Unknown,Transcriptomics,Genomics,Proteomics

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MRNA expression data from human breast cancer cell lines after demethylation treatment.

ABSTRACT: The contribution of aberrant DNA methylation and the downstream effects in tumorogenesis through silencing of tumor suppressor genes (TSGs) and microRNAs has been investigated. Since these epigenetic alterations can be reversed, we investigated the effects of the epigenetic therapy in breast cancer cell lines. We used microarrays to investigate the global gene expression profile after demethylation treatment with 5-aza-2’-deoxycytidine (DAC) in breast cancer cell lines and identified distinct classes of early and late systematic stable or transient effects of the treatment. Three selected breast cell lines including MDA-MB231 (a highly aggressive cell line), SKBR3 (a non-aggressive cell line) and HB2 (a breast epithelial cell line as control) were subject for RNA isolation before treatment, after treatment with DAC and at five point follow-ups (1st, 3rd, 5th, 7th and 10th passages) at “drug holiday” condition and hybridized on Affymetrix microarrays.

ORGANISM(S): Homo sapiens

SUBMITTER: Ramin Radpour

PROVIDER: E-GEOD-28968 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Integrated epigenetics of human breast cancer: synoptic investigation of targeted genes, microRNAs and proteins upon demethylation treatment.

Radpour Ramin R Barekati Zeinab Z Kohler Corina C Schumacher Martin M MM Grussenmeyer Thomas T Jenoe Paul P Hartmann Nicole N Moes Suzette S Letzkus Martin M Bitzer Johannes J Lefkovits Ivan I Staedtler Frank F Zhong Xiao Yan XY

PloS one 20111104 11

<h4>Background</h4>The contribution of aberrant DNA methylation in silencing of tumor suppressor genes (TSGs) and microRNAs has been investigated. Since these epigenetic alterations are reversible, it became of interest to determine the effects of the 5-aza-2'-deoxycytidine (DAC) demethylation therapy in breast cancer at different molecular levels.<h4>Methods and findings</h4>Here we investigate a synoptic model to predict complete DAC treatment effects at the level of genes, microRNAs and prote ...[more]

PMID: 22076154

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Project description:Reversal of gene promoter DNA hypermethylation and associated abnormal gene silencing is an attractive approach to cancer therapy. The DNA methylation inhibitor, decitabine (5-aza-2'-deoxycitidine), is proving efficacious for hematological neoplasms especially at lower, less toxic, doses. Experimentally, high doses induce rapid DNA damage and cytotoxicity, but these may not explain the prolonged time to response seen in patients. Transient exposure of leukemic and solid tumor cells to clinically-relevant nanomolar doses, without causing immediate cytotoxicity or apoptosis, produces sustained reduced tumorigenicity, and for leukemia cells, diminished long-term self-renewal. These effects appear triggered by cellular reprogramming and include sustained decreases in promoter DNA methylation with associated gene re-expression, and anti-tumor changes in multiple key cellular regulatory pathways, most of which are high priority targets for pharmacologic anti-cancer strategies. Thus, low dose decitabine regimens appear to have broad applicability for cancer management. [Gene expression profiling] Leukemia cell lines Kasumi-1 and KG1A are treated with 10nM DAC during 72 hours and gene expression was assayed at day 3, 7 and 14 after the start of the treatment. Appropriate mock treated samples were used as control in each case. In addition, Kasumi-1 cells were also treated with a higher dose of DAC (500nM), 100nM ARA-C and 300 nM TSA, again controlled against mock treated Kasumi-1 cells, to separate dose and agent dependent effects. MCF7 was studied as an example of a solid tumor cell line. Therefore MCF7 cells were treated with 100nM DAC and results were assayed at day 1, day 3 and day 10. [Methylation profiling] The effects of the demethylating agent DAC were studied in the leukemia cell line Kasumi-1 over a 28 day time course. Intermediate time points were studied at days 3, 7, 14 and 21. These results were verfied in KG1A and KG1 leukemia cell lines, at one selected time point. The effects on one primary sample were also studied. Four normal leukemia samples (PL1, 2, 4 and 5) were used as general controls. The effect of DAC was compared to ARA-C, TSA. Both mock treated and day 3 DAC treated Kasumi-1 cells were repeated. These results were verified at one selected time point for the DAC treated MCF7 breast cancer cell line.

Project description:In this study we performed a systematic evaluation of functional miRNA-mRNA interactions associated with the aggressiveness of breast cancer cells using a combination of integrated miRNA and mRNA expression profiling, bioinformatics prediction, and functional assays. Analysis of the miRNA expression identified 11 miRNAs that were differentially expressed, including 7 down-regulated (miR-200c, miR-205, miR-203, miR-141, miR-34a, miR-183, and miR-375) and 4 up-regulated miRNAs (miR-146a, miR-138, miR-125b1 and miR-100), in aggressive cell lines when compared to normal and less aggressive cell lines. Transient overexpression of miR-200c, miR-205, and miR-375 in MDA-MB-231 cells led to the inhibition of cell migration and invasion. The integrated analysis of miRNA and mRNA expression identified 35 known and novel target genes of miR-200c, miR-205, and mir-375, including CFL2, LAMC1, TIMP2, ZEB1, CDH11, PRKCA, PTPRJ, PTPRM, LDHB, and SEC23A. Surprisingly, the majority of these genes (27 genes) were target genes of miR-200c, suggesting that it plays a more important role in regulating the aggressiveness of breast cancer cells. We characterized one of the target genes of miR-200c, CFL2, and demonstrated that CFL2 is overexpressed in aggressive breast cancer cell lines and can be significantly down-regulated by exogenous miR-200c. Tissue microarray analysis further revealed that CFL2 expression in primary breast cancer tissue correlated with tumor grade. To our knowledge, this study is the first systematic screening of functional miRNA target genes in aggressive breast cancer cells. The results obtained from this study may improve our understanding of the role of these candidate miRNAs and their target genes in relation to breast cancer aggressiveness and ultimately lead to the identification of novel biomarkers associated with prognosis. Affymetrix U133 plus arrays were performed according to the manufacturer's directions on RNA extracted from 12 breast cancer cell lines including 4 aggressive cell lines, 6 less aggressive cell lines and 2 imortalized breast epithelium cell lines

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Dataset Information

MRNA expression data from human breast cancer cell lines after demethylation treatment.

Publications

Integrated epigenetics of human breast cancer: synoptic investigation of targeted genes, microRNAs and proteins upon demethylation treatment.

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