Circular RNA (circRNA) is a group of endogenous noncoding RNA characterized by a covalently closed cyclic structure lacking poly-adenylated tails. Recent studies have suggested that circRNAs play a crucial role in regulating gene expression by acting as a microRNA sponge, RNA binding protein sponge and translational regulator. CircRNAs have become a research hotspot because of their close association with the development of diseases. Some circRNAs are reportedly expressed in a tissue- and development stage-specific manner. Furthermore, due to other features of circRNAs including stability, conservation and high abundance in body fluids, circRNAs are believed to be potential biomarkers for various diseases. In the present review, we provide the current understanding of biogenesis and gene regulatory mechanisms of circRNAs, summarize the recent studies on circRNAs as potential diagnostic and prognostic biomarkers, and highlight the major advantages and limitations of circRNAs as novel biomarkers based on existing knowledge.

环状RNA（circRNA）是一组内源性非编码RNA，其特征是具有缺乏聚腺苷酸尾部的共价闭合环状结构。最近的研究表明，circRNA 通过充当 microRNA 海绵、RNA 结合蛋白海绵和翻译调节因子，在调节基因表达中发挥着至关重要的作用。 CircRNA因其与疾病发生的密切关系而成为研究热点。据报道，一些 circRNA 以组织和发育阶段特异性的方式表达。此外，由于circRNA的其他特征，包括稳定性、保守性和体液中的高丰度，circRNA被认为是各种疾病的潜在生物标志物。在本综述中，我们提供了目前对 circRNA 的生物发生和基因调控机制的理解，总结了 circRNA 作为潜在诊断和预后生物标志物的最新研究，并根据现有知识强调了 circRNA 作为新型生物标志物的主要优点和局限性。