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Expression profiling of glioma initiating cells (GICs) in the sphere and differentiation conditions

ABSTRACT: Glioma initiating cells (GICs) are considered responsible for the therapeutic resistance and recurrence of malignant glioma. To clarify the molecular mechanism of GIC maintenance/differentiation, we established GIC clones from GBM patient tumors having the potential to differentiate into malignant gliomas in mouse intracranial xenograft, and established an in vitro glioma induction system by using serum stimulation. Upon the serum stimulation, the GIC spheres showed increased cellular proliferation, motility, filopodia/lameripodia formation and adhesion to the culture dishes. Simultaneously, the NSC marker proteins such as CD133 and Sox2 were down-regulated, and the astrocyte/glioma marker GFAP and the malignancy marker CD44 dramatically up-regulated. To identify genes/proteins whose expression changes dynamically during the differentiation of GICs into glioma cells, these GICs were subjected to DNA microarray/iTRAQ based integrated proteomics. Within 4 hours of tumor removal from GBM patients, tissues were subjected to GIC preparation. After successive cloning, total RNA from GIC clones (GIC03A and GIC03U) on day 2 or 7 of subculture in NSC medium with or without 10% FCS was subjected to the analysis with Affymetrix microarrays. Simultaneously, the proteins extracted from the same set of cells were subjected to LC-shot gun analyses using the 8-plex iTRAQ method. We sought to obtain the information of the common molecules that were up- or down-regulated during the GSC differentiation process, and functional targets for the early onset of GIC-associated glioma.

ORGANISM(S): Homo sapiens

SUBMITTER: araki norie

PROVIDER: S-ECPF-GEOD-43762 | biostudies-other |

REPOSITORIES: biostudies-other

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Project description:BackgroundCD44 is a molecular marker associated with cancer stem cell populations and treatment resistance in glioma. More effective therapies will result from approaches aimed at targeting glioma cells high in CD44.MethodsGlioma-initiating cell lines were derived from fresh surgical glioblastoma samples. Expression of tissue transglutaminase 2 (TGM2) was attenuated through lentivirus-mediated short hairpin RNA knockdown. MTT assay [(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] was used to evaluate the growth inhibition induced by TGM2 inhibitor. Terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling was used to evaluate cell apoptosis following TGM2 inhibition. CD44(+) glioma stem cells were sorted by flow cytometry. A nude mice orthotopic xenograft model was used to evaluate the in vivo effect of TGM2 inhibitor.ResultsTGM2 was highly expressed in CD44-high glioblastoma tissues and tumor-derived glioma-initiating cell lines. TGM2 knockdown impaired cell proliferation and induced apoptosis in CD44-high glioma-initiating cell lines. Further studies indicated that expression of inhibitor of DNA binding 1 protein (ID1) is regulated by TGM2 and might be an important mediator for TGM2-regulated cell proliferation in CD44-high glioma-initiating cell lines. TGM2 inhibitor reduces ID1 expression, suppresses cell proliferation, and induces apoptosis in CD44-high glioma-initiating cell lines. Furthermore, TGM2 is highly expressed in CD44(+) glioma stem cells, while pharmacological inhibition of TGM2 activity preferentially eliminates CD44(+) glioma stem cells. Consistently, TGM2 inhibitor treatment reduced ID1 expression and induced apoptosis in our orthotopic mice xenograft model, which can be translated into prolonged median survival in tumor-bearing mice.ConclusionsTGM2 regulates ID1 expression in glioma-initiating cell lines high in CD44. Targeting TGM2 could be an effective strategy to treat gliomas with high CD44 expression.

Project description:Tumor heterogeneity of high-grade glioma (HGG) is recognized by four clinically relevant subtypes based on core gene signatures. However, molecular signaling in glioma stem cells (GSCs) in individual HGG subtypes is poorly characterized. Previously we identified and characterized two mutually exclusive GSC subtypes with distinct activated signaling pathways and biological phenotypes. One GSC subtype presented with a gene signature resembling Proneural (PN) HGG, whereas the other was similar to Mesenchymal (Mes) HGG. Classical HGG-derived GSCs were sub-classified as either one of these two subtypes. Differential mRNA expression analysis of PN and Mes GSCs identified 5,796 differentially expressed genes, revealing a pronounced correlation with the corresponding PN or Mes HGGs. Mes GSCs displayed more aggressive phenotypes in vitro and as intracranial xenografts in mice. Further, Mes GSCs were markedly resistant to radiation compared with PN GSCs. Expression of ALDH1A3 - one of the most up-regulated Mes representative genes and a universal cancer stem cell marker in non-brain cancers - was associated with self-renewal and a multi-potent stem cell population in Mes but not PN samples. Moreover, inhibition of ALDH1A3 attenuated the growth of Mes but not PN GSCs in vitro. Lastly, radiation treatment of PN GSCs up-regulated Mes-associated markers and down-regulated PN-associated markers, whereas inhibition of ALDH1A3 attenuated an irradiation-induced gain of Mes identity in PN GSCs in vitro. Taken together, our data suggest that two subtypes of GSCs, harboring distinct metabolic signaling pathways, represent intertumoral glioma heterogeneity and highlight previously unidentified roles of ALDH1A3-associated signaling that promotes aberrant proliferation of Mes HGGs and GSCs. Inhibition of ALDH1A3-mediated pathways therefore might provide a promising therapeutic approach for a subset of HGGs with the Mes signature. Here, we describe the gene expression analysis, including pre-processing methods for the data published by Mao and colleagues in PNAS [1], integration of microarray data from this study with The Cancer Genome Atlas (TCGA) glioblastoma data and also with another published study.

Project description:Glioma initiating cells (GICs) are considered responsible for the therapeutic resistance and recurrence of malignant glioma. To clarify the molecular mechanism of GIC maintenance/differentiation, we established GIC clones having the potential to differentiate into malignant gliomas, and subjected to DNA microarray/iTRAQ based integrated proteomics. 21,857 mRNAs and 8,471 proteins were identified and integrated into a gene/protein expression analysis chart. Gene Ontology analysis revealed that the expression of cell adhesion molecules, including integrin subfamilies, such as ?2 and ?V, and extracellular matrices (ECMs), such as collagen IV (COL4), laminin ?2 (LAMA2), and fibronectin 1 (FN), was significantly upregulated during serum-induced GIC differentiation. This differentiation process, accompanied by the upregulation of MAPK as well as glioma specific proteins in GICs, was dramatically accelerated in these ECM (especially FN)-coated dishes. Integrin ?V blocking antibody and RGD peptide significantly suppressed early events in GIC differentiation, suggesting that the coupling of ECMs to integrin ?V is necessary for GIC differentiation. In addition, the expression of integrin ?V and its strong ligand FN was prominently increased in glioblastomas developed from mouse intracranial GIC xenografts. Interestingly, during the initial phase of GIC differentiation, the RGD treatment significantly inhibited GIC proliferation and raised their sensitivity against anti-cancer drug temozolomide (TMZ). We also found that combination treatments of TMZ and RGD inhibit glioma progression and lead the longer survival of mouse intracranial GIC xenograft model. These results indicate that GICs induce/secrete ECMs to develop microenvironments with serum factors, namely differentiation niches that further stimulate GIC differentiation and proliferation via the integrin recognition motif RGD. A combination of RGD treatment with TMZ could have the higher inhibitory potential against the glioma recurrence that may be regulated by the GICs in the differentiation niche. This study provides a new perspective for developing therapeutic strategies against the early onset of GIC-associated glioma.

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Expression profiling of glioma initiating cells (GICs) in the sphere and differentiation conditions

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