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International Journal of Cell Biology
Volume 2012 (2012), Article ID 672462, 9 pages
http://dx.doi.org/10.1155/2012/672462
Research Article

Distinct MicroRNA Subcellular Size and Expression Patterns in Human Cancer Cells

1Laboratory of Bioinformation and Noncoding RNA and Center for Systems Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
2Graduate University of Chinese Academy of Sciences, Beijing 100080, China

Received 27 July 2011; Accepted 9 November 2011

Academic Editor: Ivana De La Serna

Copyright © 2012 Beibei Chen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Introduction. Small noncoding RNAs have important regulatory functions in different cell pathways. It is believed that most of them mainly play role in gene post-transcriptional regulation in the cytoplasm. Recent evidence suggests miRNA and siRNA activity in the nucleus. Here, we show distinct genome-wide sub-cellular localization distribution profiles of small noncoding RNAs in human breast cancer cells. Methods. We separated breast cancer cell nuclei from cytoplasm, and identified small RNA sequences using a high-throughput sequencing platform. To determine the relationship between miRNA sub-cellular distribution and cancer progression, we used microarray analysis to examine the miRNA expression levels in nucleus and cytoplasm of three human cell lines, one normal breast cell line and two breast cancer cell lines. Logistic regression and SVM were used for further analysis. Results. The sub-cellular distribution of small noncoding RNAs shows that numerous miRNAs and their isoforms (isomiR) not only locate to the cytoplasm but also appeare in the nucleus. Subsequent microarray analyses indicated that the miRNA nuclear-cytoplasmic-ratio is a significant characteristic of different cancer cell lines. Conclusions. Our results indicate that the sub-cellular distribution is important for miRNA function, and that the characterization of the small RNAs sub-cellular localizome may contribute to cancer research and diagnosis.