Circular RNAs (circRNAs) are a large class of noncoding RNAs, generated from a process called back-splicing, that possess critical regulatory functions in many cellular events. A large body of literature has reported various circRNA functions and their underlying mechanisms, including sponging miRNA, exerting transcriptional and translational regulation, interacting with proteins, and translating into peptides and proteins. CircRNA dysregulation has been implicated in many cancers, including lung, breast, liver, gastric, colorectal, and ovarian cancer. They are detectable in bodily fluids and relatively stable, making them potential cancer biomarker candidates. Furthermore, targeting circRNA expression levels is a potential therapeutic approach for treating cancers. In this review, we describe the functional mechanisms of circRNAs and discuss limitations of current mechanism studies. Following this, we outline the potential of circRNAs to be effective biomarkers in various cancers and present circRNA-based therapeutic approaches. Finally, we discuss challenges in using circRNAs as diagnostic and therapeutic tools and propose future research directions.

环状 RNA (circRNA) 是一大类非编码 RNA，由称为反向剪接的过程产生，在许多细胞事件中具有关键的调节功能。大量文献报道了各种 circRNA 功能及其潜在机制，包括海绵化 miRNA、发挥转录和翻译调控、与蛋白质相互作用以及翻译成肽和蛋白质。CircRNA 失调与许多癌症有关，包括肺癌、乳腺癌、肝癌、胃癌、结肠直肠癌和卵巢癌。它们可以在体液中检测到并且相对稳定，使其成为潜在的癌症生物标志物候选物。此外，靶向 circRNA 表达水平是治疗癌症的潜在治疗方法。在本次审查中，我们描述了 circRNA 的功能机制并讨论了当前机制研究的局限性。在此之后，我们概述了 circRNA 作为各种癌症的有效生物标志物的潜力，并提出了基于 circRNA 的治疗方法。最后，我们讨论了使用 circRNA 作为诊断和治疗工具的挑战，并提出了未来的研究方向。