Circular RNA(circRNA)is a novel type of endogenous non-coding RNA.Most circRNAs act as microRNA(miRNA)sponges to regulate the expression of functional genes.In addition,some circRNAs can be translated and interact with RNA-binding proteins to perform biological functions.The expression of circRNAs is prevalent in tissues and body fluids,and their abnormal expression is related to tumor progression.circRNAs are stable even under the treatment of RNase R because of their circular conformation.As circRNAs have construct stability,wide variety,specific regulation of tumor progression and high expression in body fluids,it is potential for circRNAs to serve as candidate diagnostic,prognostic and therapeutic targets.However,the knowledge about circRNAs remains poor.In addition to the not completely resolved functions and generation mechanisms of circRNAs,the annotations of circRNAs are also waiting for expanding.Here,we review the generation mechanisms,biological functions,and application of circRNAs in tumor research,aiming to provide integrated information for the future research.
Keywords: back-splicing; circular RNA; circular RNA database; inverted repeat sequence; tumor markers.