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BACKGROUND Molecular subtyping has allowed for the beginning of personalized treatment in children suffering from medulloblastoma (MB). However,resistance inevitably emerges against these therapies,particularly in the Sonic Hedgehog (SHH) subtype. We found that children with SHH subtype have the worst outcome underscoring the need to identify new therapeutic targets. PROCEDURE High content screening of a 129 compound library identified agents that inhibited SHH MB growth. Lead molecular target levels,p90 ribosomal S6 kinase (RSK) were characterized by immunoblotting and qRT-PCR. Comparisons were made to human neural stem cells (hNSC). Impact of inhibiting RSK with the small molecule BI-D1870 or siRNA was assessed in growth assays (monolayer,neurosphere,and soft agar). NanoString was used to detect RSK in a cohort of 66 patients with MB. To determine BI-D1870 pharmacokinetics/pharmacodynamics,100 mg/kg was I.P. injected into mice and tissues were collected at various time points. RESULTS Daoy,ONS76,UW228,and UW426 MB cells were exquisitely sensitive to BI-D1870 but unresponsive to SHH inhibitors. Anti-tumor growth corresponded with inactivation of RSK in MB cells. BI-D1870 had no effect on hNSCs. Inhibiting RSK with siRNA or BI-D1870 suppressed growth,induced apoptosis,and sensitized cells to SHH agents. Notably,RSK expression is correlated with SHH patients. In mice,BI-D1870 was well-tolerated and crossed the blood-brain barrier (BBB). CONCLUSIONS RSK inhibitors are promising because they target RSK which is correlated with SHH patients as well as cause high levels of apoptosis to only MB cells. Importantly,BI-D1870 crosses the BBB,acting as a scaffold for development of more long-lived RSK inhibitors. View Publication

Giant cell tumor of bone (GCTB) is a very rare tumor entity,which is little examined owing to the lack of established cell lines and mouse models and the restriction of available primary cell lines. The stromal cells of GCTB have been made responsible for the aggressive growth and metastasis,emphasizing the presence of a cancer stem cell population. To identify and target such tumor-initiating cells,stromal cells were isolated from eight freshly resected GCTB tissues. Tumorigenic properties were examined by colony and spheroid formation,differentiation,migration,MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay,immunohistochemistry,antibody protein array,Alu in situ hybridization,FACS analysis and xenotransplantation into fertilized chicken eggs and mice. A sub-population of the neoplastic stromal cells formed spheroids and colonies,differentiated to osteoblasts,migrated to wounded regions and expressed the metastasis marker CXC-chemokine receptor type 4,indicating self-renewal,invasion and differentiation potential. Compared with adherent-growing cells,markers for pluripotency,stemness and cancer progression,including the CSC surface marker c-Met,were enhanced in spheroidal cells. This c-Met-enriched sub-population formed xenograft tumors in fertilized chicken eggs and mice. Cabozantinib,an inhibitor of c-Met in phase II trials,eliminated CSC features with a higher therapeutic effect than standard chemotherapy. This study identifies a c-Met(+) tumorigenic sub-population within stromal GCTB cells and suggests the c-Met inhibitor cabozantinib as a new therapeutic option for targeted elimination of unresectable or recurrent GCTB. View Publication

BACKGROUND Glioblastoma (GBM),being a highly vascularised and locally invasive tumour,is an attractive target for anti-angiogenic and anti-invasive therapies. The GBM/endothelial cell response to gossypol/temozolomide (TMZ) treatment was investigated with a particular aim to assess treatment effects on cancer hallmarks. METHODS Cell viability,endothelial tube formation and GBM tumour cell invasion were variously assessed following combined treatment in vitro. The U87MG-luc2 subcutaneous xenograft model was used to investigate therapeutic response in vivo. Viable tumour response to treatment was interrogated using immunohistochemistry. Combined treatment protocols were also tested in primary GBM patient-derived cultures. RESULTS An endothelial/GBM cell viability inhibitory effect,as well as an anti-angiogenic and anti-invasive response,to combined treatment have been demonstrated in vitro. A significantly greater anti-proliferative (P=0.020,P=0.030),anti-angiogenic (P=0.040,P<0.0001) and pro-apoptotic (P=0.0083,P=0.0149) response was observed when combined treatment was compared with single gossypol/TMZ treatment response,respectively. GBM cell line and patient-specific response to gossypol/TMZ treatment was observed. CONCLUSIONS Our results indicate that response to a combined gossypol/TMZ treatment is related to inhibition of tumour-associated angiogenesis,invasion and proliferation and warrants further investigation as a novel targeted GBM treatment strategy. View Publication

INTRODUCTION Despite attempts to prevent brain injury during the hyperacute phase of stroke,most sufferers end up with significant neuronal loss and functional deficits. The use of cell-based therapies to recover the injured brain offers new hope. In the current study,we employed human neural stem cells (hNSCs) isolated from subventricular zone (SVZ),and directed their differentiation into GABAergic neurons followed by transplantation to ischemic brain. METHODS Pre-differentiated GABAergic neurons,undifferentiated SVZ-hNSCs or media alone were stereotaxically transplanted into the rat brain (n=7/group) 7 days after endothelin-1 induced stroke. Neurological outcome was assessed by neurological deficit scores and the cylinder test. Transplanted cell survival,cellular phenotype and maturation were assessed using immunohistochemistry and confocal microscopy. RESULTS Behavioral assessments revealed accelerated improvements in motor function 7 days post-transplant in rats treated with pre-differentiated GABAergic cells in comparison to media alone and undifferentiated hNSC treated groups. Histopathology 28 days-post transplant indicated that pre-differentiated cells maintained their GABAergic neuronal phenotype,showed evidence of synaptogenesis and up-regulated expression of both GABA and calcium signaling proteins associated with neurotransmission. Rats treated with pre-differentiated cells also showed increased neurogenic activity within the SVZ at 28 days,suggesting an additional trophic role of these GABAergic cells. In contrast,undifferentiated SVZ-hNSCs predominantly differentiated into GFAP-positive astrocytes and appeared to be incorporated into the glial scar. CONCLUSION Our study is the first to show enhanced exogenous repopulation of a neuronal phenotype after stroke using techniques aimed at GABAergic cell induction prior to delivery that resulted in accelerated and improved functional recovery. View Publication

The multifunctional signaling protein p75 neurotrophin receptor (p75(NTR)) is a central regulator and major contributor to the highly invasive nature of malignant gliomas. Here,we show that neurotrophin-dependent regulated intramembrane proteolysis (RIP) of p75(NTR) is required for p75(NTR)-mediated glioma invasion,and identify a previously unnamed process for targeted glioma therapy. Expression of cleavage-resistant chimeras of p75(NTR) or treatment of animals bearing p75(NTR)-positive intracranial tumors with clinically applicable gamma-secretase inhibitors resulted in dramatically decreased glioma invasion and prolonged survival. Importantly,proteolytic processing of p75(NTR) was observed in p75(NTR)-positive patient tumor specimens and brain tumor initiating cells. This work highlights the importance of p75(NTR) as a therapeutic target,suggesting that gamma-secretase inhibitors may have direct clinical application for the treatment of malignant glioma. View Publication

The quantification of cellular mechanical properties is of tremendous interest in biology and medicine. Recent microfluidic technologies that infer cellular mechanical properties based on analysis of cellular deformations during microchannel traversal have dramatically improved throughput over traditional single-cell rheological tools,yet the extraction of material parameters from these measurements remains quite complex due to challenges such as confinement by channel walls and the domination of complex inertial forces. Here,we describe a simple microfluidic platform that uses hydrodynamic forces at low Reynolds number and low confinement to elongate single cells near the stagnation point of a planar extensional flow. In tandem,we present,to our knowledge,a novel analytical framework that enables determination of cellular viscoelastic properties (stiffness and fluidity) from these measurements. We validated our system and analysis by measuring the stiffness of cross-linked dextran microparticles,which yielded reasonable agreement with previously reported values and our micropipette aspiration measurements. We then measured viscoelastic properties of 3T3 fibroblasts and glioblastoma tumor initiating cells. Our system captures the expected changes in elastic modulus induced in 3T3 fibroblasts and tumor initiating cells in response to agents that soften (cytochalasin D) or stiffen (paraformaldehyde) the cytoskeleton. The simplicity of the device coupled with our analytical model allows straightforward measurement of the viscoelastic properties of cells and soft,spherical objects. View Publication

Tumor-initiating cells (TICs) often survive therapy and give rise to second-line tumors. We tested the plausibility of sphere cultures as models of TICs. Microarray data and microRNA data analysis confirmed the validity of spheres as models of TICs for breast and prostate cancer as well as mesothelioma cell lines. Microarray data analysis revealed the Trp pathway as the only pathway upregulated significantly in all types of studied TICs,with increased levels of indoleamine-2,3-dioxygenase-1 (IDO1),the rate-limiting enzyme of Trp metabolism along the kynurenine pathway. All types of TICs also expressed higher levels of the Trp uptake system consisting of CD98 and LAT1 with functional consequences. IDO1 expression was regulated via both transcriptional and posttranscriptional mechanisms,depending on the cancer type. Serial transplantation of TICs in mice resulted in gradually increased IDO1. Mitocans,represented by α-tocopheryl succinate and mitochondrially targeted vitamin E succinate (MitoVES),suppressed IDO1 in TICs. MitoVES suppressed IDO1 in TICs with functional mitochondrial complex II,involving transcriptional and posttranscriptional mechanisms. IDO1 increase and its suppression by VE analogues were replicated in TICs from primary human glioblastomas. Our work indicates that IDO1 is increased in TICs and that mitocans suppress the protein. View Publication

Ion channels and transporters have increasingly recognized roles in cancer progression through the regulation of cell proliferation,migration,and death. Glioblastoma stem-like cells (GSCs) are a source of tumor formation and recurrence in glioblastoma multiforme,a highly aggressive brain cancer,suggesting that ion channel expression may be perturbed in this population. However,little is known about the expression and functional relevance of ion channels that may contribute to GSC malignancy. Using RNA sequencing,we assessed the enrichment of ion channels in GSC isolates and non-tumor neural cell types. We identified a unique set of GSC-enriched ion channels using differential expression analysis that is also associated with distinct gene mutation signatures. In support of potential clinical relevance,expression of selected GSC-enriched ion channels evaluated in human glioblastoma databases of The Cancer Genome Atlas and Ivy Glioblastoma Atlas Project correlated with patient survival times. Finally,genetic knockdown as well as pharmacological inhibition of individual or classes of GSC-enriched ion channels constrained growth of GSCs compared to normal neural stem cells. This first-in-kind global examination characterizes ion channels enriched in GSCs and explores their potential clinical relevance to glioblastoma molecular subtypes,gene mutations,survival outcomes,regional tumor expression,and experimental responses to loss-of-function. Together,the data support the potential biological and therapeutic impact of ion channels on GSC malignancy and provide strong rationale for further examination of their mechanistic and therapeutic importance. View Publication

Surgery is an essential component in the treatment of brain tumors. However,delineating tumor from normal brain remains a major challenge. We describe the use of stimulated Raman scattering (SRS) microscopy for differentiating healthy human and mouse brain tissue from tumor-infiltrated brain based on histoarchitectural and biochemical differences. Unlike traditional histopathology,SRS is a label-free technique that can be rapidly performed in situ. SRS microscopy was able to differentiate tumor from nonneoplastic tissue in an infiltrative human glioblastoma xenograft mouse model based on their different Raman spectra. We further demonstrated a correlation between SRS and hematoxylin and eosin microscopy for detection of glioma infiltration (κ = 0.98). Finally,we applied SRS microscopy in vivo in mice during surgery to reveal tumor margins that were undetectable under standard operative conditions. By providing rapid intraoperative assessment of brain tissue,SRS microscopy may ultimately improve the safety and accuracy of surgeries where tumor boundaries are visually indistinct. View Publication

BIX01294 (Bix) is known to be a euchromatic histone-lysine N-methyltransferase 2 inhibitor and treatment with Bix suppresses cancer cell survival and proliferation. In the present study,it was observed that sequential treatment with low-dose Bix notably increases glioblastoma cell migration and metastasis. It was demonstrated that U251 cells sequentially treated with low-dose Bix exhibited induced characteristic changes in critical epithelial-mesenchymal transition (EMT) markers,including E-cadherin,N-cadherin,β-catenin and zinc finger protein SNAI2. Notably,sequential treatment with Bix also increased the expression of cancer stem cell-associated markers,including sex determining region Y-box 2,octamer-binding transcription factor 4 and cluster of differentiation 133. Neurosphere formation was significantly enhanced in cells sequentially treated with Bix,compared with control cells (control: P=0.011; single treatment of Bix,P=0.045). The results of the present study suggest that accumulation of low-dose Bix enhanced the migration and metastatic potential of glioblastoma cells by regulating EMT-associated gene expression,which may be the cause of the altered properties of glioblastoma stem cells. View Publication

Glioblastoma multiforme (GBM) is the most common and aggressive type of primary brain tumor. Epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) receptors are frequently amplified and/or possess gain-of-function mutations in GBM However,clinical trials of tyrosine-kinase inhibitors have shown disappointing efficacy,in part due to intra-tumor heterogeneity. To assess the effect of clonal heterogeneity on gene expression,we derived an approach to map single-cell expression profiles to sequentially acquired mutations identified from exome sequencing. Using 288 single cells,we constructed high-resolution phylogenies of EGF-driven and PDGF-driven GBMs,modeling transcriptional kinetics during tumor evolution. Descending the phylogenetic tree of a PDGF-driven tumor corresponded to a progressive induction of an oligodendrocyte progenitor-like cell type,expressing pro-angiogenic factors. In contrast,phylogenetic analysis of an EGFR-amplified tumor showed an up-regulation of pro-invasive genes. An in-frame deletion in a specific dimerization domain of PDGF receptor correlates with an up-regulation of growth pathways in a proneural GBM and enhances proliferation when ectopically expressed in glioma cell lines. In-frame deletions in this domain are frequent in public GBM data. View Publication