Circular RNAs in thoracic diseases.

Circular RNAs (circRNAs) are a class of noncoding RNAs with continuous, covalently closed circular structures. Investigators have shown previously that circRNAs are regulators of gene expression in mammals. These tissue-specific transcripts are produced primarily by exonic or intronic sequences of housekeeping genes. Several biosynthetic models have been proposed for circRNAs, and consensus is lacking. CircRNAs are widely expressed in the cytoplasm and highly conserved, what is more, unlike other noncoding RNAs, circRNAs are relatively stable. These properties suggest special roles of circRNAs, such as microRNA (miRNA) sponges, regulators of selective splicing, or even protein-coding sequences. The expression of circRNAs is associated with many pathologic conditions; therefore, circRNAs may have utility as biomarker for the diagnosis or prediction of diseases. Authors previously have demonstrated that circRNAs can regulate the expression of a variety of disease-related miRNAs. The circRNA-miRNA-target gene interaction network regulates several pathways that inhibit or promote the occurrence of certain diseases. Based on their potential clinical relevance, circRNAs are a crucial topic of disease prevention and treatment research. Herein, we review current research regarding circRNAs and explore their potential clinical applications for thoracic diseases diagnosis and treatment.