Unknown,Transcriptomics,Genomics,Proteomics

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Expression data of medulloblastoma cell lines with OCT4A overexpression

ABSTRACT: Medulloblastoma is a highly aggressive pediatric brain tumor, in which expression of the pluripotency factor OCT4 has been recently correlated with poor patient survival. However, the contribution of OCT4 transcript variants to tumor aggressiveness is still poorly understood. In this study, we found that transcripts encoding OCT4A, but not OCT4B or OCT4B1, were significantly correlated with LIN28A expression, which encodes another well-known pluripotency factor. LIN28A was found to specifically bind OCT4A transcripts and interact with poly(A) binding protein and RNA helicase A in polysomal fractions of medulloblastoma cells, favoring increased OCT4A protein levels in these cells. Medulloblastoma cells stably overexpressing OCT4A displayed significantly enhanced clonogenic activity, tumorsphere generation and invasion capability, as well as increased tumorigenicity. In an orthotopic metastatic model of medulloblastoma, OCT4A overexpressing cells generated more developed, aggressive and infiltrative tumors, with tumor-bearing mice attaining advanced metastatic disease and shorter survival rates. Pro-oncogenic effects of OCT4A were found to be expression-level dependent and accompanied by distinct subchromosomal aberrations and differential expression of newly discovered, still poorly characterized, non-coding RNAs. Altogether, our findings support the relevance of pluripotency-related factors in the aggravation of medulloblastoma traits classically associated with poor clinical outcome, and underscore the prognostic and therapeutic value of OCT4A in this challenging type of pediatric brain cancer. Total RNA of 2-3 clones of each cell line (Control and OCT4A overexpression) was extracted with the RNeasy Mini kit (Qiagen), following the manufacturerâs protocol. Gene expression profiling was carried out independently for each sample using Affymetrix GeneChipÂ® Human Gene 2.0 ST whole-transcript arrays (Affymetrix, Santa Clara, CA, USA). The quality control and normalization of data were processed by AffymetrixÂ® Expression Console Software (Affymetrix). Differentially expressed genes were identified with the One-Way ANOVA, with a p-value cutoff of 0.05, using Transcriptome Analysis Console v3.0 (Affymetrix).

ORGANISM(S): Homo sapiens

SUBMITTER: Oswaldo Okamoto

PROVIDER: E-GEOD-77947 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Medulloblastoma is subdivided into different subgroups: WNt, SHH, Group 3 and Group 4. Since these subgroups are associated with different OS and metastasis rates it is crucial to understand them better. Six medulloblastoma cell lines, DAOY, ONS-76, D458, HD-MB03, CHLA-01-MED, CHLA-01R-MED, have been sequenced to compare them with medulloblastoma patient data. Methods: Medulloblastoma cell lines representating the different subgroups have been cultured and cell were harvested and RNA was isolated when 70% confluency was reached. In detail, DAOY and D458 were grown in DMEM (Thermo Fisher) with 10% FBS (HyClone, Thermo Fisher), ONS-76 and HD-MB03 were grown in RPMI 1640 (Sigma-Aldrich) with 10% FBS and CHLA-01-MED and CHLA-01R-MED were grown in DMEMF12 supplemented with B27, 20 ng/ml EGF and 20 ng/ml bFGF (all Thermo Fisher). All cells were maintained at 37 °C in a humidified atmosphere containing 5% CO2. During the course of this study, all cell lines were routinely confirmed to be mycoplasma negative (MycoAlert, Lonza, Basel, Switzerland).Cell pellets of at least 100,000 cells were washed with HBSS and frozen in liquid nitrogen. For homogenization, ceramic spheres (Lysing Matrix D, MP Biomedicals, Santa Ana, California, USA) and the FastPrep-24 homogenizer was used (MP Biomedicals, speed 4 m/s, tube holder MP:24*2 and time 20 s). Total RNA was isolated from 2D pellets using the NucleoSpin RNA Plus Kit (Macherey-Nagel, Düren, Germany) according to the manufacturer’s instructions. In total, 3 biological replicates of each cell line were processed respectively. RNA amount was determined using the Qubit RNA BR kit with the Qubit 4 (both ThermoFisher). Library preparation and RNA sequencing (transcriptome sequencing including lncRNA on Illumina PE150) were performed by Novogene (Cambridge, UK) Company Limited, Cambridge, UK. Samples with less than 100 ng or with non-qualifying RIN values were excluded from the sequencing. All prepared libraries successfully passed Novogene’s internal quality control checks and were sequenced. Following sequencing, quality control of the sequencing data was performed that confirmed all samples had high quality scores, indicating good technical performance of the sequencing. We used FastQC to perform quality checks of raw RNA data followed by adapter and low quality read filtering using the Cutadapt package (version 1.16.6) [reference]. The trimmed paired-end sequences were aligned with the human genome (hg38) and Gencode annotation (v35) using the STAR (version 2.7.5b) alignment tool. Unique reads from genomic alignment were processed and we used the featureCount tool for transcript abundance quantification. STAR read counts were used as input into edgeR. Genes with read counts greater than 10 in three or more samples were kept for subsequent analyses. After normalization analyses, counts per million (cpm) on a log2 scale were used for downstream exploratory analyses.

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Expression data of medulloblastoma cell lines with OCT4A overexpression

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