Brain Tumor Stem Cells Research Articles

Glycosylation-related gene expression is linked to differentiation status in glioblastomas undifferentiated cells

Glioblastoma Multiforme (GBM) is the most frequent malignant brain tumor with still poor prognosis. Tumor initiation, growth and recurrences might depend on Brain Tumor Stem Cells (BTSCs) which can promote tumor aggressiveness and potentially affords new therapeutic target. Recent works emphasized aberrant cell-surface glyco-conjugate expression in brain tumors suggesting that altered glycosylation is closely linked to cancer tumor metastasis and invasive process. Post-translational changes might play a key role in determining the fates of most aggressive and undifferentiated cells such as self-renewal, proliferation and differentiation. In order to characterize the glycosylation-related genes involved in differentiation status of the BTSCs, two glioblastoma cell lines, U87-MG and U251 have been cultured according to two conditions leading to undifferentiated floating cells or differentiated adherent cells. The expression level of 559 glycosylation related genes has been analyzed by Taqman Low Density Array (TLDA) analysis and allowed to isolate eight up-regulated genes specific of a subpopulation of undifferentiated cells. Protein expression has been confirmed. Among main selected genes, five are also over-expressed in the undifferentiated condition in primary cultures provided by three GBM freshly isolated from patient. This work suggests that new Glycosylation-related gene signature might improve the characterization of the most aggressive and undifferentiated cells and supports that in future, N-linked glycosylation might provide new target to develop therapeutic strategy for inhibiting tumor growth.

Peptide and Non-peptide Antagonists Targeting Endothelin Receptors in Physiology and Pathology

As for other peptides such as bradykinin, neurokinins and angiotensins, peptide antagonists for endothelin-1 (ET-1) have been early on developed towards the pharmacological characterization of both ET(A) and ET(B) receptors. Interestingly, unlike the previously mentioned three peptides, receptors for ET-1 were cloned and purified prior to the report of ET(A)and ET(B)receptor antagonists such as BQ-123 and BQ-788. The availability of such pharmacological tools and the use of molecular approaches have certainly fast-tracked the development of non-peptide ET receptor antagonists for clinical applications. Albeit rapid degradation by gastric enzymes and short half-life in plasma of peptide receptor antagonists limit their use in clinical settings, those molecules have been of importance in the identification of mediators and modulators of ET-1 induced properties in vitro and in vivo, as described further in this review. Peptide antagonists acting selectively or, with equivalent affinities against ET(A)and ET(B)receptors were reported prior to the advent of clinically relevant non-peptide blockers such as Bosentan. Confounding mechanisms involving, for example, the endogenous modulators nitric oxide and prostacyclin as well as allosteric interactions between ET receptor types, have also been clarified with the use of peptide antagonists for endothelins. Finally, peptide antagonists were also used to identify the precise pharmacology of ET-1 precursors such as big-endothelin-1 and ET-1 (1-31). The present review will thus attempt to summarize the knowledge to date and future perspectives related to use of peptide antagonists targeting endothelin receptors in physiological and pathological settings.

Expression of NANOG in human gliomas and its relationship with undifferentiated glioma cells

Stemness genes, including NANOG, which have been reported to play a significant role in embryonic stem cells (ESCs), are purported to be expressed in specific human tumor types. In the present study, we explored the expression of NANOG in gliomas to demonstrate its key roles in maintaining the undifferentiated state of glioma cells. Brain tumor stem cells (BTSCs) were isolated from the human glioma cell line U87 and cultured in simplified serum-free medium. Significantly higher NANOG mRNA and protein expression levels were demonstrated in U87 parental attached cells and suspended BTSCs as well as in 69 glioma specimens of different pathological grades. The relative levels of NANOG mRNA and protein expression were higher in the BTSCs as compared to those in the U87 parental attached cells and were significantly positively correlated with pathological grade. The coexpression and relationship of NANOG, CD133 and GFAP in situ in the cellular levels was determined through double-label immunohistochemical staining in the gliomas. A positive correlation of NANOG and CD133 expression with pathological grade of the samples was noted, while NANOG and GFAP expression correlated negatively with the pathological grade (P<0.01). Overexpression of NANOG in gliomas and its close relationship with the undifferentiated state of glioma cells invivo and in vitro indicated that NANOG may contribute to the existence of BTSCs and may be related to tumorigenesis of the cerebrum by maintaining the undifferentiated state of glioma cells, which provides a foundation to further explore its role in the biological behavior of gliomas.

Effect of doublecortin on self-renewal and differentiation in brain tumor stem cells.

Analysis of microarray probe data from glioma patient samples, in conjunction with patient Kaplan-Meier survival plots, indicates that expression of a glioma suppressor gene doublecortin (DCX) favors glioma patient survival. From neurosphere formation in culture, time-lapse microscopic video recording, and tumor xenograft, we show that DCX synthesis significantly reduces self-renewal of brain tumor stem cells (BTSC) in human primary glioma (YU-PG, HF66) cells from surgically removed human glioma specimens and U87 cells in vitro and in vivo. Time-lapse microscopic video recording revealed that double transfection of YU-PG, HF66, and U87 cells with DCX and neurabin II caused incomplete cell cycle with failure of cytokinesis, that is, endomitosis by dividing into three daughter cells from one mother BTSC. Activation of c-jun NH2-terminal kinase 1 (JNK1) after simvastatin (10 nM) treatment of DCX(+) neurabin II(+) BTSC from YU-PG, HF66, and U87 cells induced terminal differentiation into neuron-like cells. dUTP nick end labeling data indicated that JNK1 activation also induced apoptosis only in double transfected BTSC with DCX and neurabin II, but not in single transfected BTSC from YU-PG, HF66, and U87 cells. Western blot analysis showed that procaspase-3 was induced after DCX transfection and activated after simvastatin treatment in YU-PG, HF66, and U87 BTSC. Sequential immunoprecipitation and Western blot data revealed that DCX synthesis blocked protein phosphatase-1 (PP1)/caspase-3 protein-protein interaction and increased PP1-DCX interaction. These data show that DCX synthesis induces apoptosis in BTSC through a novel JNK1/neurabin II/DCX/PP1/caspase-3 pathway.

Siomycin A targets brain tumor stem cells partially through a MELK-mediated pathway

Glioblastoma multiforme (GBM) is a devastating disease, and the current therapies have only palliative effect. Evidence is mounting to indicate that brain tumor stem cells (BTSCs) are a minority of tumor cells that are responsible for cancer initiation, propagation, and maintenance. Therapies that fail to eradicate BTSCs may ultimately lead to regrowth of residual BTSCs. However, BTSCs are relatively resistant to the current treatments. Development of novel therapeutic strategies that effectively eradicate BTSC are, therefore, essential. In a previous study, we used patient-derived GBM sphere cells (stemlike GBM cells) to enrich for BTSC and identified maternal embryonic leucine-zipper kinase (MELK) as a key regulator of survival of stemlike GBM cells in vitro. Here, we demonstrate that a thiazole antibiotic, siomycin A, potently reduced MELK expression and inhibited tumor growth in vivo. Treatment of stemlike GBM cells with siomycin A resulted in arrested self-renewal, decreased invasion, and induced apoptosis but had little effect on growth of the nonstem cells of matched tumors or normal neural stem/progenitor cells. MELK overexpression partially rescued the phenotype of siomycin A-treated stemlike GBM cells. In vivo, siomycin A pretreatment abraded the sizes of stemlike GBM cell-derived tumors in immunodeficient mice. Treatment with siomycin A of mice harboring intracranial tumors significantly prolonged their survival period compared with the control mice. Together, this study may be the first model to partially target stemlike GBM cells through a MELK-mediated pathway with siomycin A to pave the way for effective treatment of GBM.

Abstract 3307: The multitasking of Sox2: Maintaining the stemness and inducing the malignant phenotype of gliomas

Abstract Glioblastoma multiforme (GBM), the most aggressive primary brain tumor, displays an enrichment gene expression related to a stem cell signature. Sox2, a major stemness factor involved in pluripotency and in the maintenance of neural stem cell identity, has been described as frequently overexpressed in poorly differentiated gliomas. However, the role that this molecule plays in brain tumors remains under investigation. In this study, we sought to ascertain the Sox2 potential function in the control of self-renewal of brain tumor stem cells (BTSCs) and the malignant phenotype of gliomas. Our results showed Sox2 expression in human surgical malignant gliomas. In addition, Sox2 expression was significantly higher in the BTSC lines than in established glioma cell lines. Downmodulation of Sox2 in BTSCs by using siRNA resulted in the loss of the self-renewal properties of this cell population, and modification in the pattern of expression of markers related with stem cells properties and differentiation. These results are of major importance since, in the TCGA, we observed Sox2 overexpression in more than 80% of the samples (n=188), gene amplification of SOX2 in 18% of the individuals, and hypomethylation of the promoter in about 90% of the samples when compared with normal tissue, suggesting the relevance of this transcription factor in the malignant phenotype of GBMs. In this regard, our results demonstrated that SOX2 plays a prominent role in the invasive and migratory capabilities of both BTSCs and established glioma cell lines. Thus, ectopic expression of Sox2 was sufficient to induce invasion of glioma cells and knockdown experiments demonstrated that Sox2 is essential for maintaining the invasive properties of glioma cells. Therefore, these results identify a multi-functional aspect of Sox2 as both, a stemness promoting molecule and an essential pro-invasive protein, elucidating the possibility of targeting Sox2 for glioma therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3307. doi:10.1158/1538-7445.AM2011-3307

Abstract 1524: Overcoming temozolomide resistance in MGMT positive glioblastoma by targeting ALDH1

Abstract Despite aggressive therapy, including radical surgical resection, radiation, and chemotherapy, the prognosis for patients with glioblastoma (GBM) remains poor and relapse occurs regularly. Implementation of the chemotherapy drug temozolomide (TMZ), as a standard in adjuvant GBM therapy, significantly increased the overall survival of patients with an epigenetic silenced MGMT promoter (MGMT-). To date, no comparable therapeutic approach for GBM patients with MGMT expression (MGMT+) is applied. Tumor re-growth in MGMT+ and MGMT- GBM corroborates the tumor stem cell (TSC) paradigm, postulating that a therapy-resistant subpopulation of cells harbors the ability to keep the tumor alive and growing. Recently, we presented aldehyde dehydrogenase 1 (ALDH1) as a marker for glioblastoma cells with stem cell capacity. In this study, we demonstrate that ALDH1 overexpression in established and primary MGMT+ GBM cell lines correlates with resistance to TMZ, while concomitant inhibition of ALDH1 by 4-diethylaminobenzaldehyde (DEAB) or tetraethylthiuramdisulfide (DSF) re-sensibilized the cells significantly. Application of TMZ in combination with DEAB strikingly attenuated the stem cell capacity of both MGMT + and MGMT – cells. For further verification of the specific impact of ALDH1 on therapy resistance, shRNA constructs were applied. Moreover, immunohistochemical analysis of ALDH1 expression in specimens of glioblastoma patients revealed a significant correlation between expression of this enzyme and a poor clinical prognosis. All these findings demonstrate that ALDH1 is a marker for brain tumor stem cells, a strong predictor of clinical outcome and a potential target for an improved therapy of MGMT positive GBM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1524. doi:10.1158/1538-7445.AM2011-1524

Abstract 3318: A distinct subpopulation within CD133 positive brain tumor cells shares characteristics with endothelial progenitor cells

Abstract The cell surface marker CD133 was proposed as a brain tumor stem cell marker. However there have been substantial controversies regarding the necessity and role of CD133 in tumorigenesis. This study aimed to characterize CD133 positive cells in brain tumors. Fresh human brain tumor specimens and whole blood were collected from the same patients [medulloblastoma (N=6), glioblastoma (N=4), ependymoma (N=1), and atypical teratoid/rhabdoid tumor (ATRT, N=2)]. Dual FACS staining for CD133/CD34, functional assay of CD133 positive cells from different origin for tumorigenesis and angiogenesis were done. We also investigated the in vivo tumorigenic potential and histological characteristics of four distinct groups on the basis of expression of CD133/CD34 markers (CD133+, CD133+/CD34+, CD133+/CD34-, and CD133-). CD133 positive brain tumor cells coexpressed significantly higher positivity for CD34 (67.97 ± 5.34 % in CD133 (+) cells vs. 11.96 ± 1.48 % in CD133 (−) cells, P&amp;lt;0.001). CD133 positive brain tumor cells formed neurosphere-like spheroids and differentiated into multiple nervous system lineages contrary to CD133 positive blood cells. Furthermore they showed biological characteristics of endothelial cells including vWF expression, LDL uptake and tube formation in vitro, unlike CD133 negative brain tumors cells. Pathologic analysis of the brains implanted with CD133+ glioma cells showed large, highly proliferative and vascular tumors with widespread necrosis and hemorrhage. Notably pure BTSC (CD133+/CD34-) or EPC (CD133+/CD34+) fraction alone did not generate tumor. Our data suggest the presence of a distinct subpopulation of CD133 positive cells isolated from human brain tumors, with characteristics of EPCs. Therefore, interpreting the results of experiments carried out with “CD133-positive BTSCs” should be extrapolated with caution. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3318. doi:10.1158/1538-7445.AM2011-3318

Abstract 3314: Potential role of mitochondrial respiration in serum-induced tumor stem cell differentiation

Abstract Glioblastoma remains the deadliest form of brain tumors. The poor prognosis of glioblastoma patients is associated with a high rate of relapse after therapy. It has been suggested that the presence of cancer stem cells, which are relatively resistant to radiation and chemotherapy, may play a significant role in the recurrence of brain tumor. Understanding the biological property of brain tumor stem cells is important to develop effective therapeutic strategies for glioblastoma. In vitro, glioblastoma stem cells cultured in serum-free medium form self-renewing neurospheres, express the neural stem marker CD133, and are highly tumorigenic. On the other hand, in the presence of fetal bovine serum (FBS), the glioblastoma stem cells tend to undergo differentiation. In this study we used glioblastoma stem cells, NSC11 and NSC23, previously isolated from glioblastoma patients and expressed stem cell markers CD133 and SOX 2, to explore their bioenergetics by monitoring the oxygen consumption as an indication of mitochondrial respiration cultured in serum-free medium in comparison with that incubated in medium containing 5% FBS. We found that NSC11 and NSC23 stem cells exhibited low mitochondrial respiration when cultured in stem cell medium without serum. Upon exposure to 5% fetal bovine serum, mitochondrial respiration increased significantly. Moreover we assessed the protein expression of the mitochondrial respiratory complex (MRC) components in the cells cultured in serum-free medium in comparison with that in medium containing 5% FBS for various lengths of time by western blotting analysis. We observed a marked up-regulation of the protein subunits of MRC complexes I and IV in glioblastoma stem cells when they were exposed to FBS. Analysis of the mRNA expression levels for the mitochondrial DNA-encoded MRC components showed an increase in the expression of these genes, indicating an increase in the mitochondria biogenesis upon the FBS exposure. Based on these preliminary findings, we postulate that maintaining low mitochondrial respiration may be important to maintain the stemness of the glioblastoma stem cells, while the activation of the respiration may promote stem cell differentiation and affect their tumorgenecity. Further studies are required to elucidate the detail molecular pathways governing glioblastoma stem cell self-renewal and differentiation and the mechanistic link to mitochondrial function. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3314. doi:10.1158/1538-7445.AM2011-3314

Abstract 3298: Structure-based computer-aided drug design to discover novel small molecules that target brain tumor stem cells

Abstract INTRODUCTION. Malignant glioma is one of the most lethal diseases in adulthood and remains refractory to the current therapies including chemoradiotherapies. The cancer stem cell theory dictates that brain tumor stem-like cells (BTSC) account for such intractability of malignant glioma. Recently, several molecularly-targeted therapies have demonstrated a varying degree of success in treatment of cancers including leukemia and breast cancer. In this study, we sought to determine the key kinases that regulate survival, self-renewal, and proliferation of BTSC, and to design novel small molecules by using the structure-based computantional modeling system. RESULTS. With the neurosphere cultures derived from our glioma patients, we identified 3 kinases that play vital roles in survival and/or proliferation of BTSC in vitro; Fibroblast Growth Factor Receptor 1, Aurora kinase B, and Maternal Embryonic Leucine-zipper Kinase. Structure-based computational modeling allowed us to perform in silico docking of various small molecule candidates to these kinases. As a result, four novel small molecules demonstrated highly specific targeting of the key structural elements of these kinases. We then synthesized these identified candidate compounds and confirmed their in vitro inhibition of the targeting kinase activities. Finally, we will also present our data about the treatment effect with these compounds on the in vitro BTSC growth and the in vivo tumor growth. CONCLUSION. Structure-based drug design will likely open up a new avenue to discover novel anti-cancer stem cell agents that can selectively target the key kinases in BTSC, leading to the growth arrest of malignant glioma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3298. doi:10.1158/1538-7445.AM2011-3298

Abstract 3302: The effects of the g-quadruplex ligand telomestatin to human brain tumor stem cell survival and growth

Abstract Glioblastoma multiforme (GBM) is the leading cause of death among primary brain tumors in adults and the current therapies have only palliative effect on prognosis of patients. Recently, stem cell-like cells in GBM (brain tumor stem-like cells; BTSC) have gained substantial attention as a potential therapeutic target. Hallmarks of BTSC include their self-renewal capacity and highly migratory potential. In this study, we demonstrate that treatment of patient-derived BTSC with a G-quadruplex ligand, telomestatin (TMS), inhibits BTSC self-renewal and maintenance of their stem cell state, and induces their apoptosis in vitro and in vivo. In contrast, both normal precursors and non-stem tumor cells from the matched samples are relatively resistant to TMS treatment. Treatment with a lower dose of TMS specifically inhibits BTSC migration into normal brain. Immunofluorescence in situ hybridization with TMS-treated GBM cells displays both telomeric and non-telomeric DNA damage in BTSC but not in non-stem tumor cells. cDNA microarray analysis identifies a proto-oncogene, c-Myb, as a target of TMS in BTSC, and the pharmacodynamic analysis with TMS-treated tumor-bearing mouse brains demonstrates reduction of c-Myb expression in tumors. An elevated c-Myb expression is found in surgical specimens of GBM compared to normal brain tissues. Lastly, TMS treatment of BTSC-derived mouse intracranial tumors reduces tumor sizes in vivo without any noticeable apoptotic cells in the normal brain, and a combined treatment of TMS with radiation or temozolomide results in additive inhibitory effects on GBM sphere growth in vitro. Collectively, these data indicate a potential avenue toward BTSC-directed therapeutic strategy using TMS via telomeric DNA damage and inhibition of c-Myb, which may offer a novel therapeutic approach for GBM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3302. doi:10.1158/1538-7445.AM2011-3302

Abstract 3317: Single-cell invasion and chemoresistance of slowly proliferating brain-tumor stem cells

Abstract Despite intense efforts in basic research and clinical medicine, glioblastoma (GBM) remains one of the most lethal types of cancer. In particular, tumor recurrence after surgical resection, aggressive chemotherapy, and targeted radiation remains an insurmountable obstacle. Recurrence may be attributed to residual cancer stem cells that re-initiate tumor growth after primary clinical intervention. Here, we provide new evidence for a subpopulation of relatively quiescent and chemoresistant cancer stem cells that invade deeply into the parenchyma. We have identified a critical transcription factor that is upregulated in these glioma stem cells, which regulates epithelial-mesenchymal transition (EMT) in other tumors. Knockdown of this transcription factor results in an increased sensitivity to chemotherapeutic agents and reduced tumor cell invasion. We hypothesize that single cell invasion of malignant gliomas is regulated by similar molecular pathways as EMT and metastasis in solid tissue tumors. These pathways allow slowly proliferating glioma stem cells to leave the site of the primary tumor, invade deeply into the surrounding parenchyma and, by virtue of their resistance to chemotherapeutic agents, evade all types of classical brain tumor therapy. This offers a potential novel model for GBM recurrence, and a potential new therapeutic target. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3317. doi:10.1158/1538-7445.AM2011-3317

CD133 expression is associated with small round blue cell tumour morphology in human central nervous system neoplasms

CD133 is considered to be a marker for brain tumour-initiating cells. However, most data on CD133 are derived from animal or in-vitro studies. The aim of this study was to characterize CD133 expression, and the distribution and morphological features of CD133(+) cells, in primary and secondary human central nervous system (CNS) neoplasms. Tumours were analysed by real-time reverse transcription polymerase chain reaction, western blot, flow cytometry and immunohistochemistry. Our results show that only small round blue cell tumours (SRBCTs) exhibit strong and consistent CD133 expression. Interestingly, glioblastomas, large-cell carcinomas and sarcomas were negative for CD133. Only glioblastomas with a focal small-cell component exhibited CD133 immunoreactivity in the SRBCT component. In addition, CD133 expression did not correlate with the expression of other markers associated with stem cell differentiation, including CD15 and nestin. CD133 expression in human CNS neoplasms is independent of the grade of malignancy but strongly correlates with SRBCT morphology. Together with recent findings showing that CD133 is quickly upregulated upon hypoxia and that CD133(-) cells can also exhibit stem cell properties, our data strongly question the suitability of CD133 as a brain tumour stem cell marker in vivo.

Inconsistent Immunohistochemical Expression Patterns of Four Different CD133 Antibody Clones in Glioblastoma

The putative tumor stem cell marker CD133 is the marker of choice for identifying brain tumor stem cells in gliomas, but the use of different CD133 antibody clones possibly recognizing different CD133 splice variants with epitopes of different glycosylation status confuses the field. The aim was to investigate if current inconsistent CD133 observations could be a result of using different CD133 antibodies for immunohistochemical identification of CD133. Ten glioblastomas were immunohistochemically stained with four different CD133 antibody clones (AC133, W6B3C1, C24B9, and ab19898) and analyzed by quantitative stereology. Moreover, the CD133 staining pattern of each antibody clone was investigated in kidney, pancreas, and placenta tissue as well as in glioblastoma and retinoblastoma cultures and cell lines. All antibody clones revealed CD133+ niches and single cells in glioblastomas, but when using different clones, their distribution rarely corresponded. Morphology of identified single cells varied, and staining of various tissues, cultures, and cells lines was also inconsistent among the clones. In conclusion, the authors report inconsistent CD133 detection when using different primary CD133 antibody clones. Thus, direct comparison of studies using different antibody clones and conclusions based on CD133 immunohistochemistry should be performed with caution.

Experimental study on dendritic cells pulsed with brain tumor stem cells for immunotherapy of glioma

Objective To investigate the effect of dendritic cells pulsed with brain tumor stem cells which are used to treat on intracranial glioma.MethodWe obtained murine brain tumor stem cells by growing C6 cells in epidermal growth factor/basic fibroblast growth factor without serum.Dendritic cells isolated from rat bone marrow were pulsed with BTSCs.Rat brain glioma models were established by stereotactic technique.107 DCs pulsed with BTSCs and C6 were injected through tail vein in group A and group B respectively.The same number of DCs and the same volume PBS were applied to group C and group D.The survival time of rats was analyzed by Log- rank survival analysis.Tumor samples were examinedwithHE staining and immunohistochemistry.Methods BTSCs expressedCD133 + and nestin.DCs appeared typical long dentrite in morphology and expressed OX62+ markers.The survival analysis showed group A was statistically significant in constrast to the other goups (P<0.05).The tumors in group A have the most inflammation and CD8 + T lymphocytes.Concluion DCs loading with BTSCs lysates can provide a higher level of immunity protect against gliomas than those loading with C6 cells,which provide a new method in the immuntherapy of brain glioma. Key words: Glioma; Brain tumor stem cells; Dendritic cells; Immunotherapy

Expression of Nanog in brain tumor stem cells

Objective To detect the expression of Nanog in glioma cell line U87 and the relationship with BTSCs.Methods BTSCs were isolated from glioma cell line U87 and cultured in simplified serum-free neural stem cell medium by nanosphere suspension culture method spheres,and purified continuously through the monoclonal formation experiment.The immunofluorescence staining of cells was employed to identify the BTSCs and differentiated cells.The expression of Nanog mRNA was examined by RT- PCR and Nanog protein was detected by immunocytochemistry in U87 and BTSCs respectively.Double immunocytochemistry staining was used to detect the co- expressions of Nanog/CD133.Methods BTSCs were isolated ,cultured and purified successfully from glioma cell line U87.Both Nanog mRNA and protein were expressed in U87 and BTSCs.The expression rate of immunopositive cells was (64.1 ±18.2)% in U87 and (97.2±1.8)% in BTSCs respectively(t =5.719,P =0.000).The Nanog+/CD133+ cells could be found co-expressed in U87 and BTSCs by using double immunocytochemistry s taining.The relative level of Nanog expression was 0.3851 ±0.0771 in U87 and0.6032±0.1223 in BTSCs(t =4.770,P =0.000).Conclusion BTSCs exist in glioma cell line U87 in vitro.The levels of Nanog expression in BTSCs were higher than that in U87.Nanog expression was associated with the genesis and differentiation state of glioma.The overexpression of Nanog and co- expression of Nanog/CD133 showed that it might contribute to the existence of BTSCs,which lay a foundation to the further explore its role in biological behaviour of glioma.Expression of Nanog in U87 indicated the close relationship between glioma and stem cell,and suggested Nanog may play a critical role in the development of glioma. Key words: Glioma; Gene expression; Nanog; Cancer stem cell

Optimization of glioblastoma multiforme stem cell isolation, transfection, and transduction

It has been postulated that brain tumor stem cells (TSCs) may be the population of cells responsible for the maintenance and recurrence of glioblastoma multiforme (GBM). The purpose of this study was to optimize a reproducible protocol for generating TSCs for their subsequent transfection or transduction. Patient GBMs were enzymatically and mechanically dissociated and tumor spheres were resuspended in appropriate media and analyzed to ensure they met stem cell criteria. These cells were then transfected with a plasmid or transduced with a viral vector to introduce a previously absent gene and then allowed to form tumor spheres. Tumor spheres were generated from patient GBMs without contamination. These cells met stringent criteria as stem cells, including multipotentiality and self-renewal. High efficiency transfection and transduction of tumor spheres was possible, even at the core of the sphere. This allowed for the introduction of new genes to the TSCs, as evidenced by fluorescent microscopy and Western blot analysis. This study is a guide to optimize the generation of patient derived GBM tumor spheres without RBC and dead cell contamination. GBM TSCs within tumor spheres can easily be transfected with plasmids or transduced with a virus. This is important from a therapeutic perspective if gene replacement is to be successful in replacing genes lost in GBM progression or to knock down or silence genes that are over-expressed in malignant brain tumors.

Constitutive androstane receptor agonist CITCO inhibits growth and expansion of brain tumour stem cells

Background:Brain tumours present unique challenges to conventional therapies and pose major health problems around the world. Brain tumour stem cells (BTSCs) represent a small fraction of tumour cells that maintain growth, drug resistance and recurrence properties. Constitutive androstane receptor (CAR) is a nuclear receptor transcription factor that regulates drug metabolism and homoeostasis. In this study, we examined the effect of CAR agonist, 6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehydeO-(3,4-dichlorobenzyl)oxime (CITCO) on BTSCs.Methods:The expression of CAR in BTSCs was detected by quantitative RT–PCR and western blot. The antiproliferative effect of CITCO on BTSCs was determined by WST-1 and 3H thymidine uptake assays. The effect of CITCO on CD133 expression, cell cycle progression and apoptosis in BTSCs was analysed by immunostaining and flow cytometry. The in vivo effect of CITCO was studied using subcutaneous (s.c.) BTSC xenograft in nude mice.Results:We show for the first time that BTSCs express altered levels of nuclear receptors compared with glioma cells. The expression of CAR mRNA and protein was low in BTSCs and that increased following treatment with CITCO in culture. CITCO induced a dose-dependent decrease in growth and expansion of CD133+ BTSCs as gliospheres in culture. Cell cycle arrest and apoptosis in BTSCs were induced by CITCO, but not in normal astrocytes. Growth of s.c BTSC xenograft in nude mice was also inhibited by CITCO.Conclusion:These findings indicate that CITCO inhibits the growth and expansion of BTSCs, suggesting the use of CAR agonists for the treatment of brain tumour.

Cryopreservation of cancer-initiating cells derived from glioblastoma

Glioblastoma multiforme (GBM) represents the most devastating adult brain tumor. GBM follows a hierarchical development in oncogenesis, with a sub-population of cells - brain tumor stem cells (BTSCs), exhibiting tumor-initiating potential. BTSCs possess extensive self-renewal capability and can repopulate the entire tumor mass. They are resistant to conventional therapies, suggesting that they are the likely candidates of tumor recurrence. Their eradication is thus important for an effective cure. Previous works showed that human-derived BTSCs could be stably maintained for 10-15 passages in serum-free condition, and gene expression and karyotypic hallmarks similar to the primary tumors were preserved. However, primary cells have been shown to sustain additional karyotypic aberrations owing to the harsh conditions of extended in vitro serial passage. Several investigators have proposed passaging these cells in xenograft models. A limitation of such an approach is the inability to return to identical passages for experimental repetitions, or the unavailability of suitably-aged mice for implantation. We have devised a method to cryopreserve BTSCs and that important characteristics were maintained, establishing a repository for drug screening endeavors.

Neural stem cells and their role in the pathology and classification of central nervous system tumors

Today, one of the most popular and controversial topics in medicine is undoubtedly the rapidly developing field of stem cell research. Some of the controversy in this field arises from lack of uniform terminology and different interpretation of concepts such as brain tumor stem cells. In addition, lack of reliable and universal markers that can identify stem cells and define precursor cells in a particular differentiation pathway further confounds the interpretation of results in many studies. Stem cells are undoubtedly critical in normal cellular development as well as tumor biology and better characterization of these cells is likely to have profound influence on the classification schemes of tumors. In this manuscript, we present the generally accepted definitions of key concepts in stem cell biology and review some of the related molecular pathways. In addition, we put forth our position on how progress in this field should be affecting the future classification schemes of central nervous system neoplasia. We strongly believe that the ever increasing knowledge in the field of neural and brain tumor stem cells should be influential in the subsequent attempts to classify brain tumors.