth properties and tumor-initiating ability. To date the most effective chemotherapy to treat GBM is represented by alkylating agents such as temozolomide (TMZ), whose activity can be regulated by histone deacetylases (HDACs) inhibitors through the modulation of O6-methylguanine-DNA methyltransferase (MGMT) expression. Levetiracetam (LEV), a relatively new antiepileptic drug, modulates HDAC levels ultimately silencing MGMT, thus increasing TMZ effectiveness. However, an improvement in the therapeutic efficacy of TMZ is needed. METHODS: Cell proliferation was investigated by BrdU cell proliferation assay and by Western Blot analysis of PCNA expression. Apoptosis was evaluated by Western Blot and Immunofluorescence analysis of the cleaved Caspase-3 expression. MGMT and HDAC4 expression was analyzed by Western Blotting and Immunofluorescence. Statistical analysis was performed using the Student's t test and Mann-Whitney test. RESULTS: Here we evaluated the effect of TMZ on the proliferation rate of the IDH-wildtype GCSCs and PCSCs derived from six patients, in comparison with the effects of other drugs such as etoposide, irinotecan and carboplatin. Our results demonstrated that TMZ was less effective compared to the other agents; hence, we verified the possibility to increase the effect of TMZ by combining it with LEV. Here we show that LEV enhances the effect of TMZ on GCSCs proliferation (being less effective on PCSCs) by decreasing MGMT expression, promoting HDAC4 nuclear translocation and activating apoptotic pathway. CONCLUSIONS: Although further studies are needed to determine the exact mechanism by which LEV makes GBM stem cells more  sensitive to TMZ, these results suggest that the clinical therapeutic efficacy of TMZ in GBM might be enhanced by the combined treatment with LEV.

Molecular Insights into Muscle Homeostasis, Atrophy and Wasting.

Muscle homeostasis is guaranteed by a delicate balance between synthesis and degradation of cell proteins and its alteration leads to muscle wasting and diseases. In this review, we describe the major anabolic pathways that are involved in muscle growth and homeostasis and the proteolytic systems that are over-activated in muscle pathologies. Modulation of these pathways comprises an attractive target for drug intervention.

Cancer stem cells from peritumoral tissue of glioblastoma multiforme: the possible missing link between tumor development and progression.

In glioblastoma multiforme (GBM), cancer stem cells (CSCs) are thought to be responsible for gliomagenesis, resistance to treatment and recurrence. Unfortunately, the prognosis for GBM remains poor and recurrence frequently occurs in the peritumoral tissue within 2 cm from the tumor edge. In this area, a population of CSCs has been demonstrated which may recapitulate the tumor after surgical resection. In the present study, we aimed to characterize CSCs derived from both peritumoral tissue (PCSCs) and GBM (GCSCs) in order to deepen their significance in GBM development and progression. The stemness of PCSC/GCSC pairs obtained from four human GBM surgical specimens was investigated by comparing the expression of specific stem cell markers such as Nestin, Musashi-1 and SOX2. In addition, the growth rate, the ultrastructural features and the expression of other molecules such as c-Met, pMet and MAP kinases, involved in cell migration/invasion, maintenance of tumor stemness and/or resistance to treatments were evaluated. Since it has been recently demonstrated the involvement of the long non-coding RNAs (lncRNAs) in the progression of gliomas, the expression of H19 lncRNA, as well as of one of its two mature products miR-675-5p was evaluated in neurospheres. Our results show significant differences between GCSCs and PCSCs in terms of proliferation, ultrastructural peculiarities and, at a lower extent, stemness profile. These differences might be important in view of their potential role as a therapeutic target.

Pivotal role of human stearoyl-CoA desaturases (SCD1 and 5) in breast cancer progression: oleic acid-based effect of SCD1 on cell migration and a novel pro-cell survival role for SCD5.

The influence of cell membrane fluidity on cancer progression has been established in different solid tumors. We previously reported that "cancer-associated fibroblasts" (CAFs) induced epithelial-mesenchymal transition and increased cell membrane fluidity and migration in poorly (MCF-7) and highly invasive (MDA-MB-231) breast cancer cells. We also found that the membrane fluidity regulating enzyme stearoyl-CoA desaturase 1 (SCD1) was upregulated in tumor cells co-cultured with CAFs and established its essential role for both intrinsic and CAF-driven tumor cell motility. Here, we further explored the mechanisms involved in the SCD1-based modulation of breast cancer cell migration and investigated the role of the other human SCD isoform, SCD5. We showed that the addition of oleic acid, the main SCD1 product, nullified the inhibitory effects produced on MCF-7 and MDA-MB-231 cell migration by SCD1 depletion (pharmacological or siRNA-based). Conversely, SCD5 seemed not involved in the regulation of cancer cell motility. Interestingly, a clear induction of necrosis was observed as a result of the depletion of SCD5 in MCF-7 cells, where the expression of SCD5 was found to be upregulated by CAFs. The necrotic effect was rescued by a 48-h treatment of cells with oleic acid. These results provide further insights in understanding the role of SCD1 in both intrinsic and CAF-stimulated mammary tumor cell migration, unveiling the metabolic basis of this desaturase-triggered effect. Moreover, our data suggest the ability of CAFs to promote the maintenance of tumor cell survival by the induction of SCD5 levels.

Characterization of inflammatory cell infiltrate of scleroderma skin: B cells and skin score progression.

BACKGROUND: The purpose of this study was to investigate the frequency and the distribution of inflammatory cell infiltrate in two sets of cutaneous biopsies derived from clinically affected and unaffected skin in patients with systemic sclerosis (SSc) and to test correlation between the cell infiltrate and the progression of skin involvement. METHODS: Skin was immunohistochemically assessed to identify CD68, CD3, CD20 and CD138-positive (+) cells in clinically affected and unaffected skin in 28 patients with SSc. Patients were followed for 6 months and the characteristics of the infiltrate were analyzed according to disease duration, clinical features and skin involvement progression. RESULTS: In all SSc cutaneous specimens, cellular infiltrates were found in a perivascular location predominantly in the mid and deeper portions of the dermis. All the analyzed biopsies showed a CD3+ and CD68+ cell infiltrate and the mean number of CD3+ and of CD68+ cells was higher in clinically involved skin (CD3+, 71.7 ± 34.6 and CD68+, 26.3 ± 8.4, respectively) than in clinically uninvolved skin (CD3+, 45.7 ± 36.0 and CD68+, 13.6 ± 6.1, respectively) (p < 0.001 for both comparisons). CD20+ cells were found in 17 (60.7%) patients and in these patients the mean number of CD20+ cells was higher in clinically involved (4.7 ± 5.9) than in uninvolved skin (1.9 ± 2.9), (p = 0.04). There was a greater number of CD20+ cells in patients with early SSc compared with patients with long-standing disease. CD138+ cells were found in 100% of biopsies of clinically involved skin and in 89.3% of biopsies of uninvolved skin. The mean number of CD138+ cells was higher in clinically involved skin (3.6 ± 2.3) than in clinically uninvolved skin (1.9 ± 1.7), (p < 0.001). Seven patients experienced more than 20% worsening in the skin score after 6 months of follow up; all of them had a CD20+ skin infiltrate on biopsy of clinically involved skin. CONCLUSIONS: Our results confirm that mononuclear cells are present in the skin of all patients with SSc, underlining the role of inflammatory cell infiltrates in skin involvement in SSc. B cells in the skin seem to characterize patients with early diffuse skin disease and to correlate with skin progression.

The caveolar membrane system in endothelium: From cell signaling to vascular pathology.

Caveolae are 50- to 100-nm cholesterol and glycosphingolipid-rich flask-shaped invaginations commonly observed in many terminally differentiated cells. These organelles have been described in many cell types and are particularly abundant in endothelial cells, where they have been involved in the regulation of certain signaling pathways. Specific scaffolding proteins termed caveolins, along with the more recently discovered members of the cavin family, represent the major protein components during caveolae biogenesis. In addition, multiple studies aimed to investigate the expression and the regulation of these proteins significantly contributed to elucidate the role of caveolae and caveolins in endothelial cell physiology and disease. The aim of this review is to survey recent evidence of the involvement of the caveolar network in endothelial cell biology and endothelial cell dysfunction.

The Beneficial Effects of Taurine to Counteract Sarcopenia.

Aging is a multifactorial process characterized by several features including low-grade inflammation, increased oxidative stress and reduced regenerative capacity, which ultimately lead to alteration in morpho-functional properties of skeletal muscle, thus promoting sarcopenia. This condition is characterized by a gradual loss of muscle mass due to an unbalance between protein synthesis and degradation, finally conveying in functional decline and disability. The development of specific therapeutic approaches able to block or reverse this condition may represent an invaluable tool for the promotion of a healthy aging among elderly people. It is well established that changes in the quantity and the quality of dietary proteins, as well as the intake of specific amino acids, are able to counteract some of the physiopathological processes related to the progression of the loss of muscle mass and may have beneficial effects in improving the anabolic response of muscle in the elderly. Taurine is a non-essential amino acid expressed in high concentration in several mammalian tissues and particularly in skeletal muscle where it is involved in the modulation of intracellular calcium concentration and ion channel regulation and where it also acts as an antioxidant and anti-inflammatory factor. The aim of this review is to summarize the pleiotropic effects of taurine on specific muscle targets and to discuss its role in regulating signaling pathways involved in the maintenance of muscle homeostasis. We also highlight the potential use of taurine as a therapeutic molecule for the amelioration of skeletal muscle function and performance severely compromised during aging.

The physiopathologic role of oxidative stress in skeletal muscle.

Muscle senescence is a complex mechanism that is usually associated with a decrease in mass, strength and velocity of contraction. This state, known as sarcopenia, is a multifactorial process and it may be the consequence of several events, including accumulation of oxidative stress. The role of oxidative stress in the physiopathology of skeletal muscle is quite complex. Transiently increased levels of oxidative stress might reflect a potentially health promoting process, while an uncontrolled accumulation might have pathological implication. The physiopathological role of oxidative stress on skeletal muscle, its involvement in aging-induced sarcopenia, and potential countermeasures will be discussed.

Evaluation of the effect of a floxed Neo cassette within the dystroglycan (Dag1) gene.

OBJECTIVE: Dystroglycan (DG) is an adhesion complex formed by two subunits, α-DG and ß-DG. In skeletal muscle, DG is part of the dystrophin-glycoprotein complex that is crucial for sarcolemma stability and it is involved in a plethora of muscular dystrophy phenotypes. Due to the important role played by DG in skeletal muscle stability as well as in a wide variety of other tissues including brain and the peripheral nervous system, it is essential to investigate its genetic assembly and transcriptional regulation. RESULTS: Herein, we analyze the effect of the insertion of a floxed neomycin (Neo) cassette within the 3' portion of the universally conserved IG1-intron of the DG gene (Dag1). We analyzed the transcription level of Dag1 and the expression of the DG protein in skeletal muscle of targeted mice compared to wild-type and we did not find any alterations that might be attributed to the gene targeting. However, we found an increase of the cross-sectional areas of tibialis anterior that might have some physiological significance that needs to be assessed in the future. Moreover, in targeted mice the skeletal muscle morphology and its regeneration capacity after injury did not show any evident alterations. We confirmed that the targeting of Dag1 with a floxed Neo-cassette did not produce any gross undesired effects.

Analysis of angiogenesis related factors in glioblastoma, peritumoral tissue and their derived cancer stem cells.

The formation of new blood vessels represents a crucial event under both physiological and pathological circumstances. In this study, we evaluated by immunohistochemistry, and/or Western blotting and/or quantitative real time-PCR the expression of HIF1α, HIF2α, VEGF, VEGFR1 and VEGFR2 in surgical glioblastoma multiforme (GBM) and peritumoral tissue samples obtained from 50 patients as well as in cancer stem cells (CSCs) isolated from GBM (GCSCs) and peritumoral tissue (PCSCs) of 5 patients. We also investigated the contribution of both GCSCs and PCSCs on the behavior of endothelial cells (ECs) in vitro. Immunohistochemistry demonstrated the expression of angiogenesis markers in both GBM and peritumoral tissue. In addition, in vitro tube formation assay indicated that both GCSCs and PCSCs stimulate EC proliferation as well as tube-like vessel formation. An increased migration aptitude was mainly observed when ECs were cultured in the presence of GCSCs rather than in the presence of PCSCs. These findings suggest that relevant neoangiogenetic events may occur in GBM. In particular, VEGF/VEGFR co-expression in PCSCs leads to hypothesize the involvement of an autocrine signaling. Moreover, our results suggest that both GCSCs and PCSCs own the skill of activating the "angiogenic switch" and the capability of modulating EC behavior, indicating that both cell types are either responsive to angiogenic stimuli or able to trigger angiogenic response. Together with our previous findings, this study adds a further piece to the challenging puzzle of the characterization of peritumoral tissue and of the definition of its real role in GBM pathophysiology.