Unknown,Transcriptomics,Genomics,Proteomics

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Identification of a microRNA expression signature for radiochemosensitivity of colorectal cancer cells, involving miRNAs-320a, -224, -132 and let7g

ABSTRACT: Purpose: Preoperative 5-fluorouracil (5-FU) based radiochemotherapy (RCT) represents the standard treatment for locally advanced rectal cancer. Both, tumor response and progression vary considerably. MicroRNAs represent master regulators of gene expression, and may therefore contribute to this heterogeneity. Results: Thirty-six miRNAs were identified to significantly correlate with sensitivity of CRC cell lines to RCT (q < 0.05). This list included miR320a as most significantly correlated as well as other miRNAs involved in the MAPK-, TGF- and Wnt-pathway. Importantly, transfection of selected miRNAs (let7g, miR-132, miR-224, miR-320a and miR-429) each induced a shift of sensitivity (p<0.00001). Moreover, high expression of miR-224 was associated with a poor prognosis in rectal cancer patients (p=0.043). Experimental design: Genome-wide microRNA (miRNA) profiling was performed from 12 colorectal cancer (CRC) cell lines. To establish an in vitro signature of radiochemosensitivity, these profiles were correlated to the individual sensitivities of each cell line to 5-FU and radiation. The functional relevance of selected miRNAs was validated by transfecting miRNA-mimics into SW480 cells, followed by treatment with 5-FU and radiation. 12 Samples with 3 replicates each.

ORGANISM(S): Homo sapiens

SUBMITTER: Frank Kramer

PROVIDER: E-GEOD-40976 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:A summary of the work associated to these microarrays is the following: MicroRNAs (miRNAs) are small non-coding RNAs involved in RNA silencing that play a role in many biological processes. They are involved in the development of many diseases, including cancer. Extensive experimental data show that they play a role in the pathogenesis of cancer as well as the development of drug resistance during treatment. MiRNA microarrays of sensitive and MTX-resistant HT29 colon cancer cells were performed. The results were analyzed using the GeneSpring GX11.5 software. Differentially expressed microRNAs in resistant cells were identified and miR-224, which was greatly underexpressed and displayed robust raw signal values, was selected for further studies. Putative targets were predicted using TargetScan 5.1 software and intersected with the data from expression microarrays previously performed. This approach allowed us to identify miR-224 targets that were differentially expressed more than 2-fold in resistant cells. Among them, ARL3, CDS2, DCP2, HSPC159, MYST3 and SLC4A4 were validated at the mRNA level by qRT-PCR. Functional assays using an anti-miR against miR-224 desensitized the cells toward MTX, mimicking the resistant phenotype. On the other hand, siRNA treatment against SLC4A4 or incubation of Poly Purine Reverse Hoogsteen (PPRH) hairpins against CDS2 or HSPC159 increased sensitivity to MTX. These results revealed a role for miR-224 and its targets in MTX resistance in HT29 colon cancer cells. KEYWORDS Methotrexate, miRNAs, drug resistance, DHFR Two cell lines are compared in the study, which are HT29 colon cancer cells sensitive to methotrexate and HT29 cells resistant to 10e-5M MTX. Six samples are provided which correspond to 3 samples for the control condition and 3 samples for the resistant condition. Data files from miRNA and mRNA (previously submitted to GEO as GSE11440) microarrays were analyzed with GeneSpring GX11.5 software (Agilent Technologies) to find differentially expressed miRNAs and their cellular target genes in the resistant cell lines compared to their sensitive counterparts.

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Identification of a microRNA expression signature for radiochemosensitivity of colorectal cancer cells, involving miRNAs-320a, -224, -132 and let7g

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