CircRNAs are a large class of endogenous single-stranded RNA that is different from other linear RNA

which are produced by back-splicing and fusion of either exons

introns

or both exon-intron into covalently closed loops. CircRNAs are found in almost all living organisms and have emerged as potentially important players effecting on all life activities. It was characterized by stable structure

resistant to RNA degradation

highly abundance and conservation and tissue-specific expression. Early circRNAs were ignored as a by-product of meaningless abnormally cut RNA and had little biological function. Currently

circRNAs have become a research hotspot due to its special characteristics. CircRNAs could function as miRNA sponges

interfere with splicing and bind to protein to regulate the expression of parental genes and so on. In recent years

an increasing number of studies have revealed that circRNAs are closely related to a series of physiological and pathological processes. Additionally

circRNAs play an important role in the occurrence and development of a variety of diseases

suggesting circRNAs may be as novel indicators or biomarkers for cancer and other diseases with which they are associated. In this article

we review the biogenesis

biological functions of circRNAs and recent advances in circRNAs research in human diseases. Results will provide new insights on the roles and new ideas of circRNAs for the diagnosis and treatment of diseases and possible directions and approach for future circRNA applications.