Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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In vivo NCL-targeting affects breast cancer aggressiveness through miRNA regulation [NanoString]

ABSTRACT: Numerous studies have described the altered expression and the causal role of miRNAs in human cancer. However, to date efforts to modulate miRNA levels for therapeutic purposes have been challenging to implement. Here, we find that Nucleolin (NCL), a major nucleolar protein, post-transcriptionally regulates the expression of a specific subset of miRNAs, including miR-21, miR-221, miR-222, and miR-103, causally involved in breast cancer initiation, progression and drug-resistance. We also show that NCL is commonly overexpressed in human breast tumors, and its expression correlates with that of NCL-dependent miRNAs. Finally, this study indicates that NCL-binding guanosine-rich aptamers affect the levels of NCL-dependent miRNAs and their target genes, reducing breast cancer cell aggressiveness, both in vitro and in vivo. These findings illuminate a path to novel therapeutic approaches based on NCL-targeting aptamers for the modulation of miRNA expression in the treatment of breast cancer. HeLa cells were transfected with the control or anti-nucleolin siRNA. After 72hours total RNA was collected and analyzed by NanoString.

ORGANISM(S): Homo sapiens

SUBMITTER: Luciano Cascione

PROVIDER: E-GEOD-41971 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Modification of microRNA sequences by the 3' addition of nucleotides to generate so-called M-bM-^@M-^\isomiRsM-bM-^@M-^] adds to the complexity of miRNA function, with recent reports showing that 3' modifications can influence miRNA stability and efficiency of target repression. Here we show that the 3' modification of miRNAs is a physiological and common post-transcriptional event that shows selectivity for specific miRNAs and is observed across species ranging from C. elegans to human. The modifications result predominantly from adenylation and uridylation, and are seen across tissue types, disease states, and developmental stages. To quantitatively profile 3' nucleotide additions, we developed and validated a novel assay based on NanoString Technologies' nCounter platform. For certain miRNAs, the frequency of modification was altered by processes such as cell differentiation, indicating that 3' modification is a biologically regulated process. To investigate the mechanism of 3' nucleotide additions, we used RNA interference to screen a panel of eight candidate miRNA nucleotidyl transferases for 3' miRNA modification activity in human cells. Multiple enzymes, including PAPD1, PAPD4, PAPD5, ZCCHC6, ZCCHC11, and TUT1, were found to govern 3' nucleotide addition to miRNAs in a miRNA-specific manner. Three of these enzymesM-bM-^@M-^SPAPD1, ZCCHC6 and TUT1M-bM-^@M-^Shave not previously been known to modify miRNAs. Collectively, our results indicate that 3' modification observed in next generation small RNA sequencing data is a biologically relevant process, and identify enzymatic mechanisms that may lead to new approaches for modulating miRNA activity in vivo. We validated the specificity of the platform by assaying three pools of synthetic RNA oligonucleotides representing canonical, variant 1, and variant 2 versions of 5 miRNAs (miR-15a, miR-15b, miR-125a-5p, miR-143 and miR-221).Each bridge pool (i.e., specific to canonical, variant 1 or variant 2) was used to assay the three mixtures of synthetic miRNA oligonucleotides. In order to assess accuracy, we also assayed mixtures of 5 synthetic miRNAs containing 60% canonical miRNA, 30% variant 1, and 10% variant 2. Triplicate technical replicates of each sample were performed.

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In vivo NCL-targeting affects breast cancer aggressiveness through miRNA regulation [NanoString]

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