Unknown,Transcriptomics,Genomics,Proteomics

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Lenti-miR Library WiDR, Pre vs Post Intrahepatic Selection

ABSTRACT: Cells were transduced with a lentiviral Lenti-miR library composed of 661 miRNAs (System Biosciences) at a low multiplicity of infection (MOI) such that each cell over-expressed a single miRNA. The transduced population was then injected intra-hepatically into NOD-SCID mice for in vivo selection of miRNAs that when over-expressed, either promoted or suppressed metastatic liver colonization. Genomic DNA PCR amplication and recovery of lenti-viral miRNA inserts was performed on cells prior to injection, and from liver nodules, according to the manufacturer’s protocol. miRNA array profiling allowed for miRNA insert quantification prior to and subsequent to in vivo selection. To use an unbiased approach to identify regulators of colon cancer metastasis, we transduced a population of colon cancer cells, WiDR, with a lenti-miR library comprising of 661 human miRNAs, such that each individual cells over-express a single miRNA. The heterogenous population is then injected into the liver of immunodeficient mice. We theorized that cells over-expressing miRNAs that modulate colon cancer metastais will have differential representation in the whole population compared to a reference pool of cells. miRNAs that suppressed colon cancer metastasis will be lost in the resulting pool, while miRNAs that promote metastasis will be over-represented compared to the reference pool. Replicate pools of cells were transduced and injected into mice. After a period of 3-5 weeks, liver nodules were taken out and processed for lenti-viral derived miRNA profiling (Post samples) and compared to the reference pool of cells that were not injected into the mice (Pre Samples). The changes in miRNA representation between cells that underwent liver colonization were analyzed.

ORGANISM(S): Homo sapiens

SUBMITTER: Jia Min Loo

PROVIDER: E-GEOD-56319 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Originally linked with development and differentiation, the role of microRNAs (miRNAs) in many important biological processes has emerged and dysregulation of miRNA expression has been connected with cancer pathogenesis. The association between abnormal expression levels of miRNAs and colon cancer has been mainly demonstrated in primary tumors; more recently, non-overlapping sets of oncomirs, tumour suppressor miRNAs and metastamirs have been associated with distinct stages of colo-rectal cancer (CRC) progression. In an attempt to identify changes in both miRNA and gene expression levels along the colon mucosa - primary tumor - liver metastasis- sequence and to classify miRNAs into distinct functional networks according to the expression of their anti-correlated and differentially expressed target genes, we analyzed a large set of sample-matched miRNA and mRNA expression profiles, including the complete non tumor tissue, primary carcinoma and liver metastasis sequence from 8 patients. Our study shows that the largest changes in miRNA and gene expression levels occur in normal mucosa to tumor transition and are almost stably maintained in the subsequent tumor to metastasis transition. Only a few miRNAs were differentially expressed between liver metastasis and primary carcinoma; however, miRNA expression profiles classified better primary tumors and metastases compared to mRNA profiles. By integration of miRNAs and target genes expression data, we were able to infer regulatory networks modulated by miRNAs during colorectal tumorigenesis and metastatic process, and associate them to the affected biological pathways. In particular, we identified a combination of interconnected miRNAs, up- or down-regulated during tumorigenesis, which are organized into distinct sub-networks, each of which includes several regulatory relationships with differentially expressed genes. Among them, the relationship between miR-182, up-regulated in colon cancer, and the anti-correlated ENTPD5 gene was identified for the first time and confirmed in an independent set of samples.

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Lenti-miR Library WiDR, Pre vs Post Intrahepatic Selection

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