Aspirin inhibits cancer stem cells properties and growth of glioblastoma multiforme through Rb1 pathway modulation.

Several clinical studies indicated that the daily use of aspirin or acetylsalicylic acid reduces the cancer risk via cyclooxygenases (Cox-1 and Cox-2) inhibition. In addition, aspirin-induced Cox-dependent and -independent antitumor effects have also been described. Here we report, for the first time, that aspirin treatment of human glioblastoma cancer (GBM) stem cells, a small population responsible for tumor progression and recurrence, is associated with reduced cell proliferation and motility. Aspirin did not interfere with cell viability but induced cell-cycle arrest. Exogenous prostaglandin E2 significantly increased cell proliferation but did not abrogate the aspirin-mediated growth inhibition, suggesting a Cox-independent mechanism. These effects appear to be mediated by the increase of p21 waf1 and p27 Kip1 , associated with a reduction of Cyclin D1 and Rb1 protein phosphorylation, and involve the downregulation of key molecules responsible for tumor development, that is, Notch1, Sox2, Stat3, and Survivin. Our results support a possible role of aspirin as adjunctive therapy in the clinical management of GBM patients.

Differentiation of human olfactory bulb-derived neural stem cells toward oligodendrocyte.

In the central nervous system (CNS), oligodendrocytes are the glial element in charge of myelin formation. Obtaining an overall presence of oligodendrocyte precursor cells/oligodendrocytes (OPCs/OLs) in culture from different sources of NSCs is an important research area, because OPCs/OLs may provide a promising therapeutic strategy for diseases affecting myelination of axons. The present study was designed to differentiate human olfactory bulb NSCs (OBNSCs) into OPCs/OLs and using expression profiling (RT-qPCR) gene, immunocytochemistry, and specific protein expression to highlight molecular mechanism(s) underlying differentiation of human OBNSCs into OPCs/OLs. The differentiation of OBNSCs was characterized by a simultaneous appearance of neurons and glial cells. The differentiation medium, containing cAMP, PDGFA, T3, and all-trans-retinoic acid (ATRA), promotes OBNSCs to generate mostly oligodendrocytes (OLs) displaying morphological changes, and appearance of long cytoplasmic processes. OBNSCs showed, after 5 days in OLs differentiation medium, a considerable decrease in the number of nestin positive cells, which was associated with a concomitant increase of NG2 immunoreactive cells and few O4(+)-OPCs. In addition, a significant up regulation in gene and protein expression profile of stage specific cell markers for OPCs/OLs (CNPase, Galc, NG2, MOG, OLIG1, OLIG2, MBP), neurons, and astrocytes (MAP2, ß-TubulinIII, GFAP) and concomitant decrease of OBNSCs pluripotency markers (Oct4, Sox2, Nestin), was demonstrated following induction of OBNSCs differentiation. Taken together, the present study demonstrate the marked ability of a cocktail of factors containing PDGFA, T3, cAMP, and ATRA, to induce OBNSCs differentiation into OPCs/OLs and shed light on the key genes and pathological pathways involved in this process.

Wharton's jelly mesenchymal stromal cells have contrasting effects on proliferation and phenotype of cancer stem cells from different subtypes of lung cancer.

Studies on the role of multipotent mesenchymal stromal cells (MSC) on tumor growth have reported both a tumor promoting and a suppressive effect. The aim of the present study was to determine the effect of MSC isolated from Wharton's jelly of umbilical cord (WJMSC) on lung cancer stem cells (LCSC) derived from human lung tumors: two adenocarcinomas (AC) and two squamous cell carcinomas (SCC). LCSC derived from SCC and AC expressed, to varying extents, the more relevant stem cell markers. The effect of WJMSC on LCSC was investigated in vitro using conditioned medium (WJ-CM): a proliferation increase in AC-LCSC was observed, with an increase in the ALDH+ and in the CD133+ cell population. By contrast, WJ-CM hampered the growth of SCC-LCSC, with an increase in the pre-G1 phase indicating the induction of apoptosis. Furthermore, the ALDH+ and CD133+ population was also reduced. In vivo, subcutaneous co-transplantation of AC-LCSC/WJMSC generated larger tumors than AC-LCSC alone, characterized by an increased percentage of CD133+ and CD166+ cells. By contrast, co-transplantation of WJMSC and SCC-LCSC did not affect the tumor size. Our results strongly suggest that WJMSC exert, both in vitro and in vivo, contrasting effects on LCSC derived from different lung tumor subtypes.

Human olfactory bulb neural stem cells mitigate movement disorders in a rat model of Parkinson's disease.

Parkinson's disease (PD) is a neurological disorder characterized by the loss of midbrain dopaminergic (DA) neurons. Neural stem cells (NSCs) are multipotent stem cells that are capable of differentiating into different neuronal and glial elements. The production of DA neurons from NSCs could potentially alleviate behavioral deficits in Parkinsonian patients; timely intervention with NSCs might provide a therapeutic strategy for PD. We have isolated and generated highly enriched cultures of neural stem/progenitor cells from the human olfactory bulb (OB). If NSCs can be obtained from OB, it would alleviate ethical concerns associated with the use of embryonic tissue, and provide an easily accessible cell source that would preclude the need for invasive brain surgery. Following isolation and culture, olfactory bulb neural stem cells (OBNSCs) were genetically engineered to express hNGF and GFP. The hNFG-GFP-OBNSCs were transplanted into the striatum of 6-hydroxydopamin (6-OHDA) Parkinsonian rats. The grafted cells survived in the lesion environment for more than eight weeks after implantation with no tumor formation. The grafted cells differentiated in vivo into oligodendrocyte-like (25 ± 2.88%), neuron-like (52.63 ± 4.16%), and astrocyte -like (22.36 ± 1.56%) lineages, which we differentiated based on morphological and immunohistochemical criteria. Transplanted rats exhibited a significant partial correction in stepping and placing in non-pharmacological behavioral tests, pole and rotarod tests. Taken together, our data encourage further investigations of the possible use of OBNSCs as a promising cell-based therapeutic strategy for Parkinson's disease.

Human olfactory bulb neural stem cells expressing hNGF restore cognitive deficit in Alzheimer's disease rat model.

In this study, we aim to demonstrate the fate of allogenic adult human olfactory bulb neural stem/progenitor cells (OBNSC/NPCs) transplanted into the rat hippocampus treated with ibotenic acid (IBO), a neurotoxicant specific to hippocampal cholinergic neurons that are lost in Alzheimer's disease. We assessed their possible ability to survive, integrate, proliferate, and differentiate into different neuronal and glial elements: we also evaluate their possible therapeutic potential, and the mechanism(s) relevant to neuroprotection following their engraftment into the CNS milieu. OBNSC/NPCs were isolated from adult human olfactory bulb patients, genetically engineered to express GFP and human nerve growth factor (hNGF) by lentivirus-mediated infection, and stereotaxically transplanted into the hippocampus of IBO-treated animals and controls. Stereological analysis of engrafted OBNSCs eight weeks post transplantation revealed a 1.89 fold increase with respect to the initial cell population, indicating a marked ability for survival and proliferation. In addition, 54.71 ± 11.38%, 30.18 ± 6.00%, and 15.09 ± 5.38% of engrafted OBNSCs were identified by morphological criteria suggestive of mature neurons, oligodendrocytes and astrocytes respectively. Taken together, this work demonstrated that human OBNSCs expressing NGF ameliorate the cognitive deficiencies associated with IBO-induced lesions in AD model rats, and the improvement can probably be attributed primarily to neuronal and glial cell replacement as well as the trophic influence exerted by the secreted NGF.

Induction of dopaminergic neurons from human Wharton's jelly mesenchymal stem cell by forskolin.

The purpose of this study was to investigate the Wharton's jelly mesenchymal stem cells differentiation ability toward neuronal fate. Human Wharton's jelly mesenchymal stem cells (hWJMSC) have been isolated from human umbilical cord of full-term births and characterized by flow cytometry analysis for their stem mesenchymal properties through specific surface markers expression (CD73, CD90, and CD105). hWJMSC mesodermal lineage differentiation ability and karyotype analysis were assessed. The trans-differentiation of hWJMSC into neural lineage was investigated in presence of forskolin, an agent known to increase the intracellular levels of cAMP. A molecular profile of differentiated hWJMSC was performed by microarray technology which revealed 1,532 statistically significant modulated genes respect to control cells. Most of these genes are mainly involved in functional neuronal signaling pathways and part of them are specifically required for the neuronal dopaminergic induction. The acquisition of the dopaminergic phenotype was evaluated via immunocytochemistry and Western blot analysis revealed the significant induction of Nurr1, NeuroD1, and TH proteins expression in forskolin-induced hWJMSC. Moreover, the treatment with forskolin promoted, in hWJMSC, a strong upregulation of the neurotrophin Trk receptors related to the high release of brain-derived neurotrophic factor. Taken together these findings show that hWJMSC may be represent an optimal therapeutic strategy for neurological diseases.

PDGF receptor alpha inhibition induces apoptosis in glioblastoma cancer stem cells refractory to anti-Notch and anti-EGFR treatment.

BACKGROUND: Cancer stem cells (CSC) represent a rare fraction of cancer cells characterized by resistance to chemotherapy and radiation, therefore nowadays there is great need to develop new targeted therapies for brain tumors and our study aim to target pivotal transmembrane receptors such as Notch, EGFR and PDGFR, which are already under investigation in clinical trials setting for the treatment of Glioblastoma Multiforme (GBM). METHODS: MTS assay was performed to evaluate cells response to pharmacological treatments. Quantitative RT-PCR and Western blots were performed to state the expression of Notch1, EGFR and PDGFRα/ß and the biological effects exerted by either single or combined targeted therapy in GBM CSC. GBM CSC invasive ability was tested in vitro in absence or presence of Notch and/or EGFR signaling inhibitors. RESULTS: In this study, we investigated gene expression and function of Notch1, EGFR and PDGFR to determine their role among GBM tumor core- (c-CSC) vs. peritumor tissue-derived cancer stem cells (p-CSC) of six cases of GBM. Notch inhibition significantly impaired cell growth of c-CSC compared to p-CSC pools, with no effects observed in cell cycle distribution, apoptosis and cell invasion assays. Instead, anti-EGFR therapy induced cell cycle arrest, sometimes associated with apoptosis and reduction of cell invasiveness in GBM CSC. In two cases, c-CSC pools were more sensitive to simultaneous anti-Notch and anti-EGFR treatment than either therapy alone compared to p-CSC, which were mostly resistant to treatment. We reported the overexpression of PDGFRα and its up-regulation following anti-EGFR therapy in GBM p-CSC compared to c-CSC. RNA interference of PDGFRα significantly reduced cell proliferation rate of p-CSC, while its pharmacological inhibition with Crenolanib impaired survival of both CSC pools, whose effects in combination with EGFR inhibition were maximized. CONCLUSIONS: We have used different drugs combination to identify the more effective therapeutic targets for GBM CSC, particularly against GBM peritumor tissue-derived CSC, which are mostly resistant to treatments. Overall, our results provide the rationale for simultaneous targeting of EGFR and PDGFR, which would be beneficial in the treatment of GBM.

Growing role of S100B protein as a putative therapeutic target for neurological- and nonneurological-disorders.

S100B is a calcium-binding protein mainly expressed by astrocytes, but also localized in other definite neural and extra-neural cell types. While its presence in biological fluids is widely recognized as a reliable biomarker of active injury, growing evidence now indicates that high levels of S100B are suggestive of pathogenic processes in different neural, but also extra-neural, disorders. Indeed, modulation of S100B levels correlates with the occurrence of clinical and/or toxic parameters in experimental models of diseases such as Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, muscular dystrophy, multiple sclerosis, acute neural injury, inflammatory bowel disease, uveal and retinal disorders, obesity, diabetes and cancer, thus directly linking the levels of S100B to pathogenic mechanisms. In general, deletion/inactivation of the protein causes the improvement of the disease, whereas its over-expression/administration induces a worse clinical presentation. This scenario reasonably proposes S100B as a common therapeutic target for several different disorders, also offering new clues to individuate possible unexpected connections among these diseases.

Neural stem cells modified to express BDNF antagonize trimethyltin-induced neurotoxicity through PI3K/Akt and MAP kinase pathways.

In vitro expansion of neural stem cells (NSC) lentivirally transduced with human BDNF may serve as better cellular source for replacing degenerating neurons in disease, trauma and toxic insults. In this study, we evaluate the functional role of forced BDNF expression by means of NSC (M3GFP-BDNF) obtained from cerebral cortex of 1-day-old mice respect to NSC-control (M3GFP). We find that M3GFP-BDNF induced to differentiate significantly accumulate BDNF and undergone to high potassium-mediated depolarization, show rapid BDNF recycle and activation of Trk receptors signaling. Differentiated M3GFP-BDNF exhibit neurons and oligodendrocytes with extended processes although quantitative analyses of NSC-derived cell lineages show none statistical significance between both cell populations. Moreover, those cells show a significant induction of neuronal and oligodendroglial markers by RT-PCR and Western blot respect to M3GFP, such as betaIII-Tubulin, microtubule associated protein 2 (MAP2), neurofilaments heavy (NF-H), oligodendroglial myelin glycoprotein (OMG) and some molecules involved in glutamatergic synapse maturation, such as receptors tyrosine kinases (TRKs), post-synaptic density (PSD-95) and N-methyl-D-aspartate receptors 2 A/B (NMDA2A/B). After treatment with the neurotoxicant trimethyltin (TMT), differentiated M3GFP-BDNF exhibit an attenuation of cellular damage which correlates with a significant activation of MAPK and PI3K/Akt signaling and delayed activation of death signals, while on M3GFP, TMT induces a significant reduction of cell survival, neuronal differentiation and concomitant earlier activation of cleaved caspase-3. We demonstrate that overexpression of BDNF firmly regulate cell survival and differentiation of NSC and protects differentiated NSC against TMT-induced neurotoxicity through the PI3K/Akt and MAPK signaling pathways.

The S100B Inhibitor Pentamidine Ameliorates Clinical Score and Neuropathology of Relapsing-Remitting Multiple Sclerosis Mouse Model.

S100B is an astrocytic protein acting either as an intracellular regulator or an extracellular signaling molecule. A direct correlation between increased amount of S100B and demyelination and inflammatory processes has been demonstrated. The aim of this study is to investigate the possible role of a small molecule able to bind and inhibit S100B, pentamidine, in the modulation of disease progression in the relapsing-remitting experimental autoimmune encephalomyelitis mouse model of multiple sclerosis. By the daily evaluation of clinical scores and neuropathologic-molecular analysis performed in the central nervous system, we observed that pentamidine is able to delay the acute phase of the disease and to inhibit remission, resulting in an amelioration of clinical score when compared with untreated relapsing-remitting experimental autoimmune encephalomyelitis mice. Moreover, we observed a significant reduction of proinflammatory cytokines expression levels in the brains of treated versus untreated mice, in addition to a reduction of nitric oxide synthase activity. Immunohistochemistry confirmed that the inhibition of S100B was able to modify the neuropathology of the disease, reducing immune infiltrates and partially protecting the brain from the damage. Overall, our results indicate that pentamidine targeting the S100B protein is a novel potential drug to be considered for multiple sclerosis treatment.

Human Olfactory Bulb Neural Stem Cells (Hu-OBNSCs) Can Be Loaded with Paclitaxel and Used to Inhibit Glioblastoma Cell Growth.

Exploitation of the potential ability of human olfactory bulb (hOB) cells to carry, release, and deliver an effective, targeted anticancer therapy within the central nervous system (CNS) milieu remains elusive. Previous studies have demonstrated the marked ability of several types of stem cells (such as mesenchymal stem cells (MSCs) to carry and release different anti-cancer agents such as paclitaxel (PTX). Herein we investigate the ability of human olfactory bulb neural stem cells (Hu-OBNSCs) to carry and release paclitaxel, producing effective cytotoxic effects against cancer cells. We isolated Hu-OBNSCs from the hOB, uploaded them with PTX, and studied their potential cytotoxic effects against cancer cells in vitro. Interestingly, the Hu-OBNSCs displayed a five-fold increase in their resistance to the cytotoxicity of PTX, and the PTX-uploaded Hu-OBNSCs were able to inhibit proliferation and invasion, and to trigger marked cytotoxic effects on glioblastoma multiforme (GBM) cancer cells, and Human Caucasian fetal pancreatic adenocarcinoma 1 (CFPAC-1) in vitro. Despite their ability to resist the cytotoxic activity of PTX, the mechanism by which Hu-OBNSCs acquire resistance to PTX is not yet explained. Collectively our data indicate the ability of the Hu-OBNSCs to resist PTX, and to trigger effective cytotoxic effects against GBM cancer cells and CFPAC-1. This indicates their potential to be used as a carrier/vehicle for targeted anti-cancer therapy within the CNS.

Identification and early characterization of genetically modified NGF-producing neural stem cells grafted into the injured adult rat brain.

OBJECTIVE: To investigate whether genetically modified mouse neural stem cells (NSC) expressing recombinant human nerve growth factor (rhNGF) and transplanted in chemically injured rat brain, can survive and eventually acquire phenotypic characteristics of early nerve cells. METHODS: Stably high expression of rhNGF in NSC was obtained by a new lentivirus-mediated expression system. To test the effectiveness of hNGF secreted by rhNGF-NSC, hereby we performed either a bioassay for neurite outgrowth in PC12 rat cells or immunoblot analysis for TrkA, the high-affinity NGF receptor, from engineered NSC. rhNGF and mock-NSC were grafted into adult injured rats striatum and 3 days later, animals were killed, and brains were removed and examined by immunohistochemical analysis. RESULTS: The results showed that rhNGF-producing NSC cultured for extended period of time release bioactive hNGF in the culture media which promotes PC12 neuronal differentiation and correlates with the up-regulation of TrkA. rhNGF-NSC transplanted into the injured brain can survive, produce hNGF and induce the expression of NGF receptors, p75(NTR) and TrkA. DISCUSSION: In vitro and in vivo experiments confirmed the ability of rhNGF-NSC to secrete bioactive hNGF. Our data provide by means of genetically modified rhNGF-producing NSC, a useful experimental tool to test the potential clinical effectiveness of trophic factors relevant to central nervous system (CNS).

The interference of Notch1 target Hes1 affects cell growth, differentiation and invasiveness of glioblastoma stem cells through modulation of multiple oncogenic targets.

The invasive and lethal nature of Glioblastoma multiforme (GBM) necessitates the continuous identification of molecular targets and search of efficacious therapies to inhibit GBM growth. The GBM resistance to chemotherapy and radiation it is attributed to the existence of a rare fraction of cancer stem cells (CSC) that we have identified within the tumor core and in peritumor tissue of GBM. Since Notch1 pathway is a potential therapeutic target in brain cancer, earlier we highlighted that pharmacological inhibition of Notch1 signalling by γ-secretase inhibitor-X (GSI-X), reduced cell growth of some c-CSC than to their respective p-CSC, but produced negligible effects on cell cycle distribution, apoptosis and cell invasion. In the current study, we assessed the effects of Hes1-targeted shRNA, a Notch1 gene target, specifically on GBM CSC refractory to GSI-X. Depletion of Hes1 protein induces major changes in cell morphology, cell growth rate and in the invasive ability of shHes1-CSC in response to growth factor EGF. shHes1-CSC show a decrease of the stemness marker Nestin concurrently to a marked increase of neuronal marker MAP2 compared to pLKO.1-CSC. Those effects correlated with repression of EGFR protein and modulation of Stat3 phosphorylation at Y705 and S727 residues. In the last decade Stat3 has gained attention as therapeutic target in cancer but there is not yet any approved Stat3-based glioma therapy. Herein, we report that exposure to a Stat3/5 inhibitor, induced apoptosis either in shHes1-CSC or control cells. Taken together, Hes1 seems to be a favorable target but not sufficient itself to target GBM efficaciously, therefore a possible pharmacological intervention should provide for the use of anti-Stat3/5 drugs either alone or in combination regimen.

In vitro analysis of mouse neural stem cells genetically modified to stably express human NGF by a novel multigenic viral expression system.

OBJECTIVES: The purpose of this study was to characterize mouse neural stem cells (NSC) transduced by a multigenic lentiviral vector (LV) and stably express recombinant human nerve growth factor (rhNGF). We obtained NSC-derived cell lines which express human NGF in relevant amount to exploit their ability for therapeutic applications. METHODS: We constructed advanced multigenic LV vectors which contain a tricistronic cassette to express simultaneously up to three independent genes: (1) rhNGF (beta subunit); (2) EGFP (enhanced green fluorescent protein) and (3) Neo(R) (neomycin antibiotic resistance gene). Lentiviruses were obtained by transfecting LV constructs plus helper plasmids in human embryonic kidney (HEK)-293T packaging cells. Lentiviral virions were released in culture media and subsequent used to infect mouse NSC. Genetycin 418-resistant NSC were obtained after 1 month of selection in the presence of antibiotic (G418). Levels of human NGF secreted by rhNGF-NSC were determined by ELISA (enzyme-linked immunosorbent assay). Features of multipotentiality of engineered NSC-derived cell lines versus naive cells (control-NSC) were assessed by immunocytochemical analysis in differentiation conditions. Self-renewal of NSC was tested by neurospheres assay (NSA). RESULTS: Levels of secreted human NGF, from conditioned media obtained by rhNGF-NSC cultures, were found to be elevated in either proliferation or differentiation conditions as compared with control cells. Moreover, released hNGF demonstrated biologic activity on PC12 cells by a functional test of neurite outgrowth. Immunocytochemical analysis revealed that engineered NSC showed to be all positives for EGFP. After thirty passages in vitro in the presence of G418, engineered cells versus naive NSC cultures maintained their multipotentiality to differentiate into neurons, astrocytes and oligodendrocytes. Furthermore, it was found that rhNGF-NSC-derived neurons expressed choline acetyltransferase (ChAT) and displayed an enhanced axonal growth. NSA showed an altered sphere forming frequency either in rhNGF-NSC or both group of control NSC. DISCUSSION: Lentivirus-mediated rhNGF gene transfer into NSC was achieved using a new version of LV vectors. We obtained rhNGF-NSC-derived cell lines which released hNGF to high levels in the culture medium. The expression of neural differentiation markers, like microtubule associated protein 2 (MAP2) (a/b), glial fibrillary acidic protein (GFAP) and chondroitin sulphate proteoglycan (NG2), was not enhanced in rhNGF-NSC compared with control cells. Secreted hNGF increased axonal sprouting by rhNGF-NSC-derived neurons which was associated with ChAT expression. rhNGF-NSC may prospectively be good candidates for the treatment of either neurodegenerative diseases such as Alzheimer disease or central nervous system injuries.

Influence of local environment on the differentiation of neural stem cells engrafted onto the injured spinal cord.

OBJECTIVES: In vitro, neural stem cells (NSCs) proliferate as undifferentiated spheroids and differentiate into neurons, astrocytes and oligodendrocytes. These features make NSCs suitable for spinal cord (SC) reconstruction. However, in vivo experiments have demonstrated that in the injured SC transplanted NSCs either remain undifferentiated or differentiate into the astrocytic phenotype. The microenvironment of the injured SC is believed to play a crucial role in driving the differentiation of the engrafted NSCs. Here, we tested the hypothesis that inflammatory cytokines (ICs) may be involved in the restricted differentiation of NSCs after grafting onto the injured SC. METHODS: As the first step, we used immunohistochemistry to analyse the expression of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and interferon (IFN)-gamma in the normal SC of mice and following traumatic injury. Then, we investigated whether a combination of TNF-alpha, IL-1beta and IFN-gamma may affect the phenotype of murine NSCs in vitro. RESULTS: We found that TNF-alpha, IL-1beta and IFN-gamma, which are absent in the normal SC, are all expressed in the injured SC and the expression of these cytokines follows a timely tuned fashion with IFN-gamma being detectable as long as 4 weeks after injury. In culture, exposure of proliferating NSCs to a combination of TNF-alpha, IL-1beta and IFN-gamma was per se sufficient to induce the astrocytic differentiation of these cells even in the absence of serum. CONCLUSIONS: In the traumatically injured SC, differentiation of engrafted NSCs is restricted towards the astrocytic lineage because of the inflammatory environment. ICs are likely to play a major role in differentiation of NSCs in the in vivo conditions.

Glioblastoma induces vascular endothelial cells to express telomerase in vitro.

Angiogenesis is essential for the growth of solid tumors. We have observed previously that the vascular endothelial cells of astrocytic brain tumors express human telomerase reverse transcriptase (hTERT) mRNA, suggesting a role for telomerase in the angiogenesis of these neoplasms. Here, we used an in vitro model to demonstrate that the telomerase machinery might be trans-activated in primary endothelial cells by glioblastoma tumor cells. We found that glioblastoma cells in vitro do induce hTERT mRNA and hTERT protein expression, as well as telomerase enzyme activity in the endothelial cells, and that this phenomenon is mediated by diffusible factor(s). These results provide strong evidence of the involvement of telomerase in tumor angiogenesis and will stimulate research on antitelomerase drugs for treatment of malignant brain gliomas.

PDGFRα depletion attenuates glioblastoma stem cells features by modulation of STAT3, RB1 and multiple oncogenic signals.

Platelet derived growth factor receptors (PDGFRs) play an important role in tumor pathogenesis, and they are frequently overexpressed in glioblastoma (GBM). Earlier we have shown a higher protein expression of PDGFR isoforms (α and ß) in peritumoral-tissue derived cancer stem cells (p-CSC) than in tumor core (c-CSC) of several GBM affected patients. In the current study, in order to assess the activity of PDGFRα/PDGF-AA signaling axis, we performed time course experiments to monitor the effects of exogenous PDGF-AA on the expression of downstream target genes in c-CSC vs p-CSC. Interestingly, in p-CSC we detected the upregulation of Y705-phosphorylated Stat3, concurrent with a decrement of Rb1 protein in its active state, within minutes of PDGF-AA addition. This finding prompted us to elucidate the role of PDGFRα in self-renewal, invasion and differentiation in p-CSC by using short hairpin RNA depletion of PDGFRα expression. Notably, in PDGFRα-depleted cells, protein analysis revealed attenuation of stemness-related and glial markers expression, alongside early activation of the neuronal marker MAP2a/b that correlated with the induction of tumor suppressor Rb1. The in vitro reduction of the invasive capacity of PDGFRα-depleted CSC as compared to parental cells correlated with the downmodulation of markers of epithelial-mesenchymal transition phenotype and angiogenesis. Surprisingly, we observed the induction of anti-apoptotic proteins and compensatory oncogenic signals such as EDN1, EDNRB, PRKCB1, PDGF-C and PDGF-D. To conclude, we hypothesize that the newly discovered PDGFRα/Stat3/Rb1 regulatory axis might represent a potential therapeutic target for GBM treatment.

Are gadolinium contrast agents suitable for gadolinium neutron capture therapy?

OBJECTIVE: Gadolinium neutron capture therapy (GdNCT) is a potential treatment for malignant tumors based on two steps: (1) injection of a tumor-specific (157)Gd compound; (2) tumor irradiation with thermal neutrons. The GdNC reaction can induce cell death provided that Gd is proximate to DNA. Here, we studied the nuclear uptake of Gd by glioblastoma (GBM) tumor cells after treatment with two Gd compounds commonly used for magnetic resonance imaging, to evaluate their potential as GdNCT agents. METHODS: Using synchrotron X-ray spectromicroscopy, we analyzed the Gd distribution at the subcellular level in: (1) human cultured GBM cells exposed to Gd-DTPA or Gd-DOTA for 0-72 hours; (2) intracerebrally implanted C6 glioma tumors in rats injected with one or two doses of Gd-DOTA, and (3) tumor samples from GBM patients injected with Gd-DTPA. RESULTS: In cell cultures, Gd-DTPA and Gd-DOTA were found in 84% and 56% of the cell nuclei, respectively. In rat tumors, Gd penetrated the nuclei of 47% and 85% of the tumor cells, after single and double injection of Gd-DOTA, respectively. In contrast, in human GBM tumors 6.1% of the cell nuclei contained Gd-DTPA. DISCUSSION: Efficacy of Gd-DTPA and Gd-DOTA as GdNCT agents is predicted to be low, due to the insufficient number of tumor cell nuclei incorporating Gd. Although multiple administration schedules in vivo might induce Gd penetration into more tumor cell nuclei, a search for new Gd compounds with higher nuclear affinity is warranted before planning GdNCT in animal models or clinical trials.

Tumor initiating cells and chemoresistance: which is the best strategy to target colon cancer stem cells?

There is an emerging body of evidence that chemoresistance and minimal residual disease result from selective resistance of a cell subpopulation from the original tumor that is molecularly and phenotypically distinct. These cells are called "cancer stem cells" (CSCs). In this review, we analyze the potential targeting strategies for eradicating CSCs specifically in order to develop more effective therapeutic strategies for metastatic colon cancer. These include induction of terminal epithelial differentiation of CSCs or targeting some genes expressed only in CSCs and involved in self-renewal and chemoresistance. Ideal targets could be cell regulators that simultaneously control the stemness and the resistance of CSCs. Another important aspect of cancer biology, which can also be harnessed to create novel broad-spectrum anticancer agents, is the Warburg effect, also known as aerobic glycolysis. Actually, little is yet known with regard to the metabolism of CSCs population, leaving an exciting unstudied avenue in the dawn of the emerging field of metabolomics.

Over-expression of hNGF in adult human olfactory bulb neural stem cells promotes cell growth and oligodendrocytic differentiation.

The adult human olfactory bulb neural stem/progenitor cells (OBNC/PC) are promising candidate for cell-based therapy for traumatic and neurodegenerative insults. Exogenous application of NGF was suggested as a promising therapeutic strategy for traumatic and neurodegenerative diseases, however effective delivery of NGF into the CNS parenchyma is still challenging due mainly to its limited ability to cross the blood-brain barrier, and intolerable side effects if administered into the brain ventricular system. An effective method to ensure delivery of NGF into the parenchyma of CNS is the genetic modification of NSC to overexpress NGF gene. Overexpression of NGF in adult human OBNSC is expected to alter their proliferation and differentiation nature, and thus might enhance their therapeutic potential. In this study, we genetically modified adult human OBNS/PC to overexpress human NGF (hNGF) and green fluorescent protein (GFP) genes to provide insight about the effects of hNGF and GFP genes overexpression in adult human OBNS/PC on their in vitro multipotentiality using DNA microarray, immunophenotyping, and Western blot (WB) protocols. Our analysis revealed that OBNS/PC-GFP and OBNS/PC-GFP-hNGF differentiation is a multifaceted process involving changes in major biological processes as reflected in alteration of the gene expression levels of crucial markers such as cell cycle and survival markers, stemness markers, and differentiation markers. The differentiation of both cell classes was also associated with modulations of key signaling pathways such MAPK signaling pathway, ErbB signaling pathway, and neuroactive ligand-receptor interaction pathway for OBNS/PC-GFP, and axon guidance, calcium channel, voltage-dependent, gamma subunit 7 for OBNS/PC-GFP-hNGF as revealed by GO and KEGG. Differentiated OBNS/PC-GFP-hNGF displayed extensively branched cytoplasmic processes, a significant faster growth rate and up modulated the expression of oligodendroglia precursor cells markers (PDGFRα, NG2 and CNPase) respect to OBNS/PC-GFP counterparts. These findings suggest an enhanced proliferation and oligodendrocytic differentiation potential for OBNS/PC-GFP-hNGF as compared to OBNS/PC-GFP.