Cohen A, Burgos-Aceves MA, Smith Y. microRNAs Downregulation in Cancer is Associated with Guanine Enrichment in the
Terminal Loop Sequences of their Precursors.
Microrna 2017;
7:20-27. [PMID:
29237393 DOI:
10.2174/2211536607666171213122032]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Revised: 10/13/2017] [Accepted: 12/04/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND
microRNAs (miRNAs) are small noncoding segments of RNA that negatively regulate gene expression at the post-transcriptional level and fine-tune gene functions. A global repression in miRNA expression is a phenomenon observed in different types of cancer. In this study we aimed to reveal a possible association of miRNAs downregulation in cancer, with the guanine (G) content in the terminal loop (TL) sequences of their precursors.
METHODS
Lists of most significantly downregulated miRNAs in different tumor types, obtained from previously published microarray experiments, were selected for bioinformatics analysis. The complete precursor, TL, and mature miRNA sequences, were analyzed for evaluation of nucleotide composition and motif enrichment.
RESULTS
Herein, we show an association of miRNAs downregulation in cancer, with G enrichment in the TL sequences of their precursors. High G (and GG) content was mostly found in repressed miRNAs of breast, lung and ovary cancers, predominantly in poorly differentiated tumors. The mature sequences of repressed miRNAs had significantly low G content and were enriched with an ACA motif.
CONCLUSION
This study suggests a new link between G enrichment of precursor miRNAs TLs and carcinogenesis, and the possible association of specific sequence motifs with the regulation of their expression.
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