ABSTRACT: The goal of this study was to evalute the genetic regulations upon knok-down of VEGFR-2 in two different glioma cell lines in partiular focussing on genes related to glioma migration and invasion as well as resistance to chemotherapy. Total RNA obtained from glioma cells harbouring shVEGFR-2 knock-down compared to controls
Project description:We have used a chimeric VEGFR-2 in which the extracellular domain of mouse VEGFR-2 was replaced with the extracellular domain of human CSF-1 receptor. VEGFR-2 was immunoprecipitated with anti-VEGFR-2 antibody from PAE cells ectopically expressing VEGFR-2. The immunoprecipitated proteins were eluted and separated on SDS-PAGE, followed by in-gel chymotrypsin or trypsin digestion. The digested samples were analyzed by nano LC/MS/MS on a Thermo Fisher LTQ Orbitrap XL. The LC-MS/MS data were analyzed using Proteome Discoverer (Thermo Fisher Scientific; Version 126.96.36.1999). MS/MS search was carried out using Sequest search algorithm against the sequence of target mouse protein from the UniProtKB database. Search parameters included chymotrypsin as the enzyme with four missed cleavage allowed; methylation at lysine and arginine, phosphorylation of serine, threonine, and tyrosine, alkylation at cysteine, and oxidation of methionine were set as dynamic modifications. Precursor and fragment mass tolerance were set to 5 ppm and 0.8 Da, respectively. The false discovery rate was calculated by enabling the peptide sequence analysis using a decoy database. High confidence peptide identifications were obtained by setting a target false discovery rate threshold of 1% at the peptide level.
Project description:Loss of the tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a prerequisite for tumor cell-specific expression of vascular endothelial growth factor receptor (VEGFR)-2 in glioblastoma defining a subgroup prone to develop evasive resistance towards antiangiogenic treatments. Immunohistochemical analysis of human tumor tissues showed VEGFR-2 expression in glioma cells in 19% of specimens examined, mainly in the infiltration zone. Glioma cell VEGFR-2 positivity was restricted to PTEN-deficient tumor specimens. PTEN overexpression reduced VEGFR-2 expression in vitro, as well as knock-down of raptor or rictor. Genetic interference with VEGFR-2 revealed proproliferative, antiinvasive and chemoprotective functions for VEGFR-2 in glioma cells. VEGFR-2-dependent cellular effects were concomitant with activation of 'kappa-light-chain-enhancer' of activated B-cells, protein kinase B, and N-myc downstream regulated gene 1. Two-photon in vivo microscopy revealed that expression of VEGFR-2 in glioma cells hampers antiangiogenesis. Bevacizumab induces a proinvasive response in VEGFR-2-positive glioma cells. Patients with PTEN-negative glioblastomas had a shorter survival after initiation of bevacizumab therapy compared with PTEN-positive glioblastomas. Conclusively, expression of VEGFR-2 in glioma cells indicates an aggressive glioblastoma subgroup developing early resistance to temozolomide or bevacizumab. Loss of PTEN may serve as a biomarker identifying those tumors upfront by routine neuropathological methods.
Project description:MAZ51 is an indolinone-based molecule originally synthesized as a selective inhibitor of vascular endothelial growth factor receptor (VEGFR)-3 tyrosine kinase. This study shows that exposure of two glioma cell lines, rat C6 and human U251MG, to MAZ51 caused dramatic shape changes, including the retraction of cellular protrusions and cell rounding. These changes were caused by the clustering and aggregation of actin filaments and microtubules. MAZ51 also induced G2/M phase cell cycle arrest. This led to an inhibition of cellular proliferation, without triggering significant cell death. These alterations induced by MAZ51 occurred with similar dose- and time-dependent patterns. Treatment of glioma cells with MAZ51 resulted in increased levels of phosphorylated GSK3? through the activation of Akt, as well as increased levels of active RhoA. Interestingly, MAZ51 did not affect the morphology and cell cycle patterns of rat primary cortical astrocytes, suggesting it selectively targeted transformed cells. Immunoprecipitation-western blot analyses indicated that MAZ51 did not decrease, but rather increased, tyrosine phosphorylation of VEGFR-3. To confirm this unanticipated result, several additional experiments were conducted. Enhancing VEGFR-3 phosphorylation by treatment of glioma cells with VEGF-C affected neither cytoskeleton arrangements nor cell cycle patterns. In addition, the knockdown of VEGFR-3 in glioma cells did not cause morphological or cytoskeletal alterations. Furthermore, treatment of VEGFR-3-silenced cells with MAZ51 caused the same alterations of cell shape and cytoskeletal arrangements as that observed in control cells. These data indicate that MAZ51 causes cytoskeletal alterations and G2/M cell cycle arrest in glioma cells. These effects are mediated through phosphorylation of Akt/GSK3? and activation of RhoA. The anti-proliferative activity of MAZ51 does not require the inhibition of VEGFR-3 phosphorylation, suggesting that it is a potential candidate for further clinical investigation for treatment of gliomas, although the precise mechanism(s) underlying its effects remain to be determined.
Project description:Analysis of the effects of targeting NOS2 at the gene expression level. Our studies demonstrated a role for NOS2 in glioma biology through the maintenance of the glioma stem cell phenotype. Microarray results provide novel targets of NOS2 and suggest mechanisms through which NOS2 contributes to glioma stem cell biology. Glioma stem cells isolated from two different human glioma xenografts were infected with a non-targeting control shRNA or two different shRNAs directed against NOS2 (each treatment in each tumor performed in technical duplicates).
Project description:Extracellular matrix remodeling, degradation and glioma cell motility are critical aspects of glioblastoma multiforme (GBM). Despite being a rich source of potential biomarkers and targets for therapeutic advance, the dynamic changes within the extracellular environment that are specific to GBM cell motility have yet to be fully resolved. The gap junction protein connexin43 (Cx43) increases glioma migration and invasion in a variety of in vitro and in vivo models. In this study, the conditioned media of Cx43-expressing C6 rat glioma cells was found to increase the motility of the parental line. Demonstrating the selective engagement of ECM-remodelling pathways, secretome analysis revealed the near-binary expression of osteopontin and matrix metalloproteinase-3 (MMP3).
Project description:BACKGROUND: Glioma cells not only secrete high levels of vascular endothelial growth factor (VEGF) but also express VEGF receptors (VEGFR), supporting the existence of an autocrine loop. The direct impact on glioma cells metabolism of drugs targeting the VEGF pathway, such as Bevacizumab (Bev) or VEGFR Tyrosine Kinase Inhibitor (TKI), is poorly known. MATERIAL AND METHODS: U87 cells were treated with Bev or SU1498, a selective VEGFR2 TKI. VEGFR expression was checked with FACS flow cytometry and Quantitative Real-Time PCR. VEGF secretion into the medium was assessed with an ELISA kit. Metabolomic studies on cells were performed using High Resolution Magic Angle Spinning Spectroscopy (HR-MAS). RESULTS: U87 cells secreted VEGF and expressed low level of VEGFR2, but no detectable VEGFR1. Exposure to SU1498, but not Bev, significantly impacted cell proliferation and apoptosis. Metabolomic studies with HR MAS showed that Bev had no significant effect on cell metabolism, while SU1498 induced a marked increase in lipids and a decrease in glycerophosphocholine. Accordingly, accumulation of lipid droplets was seen in the cytoplasm of SU1498-treated U87 cells. CONCLUSION: Although both drugs target the VEGF pathway, only SU1498 showed a clear impact on cell proliferation, cell morphology and metabolism. Bevacizumab is thus less likely to modify glioma cells phenotype due to a direct therapeutic pressure on the VEGF autocrine loop. In patients treated with VEGFR TKI, monitoring lipids with magnetic resonance spectroscopic (MRS) might be a valuable marker to assess drug cytotoxicity.
Project description:Gliomas are mostly incurable secondary to their diffuse infiltrative nature. Thus, specific therapeutic targeting of invasive glioma cells is an attractive concept. As cells exit the tumor mass and infiltrate brain parenchyma, they closely interact with a changing micro-environmental landscape that sustains tumor cell invasion. In this study, we used a unique microarray profiling approach on a human glioma stem cell (GSC) xenograft model to explore gene expression changes in situ in invading glioma cells compared to tumor core, as well as changes in host cells residing within the infiltrated microenvironment relative to the unaffected cortex. Replicate sets of mice (n=4) were inoculated with either of two different GSC's derived from from human glioma, and each mouse had samples taken from the tumor mass, the infiltrating area and the mouse brain parenchyma, resulting in 3 samples per animal. The tumor mass and infiltrating samples were hybridized on human U133Plus2 Arrays, whereas the infiltrating samples and mouse brain parenchyma were hybridized on mouse
Project description:CircRNA is a novel type of RNA molecule formed by a covalently closed loop which have no 5'-3' polarity and possess no polyA tail and relatively stable due to the cyclic structure. Therefore, they may serve as potential targets and diagnosis biomarkers for tumor therapy. cZNF292 is an important circular oncogenic RNA and plays a critical role in the progression of tube formation. This study is aimed at exploring the role of cZNF292 in human glioma tube formation and its potential mechanism of action. We found that cZNF292 silencing suppresses tube formation by inhibiting glioma cell proliferation and cell cycle progression. Cell cycle progression in human glioma U87MG and U251 cells was halted at S/G2/M phase via the Wnt/?-catenin signaling pathway and related genes such as PRR11, Cyclin A, p-CDK2, VEGFR-1/2, p-VEGFR-1/2 and EGFR. The results suggest that cZNF292 silencing plays an important role in the tube formation process and has potential for application as a therapeutic target and biomarker in glioma.
Project description:Transcriptional profiling of human glioma cells comparing control GFP expressing cells with glioma cells transfected with a human PDGF-A gene. The isogenic cell lines were used to study the impact on glioma tumorigenesis and invasion. Goal was to determine the effects of PDGF-A gene transfection on global ES gene expression. Two set of glioma cell lines, LN444 vs LN444/PDGF-A and LN443 vs LN443/PDGF-A. Biological replicates: 2 control replicates, 2 transfected replicates.
Project description:We compared a large panel of human glioblastoma stem-like (GS) cell lines, corresponding primary tumors and conventional glioma cell lines to identify cell lines that preserve the transcriptome of human glioblastomas most closely, thereby allowing identification of shared therapeutic targets. We used Affymetrix HG-U133 Plus 2.0 microarrays to compare human glioblastoma stem-like (GS) cell lines, corresponding primary tumors and conventional glioma cell lines. We extracted total RNA from 32 conventional glioma cell lines, 12 GS cell lines (8 in two different passages), 7 clonal sublines derived from two GS lines, 12 original tumors, and 4 monolayer cultures established from the same tumors as GS-lines using standard serum conditions.