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Circular RNAs and their associations with breast cancer subtypes
Journal article   Open access   Peer reviewed

Circular RNAs and their associations with breast cancer subtypes

Asha A Nair, Nifang Niu, Xiaojia Tang, Kevin J Thompson, Liewei Wang, Jean-Pierre Kocher, Subbaya Subramanian and Krishna R Kalari
Oncotarget, Vol.7(49), pp.80967-80979
12/06/2016
DOI: 10.18632/oncotarget.13134
PMCID: PMC5348369
PMID: 27829232
url
https://doi.org/10.18632/oncotarget.13134View
Published (Version of record) Open Access

Abstract

Circular RNAs (circRNAs) are highly stable forms of non-coding RNAs with diverse biological functions. They are implicated in modulation of gene expression thus affecting various cellular and disease processes. Based on existing bioinformatics approaches, we developed a comprehensive workflow called Circ-Seq to identify and report expressed circRNAs. Circ-Seq also provides informative genomic annotation along circRNA fused junctions thus allowing prioritization of circRNA candidates. We applied Circ-Seq first to RNA-sequence data from breast cancer cell lines and validated one of the large circRNAs identified. Circ-Seq was then applied to a larger cohort of breast cancer samples (n = 885) provided by The Cancer Genome Atlas (TCGA), including tumors and normal-adjacent tissue samples. Notably, circRNA results reveal that normal-adjacent tissues in estrogen receptor positive (ER+) subtype have relatively higher numbers of circRNAs than tumor samples in TCGA. Similar phenomenon of high circRNA numbers were observed in normal breast-mammary tissues from the Genotype-Tissue Expression (GTEx) project. Finally, we observed that number of circRNAs in normal-adjacent samples of ER+ subtype is inversely correlated to the risk-of-relapse proliferation (ROR-P) score for proliferating genes, suggesting that circRNA frequency may be a marker for cell proliferation in breast cancer. The Circ-Seq workflow will function for both single and multi-threaded compute environments. We believe that Circ-Seq will be a valuable tool to identify circRNAs useful in the diagnosis and treatment of other cancers and complex diseases.
Biomarkers, Tumor - genetics Biomarkers, Tumor - metabolism Breast Neoplasms - genetics Breast Neoplasms - metabolism Breast Neoplasms - pathology Cell Proliferation Computational Biology Databases, Genetic Female Gene Expression Regulation, Neoplastic Genetic Predisposition to Disease Humans MCF-7 Cells Phenotype Receptors, Estrogen - metabolism RNA - genetics RNA - metabolism Sequence Analysis, RNA - methods Workflow

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