Abstract: Circular RNAs(circRNAs) are a novel class of regulatory RNAs.They are covalently closed RNA molecules produced by precursor mRNA through back-splicing.CircRNAs are highly abundant in eukaryotes,and many of them are evolutionary conserved.Although generally expressed in low abundance when compared to their linear counterparts,they are often expressed in a tissue- and cell- specific expression patterns.Their biogenesis is regulated by specific cis-acting elements and trans-acting factors.Recent work shows that circRNAs exert important biological functions in tumorigenesis of colorectal cancer(CRC),including acting as microRNAs or protein “sponges”,and even by being translated themselves.Due to a covalent closed loop structure and resistance to RNase degradation,circRNAs are expected to become novel biomarkers for CRC.

Key words: circular RNAs, non-coding RNAs, colorectal cancer, biomarker, splicing