Unknown,Transcriptomics,Genomics,Proteomics

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A Distinct Reactive Oxygen Species Profile confers Chemoresistance in Glioma-Propagating Cells and Associates with Patient Survival Outcome

ABSTRACT: Aims: We explore the role of elevated O2-:H2O2 ratio as a prosurvival signal in glioma-propagating cells (GPCs). We hypothesize that depleting this ratio sensitizes GPCs to apoptotic triggers. Results: We observed that elevated O2-:H2O2 ratio conferred enhanced resistance in GPCs, and depletion of this ratio by pharmacological and genetic methods sensitized cells to apopotic triggers. We established the ROS Index as a quantitative measure of normalized O2-:H2O2 ratio and determined its utility in predicting chemosensitivity. Importantly, mice implanted with GPCs of reduced ROS Index demonstrated extended survival. Analysis of tumor sections revealed effective targeting of CD133- and nestin-expressing neural precursors. Furthermore, we established the Connectivity Map to interrogate a gene signature derived from varied ROS Index for patterns of association with individual patient gene expression in 2 clinical databases. We showed that patients with reduced ROS Index demonstrate better survival. These data provide clinical evidence for the viability of our O2-:H2O2-mediated chemosensitivity profiles. Innovation and Conclusion: Gliomas are notoriously recurrent and highly infiltrative, and have been shown to arise from stem-like cells. We implicate elevated O2-:H2O2 ratio as a prosurvival signal in GPC self-renewal and proliferation. The ROS Index provides quantification of O2-:H2O2-mediated chemosensitivity, an advancement in a previously qualitative field. Intriguingly, glioma patients with reduced ROS Index correlate with longer survival and the Proneural molecular classification, a feature frequently associated with tumors of better prognosis. These data emphasize the feasibility of manipulating the O2-:H2O2 ratio as a therapeutic strategy. Total RNA from primary neurosphere culture of brain tumor specimens treated with DPI and DDC as well as non-treated CD133+ and CD133- fractions were compared. Specimens were obtained from 3 patients and replicate arrays were performed for all 3 neurosphere cultures.

ORGANISM(S): Homo sapiens

SUBMITTER: Felicia Ng

PROVIDER: E-GEOD-32335 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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A distinct reactive oxygen species profile confers chemoresistance in glioma-propagating cells and associates with patient survival outcome.

Koh Lynnette Wei-Hsien LW Koh Geraldene Rong-Hui GR Ng Felicia Soo-Lee FS Toh Tan Boon TB Sandanaraj Edwin E Chong Yuk Kien YK Phong Mark M Tucker-Kellogg Greg G Kon Oi Lian OL Ng Wai Hoe WH Ng Ivan Hua-Bak IH Clement Marie-Veronique MV Pervaiz Shazib S Ang Beng Ti BT Tang Carol Soo-Leng CS

Antioxidants & redox signaling 20130412 18

<h4>Aims</h4>We explore the role of an elevated O2(-):H2O2 ratio as a prosurvival signal in glioma-propagating cells (GPCs). We hypothesize that depleting this ratio sensitizes GPCs to apoptotic triggers.<h4>Results</h4>We observed that an elevated O2(-):H2O2 ratio conferred enhanced resistance in GPCs, and depletion of this ratio by pharmacological and genetic methods sensitized cells to apoptotic triggers. We established the reactive oxygen species (ROS) Index as a quantitative measure of a no ...[more]

PMID: 23477542

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Project description:Brain tumors are among the most malignant cancers and can arise from neural stem cells or oligodendrocyte progenitor cells (OPCs). Glioma-propagating cells (GPCs) that have stem-like properties have been derived from tumor variants such as glioblastoma multiforme (GBM) and oligodendroglial tumors, the latter being more chemosensitive with better prognosis. It has been suggested that such differences in chemosensitivity arise from the different profiles of OPCs versus neural stem cells. We thus explored if GPCs derived from these glioma variants can serve as reliable in vitro culture systems for studies. We utilized gene expression analyses, since GBM and oligodendrogliomas can be molecularly classified. Accordingly, we derived a gene signature distinguishing oligodendroglial GPCs from GBM GPCs collated from different studies, which was enriched for the Wnt, Notch and TGF-beta pathways. Using a novel method in glioma biology, the Connectivity Map, we mapped the strength of gene signature association with patient gene expression profiles in 2 independent glioma databases [GSE16011, http://caintegrator-info.nci.nih.gov/rembrandt]. Our gene signature consistently stratified survival in glioma patients. This data would suggest that in vitro low passage GPCs are similarly driven by transcriptomic changes that characterize the favorable outcome of oligodendrogliomas over GBM. Additionally, the gene signature was associated with the 1p/19q co-deletion status, the current clinical indicator of chemosensitivity. Our gene signature detects molecular heterogeneity in oligodendroglioma patients that cannot be accounted for by histology or the 1p/19q status alone, and highlights the limitation of morphology-based histological analyses in tumor classification, consequently impacting on treatment decisions. Total RNA obtained from primary neurosphere culture from brain tumor specimens of 6 patients were compared. Replicate arrays were performed for all 6 neurosphere cultures.

Project description:BACKGROUND: Several in vitro assays have been used to identify “cancer stem cells” (CSC), including expression of cell surface markers and Hoechst dye efflux properties. However, each of these methods has potential pitfalls that complicate interpretation of the results. Focusing on colon cancers (CC), the CD133 antigen has been proposed as a marker of colon CSC. However, conflicting results have been reported in the literature indicating the need of a systematic analysis of CSC within CC and a complete validation of markers for the isolation of these cells. AIMS: Aim of this study was to confirm that CD133 expression is a valid method for isolating CSC in CC and verify if other antigens can increase the specificity of this marker for isolating CSC in CC. METHODS: CD133+ and CD133- cells were isolated from different human CC lines (CaCo-2, HT29, LOVO, HCT-116) by FACS sorter and the tumor-initiating potential of CD133+ cells was assessed in vitro, by soft-agar colony formation assay, and in vivo, upon transplantation into nude mice. Furthermore, the gene expression profile of CD133+ versus CD133- CaCo-2 cells was compared by the means of microarray analysis. Then, in the effort to identify a common “tumor stem cell” signature for CC, the most relevant transcripts resulting from gene expression profiling on CD133+ cells was assessed by real-time PCR on SP-fraction isolated by FACS sorter from the same CC cell lines. Finally, we deplete CD133 expression in the CaCo-2 cell line by the means of siRNA and verified by Western Blot analysis whether there was a functional correlation between CD133 and the target genes. Moreover, CaCo-2 and HCT116 cells were exposed to sodium butyrate (NaBu) for 72h. Colon cells differentiation was assessed by Alkaline phosphatase activity and expression of CD133 and target genes was tested by western blot. RESULTS: We confirmed that only CD133+ cells have a tumor-initiating potential in vitro and in vivo. Furthermore, microarray analysis of CD133+ versus CD133- CaCo-2 cells revealed a significant overexpression of various transcripts involved in cell proliferation, invasion and stemness in CD133+ cell fraction. Comparison of the transcripts by real-time PCR revealed that the genes of Endothelin-1 (END-1) and NR4A2 are highly expressed in both CD133 + cells and in SP fractions. Finally, when we deplete CD133 expression in Caco-2cells by siRNA, we observed a significant attenuation of END-1 and NR4A2 expression, thus demonstrating that CD133 is involved in the transcriptional regulation of these genes. Interestingly, we also showed that the expression of all three genes was inversely correlated with cell differentiation status as demonstrated by the fact that their expression decreases in a time- and dose-dependent manner after differentiation induced by NaBu. CONCLUSION: Overall, this study confirms the role of CD133antigen as CSC marker and showed for the first time the existence of a functional relationship between CD133, END-1 and NR4A2 expression, hypothesizing that CD133 is involved in the transcriptional regulation of these gene. Microarray analysis was performed on CD133+ and CD133- sorted CACO-2 cells. For both fractions, cells were sorted three independent times. Sample preparation was performed according to Affymetrix recommendations. A total of 6 arrays were hybridized, including 3 CD133+ replicates and 3 CD133- replicates.

Dataset Information

A Distinct Reactive Oxygen Species Profile confers Chemoresistance in Glioma-Propagating Cells and Associates with Patient Survival Outcome

Publications

A distinct reactive oxygen species profile confers chemoresistance in glioma-propagating cells and associates with patient survival outcome.

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