Unknown,Transcriptomics,Genomics,Proteomics

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Gene expression analysis of mesenchymal stem cells (MSC), osteoblasts and the U2OS (osteosarcoma) cell line

ABSTRACT: Transcriptional profiling of MSC, Osteoblasts and U2OS cells. The aim was to quantitate relative gene expression in MSC, osteoblasts and U2OS. MSC and osteoblasts were used as normal cells in this study because osteosarcoma most likely originates from MSC or osteoblasts. Cell culture and treatment: U2OS cells were cultured in McCoys 5A media (Invitrogen) containing 10% FBS. MSC and osteoblasts were cultured as described by Jaiswal et al. (J Cell Biochem 64, 295-312; 1997). Cells were treated with 5 uM 5-Azadeoxycytidine (5-Aza-CdR) or 300 nM Trischostatin-A (TSA) for 96 hours or 18 hours, respectively. Microarray analysis: Total RNA was extracted using the Qiagen kit according to the manufacturer's instructions, including a DNase step. RNA was quantified using the NanoDrop ND-100, followed by quality assessment with the 2100 Bioanalyzer (Agilent Technologies). RNA concentrations for individual samples were greater than 200ng/ul, with 28s/18s ratios greater than 2.2 and RNA integrity numbers of 10 (highest). Sample amplification and labeling procedures were carried out using the Low RNA Input Fluorescent Linear Amplification Kit (Agilent Technologies) according to the manufacturer's instructions. The labeled cRNA was purified using the RNeasy mini kit (Qiagen) and quantified. RNA spike-in controls (Agilent Technologies) were added to the RNA samples before amplification. 0.75 microgram of samples labeled with Cy3 or Cy5 were mixed with control targets (Agilent Technologies), assembled on Oligo Microarray, hybridized, and processed according to the Agilent microarray protocol. Scanning was performed with the Agilent Scanner G2505B under the default settings recommended by Agilent Technologies. Data analysis: All arrays were subject to the quality checks recommended by the manufacturer. Images were visually inspected for artifacts, and distributions of signal and background intensity of both red and green channels were examined to identify anomalous arrays. No irregularities were observed, and all arrays were retained and used. All calculations were performed using the R statistical computing platform and packages from the Bioconductor bioinformatics software project. To determine the expression levels of genes in MSC, Osteoblasts and U2OS, the data were LOWESS-normalized, the probe intensities of the mock channel (no drug treatment) were extracted and set to the same scale by quantile normalization. Mean of replicate samples were calculated for each probe.

ORGANISM(S): Homo sapiens

SUBMITTER: hari easwaran

PROVIDER: E-GEOD-27900 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The mammalian oocyte has the unique feature of supporting fertilization and normal development while being able of reprogramming the nuclei of somatic cells towards pluripotency and occasionally even totipotency. Whilst oocyte quality is known to decay with somatic aging it is not a given that different biological functions decay concurrently. In this study we tested whether oocyte reprogramming ability decreases with somatic aging. We show that oocytes isolated from mice aged beyond the usual reproductive age (climacteric) yield ooplasts that retain reprogramming capacity after somatic nuclear transfer (SCNT) at levels similar to ooplasts of young donors. Despite differences in transcriptome between ooplasts of old and young mice gene expression profiles of the resultant SCNT blastocysts were very similar. Furthermore albeit results showing global down-regulation of apoptosis-related genes in climacteric ooplasts and the reported beneficial effect of inhibiting p53 on transcription factor-induced (iPS) pluripotency reprogramming capacity of young ooplasts was not affected by specifically blocking p53. Our observations strongly suggest that the outcome of oocyte-induced reprogramming is determined by the availability of intrinsic reprogramming factors tightly regulated throughout aging as well as intracellular and environmental checkpoints during pre-implantation development towards selection of the successfully reprogrammed embryos. While oocytes are not regenerated but rather last for life we further propose that these cells can still be a resource for somatic reprogramming when they cease to be considered safe for sexual reproduction. Total mRNA was isolated for samples from young and climacteric mice (pools of 20 ooplasts and 20 SCNT blastocysts in duplicate) using a RNeasy Mini Kit (Qiagen Valencia CA USA) as described by the manufacturer (no DNase treatment). RNA concentrations as well as purity and integrity check were determined with Agilent Bioanalyzer 2100 and RNA Pico 6000 Lab-Chip Kit (Agilent Technologies Palo Alto CA USA). RiboAmp HS Plus Amplification Kit (MDS Analytical Technologies Ismaning Germany) was used to amplify the total mRNA with two rounds of amplification according to the manufacturerâ??s instructions. Amplified RNA was eluted with 15 ÂµL RE Buffer included in the RiboAmp HS Plus Amplification Kit. RNA concentrations were determined with Agilent Bioanalyzer 2100 and RNA Pico 6000 Lab-Chip Kit. Turbo Labeling CY3 Kit (MDS Analytical Technologies) was used to label 3 Âµg of amplified RNA with Cy3. Concentration and frequency of incorporation were measured with NanoPhotometer (Implen). Microarray wash and detection of the labeled RNA on GeneChips were carried out according to the manufacturerâ??s instructions (Agilent Technologies). Gene expression profiling was performed using Agilent Whole Mouse Genome Oligo Microarrays (4 x 44k each array containing 41174 features). Array image acquisition and feature extraction was performed using Agilent G2505B Microarray Scanner and Feature Extraction software v.9.5 (Agilent Technologies).

Project description:The identification and characterization of tumor suppressor genes has enhanced our understanding of the biology of cancer and enabled the development of new diagnostic and therapeutic modalities. Whereas in past decades, a handful of tumor suppressors have been slowly identified using techniques such as linkage analysis, large-scale sequencing of the cancer genome has enabled the rapid identification of a large number of genes that are mutated in cancer. However, determining which of these many genes play key roles in cancer development has proven challenging. Specifically, recent sequencing of human breast and colon cancers has revealed a large number of somatic gene mutations, but virtually all are heterozygous, occur at low frequency, and are tumor-type specific. Keywords: Microarray, Hypermethylome, DNA-hypermethylation, DAC, TSA, Epigenetic, Mutation, Colorectal Cancer, Breast Cancer The candidate hypermethylome genes were identified as described below. These genes were compared to the CAN genes identified by Sjöblom T et al (Science, 2006). Cell culture and treatment. For drug treatments, log phase MCF7, T-47D, MDA-MB231 and MDA-MB-468 cells were cultured in McCoys 5A media (Invitrogen) containing 10% BCS and 1x penicillin/streptomycin with 5M 5aza-deoxycytidine (DAC) (Sigma; stock solution: 1mM in PBS) for 96 hours, replacing media and DAC every 24 hours. Cell treatment with 300nM Trichostatin A (Sigma; stock solution: 1.5mM dissolved in ethanol) was performed for 18 hours. Control cells underwent mock treatment in parallel with addition of equal volume of PBS or ethanol without drugs. Microarray analysis. Total RNA was harvested from log phase cells using the Qiagen kit according to the manufacturers instructions, including a DNAase step. RNA was quantified using the NanoDrop ND-100 followed by quality assessment with 2100 Bioanalyzer (Agilent Technologies). RNA concentrations for individual samples were greater than 200ng/ul, with 28s/18s ratios greater than 2.2 and RNA integrity numbers of 10 (highest). Sample amplification and labeling procedures were carried out using the Low RNA Input Fluorescent Linear Amplification Kit (Agilent Technologies) according to the manufacturers instructions. The labeled cRNA was purified using the RNeasy mini kit (Qiagen) and quantified. RNA spike-in controls (Agilent Technologies) were added to RNA samples before amplification. 0.75 microgram of samples labeled with Cy3 or Cy5 were mixed with control targets (Agilent Technologies), assembled on Oligo Microarray, hybridized, and processed according to the Agilent microarray protocol. Scanning was performed with the Agilent G2565BA microarray scanner under default settings recommended by Agilent Technologies. Data analysis. All arrays were subject to quality checks recommended by the manufacturer. Images were visually inspected for artifacts and distributions of signal and background intensity of both red and green channels were examined to identify anomalous arrays. No irregularities were observed, and all arrays were retained and used. All calculations were performed using the R statistical computing platform and packages from Bioconductor bioinformatics software project. The log ratio of red signal to green signal was calculated and Loess normalization as implemented in the limma package from Bioconductor.

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Gene expression analysis of mesenchymal stem cells (MSC), osteoblasts and the U2OS (osteosarcoma) cell line

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